We report 2 cases coinfected with HIV and tuberculosis (HIV/TB), requiring drug dose adjustments guided by therapeutic drug monitoring (TDM) and/or serum drug concentrations.
Case 1: Over the course of the 9-months of TB treatment, drugs that required increased doses due to low concentrations included efavirenz (800 mg), rifampin (900 mg), and isoniazid (450 mg). Higher drug doses were well tolerated until the end of treatment.
Case 2: Over the 12-month course of TB therapy, drugs that required increased doses due to incomplete and/or delayed absorption were rifampin (1500 mg), moxifloxacin (800 mg), and ethambutol (1600 mg). Higher drug doses were well tolerated until the end of treatment. Due to delayed/incomplete drug absorption and weight gain during therapy, higher antituberculous doses may be required in patients coinfected with HIV/TB. A daily dose of efavirenz 800 mg was well tolerated in both patients (weight over 70 kg). Managing patients coinfected with HIV/TB is complex, and, therefore, TDM of drug concentrations can help guide clinical decision making.
Keywords: HIV/TB; antituberculous drugs; drug interactions; efavirenz; therapeutic drug monitoring.
© The Author(s) 2014.