Albendazole: a-tubulin inhibitor. Used for neurocysticercosis, ascariasis, and other helminth infections. Possible side effects: abdominal pain, increased liver enzymes/fat, anorexia, somnolence, and erythema multiforme.
Praziquantel: increases calcium permeability in parasites. Used for cysticercosis, schistosomiasis, and taeniasis. Possible side effects: abdominal pain, nausea, headache, dizziness, and meningismus.
Suramin, nifurtimox: inhibit enzymes (oligopeptidases) in trypanosomes. Used for trypanosomiasis. Possible side effects: nephrotoxicity, neurotoxicity, and fever.
Chloroquine: concentrates in parasite food vacuoles and inhibits heme polymerization and DNA synthesis. Long half-life (30-60 days). Used for malaria. Possible side effects: visual disorders, arrhythmias, convulsions, and pigmentation of the nail matrix and mucous membranes.
Ivermectin: enhances GABA-mediated chloride channel activity. Plasma protein binding 93%. Used for onchocerciasis, Strongyloides infection, larva migrans, scabies, and lice. Possible side effects: itching, swelling of lymph nodes, and Mazzotti reaction.
Metronidazole: forms cytotoxic nitro radicals that damage DNA. Bioavailability 99%. Used for trichomoniasis, amebiasis, giardiasis, and anaerobic infections. Possible side effects: nausea, vomiting, epigastric discomfort, dizziness, metallic taste, and disulfiram-like reactions.
Primaquine: inhibits dihydrofolate reductase and parasite DNA synthesis, and prevents schizont formation. Used for suppressive treatment of malaria.
Pyrantel: acts as a nicotinic cholinergic receptor agonist, causing paralysis. Used for Ascaris, Enterobius, and Ancylostoma. Possible side effects: headache, dizziness, and fever.
Antibacterial Drugs
Gentamicin: inhibits the 30S ribosomal subunit. Plasma protein binding 10%. Half-life 2-4 hours. Resistance: plasmid-mediated enzymes.
Dapsone: interferes with folate synthesis in bacteria. Resistance: changes in dihydropteroate synthase.
Rifampicin: inhibits RNA synthesis by blocking bacterial RNA polymerase. Penetrates the cerebrospinal fluid. Half-life 1-5 hours. Used for Mycobacterium tuberculosis. Resistance: mutations in the RNA polymerase binding site.
Penicillin V: inhibits transpeptidation of peptidoglycan (glycine-D-alanine). Tubular elimination, half-life 22 hours. Possible side effects: conjunctival irritation, hemolysis, and reversible anemia. Resistance: mutations in transpeptidase and production of beta-lactamases. Used for Streptococcus pyogenes. Mechanism of resistance: beta-lactam ring is broken.
Ceftriaxone: inhibits cell wall transpeptidation. Administered IM or IV, penetrates the cerebrospinal fluid, half-life 8 hours. Used for Neisseria infections.
Doxycycline: inhibits the 30S subunit and prevents protein synthesis.
Isoniazid: inhibits mycolic acid synthesis. Possible side effects: myelosuppression and neurotoxicity. Resistance: mutations in catalase-peroxidase (KatG), which activates the prodrug. Acetylation is rapid or slow; half-life 1 hour.
Amikacin: blocks protein synthesis (30S subunit). Oral absorption is poor (60-100%). Accumulates in fluids and is excreted in urine. Used for infections caused by bacilli resistant to gentamicin.
Norfloxacin (ciprofloxacin): inhibits DNA gyrase in gram-negative bacteria. Possible side effects: diarrhea, neuropathy, and retinopathy. Used for E. coli infections.
Chloramphenicol: inhibits the 50S subunit and protein synthesis. Bioavailability 80%. Absorption is slowed by milk and it penetrates the prostate. Used for shigellosis.
Erythromycin: inhibits protein synthesis (peptidyl transferase). Bioavailability 35%, first-pass metabolism. Possible side effects: neurological effects and digestive upset. Resistance: mutations in bacterial rRNA.
Sulfamethoxazole-trimethoprim (SMX-TMP): inhibits folic acid synthesis in bacteria. Used for urinary tract infections (E. coli). Half-life varies; biotransformed by glucuronidation.
Antifungal Drugs
Azoles: inhibit 14-alpha demethylase and ergosterol synthesis. Bioavailability 50%, plasma protein binding 99%, half-life 21 hours. Used for mucormycosis, blastomycosis, histoplasmosis, coccidioidomycosis, and cryptococcal meningitis. Possible side effects: gynecomastia and impotence.
Flucytosine: converted to 5-fluorouracil, which inhibits thymidylate synthase and DNA synthesis. Used for cryptococcosis (including in AIDS patients). Eliminated in urine, half-life 3-6 hours. Possible side effects: leukopenia and thrombocytopenia from myelosuppression.
Amphotericin B: binds to ergosterol and forms pores in the membrane. Used for aspergillosis, candidiasis, coccidioidomycosis, and mucormycosis. IV administration with deoxycholate; half-life 24-50 hours. Possible side effects: phlebitis, azotemia, anemia, and nephrotoxicity.
Griseofulvin: alters the mitotic spindle (microtubules). Used for Trichophyton, Microsporum, and Epidermophyton infections. Deposits in keratinocytes; half-life 24 hours. Interacts with warfarin and reduces the effectiveness of oral contraceptives.
Toxicology and Antidotes
Carbon monoxide (CO): binds to hemoglobin with greater affinity than oxygen, impairing oxygen transport. Clinical features: cherry-red skin, hyperpnea, and convulsions. Treatment: hyperbaric oxygen.
Ozone: causes desquamation, degeneration, and edema of the bronchial epithelium. Treatment: endotracheal intubation. Clinical features: rapid respiration, coughing, and chest tightness. Treatment: supportive care.
Cyanide: inhibits cellular respiration by blocking the use of oxygen. Clinical features: hyperpnea, almond odor, and Cheyne-Stokes respiration. Treatment: oxygen, amyl nitrite, hydroxocobalamin, and sodium thiosulfate.
Acetaminophen: causes cell death and depletes glutathione. Clinical features: hepatomegaly, jaundice, gastric irritation, and respiratory insufficiency. Treatment: gastric lavage and N-acetylcysteine.
