Chapter 6 Pharmacology PDF

Chapter 6  Chapter 6 Antiinfectives: Antibacterial Drugs Understanding Pharmacology, 3rd ed. Workman Learning Objectives—Lesson 6.1 1. Explain the names, actions, usual adult dosages, possible side effects, and adverse effects of the various types of antibac...

Chapter 6  Chapter 6 Antiinfectives: Antibacterial Drugs Understanding Pharmacology, 3rd ed. Workman Learning Objectives—Lesson 6.1 1. Explain the names, actions, usual adult dosages, possible side effects, and adverse effects of the various types of antibacterial drugs. 2. Prioritize essential information to teach patients who are taking any of the various types of antibacterial drugs. 3. Explain appropriate life span considerations for the various types of antibacterial drugs. Infection Invasion by microorganisms causing harm or disease Bacteria, viruses, fungi, protozoa, other microorganisms Human body has several general and specific mechanisms to protect itself Bacteria Single-cell organisms Classified by: Shape (rod, round, spiral) Gram stain Pathogenic and nonpathogenic Pathogenic- Causes infection, systemic disease and tissue damage Nonpathogenic- Does not cause infection… Opportunistic- only infectious in persons with compromised immune system Antibacterial Therapy Bactericidal versus bacteriostatic Spectrum of efficacy Greater spectrum of activity does not increase effectiveness Susceptible bacteria Culture and sensitivity Goal of therapy: Kill bacteria or prevent their reproduction without harming the patient Types of Antibacterial Drugs 1. Cell wall synthesis inhibitors 2. Protein synthesis inhibitors 3. Metabolism inhibitors 4. DNA synthesis inhibitors Equally common Types of Antibacterial Drugs 5. Nucleic Acid Synthesis Inhibitors 6. Membrane Function Inhibitors Visual of How Anti-bacterial Drugs Work Common Antibacterial Drugs by Mode of Action General Issues in Antibacterial Therapy Intended response: Disappearance of signs and symptoms of infection Side effects: GI disturbances, diarrhea, oral and vaginal yeast infections Adverse effects: Allergic reactions, anaphylaxis, pseudomembranous colitis Priority actions: Monitor for effectiveness of therapy and side effects/ condition of IV site Teach patients to take drugs exactly as prescribed, for as long as prescribed, and to report side effects 1. Cell Wall Synthesis Inhibitors Intended responses: Bactericidal Prevent bacteria from forming cell walls Inhibit transglycosylation (RNA manufacturing) And/or transpeptidation (Amino acids transferred from one compound to another) Side effects: More likely to cause allergic reactions With more powerful drugs—nausea/vomiting, fever, chills, “red man syndrome,” reduced hearing, reduced kidney function Adverse effects: CNS changes, kidney damage Penicillin, cephalosporins, carbapenems, monobactams, and vancomycin Administering Cell Wall Synthesis Inhibitors Check before: Allergy to penicillin (increased risk for cephalosporin allergy) Give vancomycin slowly Check after: Monitor for allergic reaction Teaching priorities: Take cephalosporins at least 1 hr before or 4 hrs after iron or antacid Life Span Considerations for Cell Well Synthesis Inhibitors Pregnancy and lactation: Penicillins, most cephalosporins—low risk for fetal harm Carbapenems, monobactams, vancomycin—low to moderate risk for fetal harm Excreted in breast milk Older adults: Carbapenems and glycopeptide antibiotics—ototoxicity, nephrotoxicity more likely 2. Protein Synthesis Inhibitors Aminoglycosides, macrolides, tetracyclines, others Bacteriostatic or bactericidal Slows protein synthesis, preventing bacteria from performing processes important to their life cycles Common Side Effects of Protein Synthesis Inhibitors Aminoglycosides Nausea, vomiting, rash, fever, lethargy streptomycin Macrolides Nausea, vomiting, diarrhea, loss of appetite, photosensitivity Azithromycin, clarithromycin, erythromycin Tetracyclines Nausea, vomiting, diarrhea, glossitis, rash, photosensitivity Yeast infections early in course of treatment Doxycycline, tigecycline, minocycline Adverse Effects of Protein Synthesis Inhibitors Aminoglycosides Ototoxicity, nephrotoxicity, neuromuscular blockade Macrolides Many serious drug interactions, irritation (parenteral forms) Tetracyclines Increased intracranial pressure Lincosamides Reduced liver function, decreased WBC counts Oxazolidinones Reduced blood cell counts, damage to optic nerve Streptogramin Increased blood levels of many drugs Administering Protein Synthesis Inhibitors (1 of 2) Check before: Aminoglycosides—assess breathing baseline, lab tests, hearing Macrolides—other medications, give IV erythromycin within 8 hours of dilution Tetracyclines—food, antacids, dairy products decrease absorption Other protein synthesis inhibitors—check patient’s lab work carefully; give drug slowly Administering Protein Synthesis Inhibitors (2 of 2) Check after: Aminoglycosides—hearing, temperature, I&O, lab values (especially BUN and creatinine) Macrolides—heart rate and rhythm every 4 hours Tetracyclines—if patient is on warfarin, observe carefully for bleeding Other protein synthesis inhibitors—blood pressure for patient taking an oxazolidinone Patient Teaching for Protein Synthesis Inhibitors Macrolides Take with food to decrease GI side effects Avoid sun exposure Tetracyclines Avoid sun exposure Take 1 hour before or 2 hours after meals; do not take with milk Linezolid Avoid taking with foods containing tyramine Life Span Considerations for Protein Synthesis Inhibitors Pediatric: Aminoglycosides can cause severe respiratory depression and kidney damage Tetracyclines should be avoided in children younger than 8 years Pregnancy and lactation: Avoid aminoglycosides and tetracyclines with pregnancy and breastfeeding Most macrolides are generally safe; pass into breast milk causing colic and diarrhea in the infant Older adults: Ototoxicity, nephrotoxicity more likely 3. Metabolism Inhibitors: Sulfonamides and Trimethoprim Bacteriostatic Treat some nonbacterial infections (e.g., shigellosis, toxoplasmosis, Pneumocystis pneumoniae) Common side effects: Sulfonamides: Headache, fever, rash, photosensitivity Trimethoprim: Headache, nausea, vomiting, skin rashes Adverse effects: Suppression of bone marrow cell division Stevens-Johnson syndrome Hyperkalemia (trimethoprim) Kidney stones (sulfonamides) Administrating Metabolism Inhibitors (1 of 2) Check before: “Sulfa” allergies Blood disorders (African-Americans or persons of Mediterranean descent) Lab tests Check after: Jaundice, bruises, petechiae, blisters Offer water every 4 hours Administrating Metabolism Inhibitors (2 of 2) Teaching priorities: Avoid direct sunlight Wear protective clothing and sunscreen Avoid tanning beds and salons Drink a full glass of water with the drug, and more fluids throughout the day Report development of jaundice, sore throat, fever, rash, blisters, or multiple bruises Life Span Considerations for Metabolism Inhibitors Pediatric: Infants younger than 2 months more likely to become jaundiced Pregnancy and lactation: Avoid during last 2 months of pregnancy; avoid during breastfeeding Older adults: More intense side effects (anemia, increased risk of bleeding) 4. DNA Synthesis Inhibitors: Fluoroquinolones (Broad Spectrum Antibiotics) Inhibit production of DNA, preventing bacterial reproduction Side effects: Rash, nausea/vomiting, headache, abdominal pain, muscle and joint pain, sun sensitivity Adverse effects: Acute confusion in older adults, serious heart dysrhythmias (especially when taken with other drugs), peripheral neuropathy, changes in blood glucose level, tendon rupture (rare) Administering Fluoroquinolones (broad spectrum systemic antibacterial) (1 of 2) Check before: Patient also taking iron, vitamins, antacids Antidysrhythmic drug therapy Give with full glass of water Check after: Heart rate and rhythm every 4 hours Blood glucose levels in diabetic patients Monitor for acute confusion in older adults Administering Fluoroquinolones (2 of 2) Teaching priorities: Take with full glass of water; increase fluids throughout day Check pulse twice daily If diabetic, check blood glucose levels more often Avoid direct sunlight, use sunscreen, wear protective clothing outdoors Report tingling, burning, numbness, and pain in the hands or feet AntiBIOGRAM – visual representation of bacteria common in the area (facility to facility) excel spreadsheet (color coded) – Dr. Kiang AntiBiogram Example Life Span Considerations for Fluoroquinolones Pediatric: Not recommended for those under 18 years Pregnancy and lactation: Avoid use in pregnant and breastfeeding women Increased risk for bone, joint, tendon defects Older adults: Tendon rupture more common Antibacterial Drug Resistance Caused by overused, overprescribed, improperly taken antibacterial drugs Multidrug-resistant (MDR) organisms Also known as “superbugs” Cause “superinfections” Examples: Methicillin-resistant Staphylococcus aureus (MRSA) Drug-resistant Streptococcus pneumoniae