Tetrabenazine

Adults: You can take Tetrabenazine with or without food. The dose has to be set for each patient, with careful weekly titration. In the 1st week the starting dose is 12.5 mg daily. In the 2nd week it goes up to 25 mg, given as 12.5 mg twice daily. After that, increase slowly at weekly intervals by 12.5 mg, until you reach a dose the patient tolerates that reduces chorea. Doses of 37.5 mg and up to 50 mg per day should be given in three divided doses, and no single dose should be more than 25 mg. Patients who need more than 50 mg per day should be genotyped for the drug-metabolizing enzyme CYP2D6, to find out whether they are poor metabolizers or extensive metabolizers. In poor metabolizers the maximum daily dose is 50 mg, with a maximum single dose of 25 mg. In extensive and intermediate metabolizers the maximum daily dose is 100 mg, with a maximum single dose of 37.5 mg. If serious adverse reactions occur, stop the titration and lower the dose. If the adverse reactions don't resolve, consider withdrawing Tetrabenazine. Pediatric and geriatric use: safety and effectiveness in pediatric patients have not been established. The pharmacokinetics of Tetrabenazine and its primary metabolites have not been formally studied in geriatric subjects.