narrow therapeutic window
2 interactions related to narrow therapeutic window
alcohol + lithium
Lithium has a narrow therapeutic window and is excreted by the kidneys. Alcohol causes diuresis and dehydration, which reduces renal lithium clearance and raises serum lithium levels — pushing patients toward lithium toxicity (tremor, confusion, ataxia, arrhythmia). Alcohol also worsens mood instability in bipolar disorder.
alcohollithiumbipolarmood stabilizerlithium toxicitydehydrationnarrow therapeutic windowdrug interaction
smoking + theophylline
Polycyclic aromatic hydrocarbons in tobacco smoke induce CYP1A2, increasing theophylline clearance by 58-100% and shortening its half-life by roughly 63%. Smokers often need 1.5-2 times the usual theophylline dose, and abrupt cessation can rapidly produce toxic levels.
smokingtheophyllinecyp1a2asthmacopddrug interactiontobaccosmoking cessationnarrow therapeutic window