Antibiotic Toxicities: The Big 5
Aminoglycosides (gentamicin, tobramycin, amikacin): nephrotoxicity (tubular damage, non-oliguric ATN) + ototoxicity (irreversible cochlear and vestibular damage). Monitor trough levels. Avoid with loop diuretics (additive ototoxicity). Vancomycin: Red Man Syndrome (not allergic) — flushing, pruritus, erythema from histamine release during rapid infusion; treat by slowing infusion rate ± diphenhydramine. Nephrotoxicity especially with aminoglycosides. Monitor trough (15-20 mg/L for serious infections). Tetracyclines (tetracycline, doxycycline, minocycline): chelate divalent cations (take away from dairy/antacids), photosensitivity, GI upset. Contraindicated in pregnancy (teeth/bone) and children <8. Exception: doxycycline can be used in renal failure (fecal excretion). Fluoroquinolones (ciprofloxacin, levofloxacin): tendinopathy/tendon rupture (especially Achilles, in elderly + steroid users), QT prolongation, CNS effects (seizures, confusion), contraindicated in pregnancy and children. Chloramphenicol: Gray Baby Syndrome (neonates lack glucuronosyltransferase for conjugation) — cardiovascular collapse, gray discoloration; aplastic anemia (idiosyncratic, rare, fatal).
Cardiac Drug Toxicities
Amiodarone ('the drug with 100 side effects'): pulmonary fibrosis (most dangerous — baseline and annual PFTs/CXR), hepatotoxicity (LFTs), hypothyroidism OR hyperthyroidism (40% iodine by weight), corneal microdeposits (almost universal, usually asymptomatic), photosensitivity (blue-gray skin), peripheral neuropathy. Monitor: TFTs, LFTs, CXR/PFTs. Half-life: 40-55 days. Digoxin toxicity: nausea/vomiting/visual changes ('yellow-green halos,' xanthopsia) are early signs. Cardiac: any arrhythmia, especially PVCs and junctional tachycardia with AV block (pathognomonic). Risk factors: hypokalemia (hypokalemia displaces digoxin from Na-K ATPase, potentiates toxicity), hypomagnesemia, renal failure. Treat: digoxin-specific Fab fragments (Digibind). Statins: myopathy/rhabdomyolysis (CK elevation, myalgias — most with simvastatin, least with pravastatin); hepatotoxicity; teratogenic (Category X in pregnancy). Highest risk: simvastatin + gemfibrozil combination. Thiazide diuretics: hypokalemia, hyponatremia, hyperuricemia (gout), hyperglycemia, hypercalcemia, hyperlipidemia. Mnemonic: 'HyperGLUC' (glucose, lipids, uric acid, calcium) up; K+ down.
CNS and Psych Drug Toxicities
TCAs (tricyclic antidepressants): anticholinergic effects (dry mouth, urinary retention, constipation, blurred vision, tachycardia — 'hot as a hare, dry as a bone, blind as a bat, mad as a hatter'), sedation, orthostatic hypotension. OD: prolonged QRS (sodium channel blockade → wide complex arrhythmia), seizures, hypotension. Treat OD with sodium bicarbonate (alkalinizes plasma, reverses Na channel block). Lithium toxicity: narrow therapeutic window (0.8-1.2 mEq/L therapeutic; >1.5 early toxicity; >2.0 severe). Signs: TREMOR (fine tremor first, then coarse) + nephrogenic DI (polyuria/polydipsia, NDI) + hypothyroidism. Acute toxicity: GI (N/V/D). Chronic toxicity: neurologic (ataxia, confusion, seizures). Triggers: NSAIDs, ACE inhibitors, dehydration (all increase lithium levels). Antipsychotics (typical — haloperidol, chlorpromazine): EPS = extrapyramidal symptoms. Acute dystonia (hours-days — treat with diphenhydramine/benztropine), akathisia (restlessness — treat with propranolol/benzodiazepines), parkinsonism (weeks — treat with benztropine), tardive dyskinesia (months-years — perioral movements, choreoathetosis, largely irreversible). NMS (Neuroleptic Malignant Syndrome): hyperthermia + rigidity + altered mental status + autonomic instability — treat with dantrolene + bromocriptine + supportive care.
Chemotherapy Toxicities
Bleomycin: pulmonary fibrosis (dose-limiting) + Raynaud phenomenon. Avoid high FiO2 intraoperatively (oxygen worsens pulmonary toxicity). Doxorubicin (Adriamycin): dilated cardiomyopathy (dose-dependent — limit cumulative dose), + alopecia, myelosuppression. Mnemonic: 'A for Adriamycin = Arrhythmia/cardiomyopathy.' Cisplatin: nephrotoxicity (ATN — pre-hydrate with NS to prevent) + peripheral neuropathy + ototoxicity. Mnemonic: Cisplatin = Cistern (kidney) damage. Cyclophosphamide: hemorrhagic cystitis (acrolein metabolite irritates bladder — prevent with mesna + hydration), SIADH, bladder cancer risk with prolonged use. Methotrexate: myelosuppression + mucositis + hepatotoxicity (cirrhosis with long-term use). Leucovorin rescue limits toxicity. Vincristine: peripheral neuropathy (dose-limiting) + SIADH; notably does NOT cause myelosuppression (distinguishes it from other chemo agents).