PH 5 Drugs for Bacterial Infections.pdf

5 Anti-Infective Drugs Antibacterial, Antitubercular, and Antifungal Agents LEARNING OUTCOMES 1. Explain how infections, pathogens, drug spectrum, drug resistance, and drug generation affect antibiotic drug therapy. 2. List the names, actions, possible side effects, and adverse effects of the penic...

5 Anti-Infective Drugs Antibacterial, Antitubercular, and Antifungal Agents LEARNING OUTCOMES 1. Explain how infections, pathogens, drug spectrum, drug resistance, and drug generation affect antibiotic drug therapy. 2. List the names, actions, possible side effects, and adverse effects of the penicillins and cephalosporins. 3. Explain what to teach patients and families about penicillins and cephalosporins. 4. List the names, actions, possible side effects, and adverse effects of the common tetracyclines, macrolides, and aminoglycosides. 5. Explain what to teach patients and families about tetracyclines, macrolides, and aminoglycosides. 6. List the names, actions, possible side effects, and adverse effects of the common sulfonamides and fluoroquinolones. 7. Explain what to teach patients and families about sulfonamides and fluoroquinolones. 8. List the names, actions, possible side effects, and adverse effects of first-line antitubercular drugs. 9. List the names, actions, possible side effects, and adverse effects of antifungal drugs. 10. List the names, actions, possible side effects, and adverse effects of antiparasitic drugs. KEY TERMS antibacterial (ăn-tē-băk-TĬR-ē-ăl, p. 66) Antimicrobial drugs that kill or slow the reproduction of bacteria only. Often used interchangeably with antibiotics. antibiotic (ăn-tĭ-bī-ŎT-ĭk, p. 66) Any drug that has the ability to destroy or interfere with the development of a living organism. Often used interchangeably with antibacterials. antimicrobial drug (ăn-tĭ-mī-KRŌ-bē-ăl, p. 66) A general term for any drug that has the purpose of killing or inhibiting the growth of pathogenic microorganisms. antimicrobial resistance (ăn-tĭ-mī-KRŌ-bē-ăl rĭ-ZĬS-tăn(t)s, p. 66) The ability of an 144 organism to resist the killing or growth suppressing effects of anti-infective drugs. antifungal drug (ăn-tī-FŬN-găl, p. 84) Any drug used to treat a fungal infection, also called a fungicide or fungistatic. bacteria (băk-tēr-ē-ă, p. 65) Microscopic living organisms that exist everywhere and are both beneficial and dangerous. They are capable of both preventing and causing infection. bactericidal (băk-tēr-ĭ-SĪD-ăl, p. 66) Drugs with mechanisms of action that kill bacteria. bacteriostatic (băk-tēr-ē-ō-STĂT-ĭk, p. 66) Drugs with mechanisms of action that only suppress or slow bacterial growth. fungus (FŬN-gŭs, p. 65) A group of microorganisms that are everywhere and exist by absorbing nutrients from a host organism. Includes yeasts and molds. A fungal infection is called a mycosis. generation (JĚN-ěr-Ā-shun, p. 67) A new group of drugs developed from other similar drugs is called a drug generation. Each new generation of antibiotics manufactured from the original generation has significantly greater antimicrobial properties than the preceding generation. normal flora (p. 65) Organisms of many different types that are usually present on the skin, the mouth, the intestinal tract, and the vagina of a healthy individual and do not cause infection unless the person has reduced immunity or the organisms are located in the wrong body area. parasite (PĀR-ă-sīt, p. 65) An organism that lives on or in a human and relies on the human for its food and other functions. pathogen (PĂTH-ō-jěn, p. 65) An organism that that is expected to cause infection even among people with a strong immune system. pseudomembranous colitis (sū-dō-MĔM-bră-nŭs kō-LĪ-tĭs, p. 67) An abnormal intestinal reaction to a strong antibiotic that causes excessive watery, bloody diarrhea, abdominal cramps, and low-grade fever and can lead to dehydration, as well as damage the walls of the intestinal tract. spectrum (SPĔK-trŭm, p. 67) The number of different specific organisms the drug is effective against. virus (p. 65) A small infectious agent that can replicate (reproduce itself) only inside the living cells of organisms. Infection An infection is an invasion of body tissue by disease-producing pathogens that multiply and produce toxins that react in a dangerous way and produce illness in a host organism. Infections can be caused by bacteria, viruses, parasites, fungi, and insects. Anti-infective drugs are some of the most commonly given drugs because of the many different types of infections that these drugs have been developed to treat. These drugs are most effective and have fewer side effects when taken correctly. Thus it is important for you to learn as much as possible about these drugs and what 145 to teach patients who are taking them. Normal Flora Organisms of many different types are always on the skin, the mouth, the intestinal tract, and the vagina of a healthy person. These organisms are known as normal floras and are considered nonpathogens because they usually do not cause infection. Conditions in which normal floras can cause infection include when a person has very low immunity, if the organisms are present in excessive amounts and overwhelm the body, or if they are located in the wrong place. For example, if Escherichia coli, which are normal floras in the bowel, are present in the bladder or other parts of the renal/urinary system, they can cause an infection in the urinary tract. If skin floras enter a surgical incision, a wound infection can develop. Infants, young children, people with AIDS, anyone receiving cancer chemotherapy, anyone who is taking a drug that suppresses the immune system, and older adults have the greatest risk for infection. Other factors that increase the risk for infection include poor circulation, poor nutritional status, or chronic diseases. Antibiotic use can upset the normal flora balance in the body and cause yeast or fungal infections to occur. Candida is a common body yeast and often overgrows to cause a fungal infection. When a person is given antibiotics to kill infectious bacteria, the normal flora is killed off as well. The gut, mouth, and vaginal mucosa have bacterial flora that acts as a barrier against fungal infections. When the barrier weakens, yeast infections can occur. If a yeast infection occurs after antibiotic therapy, it is known as a secondary infection or a superinfection. There is evidence to support using probiotic bacteria with an antibiotic as a strategy to prevent yeast infections. Probiotic (beneficial) bacteria can be found in many foods, as well as in capsule form. Yogurt, dark chocolate, miso soup, pickles, and sauerkraut are some foods that can easily be added to a diet. The healthcare provider can prescribe probiotics in capsule form and recommend any necessary dietary changes. Pathogens An organism that is expected to cause infection even among people with a strong immune system is a pathogen. A variety of pathogenic organisms exist and may cause disease in different ways. For example, they may be able to divide rapidly and overwhelm the immune system or produce toxins. Bacteria are a large domain of single-celled microorganisms that exist everywhere. Bacteria are both beneficial and dangerous. For example, E. coli bacteria in the intestines benefit digestion but become infective if overgrowth occurs. Bacteria have different shapes and characteristics. They are shaped as rods, spheres, or spirals; they can survive with oxygen (aerobic) or without oxygen (anaerobic). When stained with a Gram solution, they can stain either violet (gram-positive) or red (gram-negative). Gram-positive bacteria have a thick cell wall and outer capsule. The cell wall of gram-negative bacteria is much more complex, with an outer capsule and two cell wall membranes. This complex cell wall makes gram-negative bacterial infections more difficult to treat. It is harder for the antibiotic to penetrate the gram-negative bacterial wall. A fungus is a member of a large group of microorganisms that include yeasts and molds, which have cell features that are similar to those of human cells. Fungi are 146 everywhere and exist by absorbing nutrients from a host organism. A fungal infection is called a mycosis. A virus is a small infectious agent that can replicate (reproduce itself) only inside the living cells of organisms. Viral infection and antiviral drugs are discussed in Chapter 6. A parasite is an organism that lives on or in a human and relies on the human for its food and other functions. Common human parasites include worms (helminthes), amoebas, and protozoa, to name only a few examples. Memory Jogger Gram-negative bacteria have cells walls that antibiotics have a difficult time penetrating, which makes infections caused by gram-negative bacteria more difficult to treat. Determination of Infection Some infections are diagnosed by the healthcare provider based on the patient's symptoms and the type of organism that commonly causes a specific infection type in that community. In this situation the healthcare provider usually knows what the most likely organism is and which drug or drugs are effective against it. Prescribing a drug without identification of the specific organism is called empiric treatment or empirical therapy and is based on experience and clinical expertise. However, at other times the cause of the infection is not known, and the infection must be evaluated to identify the specific pathogenic organism and the drug that will be most effective against it. Bacteria are often stained, cultured, and tested to determine which drugs are effective against them (antimicrobial sensitivity). A specimen of the infective material is taken for culture and sensitivity testing that is performed before anti-infective therapy is begun. Learning what organism is present allows the healthcare provider to order the correct drugs that will kill or stop the reproduction of that organism before the illness worsens. Anti-Infectives Anti-infective agents are drugs that can either kill or inhibit the spread of an infectious agent such as bacteria, viruses, fungi, or protozoans. It is a general term used synonymously with the term antimicrobial. A few antimicrobial drug classification examples are antibacterials, antivirals, antifungals, and anthelminthics (also called anthelminthics). These drugs are classified by their chemical structures, mechanisms of action, and type of organism they effectively combat. For example, antimicrobials that kill or slow the reproduction of bacteria are called antibacterials. An antibiotic is any drug that has the ability to destroy or interfere with the development of a living organism. In anti-infective therapy the term antibiotic is used interchangeably with antibacterial. Drug Susceptibility and Resistance Overuse or unnecessary use of antibiotics has led to several current problems for 147 infection management. When antibacterials are overused, prescribed for conditions not responsive to these drugs, or taken improperly, drug-resistant strains of bacteria develop. Antimicrobial resistance is the ability of an organism to resist the killing or growth-suppressing effects of anti-infective drugs. Organisms that either can be killed or have their reproduction suppressed by anti-infective drugs are susceptible. Those that are neither killed nor suppressed by anti-infective drugs are resistant organisms. Many organisms, especially bacteria, that were once susceptible to a variety of anti-infective drugs are now resistant to most types. When an organism is resistant to three or more different types of drugs to which it was once susceptible, it is a superbug or a multidrug-resistant (MDR) organism. Each year more organisms have become resistant to standard anti-infective drugs. Infections caused by resistant organisms cost more to treat, increase the length of hospital stays, and lead to higher mortality rates. Often the drugs used against MDR organisms are more powerful and have more side effects than standard anti-infective drugs. Drug resistance has developed in many disease-causing bacteria, viruses, retroviruses, fungi, and some parasites. The Centers for Disease Control and Prevention (CDC) has identified 18 drug-resistant threats in the United States. Of those threats, three are considered urgent: Clostridium difficile (C. diff.), carbapenemresistant Enterobacteriaceae (CRE), and Neisseria gonorrhoeae. Bookmark This! Bacterial resistance to antibiotics is a constant threat. To keep current on bacterial resistance and treatment options, check out the CDC at: https://www.cdc.gov/drugresistance/index.html. Beta-lactamases (or penicillinase) are enzymes that some bacteria produce that give them resistance against beta-lactam antibiotics, which include penicillins, cephalosporins, monobactams, and carbapenems. Inhibitor agents are added to the primary antibiotic (e.g., amoxicillin/clavulanate potassium) to make the antibiotics less resistant to β-lactamases. General Considerations for Anti-Infective (Antimicrobial) Drug Therapy Drug management for infection is very common and usually short-term. Even though there are many different types of antimicrobial drugs, some nursing interventions are the same for all of them. In addition, many of the points to teach patients and families about these drugs are the same. Box 5.1 describes these common nursing interventions, and Box 5.2 describes general patient teaching points. Specific interventions and patient teaching issues are listed in the individual drug categories. Box 5.1 148 General Nursing Implications for Antimicrobial Drug Therapy Assessment • Take a complete drug history from the patient to prevent possible drug interactions. • If ordered, obtain specimens for culture and sensitivity before starting antibiotic therapy to ensure drug sensitivity. • Do a focused assessment to include the current condition of the infectious site, vital signs, WBC count, and other baseline laboratory data like liver enzymes, kidney function, and drug levels that may be ordered before therapy to establish a baseline. • A patient can have an allergy to any anti-infective drug. Always ask patients about specific drug allergies and what specific type of problem occurred as part of the allergy before starting any new antimicrobial drug. • Have emergency drugs and equipment available to treat allergic and/or anaphylaxis (diphenhydramine, epinephrine, crash cart). • If a female patient is on oral contraceptives and does not wish to be pregnant, an alternative or additional method of contraception should be recommended while taking antibiotic therapy. Planning and Intervention • If the patient develops a rash or itching while on the drug, immediately report the problem to the healthcare provider. If the patient has difficulty breathing, a lump in the throat, or a sudden, severe drop in blood pressure, call the emergency team. • A common and expected side effect of anti-infective therapy, especially the antibacterial drugs, is diarrhea. This response is caused by the drug reducing the numbers of normal floras in the intestinal tract that have the job of helping digestion. With less intestinal floras, diarrhea results. This is not an allergy. • Some very strong antibiotics can cause severe and damaging inflammation of the colon when there is overgrowth of the organism C. diff. This serious and abnormal complication is pseudomembranous colitis with symptoms that include excessive watery, bloody diarrhea, abdominal cramps, and low-grade fever. • Many antibiotics allow yeast to overgrow when normal flora are reduced in the mouth and vagina. In the mouth, white patches (thrush) appear especially on the tongue and roof. In the vagina, an itchy discharge may occur. Both problems may need antifungal therapy. • Antimicrobials work best against infection when blood drug levels remain consistent, so it is best to give them on an even schedule around-the-clock. If an antibiotic is ordered to be given four times a day, the schedule should be every 6 hours. For example, remind the prescriber or the person making the schedule 149 to use 6:00 a.m., noon, 6:00 p.m., and midnight instead of 9:00 a.m., 1:00 p.m., 5:00 p.m., and 9:00 p.m. If the drugs were given on the 9, 1, 5, and 9 schedule, during the 12 hours the drugs were not given, the blood level would be so low that the organisms would start growing again. • Many antimicrobials given parenterally have interactions with other drugs. Be sure to consult a pharmacist or drug reference to determine whether a specific drug can be given in the same IV line used for other drugs. • Most parenteral antimicrobial drugs must be given slowly, over 30 to 60 minutes. Consult a pharmacist or drug reference to determine the time needed to give a specific drug intravenously. • Some antimicrobial drugs have toxic side effects and their use has a time limit. For example, the aminoglycoside antibiotics can damage the nerves of the ear and cause hearing loss. Usually these drugs are used for only 5 days. It is important for you to know the start and stop dates of antimicrobial drugs to prevent accidental excessive exposure to the drug. • Duration of antimicrobial therapy varies for different types of infections. For example, some uncomplicated bladder infections (cystitis) may require only 3 days of a specific antibacterial drug for complete therapy. In contrast, tuberculosis (TB) usually requires at least 6 months of four different types of drugs to suppress the infection. Most often the duration of antibiotic therapy is 10–14 days. Evaluation • A major nursing responsibility with antimicrobial therapy is evaluating the effectiveness of the drug prescribed for the infection. Therefore it is important to know the patient's infection symptoms and monitor them daily to assess whether the drug therapy is reducing them. • If symptoms continue at the same intensity beyond 72 hours or become worse, notify the prescriber. • Whatever duration is prescribed, it is important for the patient to receive all of the therapy. Stopping antimicrobial therapy after infection symptoms are no longer present but before the prescribed duration is completed leads to increased risk for infection recurrence and for the development of drugresistant organisms. • Reevaluate any laboratory work that has been ordered so that adverse effects like liver and kidney damage or altered drug levels can be prevented. Box 5.2 General Teaching Points for Patients and Families During Antimicrobial Drug Therapy • Explain to patients that ordinary diarrhea is an expected side effect and not an 150 allergic response to antimicrobial drugs. It is not generally a reason to stop the drug. However, excessive watery and bloody diarrhea with severe abdominal pain and fever is a complication and needs to be reported to the prescriber immediately. • Stress to patients that if they develop a lump in the throat, difficulty breathing, or swelling of the lips, tongue, or throat to call 911 immediately. • Instruct patients to take their prescribed antimicrobial drugs exactly as prescribed and for as long as prescribed to prevent infection recurrence and drug resistance. • Instruct patients to stop taking the drug and notify the healthcare provider if a rash or hives develop while taking an antimicrobial drug. A drug allergy can develop at any time after the patient begins treatment. • Remind patients to report to the healthcare provider any new symptoms that occur while taking antimicrobial therapy because they may represent an adverse reaction. • Tell patients that even though it may be inconvenient to take a drug in the middle of the night, it is important to space the drugs out evenly during the 24 hours for best results. • Instruct patients not to save antimicrobial drugs because many expired drugs deteriorate and become less effective. Lifespan Considerations Breast-feeding Breast-feeding should be avoided during antimicrobial therapy because most of these drugs are excreted into breast milk and the infant (who may not have an infection) will be exposed to the actions, side effects, and adverse effects. Antibiotics Antibiotics work in different ways to affect pathogenic bacteria (Fig. 5.1). They may attack a bacterium's internal cellular processes, which are vital to its existence, or they may destroy the external cell wall, making it weaker or unable to reproduce; in some cases, they actually kill the organism. Drugs that are bactericidal kill the bacteria; those that are bacteriostatic limit or slow the growth of the bacteria, weakening or eventually leading to the death of the bacteria. 151 FIG. 5.1 Sites of antimicrobial bactericidal or bacteriostatic action on bacterial pathogens. Five general actions include: (1) inhibition of synthesis or building of cell wall; (2) damage to cell membrane; (3) modification of nucleic acid synthesis; (4) modification of protein synthesis (at ribosomes); and (5) modification of energy metabolism within the cytoplasm (at the folate cycle). DHFA, Dihydrofolic acid; mRNA, messenger RNA; PABA, paraaminobenzoic acid; THFA, tetrahydrofolic acid; tRNA, transfer RNA. (From Wecker L: Brody's human pharmacology, ed 5, Philadelphia, 2009, Elsevier.) Memory Jogger The cidal or static part of the word describing the antibiotic gives a hint about its activity. Bactericidal drugs kill the bacteria (think about the word homicide). Bacteriostatic drugs only limit or slow the growth of bacteria, relying on the patient's immune system to kill the organism. Bacteria are often classified as gram-positive or gram-negative. The number of different specific organisms the drug is effective against is described as its spectrum. Some antibiotics are effective against only a few types of bacteria and are called narrow-spectrum drugs. Other drugs that are effective against more types of bacteria, including both gram-negative and gram-positive bacteria, are known as broadspectrum drugs. Some drugs have become more refined, purified, and sensitive as a result of longterm testing. Each new group of these drugs developed from other, similar drugs is called a drug generation. The original drugs are referred to as first-generation drugs, and later groups are called second-generation drugs, third-generation drugs, and so 152 on. Usually each new generation of drugs has certain advantages over the oldergeneration drugs. For example, the newer drugs may have improved effectiveness, fewer side effects, or a faster onset of action. Some of the newer generation of drugs have a narrower spectrum of bacteria that are susceptible to them but are more powerful than previous generations against the susceptible bacteria. Penicillins All bacteria have plasma membranes just like human cells do (see number 2 in Fig. 5.1). In addition to a plasma membrane, some bacteria also have the extra protection of cell walls that surround the bacterium outside of the plasma membrane (see number 1 in Fig. 5.1). The cell walls are much tougher than plasma membranes and are built like a brick wall. Just like a brick wall, the cell wall needs to be continuously maintained and repaired to prevent holes and wall crumbling, which would make the rest of the bacterium inside the cell wall less protected. A variety of substances work like bricks and mortar to hold the wall together. Different enzymes help make the mortar, replace old or crumbling bricks, and keep the cell wall intact. Action Penicillins are one type of a class of drugs known as cell wall synthesis inhibitors. They interfere with the creation and repair of bacterial cell walls. They also bind or stick to specific enzymes that the bacteria need so the bacteria cannot use them. This process makes the bacterial cell weak and allows it to break down more easily. This action is bactericidal for bacteria susceptible to penicillin actions. Pure penicillin may be combined with other ingredients to make the drug stay in the body longer or to prevent the drug from being destroyed by bacterial enzymes. Penicillin and other cell wall synthesis inhibitors are effective only against bacteria that have cells walls, and they have no action against bacteria without cells walls. Although penicillin can be very effective, over time many organisms have become resistant to its killing effects. Uses Penicillin was created in 1929 from a fungus by Alexander Fleming. It was used as an antibiotic throughout World War II. Since that time five generations of synthetic penicillins have been developed. Sadly, bacterial resistance to many penicillin drugs have developed as well. Regardless of the increased resistance, penicillin G remains the drug of choice for many infections, including syphilis and certain types of endocarditis. Penicillins are used for infections that occur in the mouth, throat, skin, soft tissue, heart, lungs, and ears. Penicillin is also used for prophylactic (preventive) treatment against bacterial endocarditis in patients with rheumatic or heart disease before they have dental procedures or surgery of the upper respiratory tract, genitourinary tract, or GI tract. Some penicillins may be used for treating exposure to agents of biological warfare. Penicillins are still considered the safest antibiotics and are the broad-spectrum drugs of choice for susceptible gram-negative and grampositive organisms. Many penicillin products are available in a variety of forms, ranging from oral 153 drugs to parenteral drugs. There are five generations of penicillins. 1. Natural penicillins (e.g., penicillin G and penicillin V) combat non-betalactamase–producing gram-positive cocci, including Streptococcus viridans, group A Streptococci, Streptococcus pneumoniae, and Anaerobic streptococcus. 2. Penicillinase-resistant penicillins (e.g., dicloxacillin, nafcillin, and oxacillin) combat Staphylococcus but are not effective against methicillin-resistant Staphylococcus aureus (MRSA) or methicillin-resistant Staphylococcus epidermidis (MRSE). Methicillin is no longer manufactured. 3. Aminopenicillins (e.g., ampicillin and amoxicillin) combat the same bacteria as the natural penicillins but have improved activity against some gramnegative bacteria. Combining an aminopenicillin with a beta-lactamase inhibitor (clavulanic acid or sulbactam) treats infections caused by betalactamase–producing organisms. 4. Carboxypenicillins (e.g., carbenicillin and ticarcillin) have increased activity to penetrate the cell wall, so they are used for gram-negative bacteria such as Pseudomonas aeruginosa and Proteus. 5. Ureidopenicillins and piperazine penicillin (e.g., piperacillin) are the latest class of penicillin antibiotics that combat gram-negative bacteria such as Klebsiella. When a beta-lactamase inhibitor is added (piperacillin and tazobactam), it becomes a very powerful broad-spectrum antibiotic against many grampositive and gram-negative bacteria, and it is used only in cases where other antibiotics have been ineffective to prevent resistance. These penicillins and the carboxypenicillins are only used intravenously. Table 5.1 lists examples of common penicillins, their dosages, and nursing implications. Be sure to consult a drug reference book or a pharmacist for information about a specific penicillin. Table 5.1 Examples of Common Penicillins and Cephalosporins Penicillins and cephalosporins are cell wall synthesis inhibitors that kill susceptible bacteria within cell walls by preventing cells walls from being made and maintained. PENICILLINS DRUG/ADULT DOSAGE RANGE NURSING IMPLICATIONS amoxicillin (Moxatag) 500 mg orally • Shake the liquid suspension drugs thoroughly before giving because this drug form separates. every 12 hours or 775 mg to 1 g orally • Give Moxatag within 1 hour of the patient completing a meal for best absorption and fewer GI side effects. once daily • Remind patients not to chew the extended-release forms to avoid counteracting the slow-release feature. amoxicillin/clavulanic acid (Augmentin) • Penicillin G procaine is never injected into a blood vessel because the procaine it contains can cause severe 875/125 mg combination orally every 12 neurovascular complications. hours (immediate-release formula) • With penicillin G, use the Z-track method of IM injection deep into the muscle to prevent drug from leaking penicillin G benzathine (Bicillin L-A) 1.2 out through the tissues and causing pain or damage. million units IM as a single injection • Aspirate before injecting the IM dose to ensure the drug is not injected into the bloodstream. penicillin G procaine 600,000 to 1.2 • Do not interchange the various suspensions of amoxicillin clavulanic acid because they contain different million units IM once daily for 10 days amounts of clavulanic acid. penicillin VK (Veetids) 250–500 mg orally • Concentrations of Penicillin V are higher when taken on an empty stomach, but if GI upset occurs, it can be every 6 hours taken with food. CEPHALOSPORINS DRUG/ADULT DOSAGE RANGE NURSING IMPLICATIONS First Generation • Make sure to check for a penicillin allergy before giving a cephalosporin because patients may have a crosscefazolin 250–1000 mg IM or IV every 8 sensitivity to the drug. hours • Do not give oral cephalosporins within 1 hour of taking antacids because they interfere with absorption of cephalexin (Keflex) 500 mg orally every cephalosporins. 12 hours • Give IM cefazolin, cefuroxime, ceftriaxone, and cefepime using the Z-track method of IM injection deep into the muscle to prevent drug from leaking out through the tissues and causing pain or damage. Second Generation cefaclor 250–500 mg orally every 8 hours • Aspirate before injecting the IM dose to ensure the drug is not injected into the bloodstream. • Reconstitute parenteral cephalosporins only according to manufacturer's direction to ensure the greatest cefuroxime (Ceftin) 250–500 mg orally every 12 hours or 750 mg IM or IV every potency of the drug. • Cefaclor extended-release tablets must be taken whole with food and never crushed to avoid getting too 8 hours 154 Third Generation cefdinir (Omnicef) 300 mg orally every 12 hours or 600 mg orally once daily ceftriaxone 1–2 g IM or IV every 12–24 hours Fourth Generation cefepime (Maxipime) 0.5–2 g IM or IV every 8–12 hours VANCOMYCIN DRUG/ADULT DOSAGE RANGE vancomycin (Vancocin) 500 mg IV every 6 hours or 1 g IV every 12 hours; 125 mg orally every 6 hours for pseudomembranous colitis caused by Clostridium difficile CARBAPENEMS DRUG/ADULT DOSAGE RANGE imipenem (Primaxin) 500–1000 mg IV every 6–8 hours or 500–750 mg IM every 12 hours meropenem (Merrem) 1–2 g IV every 6–8 hours ertapenem (Invanz) 1 g IM or IV once daily much of the drug at one time. • Cefuroxime tablets and suspension cannot be substituted milligram to milligram because they are not bioequivalent. • Cefuroxime suspension must be given with food to ensure a consistent blood drug level. • IV ceftriaxone cannot be given with Ringer lactate because Ringer lactate contains calcium and will precipitate the drug. • IV ceftriaxone and cefepime cannot be given by IV push and must be infused over 30 minutes to reduce the risk for immediate cardiac side effects. • Warn patients not to drink alcohol while taking cephalosporins to reduce the side effects of copious vomiting, hypotension, dyspnea, and chest pain. NURSING IMPLICATIONS • Ask patients who are prescribed vancomycin whether they have a corn allergy because they may also be allergic to this drug. • Vancomycin tablets must be swallowed whole, not crushed, to avoid altered dosing. • Regularly assess hearing and monitor urine, BUN/creatinine intermittently; notify the healthcare provider for outlying values because this drug is toxic to the ears and kidneys, and accumulates in the body. • IV vancomycin must be infused over at least 60 minutes or no more than 10 mg/min to avoid red man syndrome, a histamine response. Stopping or slowing the infusion will decrease the response. • Parenteral doses of vancomycin must be monitored using serum vancomycin concentrations peak and trough levels because the drug can accumulate to toxic levels quickly. Make sure that the trough is drawn within 30 minutes before the next dose is to be given (so it accurately reflects the drug's lowest level) and that the peak is drawn 1–2 hours after the dose is infused to accurately reflect the drug's highest level. • Monitor urine output and renal blood tests very closely when vancomycin is given with other renal-toxic drugs (such as aminoglycosides) because renal toxicity occurs even faster. • Administration of vancomycin with cidofovir is contraindicated because these drugs together cause severe renal toxicity. NURSING IMPLICATIONS • Do not use the IM formulation of imipenem or ertapenem for IV use because it contains lidocaine, which can cause severe cardiac side effects. • Give IM injections of the carbapenems using the Z-track method of IM injection deep into the muscle to prevent the drug from leaking out through the tissues and causing pain or damage. • Aspirate before injecting the IM dose to ensure the drug is not injected into the bloodstream. • Monitor patients receiving carbapenems closely for confusion and seizure activity because these drugs can cause central nervous system (CNS) changes. • Carbapenem use with ganciclovir or valproic acid can cause seizures because simultaneous use increases the risk for seizure activity. • Monitor patients receiving carbapenems with warfarin for bleeding abnormalities and changes in the international normalized ratio (INR) levels because carbapenems increase warfarin action, which increases the risk for bleeding. • When carbapenems are used along with other antibiotics, monitor urine and laboratory tests closely and report abnormal results to the healthcare provider because the combination greatly increases the risk for kidney damage. Expected Side Effects Penicillin overall has fewer side effects and fewer drug interactions than other antibiotics. The most common side effect of penicillin (and many other antibiotics) is simple diarrhea of two to four loose stools daily. This is not an allergy but is caused by the drug killing off some of the normal floras of the GI tract that help digest food. If the diarrhea is severe, the healthcare provider needs to be notified for any additions or changes that need to occur with therapy. Other common and expected side effects include nausea, vomiting, and epigastric distress. C. diff. is an infectious form of diarrhea caused by antibiotic use, particularly with amoxicillin/clavulanate potassium. If C. diff. is suspected, notify the healthcare provider and obtain a stool culture before treatment with another antibiotic. Adverse Reactions Allergy to penicillin occurs in 2% to 5% of the population, producing rash, erythema (redness or inflammation), urticaria (hives), angioedema (swelling of the skin and mucous membranes), laryngeal edema (swelling of the larynx), and anaphylaxis (shock). These allergic reactions may occur suddenly or after the patient has been taking the drug for some time and may cause life-threatening anaphylactic shock. Some patients with penicillin allergy may also have an allergy to the cephalosporins because of a cross-sensitivity. Drug Interactions 155 Other bacteriostatic antibiotics such as tetracycline and erythromycin may decrease the bactericidal effect of penicillin. Probenecid blocks the excretion of penicillin, prolonging blood levels and making the antibiotic more effective. Ampicillin reduces the effectiveness of oral contraceptives, which can lead to an unplanned pregnancy. Indomethacin, phenylbutazone, or aspirin may increase serum penicillin levels. Antacids may decrease the absorption of penicillin. Penicillin may change the results of some laboratory tests. Top Tip for Safety Teach women who are taking oral birth control pills to use another reliable method of pregnancy protection while taking penicillin and for 1 month after completing penicillin therapy to prevent an unplanned pregnancy. Nursing Implications and Patient Teaching In addition to the general nursing implications and teaching points for all antimicrobial drugs, specific ones for the penicillins are listed in Table 5.1. Top Tip for Safety With all IM injections, including penicillin, use the Z-track method and aspirate before injecting the drug. If blood appears in the syringe, remove the syringe, dispose of the drug, and prepare another dose. Take the patient's vital signs before giving IM penicillin injections to have baseline information. In an office or clinic setting, keep the patient for 30 minutes after giving the first dose orally or IM to observe him or her for signs of adverse or allergic reactions. Cephalosporins Action Cephalosporins are cell wall synthesis inhibitors that are chemically similar to penicillin and work in the same way to kill bacteria. Over the years, five generations of cephalosporins have been developed, all of which have broad-spectrum activity (see Table 5.1). Uses The first generation of cephalosporins have mostly gram-positive coverage and limited coverage against gram-negative bacteria (e.g., cefazolin and cephalexin). The second-generation drugs have the same gram-positive coverage as the first generation and are more effective against gram-negative and anaerobic organisms (e.g., cefoxitin and cefotetan). Third-generation drugs are more potent against gramnegative bacteria than the earlier generations but are less active against grampositive bacteria (e.g., ceftriaxone and ceftazidime). The fourth-generation 156 cephalosporin (cefepime) has increased activity against both gram-negative and gram-positive bacteria and is only available intravenously. The fifth generation (e.g., ceftaroline) is also only available in IV form and has the broadest spectrum against both gram-negative and gram-positive bacteria. It is the only cephalosporin that can treat MRSA. Memory Jogger Most cephalosporin drugs have ceph, cef, or kef in their names. Cephalosporins are used for uncomplicated skin and soft tissue infections; infections of the lower respiratory tract, central nervous system (CNS), genitourinary system, joints, and bones; and for serious infections, such as bacteremia and septicemia (infections of the blood). Expected Side Effects Common side effects of cephalosporins are similar to those of penicillin. Nausea, vomiting, and diarrhea are frequent but usually mild. Adverse Reactions The most common adverse effect is acute hypersensitivity (allergy). Although some patients may have only a minor rash and itching, a major event with anaphylaxis is possible. Patients who are allergic to penicillins have a risk of also being allergic to cephalosporins because cephalosporins are so similar to penicillins. This is known as a cross-sensitivity, and if a cephalosporin must be used, it is used with caution. If a patient had an anaphylactic reaction to penicillin, then cephalosporins should not be used at all. Nephrotoxicity (kidney toxic effects) has been reported with some cephalosporins, and the incidence is greater in older adult patients and in patients with poor renal function. There may also be severe pain at the injection site. Drug Interactions Alcohol taken with cephalosporins may produce a disulfiram reaction (a drug used to prevent alcohol use by producing a severe sensitivity to alcohol). The effects result in severe flushing, copious vomiting, throbbing headache, dyspnea, tachycardia, hypotension, and chest pain. Antacids and iron can cause decreased absorption of some cephalosporins, and probenecid can decrease elimination of the drug. Nursing Implications and Patient Teaching In addition to the general nursing implications and teaching points for all antimicrobial drugs, those specific for the cephalosporins are listed in Table 5.1. Top Tip for Safety 157 Patients who are allergic to penicillin are often allergic to the cephalosporins because the chemical structures are similar. Inform the prescriber about a penicillin allergy. Many cephalosporins are given by the IV or IM route because some formulations are not absorbed from the GI tract. Table 5.1 presents a summary of the names, dosages, and nursing implications of common cephalosporins. Be sure to consult a drug reference book or a pharmacist for information about a specific cephalosporin. Other Cell Wall Synthesis Inhibitors Two other very powerful cell wall synthesis inhibitors are vancomycin and a group known as carbapenems (see Table 5.1). The carbapenems (imipenem/cilastatin, meropenem, ertapenem, and doripenem) have the broadest spectrum of antibacterial activity against gram-positive and gram-negative bacteria. These drugs generally are used for infections caused by MDR bacteria in hospitalized patients. Side effects and adverse effects are severe, so the use of these drugs is generally limited to severe and life-threatening bacterial infections. Vancomycin is used to treat MRSA and other drug-resistant infections. Vancomycin-resistant enterococci (VRE) and CRE now exist. Enterococci are bacteria present in the intestines and in the female genital tract, and Enterobacteriaceae such as E. coli and Klebsiella are normal floras in the intestines. Usually only hospitalized or nursing home patients who are critically ill and on numerous antibiotics are susceptible to these resistant bacteria. These drugs are given intravenously by IV push or by infusion over an hour or more in an acute care setting. Dosages and schedules are based on the patient's weight, organ health, and the severity of the infection. Vancomycin has an oral form that is used to combat the pseudomembranous colitis caused by C. diff. Imipenem/cilastin comes in an IM form that contains lidocaine. Expected Side Effects and Adverse Reactions Nausea, vomiting, diarrhea, headache, rash, fever, and chills can occur with these powerful drugs. Vancomycin often causes flushing and hypotension. An unusual response is a deep red rash on the upper body known as red man syndrome that is produced by a histamine-released reaction. Slowing the infusion rate and pretreating the patient with antihistamines and an H2 receptor blocker offers protection against red man syndrome. Carbapenems can cause adverse CNS effects such as confusion and seizures. Vancomycin and carbapenems in high doses can produce nephrotoxicity and ototoxicity. Drug Interactions Carbapenem drugs compete with probenecid, so these drugs should not be given at the same time. The drug may reduce the activity of valproic acid, which is given to prevent seizures. Simultaneous use of carbapenems with ganciclovir increases the risk for seizures. Vancomycin adds to the toxicity of other antibiotics such as the aminoglycosides and other drugs that are ototoxic or nephrotoxic. Cholestyramine and colestipol 158 decrease the absorption of the oral form of the drug. Memory Jogger When a drug is nephrotoxic (toxic to the kidneys), it is ototoxic (toxic to the ears) as well because ear and kidney tissue are immunologically and biologically related. Tetracyclines Action Tetracyclines are one type of a group of antibacterial drugs classified as protein synthesis inhibitors (tetracyclines, macrolides, and aminoglycosides). All protein synthesis inhibitors (not to be confused with cell wall synthesis inhibitors) enter the bacterium and interfere with the processes used by the bacterium to make important proteins needed for growth. If the bacteria cannot make protein, it will either not be able to reproduce or it will die. Usually tetracyclines only have bacteriostatic action against susceptible organisms. This means that bacterial reproduction is reduced and that the patient's immune system must rid the body of the organism. Uses The tetracyclines are broad-spectrum drugs that are similar to penicillins in that they are effective against many gram-negative and gram-positive organisms. Many other drugs are more effective against those organisms, so tetracyclines are the first choice drugs in only a few diseases, such as acne, urinary tract infections, infections of the skin and respiratory tract, Lyme disease, stomach ulcers caused by Helicobacter pylori, Chlamydia, Rocky Mountain spotted fever, typhoid fever, sexually transmitted diseases (chlamydia, syphilis, and gonorrhea), and inhalation anthrax exposure. Expected Side Effects The tetracyclines commonly produce mild episodes of nausea, vomiting, and diarrhea that may require stopping the drug. These effects are often dose related, and they result from irritation of the GI tract, changes in the normal bacteria in the bowel, and overgrowth of yeast. The tetracyclines increase the sensitivity of the skin to the sun and severe sunburns are possible, even among people with dark complexions. Yeast infections of the mouth (thrush) and the vagina are common when tetracycline therapy lasts longer than 10 days or in patients who are immunosuppressed or have diabetes. Yeast infections can be treated either topically or orally with antifungal drugs. Adverse Effects Use of tetracycline is contraindicated in women who are pregnant or breast-feeding, as well as in children younger than 8 years. These drugs may cause inadequate bone or tooth development, produce permanent yellow-brown tooth discoloration, and/or cause permanent damage (skeletal retardation) to a developing fetus. Tetracycline should be used with caution in patients with poor liver function, because the drug may cause liver toxicity. In high doses, tetracyclines can decrease 159 kidney function. Persistent dizziness, blurred vision, ringing in the ears, confusion, and headache can occur and may indicate increased pressure inside the brain. Lifespan Considerations Unless an infection is life-threatening and the organism is sensitive only to tetracycline, this drug is not given to pregnant women or young children. Tetracycline interferes with bone development and the development of tooth enamel. Exposure can cause permanent tooth staining. Drug Interactions Food, dairy products, aluminum, magnesium and calcium interfere with the intestinal absorption of tetracyclines. For this reason tetracycline is best taken with water on an empty stomach 1 hour before eating or 2 hours after eating. In addition to the general nursing implications and teaching points for all antimicrobial drugs, those specific for the tetracyclines are listed in Table 5.2. Table 5.2 Examples of Common Tetracyclines, Macrolides, and Aminoglycosides Tetracyclines, macrolides, and aminoglycosides are all protein synthesis inhibitors that are able to get inside the bacterium and prevent it from making important life-cycle proteins. Most are bacteriostatic rather than bactericidal and depend on the patient's immune system to fully rid the body of the infectious organisms. TETRACYCLINES DRUG/ADULT DOSAGE RANGE NURSING IMPLICATIONS doxycycline 100 mg orally every 12 • Remind patients taking tetracyclines to wear sun-protective clothing and sunscreen when going outdoors hours because these drugs increase skin sun sensitivity and can cause severe sunburns. minocycline hydrochloride (Minocin) • Instruct patients to take these drugs 1 hour before a meal or drinking milk or 2 hours after eating a meal or 100–200 mg orally or intravenously drinking milk because food and milk inhibit intestinal absorption. every 12 hours • Ask patients if they are using retinoids (isotretinoin, acitretin) for acne because using these drugs with tetracycline 250–500 mg orally every 6– tetracycline can cause a severe rise in intracranial pressure and is contraindicated. 12 hours MACROLIDES DRUG/ADULT DOSAGE RANGE NURSING IMPLICATIONS azithromycin (Zithromax) 500 mg orally • Consult with the healthcare provider and the pharmacist for patients taking other drugs with macrolides for one dose then 250 mg orally once because they interact with many drugs. daily for 4 days • Clarithromycin and erythromycin should not be used with moxifloxacin, pimozide, thioridazine, or other clarithromycin (Biaxin) 250–500 mg drugs that may prolong the QT interval because life-threatening dysrhythmias can occur. orally every 12 hours • Tell patients that if palpitations and chest pain occur while taking clarithromycin or erythromycin to seek clarithromycin extended release (Biaxin emergency help immediately because these drugs can cause cardiac dysrhythmias. XL) 1000 mg orally once daily • Instruct patients to take erythromycin with food or milk because the drug is not absorbed as well if taken on erythromycin (E.E.S.) 250–500 mg by an empty stomach. mouth every 6–12 hours • Monitor liver enzymes and assess for jaundice in patients taking a macrolide because this drug can cause liver damage, especially in older people. AMINOGLYCOSIDES DRUG/ADULT DOSAGE RANGE NURSING IMPLICATIONS amikacin 15–30 mg/kg IV every 8–12 • Be sure to give these drugs only for as long as prescribed because they can cause kidney damage and hearing hours loss. gentamicin 3–5 mg/kg per day IV or IM • When giving these drugs intravenously, be sure to dilute them well and give over 30–60 minutes to reduce streptomycin 1–2 g IM every 6 or 12 vein irritation and prevent cardiac side effects. hours • Assess patients for confusion, weakness, sleep disorders, or eye disorders because these drugs, especially streptomycin, can induce nervous system toxicities. If these appear, notify the healthcare provider immediately to prevent severe complications. MISCELLANEOUS PROTEIN SYNTHESIS INHIBITORS DRUG/ADULT DOSAGE RANGE NURSING IMPLICATIONS clindamycin (Cleocin) 150–450 mg orally • Give with food or a full glass of water to minimize GI irritation. every 6 hours linezolid (Zyvox) 600 mg orally or IV • If patients are on an selective serotonin reuptake inhibitor antidepressant, monitor their blood pressure and every 12 hours heart rate because the risk for serotonin syndrome is increased. • Ask patients if they are on monoamine oxidase inhibitor antidepressants because use with linezolid could cause severe cardiac problems and is contraindicated. • Tell patients that if unusual bruising or bleeding occurs to notify their healthcare provider because these may be symptoms of a low platelet count. • Tell patients to avoid alcohol and tyramine-containing foods to avoid severe hypertension. dalfopristin/quinupristin (Synercid) 7.5 • Mix the drug according to manufacturer's instructions and give the infusion over 60 minutes to reduce vein mg/kg IV every 12 hours irritation and injection-site reactions. • Consult with the pharmacist for patients taking other IV drugs with macrolides because this drug is not 160 compatible with some other IV drugs. • Consult with the healthcare provider and the pharmacist for patients taking other drugs with dalfopristin/quinupristin because it interacts with many drugs. Macrolides Actions Macrolides are protein synthesis inhibitors that work in the same way as tetracyclines do. Macrolides are either bactericidal or bacteriostatic depending on the organisms and the dose used. Azithromycin and clarithromycin are considered advanced-generation macrolides compared with erythromycin, which was the first macrolide antibiotic. The later macrolides have a longer duration of action than erythromycin, fewer side effects, and can penetrate the tissues better, making them more effective at destroying bacteria. Their blood levels remain higher longer, so fewer doses are needed daily and therapy is often of shorter duration. Uses The macrolides are effective against many of the same infectious organisms that are sensitive to penicillin. Macrolides are used as alternatives to penicillin for patients who have a penicillin allergy and for infections caused by organisms that are resistant to penicillin. These drugs are effective against aerobic and anaerobic grampositive cocci. They are not effective against MRSA or some other staphylococcus bacteria, as well as some types of streptococci. Additional uses of macrolides include Mycoplasma pneumoniae and Chlamydia infections. They are also used in Legionnaires' disease and in the treatment of pertussis (“whooping cough”). Expected Side Effects The most common side effects of macrolides are associated with the GI tract and include mild abdominal pain, nausea, flatulence, and diarrhea. In addition, these drugs increase the sensitivity of the skin to sunlight. Severe sunburns are possible even among people with darker skin. Adverse Effects Macrolides can impair the liver and cause jaundice. When macrolides are given intravenously, phlebitis and other types of vein irritation are common. Drug Interactions Macrolides are protein bound and metabolized by the liver, making them capable of having numerous drug interactions. Macrolides enhance the action of digoxin, theophylline, warfarin, cyclosporine, and carbamazepine. Toxic effects of these drugs can occur if levels are not followed closely. The combination of a macrolide with other drugs, such as ergotamine for migraines or pimozide for Tourette syndrome, can precipitate life-threatening cardiac dysrhythmias. Anesthetic agents and anticonvulsant drugs may interact to cause high serum drug levels and toxicity. Consult a drug reference book or a pharmacist for information when other drugs are prescribed during macrolide therapy. 161 Nursing Implications and Patient Teaching The major differences between erythromycin and the newer macrolides include better GI tolerability, a broader spectrum of activity, and less dosing frequency for the newer products. The strength of erythromycin varies by product. Stomach acid inactivates erythromycin. This is the reason erythromycin is prepared as an entericcoated drug combined with other products to form different drugs such as erythromycin base, erythromycin estolate, erythromycin ethylsuccinate, or erythromycin stearate. There are differences in dosages among these different erythromycin preparations. Thus one type of erythromycin tablet should never be substituted for another type unless advised to do so by the pharmacist or healthcare provider. Many macrolides may be given orally or parenterally. Topical application should be avoided to prevent sensitization. Keep the patient well hydrated (supplied with fluids). Drinking extra fluids to ensure a minimum urine output of 1500 mL decreases the odds of renal toxicity. In addition to the general nursing implications and teaching points for all antimicrobial drugs, those specific for the macrolides are listed in Table 5.2. Aminoglycosides Action Like other protein synthesis inhibitors, aminoglycosides weaken the bacteria by limiting the production of protein, which is essential to the life of the bacteria. Uses Aminoglycosides, such as gentamicin and amikacin, are used in the treatment of serious aerobic gram-negative infections, including those caused by E. coli, Serratia, Proteus, Klebsiella, and Pseudomonas; aerobic gram-negative bacteria; mycobacteria; and some protozoans. Some drugs are used to sterilize the bowel before intestinal surgery and to treat hepatic encephalopathy. Expected Side Effects When given intravenously, aminoglycosides are irritating to the veins. Additional common side effects include nausea, vomiting, rash, lethargy, and fever. Adverse Reactions Aminoglycosides can cause serious adverse effects including damage to the kidney (nephrotoxicity) that is usually reversible if the drug is stopped quickly. They can also produce permanent damage to the inner ear (ototoxicity), or hearing impairment, dizziness, loss of balance, ringing in the ears, and persistent headache or other types of neurotoxicity, particularly with drugs such as gentamicin. Aminoglycosides have a narrow therapeutic range (when the lowest and highest acceptable drug levels are not far apart). This requires that the sample for the antibiotic blood level be drawn just before the next scheduled dose is given. This sample will show the lowest blood level of the antibiotic (trough), rather than a blood level at a higher range (peak). The lowest blood level will determine whether the dosage needs to be adjusted to stay within the therapeutic range and not reach the 162 toxic level or go below the effective level. Aminoglycoside dosage is calculated on the basis of the patient's weight. Dosage is adjusted based on creatinine clearance that is based on creatinine blood levels so that a therapeutic level is maintained without nephrotoxicity. Blood urea nitrogen (BUN) and glomerular filtration rates are also closely monitored. Drug Interactions Using aminoglycosides with many other drugs, particularly vancomycin, increases the risk for nephrotoxicity. Ototoxicity is also increased with aspirin, furosemide, ethacrynic acid, and many other drugs. Consult a drug reference book or a pharmacist for information when other drugs are prescribed during aminoglycoside therapy. Nursing Implications and Patient Teaching In addition to the general nursing implications and teaching points for all antimicrobial drugs, those specific for the aminoglycosides are listed in Table 5.2. Aminoglycosides are given parenterally for systemic bacterial infections because they are poorly absorbed from the GI tract. Patients should have frequent hearing and urine tests to monitor for ototoxicity and nephrotoxicity, respectively. For patients taking these aminoglycosides, particularly in the hospital, the nurses will be involved in monitoring the blood levels of these drugs. The drug levels peak and trough (go up and down) and thus close monitoring is important. Miscellaneous Protein Synthesis Inhibitors Three other classifications of protein synthesis inhibitors do not fit into other categories and are not used commonly: lincosamides, oxazolidinones, and streptogramins. They are usually given intravenously to treat bacterial infections that have not responded to other antibiotics, and their use is limited to lifethreatening infections such as MRSA and VRSA. Clindamycin is a lincosamide that can be given orally for skin infections such as impetigo, cellulitis, and complicated skin and soft tissue infections such as diabetic foot ulcers. It is used intravenously for bone infections, intra-abdominal abscess, peritonitis, cellulitis, septicemia, bacteremia, and anaerobic pneumonia. Clindamycin is an older drug, and more organisms are resistant to it. In addition, it is more likely to cause antibioticassociated diarrhea, including C. diff. colitis, than other antibiotics. Linezolid (Zyvox) is an oxazolidinone that can be given orally or intravenously. It is used for MRSA, VRE, and sepsis after treatment with vancomycin has failed. Dalfopristin/quinupristin can only be given intravenously and is reserved for patients with bacteremia or sepsis. See Table 5.2 for specific implications when giving these drugs. Safety Alert! Do not confuse Zyvox with Zovirax or Zyban. 163 Zyvox is an antibiotic, Zovirax is an antiviral, and Zyban is a drug used for smoking cessation. Bookmark This! For a full list of sound-alike drugs, you can download a pdf file from the Institute of Safe Medical Practices at https://www.ismp.org/Tools/confuseddrugnames.pdf. Sulfonamides Action Sulfonamides are antibacterial drugs from a class known as metabolism inhibitors. They enter the bacteria and prevent them from making the final form of folic acid, which is needed for bacterial growth and function. Sulfonamides are bacteriostatic rather than bactericidal because they do not actually kill the bacteria. Uses Sulfonamides have a broad spectrum of activity. They are eliminated by the kidneys, so they have a high concentration of activity in the kidneys. This makes sulfonamides a good choice for treating acute and chronic urinary tract infections,