Editing Pharmacology (section)

=== Anti-infectives ===

* Obtain '''cultures before''' the first antibiotic dose whenever feasible, and teach patients to complete the full course.
* '''Penicillins and cephalosporins''': monitor for allergy and anaphylaxis; cross-sensitivity with cephalosporins exists but is lower than historically taught.
* '''Vancomycin''': monitor trough levels and renal function. Infuse over at least 60 minutes; rapid infusion causes an infusion reaction with flushing of the face, neck, and upper torso. Ototoxicity and nephrotoxicity are the main toxicities.
* '''Aminoglycosides''' (gentamicin, tobramycin): nephrotoxic and ototoxic. Monitor peaks, troughs, creatinine, and hearing, and report tinnitus or new hearing loss.
* '''Fluoroquinolones''': tendinitis and tendon rupture, QT prolongation, photosensitivity, and central nervous system effects. Separate from antacids, calcium, iron, and zinc by at least 2 hours.
* '''Tetracyclines and doxycycline''': avoid in pregnancy and in young children because of tooth discoloration; chelated by dairy, antacids, and iron; photosensitivity.
* '''Macrolides''': gastrointestinal upset, QT prolongation, and significant CYP interactions with erythromycin and clarithromycin.
* '''Sulfonamides''' (trimethoprim-sulfamethoxazole): encourage fluids, watch for rash including Stevens-Johnson syndrome, hyperkalemia, and interaction with warfarin.
* '''Metronidazole''': avoid alcohol during therapy and for at least 3 days after because of a disulfiram-like reaction; may cause a metallic taste and dark urine.
* '''Antitubercular therapy''': isoniazid causes peripheral neuropathy, prevented with pyridoxine (vitamin B6), and hepatotoxicity. Rifampin turns urine, sweat, and tears orange, permanently stains soft contact lenses, and reduces the effectiveness of oral contraceptives. Ethambutol causes optic neuritis with changes in visual acuity and red-green color discrimination.