rifampin and Lung-Diseases--Obstructive

Topics: Acquired Immunodeficiency Syndrome; Antitubercular Agents; Dermatitis; Humans; Lung Diseases; Lung Diseases, Obstructive; Lymphadenitis; Male; Mycobacterium Infections; Mycobacterium Infections, Nontuberculous; Nontuberculous Mycobacteria; Rifampin; Risk Factors; Tuberculin Test

Rifampin is known to lower plasma warfarin concentrations by increasing the rate of warfarin clearance. We have described a patient in whom an additional potentiating influence on warfarin effect was observed during treatment with rifampin and isoniazid. After cessation of rifampin and isoniazid, prothrombin time was maintained within the same range by a 50% reduction of warfarin doses, despite a twofold rise in the plasma warfarin concentration. This rise in warfarin concentrations can be explained by the known mechanism by which rifampin increases warfarin clearance. After cessation of rifampin, warfarin fractional clearance decreased from 15.2 to 4.2 ml/min; however, the unchanged prothrombin time in the face of the increased warfarin concentration can be explained only by the removal of a potentiating effect that had been present during the coadministration of rifampin and isoniazid. It is likely that rifampin is responsible for this additional potentiating interaction, probably not through a change in warfarin binding, but through a differential effect on warfarin stereoisomer metabolism or through an altered dynamic effect. The role of isoniazid in this interaction cannot be completely ruled out.

Topics: Adult; Drug Administration Schedule; Drug Synergism; Drug Therapy, Combination; Female; Humans; Isoniazid; Lung Diseases, Obstructive; Prothrombin Time; Rifampin; Stimulation, Chemical; Tuberculosis, Pulmonary; Warfarin

This paper reports a case of tuberculosis relapse and chronic obstructive lung disease treated with rifampicin and isoniazid. The subsequent introduction of slow-release theophylline therapy revealed a delay in the theophylline elimination kinetics resulting in a toxic plasma level. Interference with hepatic microsomal enzymes is considered to occur.

Topics: Delayed-Action Preparations; Drug Interactions; Drug Therapy, Combination; Humans; Isoniazid; Lung Diseases, Obstructive; Male; Middle Aged; Recurrence; Rifampin; Theophylline; Time Factors; Tuberculosis, Pulmonary

Theophylline pharmacokinetics were studied before and after rifampicin administration (600 mg daily for 1 wk). Rifampicin reduced the area under the concentration-time curve by 18% after the oral administration of sustained release aminophylline (450 mg) to 7 normal subjects (p less than 0.05) and increased the metabolic clearance and volume of distribution by 45% (p less than 0.05) and 17% (p less than 0.05), respectively, after the intravenous administration of aminophylline (5 mg/kg over 30 min) to 8 normal subjects. These findings are consistent with an inducing and choleretic effect of rifampicin on theophylline disposition. In patients receiving theophylline, blood levels should be monitored closely and dosage adjusted if rifampicin therapy is introduced or withdrawn.

Topics: Adult; Asthma; Drug Interactions; Humans; Kinetics; Lung Diseases, Obstructive; Male; Rifampin; Theophylline

Topics: Aged; Aortic Valve Stenosis; Chemical and Drug Induced Liver Injury; Humans; Isoniazid; Liver; Lung Diseases; Lung Diseases, Obstructive; Male; Mycobacterium Infections; Rifampin