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CHAPTER 3 CHAPTER 6 KEY TERMS Blood dyscrasia: bone marrow suppression caused by drug effects on the rapidly multiplying cells of the bone marrow;...

CHAPTER 3 CHAPTER 6 KEY TERMS Blood dyscrasia: bone marrow suppression caused by drug effects on the rapidly multiplying cells of the bone marrow; Alternative Therapy: includes herbs and other "natural" products lower-than-normal levels of blood components can be seen. as often found in ancient records; since they are considered dietary Dermatological reactions: skin reactions commonly seen as supplements, these products are not controlled or tested by the U.S. adverse effects of drugs; can range from simple rash to potentially Food and Drug Administration in the same way that medications fatal exfoliative dermatitis. are controlled Drug allergy or Hypersensitivity: usually involves the formation Biological weapons: so-called germ warfare; the use of bacteria, of antibodies to a drug or drug protein; causes an immune response viruses, and parasites on a large scale to incapacitate or destroy a when the person is next exposed to that drug population Poisoning: overdose of a drug that causes damage to multiple body Cost comparison: a comparison of the relative cost of the same systems and has the potential for fatal reactions drug provided by different pharmacies or manufacturers to Stomatitis: inflammation of the mucous membranes related to drug determine the costs to the consumer effects; can lead to alterations in nutrition and dental problems self-care: patients self-diagnosing and determining their own Superinfections: infections caused by the destruction of normal treatment needs flora bacteria by certain drugs, which allow other bacteria to grow street drugs: nonprescription drugs with no known therapeutic use; out of control and cause infection; may occur during antibiotic used to enhance mood or increase pleasure therapy Over-the-Counter Drugs ALTERNATIVE THERAPIES AND HERBAL MEDICINE OTC medications allow people to take care of simple medical problems Alternative therapies are often found in ancient records, and some have without seeking advice from healthcare providers. Many of these been the basis for the discovery of an active ingredient that is later medications were "grandfathered in" as drugs when stringent testing and developed into an FDA-regulated medication. Today, alternative evaluation systems became law. Aspirin, one of the nonprescription therapies can also include non drug measures, such as imagery, massage, standbys for many years, falls into this category. acupuncture, and relaxation Diffusion: movement of solutes from high to low concentration CHAPTER 7 across a concentration gradient Key Terms Endocytosis: the process of engulfing substances and moving them into a cell by extending the cell membrane around the substance Cell Cycle: life cycle of a cell, which includes the phases G0 Endoplasmic reticulum: site of chemical reactions within the cell (resting phase), G1 ( Gap phase or DNA formation), G2 Exocytosis: removal of substances from a cell by pushing them (replication or another gap phase), S (synthesis phase or the through the cell membrane DNA doubled) and M (Cell division or splits to form two Genes: make up the physical and functional units of heredity and identical daughter cells) can play a role in susceptibility to disease and reaction to Cell membrane: lipoprotein structure that separates the interior of medication a cell from the external environment; regulates what can enter and Golgi apparatus: a series of flattened sacs in the cytoplasm that leave a prepare hormones or other substances for secretion and may Cell cytoplasm: lies within the cell membrane; contains organelles produce lysosomes and store other synthesized proteins  Histocompatibility antigens: proteins found on the surface of the Cytoplasm osmosis: movement of water from an area of low to cell membrane high solute concentration in an attempt to equalize the Lipoprotein: structure composed of proteins and lipids; the bipolar concentrations arrangement of the lipids monitors substances passing in and out of Ribosomes: membranous structures that are the sites of protein the cell production within a cell Lysosomes: encapsulated digestive enzymes found within a cell; Chemotherapy drugs: are used to destroy both organisms that they digest old or damaged areas of the cell and are responsible for invade the body and abnormal cells within the body destroying the cell when the membrane ruptures and the cell dies Receptor sites: are type of protein located on the cell membrane Mitochondria: rod-shaped organelles that produce energy within reacts with specific chemicals outside the cell to stimulate a the cell in the form of adenosine triphosphate (ATP) reaction within the cell Mitosis: cell division resulting in two identical daughter cells PASSIVE TRANSPORT: happens without the expenditure of Nucleus: the part of a cell that contains the DNA and genetic energy and can occur across a semipermeable membrane. material Facilitated diffusion: substance cannot move freely on its own in Organelles: distinct structures found within the cell or out of a cell CHAPTER 8: ANTI-INFECTIVE AGENTS KEY TERMS Bactericidal: substance that causes the death of bacteria Bacteriostatic: substance that prevents or slows the replication of bacteria  Bacteria culture: sample of the bacteria (e.g., from sputum, cell scrapings, urine) to be grown in a laboratory to determine the species of bacteria causing a particular infection Prophylaxis: treatment to prevent an infection before it occurs or to prevent a second infection, as in the use of antibiotics to prevent bacterial endocarditis in high-risk patients or antiprotozoals to prevent malaria Resistance: ability of pathogens over time to adapt to an anti-infective to produce cells that are no longer affected by a particular drug Selective toxicity: the ability to affect certain proteins or enzyme systems that are used by the infecting organism but not by human cells Sensitivity testing: evaluation of pathogens obtained in a culture Spectrum: range of bacteria against which an antibiotic is effective Superinfection: infections that occur when opportunistic pathogens have the opportunity to invade tissues and cause infections because the normal flora bacteria that kept them in check have been destroyed by antibiotic therapy Anti-infective agents are drugs designed to target foreign organisms that have invaded and infate used body of a human host. THERAPEUTIC ACTIONS ➔ to prevent it from reproducing and to cause cell death without affecting host cells. Treatment of Systemic Infections ➔ Many infections that once led to lengthy, organ damaging, or even fatal illnesses are now managed quickly and efficiently with the use of systemic anti-infective agents. Several factors should be considered before beginning a systemic anti-infective regimen to ensure that the patient obtains the greatest benefit possible with the fewest adverse effects. Identification of the Pathogen ➔ Identification of the infecting pathogen is done by culturing a tissue sample from the infected area. Adverse Reactions to Anti-Infective Therapy Because anti-infective agents affect cells, it is always possible that the host cells will also be damaged. No anti-infective agent has been developed that is completely free of adverse effects. The most common adverse effects associated with the use of anti-infective agents are direct toxic effects on the kidney, GI tract, and nervous system. Hypersensitivity reactions and superinfections also can occur. Kidney Damage Kidney damage occurs most frequently with drugs that are metabolized by the kidney or eliminated in the urine. When patients are taking these drugs (eg., aminoglycosides), they should be monitored closely for any sign of renal dysfunction. To prevent any accumulation of the drug in the kidney, patients should be well hydrated throughout the course of the drug therapy. Gastrointestinal Toxicity GI toxicity is very common with many anti-infectives. Many of these agents have direct toxic effects on the cells lining the GI tract, causing nausea, vomiting, stomach upset, or diarrhea; such effects are sometimes severe. There is also some evidence that the death of the microorganisms releases chemicals and toxins into the body, which can stimulate the chemoreceptor trigger zone in the medulla and induce nausea and vomiting. Neurotoxicity Some anti-infectives can damage or interfere with the function of nerve tissue, usually in areas where drugs tend to accumulate in high concentrations. Hypersensitivity Reactions Allergic or hypersensitivity reactions occur with many antimicrobial agents. Most of these agents, which are protein bound for transfer through the cardiovascular system, are able to induce antibody formation in susceptible people. With the next exposure to the drug, immediate or delayed allergic responses may occur. Superinfections One effect of the use of it, especially broad-spectrum anti in fare ive is destruction of the normal flora. Common superinfections include vaginal or Gl yeast infections, which are associated wits, the emergence of has caused by Candida. SUMMARY: develops alternative routes to obtain nutrients or maintain the cell ★ Anti-infectives are drugs designed to act with selective toxicity on membrane. foreign organisms that have invaded and infected the human host, ★ An important aspect of clinical care involving anti-infective agents which means that they affect biological systems or structures found is preventing or delaying the development of resistance. This can in the invading organisms but not in the host. be done by ensuring that the particular anti-infective agent is the ★ Anti-infectives include antibiotics, antivirals, antifungals, drug of choice for the specific pathogen involved and that it is antiprotozoals, and anthelmintic agents. given in high enough doses for sufficiently long periods to rid the ★ The goal of anti infective therapy is interference with the normal body of the pathogen. function of invading organisms to prevent them from reproducing ★ Anti-infectives can have several adverse effects on the human host, and promoting cell death without negative effects on the host cells. including renal toxicity, multiple Gl effects, neurotoxicity, The infection should be eradicated with the least toxicity to the hypersensitivity reactions, and superinfections. host and the least likelihood for development of resistance. ★ Some anti-infectives are used as a means of prophylaxis when ★ Pathogens can develop resistance to the effects of anti-infectives patients expect to be in situations that will expose them to a known over time when (a) mutated organisms that do not respond to the pathogen, such as travel to an area where malaria is endemic, or anti-infective become the majority of the pathogen population or before oral or invasive GI surgery if the patient is a high-risk (b) the pathogen develops enzymes to block the anti-infectives or person who is susceptible to subacute bacterial endocarditis CHAPTER 9: ANTIBIOTICS KEY TERMS: aerobic: bacteria that depend on oxygen for survival anaerobic: bacteria that survive without oxygen, which are often found in chronic infections and in the Gl tract  antibiotic: chemical that inhibits the growth of specific bacteria or causes the death of susceptible bacteria gram-negative: bacteria that have only a thin layer of peptidoglycan, making them less likely to absorb stain or become decolorized by alcohol; these bacteria are frequently associated with infections of the genitourinary or gastrointestinal (Gl) tract gram-positive: bacteria that have cell walls with more peptidoglycan layers, which absorb more stain or resist decolorization with alcohol during preliminary identification; these bacteria are frequently associated with infections of the respiratory tract and soft tissues Gram staining: a process used to identify between types of bacteria based on differences of components in their cell walls synergistic: drugs that work together to increase drug effectiveness 1. AMINOGLYCOSIDES (-MYCIN, -CIN, -MICIN) The aminoglycosides are a group of antibiotics used to treat infections caused by primarily aerobic gram-negative bacilli. Because most of these drugs have potentially serious adverse effects, Less-toxic drugs have replaced aminoglycosides in the treatment of some infections. Therapeutic Actions and Indications ★ The aminoglycosides are bactericidal. They inhibit protein synthesis in susceptible strains of aerobic gram-negative bacteria. They irreversibly bind to a unit of the bacteria ribosomes, leading to misreading of the genetic code and cell death Pharmacokinetics ★ The aminoglycosides are poorly absorbed from the GI tract but rapidly absorbed after intramuscular (IM) injection, reaching peak levels within 1 hour. These drugs have an average half-life of 2 to 3 hours. They are widely distributed throughout the body, cross the placenta and enter human milk, and are excreted unchanged in the urine. Amikacin is available for short-term IM or intravenous (IV) use. Contraindications and Cautions The risks and benefits of aminoglycosides must be carefully weighed in the following conditions: ★ known allergy to any of the aminoglycosides, renal disease , preexisting hearing loss and myasthenia gravis or parkinsonism Caution is necessary when these agents are administered during pregnancy because aminoglycosides cross the placenta and may have potential adverse effects on the fetus. Streptomycin has been associated with deafness in newborns when administered to people who are pregnant. Adverse Effects The serious adverse effects associated with aminoglycosides limit their usefulness. The drugs come with a boxed warning alerting health care professionals to the serious risk of ototoxicity and nephrotoxicity. Renal toxicity, which may progress to renal failure. Clinically Important Drug-Drug Interactions Most aminoglycosides have a synergistic bactericidal effect when given with penicillins or cephalosporins. Key Points: Aminoglycosides inhibit protein synthesis in susceptible strains of aerobic gram-negative bacteria. These drugs are reserved for use in serious infections because of potentially serious adverse effects.Monitor for hypersensitivity, ototoxicity, renal toxicity, Gl disturbances, bone marrow depression, and superinfections.  2. CARBAPENEMS The carbapenems are a class of broad spectrum beta lactam antibiotics effective against gram-positive and gram-negative bacteria. Therapeutic Actions and Indications ★ The carbapenems are bactericidal. They inhibit cell membrane synthesis in susceptible bacteria, leading to cell death. These drugs are used to treat serious infections caused by susceptible strains of S. pneumoniae, Haemophi-lus influenzae, Moraxella catarrhalis and other susceptible bacteria. They are indicated for treating serious intraabdominal, urinary tract, skin and skin structure, bone and joint, and gynecological infections. Pharmacokinetics ★ These drugs are rapidly absorbed if given IM and reach peak levels at the end of the infusion if given IV. They are widely distributed throughout the body. Carbapenems are excreted unchanged in the urine and have an average half-life of 1 to 4 hours. Doripenem is given IV every 8 hours by a 1-hour IV infusion. Ertapenem can be given IV or IM. Imipenem-cilastatin can be given IM or IV and is approved for use in children. Contraindications and Cautions ★ Carbapenems are contraindicated when there is a known allergy to any of the carbapenems or beta-lactams. Use caution during pregnancy and lactation Adverse Effects ★ Toxic effects on the Gl tract can limit the use of carbapenems in some patients Key Points: Carbapenems are beta-lactam antibiotics used to treat serious infections caused by a wide range of bacteria. Monitor for hypersensitivity, Gl effects, serious diarrhea, dizziness, and superinfections  3. CEPHALOSPORINS (CEFA, CEPHA) ★ The cephalosporins are a type of beta-lactam antibiotic that were first introduced in the 1960s. These drugs are similar to the penicillins in structure and activity. First-generation cephalosporins are largely effective against the same gram-positive bacteria that are affected by penicillin G, as well as the gram-negative bacteria. First-generation drugs include cefazolin (generic), cefadroxil (generic), and cephalexin (Keflex). Second-generation cephalosporins are effective against the previously mentioned strains, as well as H. influenzae, Enterobacter aerogenes, and Neisseria spp. Second-generation drugs are less effective against some gram-positive bacteria. These include cefaclor (Ceclor), cefotetan (generic); cefoxitin (generic), cefprozil (generic), and cefuroxime (Zinacef). Third-generation cephalosporins, which are effective against all of the previously mentioned strains, have less activity against gram-positive bacteria but are more active against the gram-negative bacilli, as well as against Serratia marcescens. Third-generation drugs include cefdinir (Omnicef), cefotaxime (Claforan), cefpodoxime (generic), ceftazidime (Ceptaz, Tazicef), and ceftriaxone (Rocephin). Cefepime (Maxipime) is the fourth-generation cephalosporin. Cefepime (Maxipime) is active against gram-neg-ative and gram-positive organisms Therapeutic Actions and Indications ★ The cephalosporins are both bactericidal and bacteriostatic, depending on the dose used and the specific drug involved. They prevent the bacteria from bio synthesizing the framework of their cell walls. Pharmacokinetics ★ Most cephalosporins are primarily excreted unchanged in the urine. Lower doses may be prescribed for those with renal impairment. However, ceftriaxone is eliminated primarily by the liver. These drugs cross the placenta and enter human milk and provide calculation practice using cefdinir. Contraindications and Cautions Use caution when a cephalosporin is prescribed in patients with known allergies to cephalosporins or penicillins, as cross-sensitivity may occur. Use with caution in patients with hepatic or renal impairment because these drugs are toxic to the kidneys and could interfere with the metabolism and excretion of the drug. Adverse Effects The most common adverse effects of the cephalosporins involve the GI tract and include nausea, vomiting, diarrhea, anorexia, abdominal pain, and flatulence.  4. FLUOROQUINOLONES ( -FLOXACIN ) ★ The Fluoroquinolones are a synthetic class of bactericidal antibiotics with a broad spectrum of activity. Systemic fluoroquinolones include ciprofloxacin (Cipro), delafloxacin (Baxdela), levofloxacin (Levaquin), moxifloxacin (Avelox), and ofloxacin (generic). Therapeutic Actions and Indications ★ The fluoroquinolones enter the bacterial cell by passive diffusion through channels in the cell membrane. The fluoroquinolones are indicated for treating infections caused by susceptible strains of gram-positive and gram-negative bacteria. These infections frequently include urinary tract, respiratory trach and skin infections. Some of the fluoroquinolones are able to prevent or treat post exposure to anthrax infection. Pharmacokinetics The fluoroquinolones are absorbed from the GI tract, metabolized in the liver, and excreted in the urine and feces. These drugs are widely distributed in the body and cross the placenta and enter human milk. Ciprofloxacin and ofloxacin are available in injectable, oral, and topical forms. Contraindications and Cautions ★ could occur: tendinitis, tendon rupture, peripheral neuropathy, CNS effects, and exacerbation of muscle weakness in patients with myasthenia gravis. Because of these issues, these drugs are no longer recommended for treating uncomplicated infections except when no other drug treatment is possible. They are also contraindicated in patients with a known allergy to any fluoroquinolone. The use of fluoroquinolones is not recommended in pregnant or lactating patients except in specific circumstances. Most infections in patients who are pregnant should be treated with an alternative class of antibiotics. Use with caution in the presence of renal dysfunction, which could interfere with the excretion of the drug, and seizures, which could be exacerbated by the drugs' effects on cell membrane channels.  5. PENICILLIN AND PENICILLINASE RESISTANT ANTIBIOTICS (-CILLIN) ★ Penicillin was the first antibiotic introduced for clinical use. Sir Alexander Fleming used Penicillium molds to produce the original penicillin in the 1920s.. The natural penicillins include penicillin G benzathine (Bicillin L.A., Permapen), penicillin G potassium (Pfizerpen), penicillin G procaine (generic), and penicillin V (Penicillin-VK). Pharmacokinetics ★ Most of the penicillin reaching peak levels in 1 HOUR are sensitive to gastric acid levels in the stomach and should be taken on an empty stomach to ensure adequate absorption. Penicillins are excreted unchanged in the urine, making renal function an important factor in safe use of the drug. Penicillins enter human milk and can cause adverse reactions Contraindications and Cautions ★ These drugs are contraindicated in patients with allergies to penicillin or other allergens. Use with caution in patients with renal disease (lowered doses are necessary because excretion is reduced). Use in patients who are pregnant or lactating should be limited to situations. Adverse Effects ★ The major adverse effects of penicillin therapy involve the GI tract. Common adverse effects include nausea, vomiting, diarrhea, abdominal pain, glossitis, stomatitis, gastritis, sore mouth, and furry tongue. These effects are primarily related to the loss of bacteria from the normal flora and the subsequent opportunistic infections that occur.  6. SULFONAMIDES (SULF-) ★ The sulfonamides, or sulfa drugs, are drugs that inhibit folic acid synthesis. Sulfonamides include sulfadiazine (generic) and cotrimoxazole or trimethoprim-sulfa-methoxazole (Septra, Bactrim). Therapeutic Actions and Indications ★ Folic acid is necessary for the synthesis of purines and pyrimidines, which are precursors of RNA and DNA. For cells to grow and reproduce, they require folic acid. Humans cannot synthesize folic acid and depend on the folate in their diet to obtain this essential substance. Bacteria are impermeable to folic acid and must synthesize it inside the cell. This includes gram-negative and gram-positive bacteria such as Chlamydia trachomatis and Nocardia and some strains of H. influenzae, E. coli, and P. mirabilis. Because of the emergence of resistant bacterial strains and the development of newer antibiotics, the sulfa drugs are not used as frequently. However, they remain an inexpensive and effective treatment for UTis and trachoma, especially in developing countries and when cost is an issue. These drugs are used to treat trachoma (a leading cause of blindness from C. trachomatis infection), nocardiosis (which causes pneumo-nias, as well as brain abscesses and inflammation), and UTIs.  7. TETRACYCLINES (-CYCLINE) ★ The tetracyclines were developed as semisynthetic antibiotics based on the structure of a common soil mold. They are composed of four rings, which is how they got their name. Researchers have developed newer tetracyclines to increase absorption and tissue penetration. Tetracyclines include tetracycline (generic), demeclocycline (generic), doxycycline (Doryx, Acticlate), eravacycline (Xerava), (omadacycline Nuzyra), minocycline (Arestin, Minocin), and sarecycline (Seysara). Therapeutic Actions and Indications ★ The tetracyclines are bacteriostatic and work by inhibiting protein synthesis in a wide range of bacteria, leading to the inability of the bacteria to multiply. Because the affected protein is similar to a protein found in human cells, these drugs can be toxic to humans at high concentrations. Pharmacokinetics ★ Tetracyclines are absorbed adequately, but not completely, from the GI tract. Their absorption is affected by food, iron, calcium, and other drugs in the stomach. The tetracyclines have half-lives that range from 12 to 25 hours. Contraindications and Cautions ★ Tetracyclines are contraindicated in patients with known allergy to tetracyclines and during pregnancy and lactation because of effects on developing bones and teeth. Tetracyclines should be used with caution in children younger than 8 years of age because they can potentially damage developing bones and teeth. Adverse Effects ★ The major adverse effects of tetracycline therapy involve direct irritation of the GI tract and include nausea, vomiting, diarrhea, abdominal pain, glossitis, and dysphagia. Key Points: Tetracyclines are bacteriostatic; they inhibit protein synthesis and prevent bacteria from multiplying. Tetracyclines can cause damage to developing teeth and bones and should not be used with people who are pregnant or children younger than 8 years of age. Monitor the patient for Gl effects, bone marrow depression, rash, and superinfections.  8. ANTIMYCOBACTERIALS ★ Mycobacteria-the group of bacteria that contains the pathogens that cause tuberculosis and leprosy-are classified on the basis of their ability to hold a stain even in the presence of a "destaining" agent such as acid. Because of this property, they are called "acid-fast" bacteria. Mycobacteria cause serious infectious diseases. The bacterium Mycobacterium tuberculosis causes tuberculosis, the leading cause of death from infectious disease in the world. Mycobacterium leprae causes leprosy, also known as Hansen disease, which is characterized by disfiguring skin lesions and destructive effects on the respiratory tract. Antituberculosis Drugs Tuberculosis can lead to serious damage in the lungs, the GU tract, bones, and the meninges. Because Mycobacterium tuberculosis is so slow growing, the treatment must be continued for 6 months to 2 years. Using the drugs in combination helps to decrease the emergence of resistant strains and to affect the bacteria at various phases during their long and slow life cycle. The first-line drugs for treating tuberculosis are isoniazid (generic), rifampin (Rifadin), pyrazinamide (generic), ethambutol (Myambutol), rifabutin (Mycobutin), and rifapentine (Priftin). The second-line drugs include ethionamide (Treca-tor-SC), capreomycin (Capastat), and cycloserine (Seromy-cin), and Bedaquiline (Sirturo) had accelerated approval from the FDA to treat adult and pediatric patients diagnosed with pulmonary multidrug-resistant tuberculosis in combination with other medications. In addition, drugs from other antibiotic classes have been found to be effective in second-line treatment, such as levofloxacin (Levaquin), moxifloxacin (Avelox), and streptomycin. Leprostatic Drugs The antibiotic used to treat leprosy is dapsone (generic), which has been the mainstay of leprosy treatment for many years. It inhibits folate synthesis in susceptible bacteria. Therapeutic Actions and Indications Most of the antimycobacterial agents act on the DNA and/ Or RNA of the bacteria, leading to a lack of growth and eventually to bacterial death. Pharmacokinetics The antimycobacterial agents are generally well absorbed from the GI tract. These drugs, given orally, are metabolized in the liver and excreted in the urine; they cross the placenta and enter human milk, placing the fetus or child at risk for adverse reactions Contraindications and Cautions Antimycobacterials are contraindicated for patients with any known allergy to these agents and in patients with severe renal or hepatic failure, which could interfere with the metabolism or excretion of the drug. If an anti tuberculosis regimen is necessary during pregnancy, the combination of isoniazid, ethambutol, and rifampin is considered the safest. Adverse Effects CNS effects, such as neuritis, dizziness, headache, malaise, drowsiness, and hallucinations, are often reported and are related to direct effects of the drugs on neurons.These drugs also are irritating to the GI tract, causing nau-sea, vomiting, anorexia, stomach upset, abdominal pain, and, rarely, pseudomembranous colitis. Key Points The mycobacteria have an outer coat of mycolic acid that protects them from many disinfectants and allows them to survive for long periods in the environment. These slow growing bacteria may need to be treated for several months or years before they can be eradicated. They cause tuberculosis and leprosy. Antituberculosis drugs are used in combination to increase effectiveness and decrease the emergence of resistant strains. These drugs are divided into first-line and second-line drugs. Adverse effects include rashes, an orange tint to body fluids, liver impairment, peripheral neuropathy, and Gl reactions. Dapsone can be used to treat leprosy or Hansen's disease. Thalidomide can be used to treat a complication of leprosy called erythema nodosum leprosum. Other Antibiotics 9. LINCOSAMIDES (-MYCIN) The lincosamides are similar to the macrolides. They are bacteriostatic and interfere with protein synthesis of gram-positive bacteria. These drugs include clindamycin (Cleocin) and lincomycin (Lincocin). Therapeutic Actions and Indications The lincosamides react at almost the same site in bacterial protein synthesis and are effective against the same strains of bacteria. They can be used to treat infections caused by gram-positive and some anaerobic bacteria. Pharmacokinetics The lincosamides are rapidly absorbed from the GI tract or from IM injections but are typically administered IV. They are metabolized in the liver and excreted in the urine and feces. These drugs cross the placenta and enter human milk. Clindamycin has a half-life of 2 to 3 hours. Lincomycin has a half-life of 5 hours. It can be given IM or IV Contraindications and Cautions Use lincosamides with caution in patients with hepatic impairment, which could interfere with the metabolism and excretion of the drug. Dose adjustment is recommended for lincomycin if severe renal impairment is present. Use during pregnancy and lactation only if the benefit clearly outweighs the risk to the fetus or neonate. Adverse Effects Severe GI reactions, including fatal pseudomembranous colitis, have occurred, limiting the usefulness of lincosamides. However, for a serious infection caused by a susceptible bacterium, a lincosamide may be the drug of choice. Some other toxic effects that limit usefulness are abdominal discomfort, skin reactions, and bone marrow depression.  10. LIPOGLYCOPEPTIDES (-CIN, -MYCIN) The lipoglycopeptides class of antibiotics was first introduced in 2010. Drugs in this class include telavancin (Vibativ), dalbavancin (Dalvance), oritavancin (Orbactiv), and the original drug in the class vancomycin (Vancocin, Firvang). Therapeutic Actions and Indications Lipoglycopeptides are semisynthetic derivatives of the original drug in this class, vancomycin. The lipoglycopeptides are effective against susceptible strains of the gram-positive organisms. The most common approved use for the newer lipoglycopeptides drugs is treating complicated skin and skin structure infections in adults. Vancomycin is used in the oral form to treat C. difficile diarrhea and S. aureus-induced enterocolitis, including methicillin-resistant strains, and in the parenteral form, it is used to treat serious infections responsive to the drug. Pharmacokinetics Lipoglycopeptides are available as IV drugs; only vancomycin has an oral form. However, oral vancomycin is poorly absorbed and is not used to treat systemic infections. The lipoglycopeptides reach peak levels at the end of the infusion. These drugs are widely distributed, may cross the placenta, and may pass into human milk. Adverse Effects The adverse effects associated with the lipoglycopeptides are largely secondary to toxic effects on the GI tract: nausea, vomiting, taste alterations, diarrhea, loss of appetite, and risk of C. difficile diarrhea.  11. MACROLIDES (-MYCIN) The macrolides are antibiotics that bind to the subunit of the ribosome within the bacterial cell and interfere with protein synthesis in susceptible bacteria. Macrolides include erythromycin (Ery-Tab, Eryc, and others), azithromycin (Zithromax and others), clarithromycin (Biaxin), and fidaxomicin (Dificid). Therapeutic Actions and Indications The macrolides, which may be bactericidal at high doses or bacteriostatic, exert their effect by binding to the ribosomes within the cell and changing protein synthesis. Pharmacokinetics Most of the macrolides are widely distributed throughout the body. These drugs are absorbed in the Gl tract. Erythromycin and azithromycin are primarily metabolized in the liver, with excretion mainly in the bile to feces. The half-life of erythromycin is 1.6 hours. The half-life of azithromycin is 68 hours, making it useful for patients who have trouble remembering to take pills because it can be given once a day. The half-life of clarithromycin is 3 to 7 hours. Fidaxomicin has a half-life of 9 hours.  12. MONOBACTAM ANTIBIOTIC The only monobactam antibiotic currently available for use is aztreonam (Azactam) Therapeutic Actions and Indications Among the antibiotics, aztreonam's structure is unique, and little cross-resistance occurs. It is effective against gram-negative enterobacteria and has no effect on gram-positive or anaerobic bacteria. Pharmacokinetics Arteonam is available for IV and IM use only and reaches Peak effect levels immediately if the route of administration is IV but slower if it is IM. Its half-life is 1.5 to 2 hours. The drug is excreted unchanged in the urine. It crosses the placenta and enters human milk. Contraindications and Cautions Aztreonam is contraindicated with any known allergy to aztreonam. Use with caution in patients with a history of acute allergic reaction to penicillins or cephalosporins because of the possibility of cross-reactivity; in patients with renal dysfunction that could interfere with the clearance and excretion of the drug; and in pregnant and lactating patients because of potential adverse effects on the fetus or neonate. Adverse Effects The adverse effects associated with the use of aztreonam are relatively mild. Local GI effects include nausea, GI upset, vomiting, and diarrhea. Hepatic enzyme elevations related to direct drug effects on the liver may also occur. Other effects include inflammation, phlebitis, and discomfort at injection sites, as well as the potential for allergic response, including anaphylaxis. Clinically Important Drug-Drug Interactions Aztreonam and aminoglycosides may have synergistic effects when used together to treat certain organisms. Key Points Lincosamides are similar to macrolides. They are used to treat severe infections. Monitor the patient for pseudomembranous colitis, bone marrow depression, pain, and CNS effects. Lipoglycopeptides, including vancomycin, telavancin, oritavancin, and dalbavancin, prevent the synthesis of the bacterial cell wall, which leads to cell death. Some are associated with high risk to the fetus. Monitor patients for prolonged QT interval, changes in renal function, Gl effects, and foamy urine. Macrolides are in a class of older antibiotics that can be bactericidal or bacteriostatic. They are used to treat upper respiratory infections (URIs), bacterial endocarditis, Legionnaires' disease, pertussis, acute diphtheria, and chlamydial infections, and are often used when patients are allergic to penicillin. Monitor the patient for nausea, vomiting, diarrhea, dizziness, and other CNS effects. Monitor liver function if indicated for long-term use. The monobactam antibiotic aztreonam is effective against only gram-negative bacteria; it is safely used when patients are allergic to penicillin or cephalosporins.Monitor the patient taking aztreonam for Gl problems, liver toxicity, and pain at the injection site. SUMMARY Antibiotics work by disrupting protein or enzyme systems within a bacterium, causing cell death (bactericidal) or preventing multiplication (bacteriostatic). The proteins or enzyme systems affected by antibiotics are more likely to be found or used in bacteria than in human cells. The longer an antibiotic has been available, the more likely that resistant bacterial strains will have developed. The most common adverse effects of antibiotic therapy involve the Gl tract (nausea, vomiting, diarrhea, anorexia, abdominal pain) and superinfections (invasion of the body by normally occurring microorganisms that are usually kept in check by the normal flora). To prevent or contain the growing threat of drug-resistant strains of bacteria, it is very important to use antibiotics cautiously, to complete the full course of an antibiotic prescription, and to avoid saving antibiotics for self-medication in the future.