Description of Meprobamate

Meprobamate is an oral carbamate derivative used as an anxiolytic. It is similar in structure to carisoprodol; in fact, meprobamate is an active metabolite of carisoprodol. Meprobamate is indicated for the treatment of anxiety disorders or for the short-term symptomatic treatment of anxiety in adults and children 6 years and older; however, historically the drug has also been used for its sedative properties.

Due to the availability of other therapies, meprobamate is not considered a treatment of choice for anxiety disorders in adults or pediatric patients. Clinical studies evaluating its effectiveness for prolonged therapy (more than 4 months) have not been conducted. Meprobamate is known to have potential for physical dependence, psychological dependence, and abuse. It was initially marketed in the U.S. in 1955.

Mechanism of Action

Meprobamate’s exact mechanism of action is unknown. It appears to exert CNS-depressive action at several sites in the CNS including the spinal cord, limbic system, hypothalamus, and thalamus. Skeletal muscle relaxation is believed to occur secondary to the sedative effect and is of negligible clinical significance. Overdosage can cause vasomotor and respiratory depression and coma.

Pharmacokinetics of Meprobamate

Meprobamate is administered orally. The drug is distributed throughout the body. Meprobamate crosses the placenta in concentrations similar to maternal plasma concentrations and is distributed into breast milk in amounts 2—4 times those of maternal plasma concentrations (see Contraindications).

Meprobamate is metabolized in the liver to inactive metabolites consisting of 2—hydroxymeprobamate and glucosyluronide and glucuronide conjugates. It is an inducer of hepatic enzymes. The plasma half-life is 10—11 hours. Renal elimination of unchanged meprobamate is approximately 10—12% of a dose within 24 hours, with the remainder occurring as metabolites.

Route-Specific Pharmacokinetics
Oral Route
After oral administration, meprobamate is readily absorbed from the GI tract. Peak plasma concentrations are achieved in 1—3 hours, with the onset of sedation occurring within 1 hour.

• Meprobamate

• Mb-Tab
• Miltown
• Trancot

• Antianxiety
• Carbamate

• Anxiety: Adult
• Anxiety: Pediatric: yes (6 y and older)

Common Effects

• Gastrointestinal: Diarrhea, Nausea, Vomiting
• Neurologic: Asthenia, Ataxia, Dizziness, Headache, Paresthesia, Somnolence, Vertigo

Serious Effects

• Cardiovascular: Cardiac dysrhythmia, Hypotension, Crisis
• Dermatologic: Bullous dermatosis (Rare ), Stevens-Johnson syndrome (Rare )
• Hematologic: Agranulocytosis, Aplastic anemia
• Immunologic: Anaphylaxis (Rare ), Hypersensitivity reaction
• Neurologic: Seizure
• Other: Drug withdrawal

• Oral Tablet: 200 MG, 400 MG

Adult Dose

• Important Note: Beers Criteria: Avoid use as potentially inappropriate in older adults .
• Anxiety: 1200 to 1600 mg/day ORALLY in 3 or 4 divided doses; MAX dose 2400 mg/day

• Important Note: Beers Criteria: Avoid use as potentially inappropriate in older adults .
• General Dosage Information: not recommended for children under age 6
• Anxiety: (ages 6 to 12 y) 200 to 600 mg/day ORALLY in 2 or 3 divided doses