Pharm Exam 9 - Antimicrobials

Cell Wall Synthesis Inhibitors

Penicillins, Cephalosporins, Carabpenems, Vancomycin

Penicillins

Drugs: “-cillin”

Category: Broad & narrow spectrum

MOA: Disrupts bacterial cell wall synthesis via beta-lactam ring, causing cell lysis

ADR: GI symptoms, allergies, superinfections, diarrhea with “am-” drugs

Notes: High rates of resistance d/t history; Pen. G unstable in stomach acid → IV or IM, “Am-” drugs given via IV or PO

Cephalosporins

Drugs: Start with “Cef-” or “Ceph-”

Category: Broad spectrum

MOA: Disrupts bacterial cell wall synthesis via beta-lactam ring, causing cell lysis

ADR: Superinfections, GI disturbances, cross allergy for penicillin allergy

Note: Disulfiram-like rxn (flushing, HTN, n/v) with alcohol; can promote bleeding with anticoagulants/Warfarin

Carbapenems

Drugs: End in “-penem”

Category: Very broad spectrum (not effective against MRSA)

MOA: Disrupts bacterial cell wall via beta-lactam ring, causing cell lysis

ADR: GI disturbances, superinfections, may have cross allergy with other beta-lactam drugs

Note: IV only

Vancomycin

Category: Narrow spectrum

MOA: Inhibits cell wall synthesis, causing lysis

ADR: Nephrotoxicity, ototoxicity, vancomycin infusion rxn (flushing, rash, pruritus, tachycardia, hypoTN)

Monitor: Peak & trough levels, creatinine

Note: Most widely used antibiotic in U.S.; give IV (primarily) or PO for intestinal infections (C. diff, MRSA)

Protein Synthesis Inhibitors

Tetracyclines, Macrolides, Clindamycin, Linezolid (Zyvox), Aminoglycosides

Tetracyclines

Drugs: End in “-cycline”

Category: Broad spectrum bacteriostatic

Indication: Acne (PO/topical), H. pylori, periodontal disease, rickettsial diseases, chlamydia, Lyme disease, anthrax

MOA: Inhibits bacterial protein synthesis (binds to calcium in bones & teeth)

ADR: Teratogenic & tooth discoloration in children <8; photosensitivity, hepatotoxicity, nephrotoxicity, superinfections

Note: Take on empty stomach with water; avoid milk, calcium, iron, or antacids; contrainidicated in pregnancy & kids <8

Macrolides

Drugs: End in “-thromycin”

Category: Broad spectrum bacteriostatic

MOA: Inhibits protein synthesis

ADR: Small risk of QT prolongation, GI symptoms, rare allergic rxns, superinfectiosn

Note: Commonly used as alternative for pts. with penicillin allergy; take with food 3-4x/day

Clindamycin

Drugs: End in “-mycin”

Category: Narrow spectrum bacteriostatic

MOA: Inhibits protein synthesis on anaerobic infections outside CNS

ADR: C. diff associated diarrhea (CDAD)

Note: PO, IV, IM, topical (acne only)

Linezolid (Zyvox)

Category: Narrow spectrum bacteriostatic

MOA: Inhibits protein synthesis in a unique way

ADR: Diarrhea, nausea, headache, myelosuppression

Note: Monitor CBC

Aminoglycosides

Drugs: Neomycin & Tobramycin; end in “-micin” or “-cin”

Category: Narrow spectrum bactericidal

MOA: Protein synthesis inhibitor resulting in rapid bacterial death

ADR: Ototoxicity (tinnitus), nephrotoxicity

Monitor: Peak & trough levels, hearing, UO, BUN, creatinine

Note: Given IM or IV; more potent than other antibiotics; narrow therapeutic window

Other Antimicrobials

Sulfonamides & Trimethoprim (TMP/SMX), Fluroquinolones, Metronidazole (Flagyl)

Sulfonamides & Trimethoprim (TMP/SMX)

Drugs: TMP/SMX, Silver sulfadiazine, Mafenide

Category: Broad spectrum

Indication: UTIs

MOA: Disrupts synthesis of tetrahydroflate

ADR: Crystalluria (renal damage), severe hypersensitivity (Stevens-Johnson syndrome), blood dyscrasias

Monitor: Renal fxn, CBC, bleeding

Note: Increase fluid intake to 2000 mL/day

Fluoroquinolones

Drugs: End in “-floxacin”

Category: Broad spectrum

Indication: UTIs & pyelonephritis; skin, bone, resp., genital infections

MOA: Disrupts bacterial DNA replication

ADR: Tendonitis/tendon rupture, photosensitivity, GI upset, CNS effects, superinfections

Metronidazole (Flagyl)

Category: Broad spectrum; antibiotic & antiprotozoal agent

Indication: GI/GU infections, C. diff, trichomoniasis, colorectal surgical prophylaxis

MOA: Disrupts bacterial DNA/biochemical processes

ADR: Disulfiram-like rxn with alcohol (flusing, HTN, n/v), dark urine, metallic taste, GI upset

Note: IV & PO; take with food

Urinary Tract-Specific Agents

Nitrofurantoin (Macrobid), Phenazopyridine (Pyridium)

Nitrofurantoin (Macrobid)

Category: Broad spectrum

MOA: Concentrates urine & acts directly on organisms in urinary tract

ADR: Pulmonary rxns (dyspnea, chest pain, chils/fever), hematologic rxns (agranulocytosis, leukopenia), peripheral neuropathy, hepatotoxicity, GI effects

Monitor: Renal fxn & UO, bowel fxn, resp. status, CBC, liver fxn

Note: Take with food, do not drive or operate machinery, increase fluid intake

Phenazopyridine (Pyridium)

Category: Non-antibacterial/urinary tract symptom relief

MOA: Analgesic effect on urinary tract mucosa

ADR: Discolors urine (red-orange), may stain clothing/contacts

Note: Take until symptoms are gone, available OTC

Antifungals

Polyenes (Amphotericin B), Nystatin, Azoles

Polyenes

Drug: Amphotericin B

Category: Broad spectrum for systemic fungal infections

MOA: Disrupts fungal cell membrane integrity

ADR: Highly nephrotoxic, bone marrow suppression, infusion rxn (fever/chills, nausea, headache, flushing)

Monitor: UO, BUN, creatinine, renal fxn

Note: IV administration

Nystatin

Category: Narrow spectrum

Indication: Used only for Candidas infections (intestinal, oral, esophagus, vaginal)

Administration: PO or topical

Note: Instruct pt. to swish liquid in mouth for several minutes & swallow

Azoles

Drugs: Ends in “-azole”

Category: Broad spectrum

MOA: Inhibits cytochrome P450 enzymes

ADR: Hepatic liver enzyme inhibition, organ toxicity, allergies

Note: Given PO or topically

Antivirals

Antivirals, Antiretrovirals

Antivirals

Drugs: Acyclovir; contain “-vir-”

Indications: First choice for Herpes & Varicella viruses; treatment & prevention of infection, recurrent Herpes Labialis (cold sores)

MOA: Inhibit viral replication (DNA replication), does not kill virus

ADR: Nephrotoxicity, affects renal fxn

Monitor: Kidney fxn, BUN, creatinine, UO

Note: Topical, PO, IV; can be used in pregnancy; encourage fluid intake

Antiretrovirals (HAART)

Drugs:

Indications: HIV/AIDS treatment (HAART/ART); pre-exposure prophylaxis (PrEP); post-exposure prophylaxis (PEP)

MOA: Inhibitd essential HIV replication enzymes (reverse transcriptase, protease, integrase) or viral entry into host cells

ADR: Anemia, neutropenia, GI effects (anorexia, nausea), long-term metabolic side effects, serious drug interactions