Pharmacokinetic and Bioequivalence Comparison of Baclofen and Chlorzoxazone Administered Individually or Concurrently

Combination treatment with baclofen and chlorzoxazone (CHZ) is under investigation for the treatment of spinocerebellar ataxia types 1 and 2. Achievement of therapeutic benefit with this combination approach requires that effective concentrations of both agents reach the systemic circulation, and ultimately reach the intended pharmacologic target. This in turn requires understanding of the clinical pharmacokinetic properties of both drugs when administered individually, as well as knowledge of the extent to which the agents might interact when given concurrently. Study Objectives: 1. To evaluate the pharmacokinetic properties of baclofen and CHZ when administered as individual entities at separate times, using customary clinical doses. 2. To compare the pharmacokinetic properties, and assess the bioequivalence, of each drug administered separately compared to administration of the two drugs concurrently. 3. To assess adverse events attributed to the two drugs when administered separately or together.