Case report: interaction of rifampin and nortriptyline.

Rifampin is well documented to cause numerous clinically significant drug interactions because of its induction of the hepatic cytochrome P450 system. The metabolism of nortriptyline and other tricyclic antidepressants is induced and inhibited by this enzyme system. To the authors' knowledge, this is only the second case report in the literature regarding a possible interaction between rifampin and a tricyclic antidepressant. Nortriptyline serum concentrations were not detectable while rifampin was given concurrently. Two weeks after discontinuation of rifampin, nortriptyline concentrations increased dramatically. Further study of this possible interaction is warranted.

Quinolones: a practical review of clinical uses, dosing considerations, and drug interactions.

A review of the literature on quinolones reveals numerous clinically relevant points regarding indications, dosing considerations, and drug interactions. Quinolones are useful in the treatment of several infectious diseases. Unfortunately, indiscriminate use of these valuable antimicrobials has resulted in increased patterns of resistance. It is important to consider carefully the site of infection and the potential pathogens in each patient before dosing. Quinolones have excellent oral absorption, with peak serum concentrations approaching those achieved with intravenous administration. When prescribing quinolones, the dose should be based on estimated creatinine clearance. Quinolones are associated with several clinically significant drug interactions. Some of these agents are well-documented inhibitors of hepatic metabolism of theophylline, caffeine, and warfarin. It has been well documented that divalent and trivalent cations in antacids, sucralfate, and some other products significantly reduce the absorption of quinolones. Avoidance or proper management of these interactions is required to ensure optimal safety and efficacy.