MILTOWN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MILTOWN (MILTOWN).
Miltown (meprobamate) is a carbamate derivative that acts as a central nervous system depressant. Its mechanism of action is not fully understood, but it is believed to exert its effects by modulating GABAergic neurotransmission, possibly by binding to GABA receptors and enhancing inhibitory neurotransmission. It also has sedative, anxiolytic, and muscle relaxant properties.
| Metabolism | Primarily hepatic metabolism via CYP2C19 and other unidentified pathways; metabolites are excreted in urine. |
| Excretion | Primarily renal, with 10-20% excreted unchanged; remainder as inactive metabolites (e.g., hydroxymeprobamate). Less than 2% fecal. |
| Half-life | 10 hours (range 6-17 hours); prolonged in hepatic or renal impairment. |
| Protein binding | 20% bound to albumin. |
| Volume of Distribution | 0.7 L/kg; distributes widely, including CNS. |
| Bioavailability | Oral: 90% (well absorbed); IM: comparable to oral. |
| Onset of Action | Oral: 30-60 minutes; IM: 15-30 minutes. |
| Duration of Action | 6-8 hours for anxiolytic effect; longer with hepatic dysfunction. |
400 mg orally 3-4 times daily; maximum 2400 mg/day.
| Dosage form | TABLET |
| Renal impairment | GFR 10-50 mL/min: administer 50% of usual dose; GFR <10 mL/min: use not recommended. |
| Liver impairment | Child-Pugh Class A: no adjustment; Class B: reduce dose by 50%; Class C: contraindicated. |
| Pediatric use | Children 6-12 years: 100-200 mg orally 2-4 times daily; maximum 1200 mg/day. Not recommended under 6 years. |
| Geriatric use | Initiate at 200 mg orally twice daily; increase gradually based on response and tolerability; maximum 1200 mg/day. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for MILTOWN (MILTOWN).
| Breastfeeding | Meprobamate is excreted into breast milk. M/P ratio is approximately 2-4. Concentrations in milk may reach 2-4 times maternal plasma levels. Risk of sedation and poor feeding in the infant. Use while breastfeeding is not recommended. |
| Teratogenic Risk | Miltown (meprobamate) is Pregnancy Category D. First trimester: Increased risk of congenital malformations, particularly cardiovascular defects and cleft lip/palate. Second and third trimesters: Risk of neonatal withdrawal syndrome, respiratory depression, hypotonia, and poor feeding. Use contraindicated in pregnancy unless no safer alternative. |
■ FDA Black Box Warning
WARNING: Potential for dependence and abuse; may cause severe withdrawal symptoms including seizures and delirium. Use extreme caution in patients with a history of substance abuse. Do not discontinue abruptly.
| Serious Effects |
Hypersensitivity to meprobamate or related compounds. Porphyria. Patients with severe hepatic or renal impairment. Pregnancy (especially first trimester) and lactation (relative). Concomitant use of MAOIs.
| Precautions | May cause drowsiness, impairment of cognitive and motor function. Use with caution in elderly patients. Risk of respiratory depression when combined with other CNS depressants (alcohol, opioids). Avoid use in patients with porphyria. History of substance abuse. |
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| Fetal Monitoring | Monitor for maternal sedation, respiratory depression, and hypotension. In fetus/neonate: Assess for signs of withdrawal (irritability, tremors, feeding difficulties) after delivery. Ultrasound for fetal anatomy if exposed in first trimester. |
| Fertility Effects | Meprobamate may impair female fertility through disruption of ovulatory cycles and hormonal changes. In males, potential for reduced libido and erectile dysfunction. Effects likely reversible upon discontinuation. |