Carisoprodol

Pronunciation

Pronunciation: kar-EYE-soe-PROE-dol
Class: Skeletal muscle relaxant, centrally acting

Trade Names

Soma
- Tablets 250 mg
- Tablets 350 mg

Pharmacology

Produces skeletal muscle relaxation, probably as result of its sedative properties.

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Pharmacokinetics

Absorption

Mean T max is 1.5 to 2 h. C max following oral administration of 250 and 350 mg is 1.2 and 1.8 mcg/mL, respectively.

Metabolism

Metabolized in the liver, primarily by CYP2C19, to form meprobamate.

Elimination

t ½ is approximately 2 h.

Onset

Eliminated by renal and nonrenal routes.

Duration

4 to 6 h.

Special Populations

Renal Function Impairment

Pharmacokinetics have not been evaluated.

Hepatic Function Impairment

Pharmacokinetics have not been evaluated.

Gender

Carisoprodol exposure is 30% to 50% higher in women than men; however, meprobamate exposure is not affected by gender.

Race

Individuals with reduced CYP2C19 activity have a 4-fold increase in carisoprodol exposure and a 50% reduced exposure to meprobamate compared with normal CYP2C19 metabolizers. Prevalence of poor metabolizers in white and black patients is approximately 3% to 5% and in Asian patients approximately 15% to 20%.

Indications and Usage

Relief of discomfort associated with acute, painful musculoskeletal conditions in adults.

Contraindications

Acute intermittent porphyria; hypersensitivity to related compounds, such as meprobamate.

Dosage and Administration

Adults

PO 250 to 350 mg 3 times a day and at bedtime.

General Advice

  • Recommended maximum duration of administration is 2 to 3 wk.

Storage/Stability

Store at 59° to 86°F.

Drug Interactions

Alcohol and other CNS depressants

May cause additive CNS depression.

CYP2C19 inducers (eg, rifampin, St. John's wort)

May decrease carisoprodol exposure and increase meprobamate, a metabolite of carisoprodol, exposure.

CYP2C19 inhibitors (fluvoxamine, omeprazole)

May increase exposure to carisoprodol and decrease exposure to meprobamate.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Facial flushing, postural hypotension, syncope, tachycardia (postmarketing).

CNS

Drowsiness (17%); dizziness (8%); headache (5%); agitation, ataxia, depressive reactions, insomnia, irritability, seizures, tremor, vertigo (postmarketing).

GI

Epigastric discomfort, nausea, vomiting (postmarketing).

Hematologic-Lymphatic

Leukopenia, pancytopenia (postmarketing).

Precautions

Monitor

Idiosyncratic response

Monitor for the following signs of idiosyncratic response: agitation, ataxia, disorientation, dizziness, euphoria, extreme weakness, impaired verbal communication, transient quadriplegia, vision disturbances. These reactions may appear within minutes or hours of first dose. Symptoms usually subside over several hours. If such reactions occur, withhold drug.


Pregnancy

Category C .

Lactation

Excreted in breast milk.

Children

Safety and efficacy not established in children younger than 16 yr of age.

Elderly

Safety and efficacy not established in patients older than 65 yr of age.

Renal Function

Use with caution.

Hepatic Function

Use with caution.

Abuse

Administer with caution to patients with history of drug abuse.

Drug dependency

Use with caution in addiction-prone patients.

Sedation

Drug may impair mental and physical abilities required for performance of potentially hazardous tasks such as driving a motor vehicle or operating machinery.

Withdrawal

Withdrawal symptoms have been reported.

Overdosage

Symptoms

Blurred vision, CNS depression, coma, death, delirium, dystonic reactions, euphoria, hallucinations, headache, hypotension, muscular incoordination, mydriasis, nystagmus, respiratory depression, rigidity, seizures.

Patient Information

  • Instruct patient to take last daily dose at bedtime.
  • Tell patient to take medication with meals if GI upset occurs.
  • Instruct patient to report these symptoms to health care provider: ataxia, hiccough, palpitations, tremors.
  • Advise patient to avoid intake of alcoholic beverages or other CNS depressants.
  • Caution patient that drug may cause drowsiness and to use caution while driving or performing other tasks requiring mental alertness.

Copyright © 2009 Wolters Kluwer Health.

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