narrow therapeutic index
2 interactions related to narrow therapeutic index
caffeine + theophylline
Caffeine and theophylline are closely related methylxanthines that share the CYP1A2 metabolic pathway and act on the same adenosine receptors. Taking them together can slow theophylline clearance and add to its stimulant and cardiovascular effects, which matters because theophylline has a very narrow safety margin.
caffeinetheophyllinemethylxanthineasthmacopdcyp1a2narrow therapeutic indextoxicity
lithium + caffeine
Caffeine increases the kidneys' clearance of lithium, so a steady caffeine habit is effectively built into your lithium dose. The risk is sudden change: stopping caffeine abruptly can push lithium levels up toward the toxic range, while sharply increasing caffeine can lower levels and let mood symptoms return.
lithiumcaffeinebipolar disorderrenal clearancedrug monitoringpsychiatric medicationcoffeenarrow therapeutic index