Pharmacology of Antibiotics, Antifungals, and Antivirals: Mechanisms, Uses, and Side Effects

Penicillin

Bacterial infections (strep, pneumonia, ear infections) | Kills bacteria by breaking cell wall | Allergic reactions | Oral contraceptives

Amoxicillin

Respiratory, ear, sinus, urinary infections | Kills bacteria by breaking cell wall | Rash/diarrhea | Oral contraceptives/warfarin

Amoxicillin-Clavulanate (Augmentin)

Resistant bacterial infections | Kills bacteria + blocks bacterial enzymes | Diarrhea/nausea | Warfarin

Cephalexin (Keflex)

Respiratory, skin, urinary infections | Inhibits bacterial cell wall synthesis | Allergic reactions/diarrhea | Alcohol/anticoagulants

Sulfamethoxazole/Trimethoprim (Bactrim)

UTIs, respiratory infections | Blocks bacterial folic acid synthesis | Rash/photosensitivity | Warfarin/sulfonylureas

Levofloxacin

Fluoroquinolone | Respiratory, urinary, skin infections | Inhibits bacterial DNA replication | Tendon rupture/GI upset | Antacids/warfarin

Azithromycin

Macrolide | Respiratory infections, STIs | Inhibits bacterial protein synthesis | GI upset/QT prolongation | Warfarin/statins

Gentamicin

Aminoglycoside | Severe gram-negative infections | Inhibits bacterial protein synthesis | Nephrotoxicity/ototoxicity | Loop diuretics/other nephrotoxic drugs

Doxycycline

Tetracycline | Acne, respiratory infections, Lyme disease | Inhibits bacterial protein synthesis | Photosensitivity/teeth staining | Antacids/iron supplements/oral contraceptives

Amphotericin B

Antifungal | Severe systemic fungal infections | Binds fungal cell membrane → kills fungi | Nephrotoxicity/infusion reactions | Other nephrotoxic drugs

Fluconazole

Antifungal | Candida infections, systemic fungal infections | Inhibits fungal cell membrane synthesis | GI upset/liver toxicity | Warfarin/antidiabetics

Nystatin

Antifungal | Oral or topical candidiasis | Binds fungal cell membrane → kills fungi | Local irritation/nausea | Minimal

Acyclovir

Antiviral | Herpes simplex/shingles | Inhibits viral DNA replication | Nephrotoxicity/headache | Other nephrotoxic drugs

Tamiflu (Oseltamivir)

Antiviral | Influenza | Inhibits viral neuraminidase → prevents virus release | Nausea/vomiting | Minimal

Antiretrovirals (general)

HIV/AIDS | Inhibit viral replication | GI upset/liver toxicity | Many (other antivirals, antibiotics, antifungals)

Vancomycin

Glycopeptide | MRSA, serious gram-positive infections | Inhibits bacterial cell wall synthesis | Nephrotoxicity/ototoxicity/Red-man syndrome | Other nephrotoxic/ototoxic drugs