Generic Soma

 

 

Mode of Action

It is unclear how Soma Carisoprodol works to reduce discomfort caused by acute painful musculoskeletal conditions. Animal studies have shown that it brings muscle relaxation by acting upon altered interneuronal activity in the spinal cord and in the descending reticular formation of the brain.

Pharmacodynamics

This medication does not directly lead to skeletal muscles relaxation. Meprobamate, has anxiolytic and sedative compounds that metabolize this drug. The level to which these properties of meprobamate donate to the safety and efficacy of SOMA has not been identified.

Pharmacokinetics

A study was made on the pharmacokinetics of carisoprodol and its metabolite meprobamate in which 24 healthy subjects (12 male and 12 female) were administered single doses of 250 mg and 350 mg SOMA.

The revelation of carisoprodol and meprobamate was dose relative between the 250 mg and 350 mg doses. The Cmax of meprobamate was 2.5 ± 0.5 ug/mL (mean ± SD) after administration of a single 350 mg dose of SOMA, which is about 30% of the Cmax of meprobamate (approximately 8 ug/mL) after given of a single 400 mg dose of meprobamate.

Table 2. Pharmacokinetic Parameters of Carisoprodol and Meprobamate (Mean ± SD, n=24)

 

	250 mg SOMA	350 mg SOMA
Carisoprodol
Cmax (µg/mL)	1.2 ± 0.5	1.8 ± 1.0
AUC inf (µg*hr/mL)	4.5 ± 3.1	7.0 ± 5.0
Tmax (hr)	1.5 ± 0.8	1.7 ± 0.8
T 1/2 (hr)	1.7 ± 0.5	2.0 ± 0.5
Meprobamate
Cmax (µg/mL)	1.8 ± 0.3	2.5 ± 0.5
AUC inf (µg*hr/mL)	32 ± 6.2	46 ± 9.0
Tmax (hr)	3.6 ± 1.7	4.5 ± 1.9
T 1/2 (hr)	9.7 ± 1.7	9.6 ± 1.5

Absorption

Absolute bioavailability of this drug has not been identified. The mean time to peak plasma concentrations (Tmax) of carisoprodol was approximately 1.5 to 2 hours. A high-fat meal when taken with SOMA (350 mg tablet), it showed no effect on the pharmacokinetics of carisoprodol. Consequently, SOMA may be taken with or without food.

Metabolism

This drug is mainly metabolized by the liver by cytochrome enzyme CYP2C19 to form meprobamate. This enzyme displays genetic polymorphism.

Elimination

This medication is abolished by both renal and non-renal routes with a terminal elimination half-life of around 2 hours. In case of meprobamate , the half-life is about 10 hours.

Gender

Exposure of carisoprodol is greater in female than in male subjects (about 30-50% on a weight adjusted basis). Overall exposure of meprobamate is equivalent between female and male subjects.

Patients with Reduced CYP2C19 Activity

Caution is needed in patients with reduced CYP2C19 activity while using SOMA. Published studies specify that patients who are poor CYP2C19 metabolizers show a 4-time rise in exposure to carisoprodol, and concomitant 50% reduced exposure to meprobamate compared to normal CYP2C19 metabolizers. The prevalence of poor metabolizers in Caucasians and African Americans is just about 3-5% and in Asians is around 15-20%.