Carisoprodol elimination in humans

Area of Science:

• Pharmacology
• Drug Metabolism

Background:

• Carisoprodol is a widely prescribed muscle relaxant.
• Understanding its metabolic pathways and elimination is crucial for clinical application.

Purpose of the Study:

• To investigate the elimination and metabolic conversion of carisoprodol in healthy volunteers.
• To assess the potential contribution of meprobamate to carisoprodol's effects.

Main Methods:

• Administered an oral dose of 700 mg carisoprodol to 10 healthy volunteers.
• Measured carisoprodol and meprobamate serum concentrations over time.
• Determined drug half-life and protein binding.

Main Results:

• Nine subjects rapidly eliminated carisoprodol (mean half-life 99 min) and extensively converted it to meprobamate.
• Meprobamate serum levels exceeded carisoprodol levels within 2.5 hours in most subjects.
• One subject, a poor mephenytoin metabolizer, showed prolonged carisoprodol elimination and minimal meprobamate formation.
• Carisoprodol protein binding ranged from 41-67%, while meprobamate binding was lower (14-24%).

Conclusions:

• Carisoprodol is extensively metabolized to meprobamate, which may contribute to its therapeutic effects.
• Genetic variations in metabolism (e.g., poor mephenytoin metabolizers) can significantly alter carisoprodol elimination.
• These findings highlight inter-individual variability in carisoprodol pharmacokinetics.