(carisoprodol)
Tablets, USP
DESCRIPTION
`SOMA' (carisoprodol) Tablets, USP is available as 350 mg round, white tablets.
Chemically, carisoprodol is N-isopropyl-2-methyl-2-propyl-1,3-propanediol dicarbamate.
Carisoprodol is a white, crystalline powder, having a mild, characteristic odor and a bitter
taste. It is very slightly soluble in water; freely soluble in alcohol, in chloroform, and in
acetone; its solubility is practically independent of pH. Carisoprodol is present as a
racemic mixture. The molecular formula is C 12 H 24 N 2 O 4 , with a molecular weight of
260.33. buy carisoprodol
OVERDOSAGE
Overdosage of carisoprodol produces CNS depression, and in severe cases coma. Shock,
respiratory depression, seizures and death have also been reported rarely. The following
signs and symptoms may be associated with carisoprodol overdosage: horizontal and
vertical nystagmus, blurred vision, mydriasis, mild tachycardia and hypotension,
respiratory depression, euphoria, CNS stimulation, muscular incoordination, and/or
rigidity, confusion, headache, hallucinations, and dystonic reactions. The effects of an
overdosage of carisoprodol and alcohol or other CNS depressants or psychotropic agents
can be additive even when one of the drugs has been taken in the usual recommended
dosage. Fatal accidental and non-accidental overdoses have been reported alone or in
combination with alcohol or psychotropic drugs. buy carisoprodol
DOSAGE AND ADMINISTRATION
The usual adult dosage of `SOMA' (carisoprodol) Tablets, USP is one 350 mg tablet,
three times daily and at bedtime. Usage in patients under age 12 is not recommended. buy carisoprodol
Absorption, Distribution, Metabolism, Excretion
Following a single oral dose of carisoprodol, the time to maximum concentration (Tmax)
was 1.98 ± 1.16 hours and the terminal elimination half-life was 2.44 ± 0.93 hours. By
normalizing to a single 350 mg carisoprodol tablet, the mean peak plasma concentration
(Cmax) was 2.29 ±- 0.68 ug/mL, the area under the plasma level time curve (AUC 0-∞ )
was 10.33 ± 3.87 ug/mL* hour, and the oral clearance (Cl/F) was 39.52 ± 16.83 L/hour.
The mean Cmax of metabolite, meprobamate, was 2.08 ± 0.48 ug/mL, a subtherapeutic
concentration when compared to a plasma concentration of a single oral meprobamate
400 mg tablet which would yield a meprobamate concentration of approximately 8.0
ug/mL.
Pharmacokinetics
Absorption
The pharmacokinetics of carisoprodol was determined in a small in vivo biostudy of 5
men and 5 women. When the dose was normalized to 350 mg, the mean peak plasma
concentration (Cmax) achieved was 2.29 ± 0.68 ug/mL. Women tended to reach peak
plasma concentrations earlier than men (1.45 vs. 2.5 hours) and had a faster apparent oral
clearance (0.772 vs. 0.38 L/hour/kg). The clinical significance of these findings is
unknown and they may in part be due to the small number of subjects present in the trial.
Metabolism
Carisoprodol is metabolized in the liver via cytochrome P450 enzyme, CYP2C19. This
enzyme exhibits genetic polymorphism. For example, 15-20% of Asian populations may
be expected to be poor metabolizers. For Caucasians and Blacks, the prevalence of poor
metabolizers is 3-5%. Following a single 350 mg dose of carisoprodol, the
corresponding normalized peak concentration of meprobamate, which is a metabolite of
carisoprodol, was 2.08 ± 0.48 ug/mL. These levels are approximately ¼ of those seen
following a single 400 mg dose of meprobamate.
Elimination
Carisoprodol is eliminated by both renal and non-renal routes with a terminal elimination
half-life of 2.44 ± 0.93 hours. It is dialyzable by peritoneal and hemodialysis.
Special Populations
The pharmacokinetic profile of carisoprodol in patients with renal impairment or hepatic
impairment has not been evaluated. Because carisoprodol is metabolized by the liver and
excreted by the kidneys, possible increased exposure of carisoprodol is expected if
hepatic and/or renal function is impaired. The drug should be used with caution in
patients with impaired hepatic or renal function.
CLINICAL PHARMACOLOGY
Carisoprodol is a centrally acting skeletal muscle relaxant that does not directly relax
tense skeletal muscles in man. The mode of action of carisoprodol in relieving acute
muscle spasm of local origin has not been clearly identified, but may be related to its
sedative properties. In animals, carisoprodol has been shown to produce muscle
relaxation by blocking interneuronal activity and depressing transmission of polysynaptic
neurons in the spinal cord and in the descending reticular formation of the brain. The
onset of action is rapid and lasts four to six hours.
Carisoprodol is metabolized in the liver and is excreted by the kidneys. One of the
products of metabolism, meprobamate, is active as an anxiolytic. The degree to which it
contributes to the efficacy of carisoprodol is unknown. Carisoprodol is dialyzable by
peritoneal and hemodialysis.
