Carisoprodol

• Acute Musculoskeletal Pain:
  Carisoprodol is indicated as a short-term (typically up to 2–3 weeks) adjunct to rest, physical therapy, and other treatments for acute, painful musculoskeletal conditions such as muscle spasms or strains.
• Off-label / Clinically Accepted Uses:
• Muscle spasm relief in chronic musculoskeletal disorders (use with caution).
• Adjunctive treatment in tension-type headaches with muscle involvement (limited evidence).

• Route: Oral.
• Adults:
• Usual dose: 250 mg to 350 mg taken 3 times daily and at bedtime.
• Maximum daily dose: 1,500 mg.
• Duration: Generally limited to 2–3 weeks due to lack of evidence for long-term efficacy and potential for dependence.
• Elderly:
• Use lower doses or extended dosing intervals due to increased sensitivity and risk of sedation.
• Pediatrics:
• Safety and efficacy not established; use generally not recommended.
• Renal/Hepatic Impairment:
• Use with caution; dosage adjustment may be necessary in severe impairment due to slower metabolism and elimination.
• Administration Notes:
• Can be taken with or without food.
• Avoid alcohol and other CNS depressants during treatment.

Carisoprodol acts centrally in the nervous system to produce muscle relaxation, though its precise mechanism is not fully understood. It is believed to interrupt neuronal communication within the reticular formation and spinal cord, leading to sedation and alteration of interneuronal activity, which reduces skeletal muscle spasms. Its major active metabolite, meprobamate, has anxiolytic and sedative properties contributing to the overall muscle relaxant effect.

• Absorption: Rapidly absorbed from the gastrointestinal tract; peak plasma concentration occurs within 1.5 hours.
• Distribution: Widely distributed in body tissues; crosses the blood-brain barrier.
• Metabolism: Primarily metabolized in the liver via CYP2C19 to active metabolite meprobamate.
• Elimination:
• Half-life of carisoprodol: approximately 2 hours.
• Half-life of meprobamate: 10 hours or longer, contributing to prolonged effects.
• Excreted mainly via the kidneys as metabolites.

• Pregnancy:
• FDA Category C — animal studies have shown adverse effects; no adequate human studies. Use only if potential benefit justifies potential risk.
• Lactation:
• Excreted in breast milk; potential for sedation and respiratory depression in nursing infants.
• Breastfeeding not recommended during treatment.

• Primary Class: Skeletal muscle relaxant
• Subclass: Centrally acting muscle relaxant

• Known hypersensitivity to carisoprodol, meprobamate, or related compounds.
• Acute intermittent porphyria.
• History of drug abuse or dependence due to abuse potential.
• Severe hepatic or renal impairment (relative contraindication).

• Risk of dependence, abuse, and addiction; use only as prescribed and for short duration.
• CNS depressant effects including sedation, dizziness, and impaired motor skills; avoid driving or hazardous activities.
• Potential for respiratory depression, especially when combined with other CNS depressants or alcohol.
• Use caution in elderly or debilitated patients due to increased sensitivity.
• Abrupt discontinuation after prolonged use may cause withdrawal symptoms.
• Use caution in patients with seizure disorders; may lower seizure threshold.

Common:

• Drowsiness, dizziness, headache, nausea, vomiting, lightheadedness, somnolence.

Less Common:

• Anxiety, tremor, confusion, ataxia, rash, hypotension.

Serious (Rare):

• Seizures, respiratory depression, severe allergic reactions, dependence, withdrawal syndrome.

• Alcohol: Potentiates CNS depressant effects; concomitant use contraindicated.
• Other CNS depressants: Additive sedation with benzodiazepines, opioids, barbiturates, antihistamines.
• CYP2C19 inhibitors/inducers: May alter metabolism of carisoprodol and meprobamate, affecting plasma levels.
• CYP3A4: Minor involvement; monitor for interactions with strong inhibitors/inducers.

• Recent guidelines emphasize limiting carisoprodol use to short-term therapy due to abuse potential.
• Some regulatory agencies have reclassified carisoprodol as a controlled substance in multiple countries.
• Increased awareness of dependence risk has led to recommendations for careful patient selection and monitoring.

• Store at 20°C to 25°C (68°F to 77°F).
• Protect from moisture and light.
• Keep container tightly closed.
• Keep out of reach of children.