meprobamate
Apo-Meprobamate ◆, Equanil, Meprospan-200, Meprospan-400, Miltown, Neuramate

Available forms
Available by prescription only
Capsules (sustained-release): 200 mg, 400 mg
Tablets: 200 mg, 400 mg, 600 mg

Indications and dosages
 Anxiety and tension. Adults: 1.2 to 1.6 g P.O. daily in three or four equally divided doses. Maximum dose is 2.4 g daily (sustained-release capsules, 400 to 800 mg b.i.d.).
Children ages 6 to 12: 100 to 200 mg P.O. b.i.d. or t.i.d. Or, 25 mg/kg daily or 700 mg/m² daily in two or three divided doses. Sustained-release capsules, 200 mg b.i.d.
 Preoperative sedation and relief of anxiety. Adults: 400 mg P.O.
Children: 200 mg P.O.

Pharmacodynamics
Anxiolytic action: Cellular mechanism is unknown, but drug causes nonselective CNS depression similar to that of barbiturates. Meprobamate acts at multiple sites in the CNS, including the thalamus, hypothalamus, limbic system, and spinal cord, but not the medulla or reticular activating system.

Pharmacokinetics
Absorption: Well absorbed after oral administration. Sedation usually occurs within 1 hour.
Distribution: Distributed throughout the body; 20% is protein-bound. Drug appears in breast milk at two to four times the serum level; meprobamate crosses the placental barrier.
Metabolism: Metabolized rapidly in the liver to inactive glucuronide conjugates. Half-life of drug is 6 to 17 hours.
Excretion: Metabolites of drug and 10% to 20% of a single dose as unchanged drug are excreted in urine.

Contraindications and precautions
Contraindicated in patients with porphyria and in those hypersensitive to meprobamate or related compounds, such as carbromal, carisoprodol, mebutamate, and tybamate. Avoid use of drug in pregnant women (during first trimester) and breast-feeding women.
  Use cautiously in geriatric or debilitated patients and in those with impaired renal or hepatic function, seizure disorders, or suicidal tendencies.

Interactions
Drug-drug. Antihistamines, barbiturates, narcotics, tranquilizers, other CNS depressants: Potentiates effects. Use together cautiously.
Drug-lifestyle. Alcohol use: Potentiates effects. Discourage alcohol use.

Adverse reactions
CNS: drowsiness, ataxia, dizziness, slurred speech, headache, syncope, vertigo, seizures.
CV: palpitations, tachycardia, hypotension, arrhythmias.
GI: nausea, vomiting, diarrhea.
Hematologic: aplastic anemia, thrombocytopenia, agranulocytosis.
Skin: pruritus, urticaria, erythematous maculopapular rash, hypersensitivity reactions.

Effects on lab test results
• May decrease hemoglobin and platelet and granulocyte counts.

Overdose and treatment
Signs and symptoms of overdose include drowsiness, lethargy, ataxia, coma, hypotension, shock, and respiratory depression.
 Treatment of overdose is supportive and symptomatic, including maintaining adequate ventilation and a patent airway, with mechanical ventilation, if needed.
 Treat hypotension with fluids and vasopressors as needed. Empty gastric contents by emesis or lavage if ingestion was recent, followed by activated charcoal and a cathartic. Treat seizures with parenteral diazepam. Peritoneal dialysis and hemodialysis may effectively remove drug. Serum levels of more than 100 mcg/ml may be fatal.

Special considerations
• Safety precautions, such as raised bed rails, are needed, especially for geriatric patients, when starting treatment, or when increasing the dose. Patient may need assistance when walking.
• Drug abuse and addiction may occur.
• Withdraw drug gradually; otherwise, withdrawal symptoms may occur if patient has been taking drug for a long time. After abrupt withdrawal of long-term therapy, patient may experience severe generalized tonic-clonic seizures.
• Assess level of consciousness and vital signs frequently.
• Evaluate CBC periodically during long-term therapy.
• Monitor hepatic and renal function.
• Drug may falsely elevate urinary 17-ketosteroids, 17-ketogenic steroids (as determined by the Zimmerman reaction), and 17-hydroxycorticosteroid levels (as determined by the Glenn-Nelson technique).
• Store drug at 59° to 86° F (15° to 30° C); it expires 2 to 5 years from date of manufacture.
Breast-feeding patients
• Drug is found in breast milk at two to four times the serum level. Don’t use in breast-feeding women.
Pediatric patients
• Safety hasn’t been established in children younger than age 6.
Geriatric patients
• Geriatric patients may have more pronounced CNS effects. Use lowest dose possible.

Patient education
• Tell patient to avoid alcohol and other CNS depressants, such as antihistamines, narcotics, and tranquilizers, while taking drug, unless prescribed.
• Advise patient not to increase dose or frequency and not to abruptly discontinue or decrease dose unless prescribed.
• Tell patient to avoid tasks that require mental alertness or physical coordination until CNS effects of drug are known.
• Recommend sugarless candy or gum or ice chips to relieve dry mouth.
• Advise patient to report sore throat, fever, or unusual bleeding or bruising.
• Inform patient of potential for physical or psychological dependence with long-term use.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use