Suicidal attempts with meprobamate have resulted in drowsiness, lethargy, stupor, ataxia, coma, shock, vasomotor, and respiratory collapse. Some suicidal attempts have been fatal.
The following data on meprobamate tablets have been reported in the literature and from other sources. These data are not expected to correlate with each case (considering factors such as individual susceptibility and length of time from ingestion to treatment), but represent the usual ranges reported.
Acute simple overdose (meprobamate alone): Death has been reported with ingestion of as little as 12 g meprobamate and survival with as much as 40 g.
0.5-2 mg% represents the usual blood level range of meprobamate after therapeutic doses. The level may occasionally be as high as 3 mg%.
3-10 mg% usually corresponds to findings of mild to moderate symptoms of overdosage, such as stupor or light coma.
10-20 mg% usually corresponds to deeper coma, requiring more intensive treatment. Some fatalities occur.
At levels greater than 20 mg%, more fatalities than survivals can be expected.
Acute combined overdose (meprobamate with alcohol or other CNS depressants or psychotropic drugs): Since effects can be additive, a history of ingestion of a low dose of meprobamate plus any of these compounds (or of a relative low blood or tissue level) cannot be used as a prognostic indicator.
In cases where excessive doses have been taken, sleep ensues rapidly and blood pressure, pulse, and respiratory rates are reduced to basal levels. Any drug remaining in the stomach should be removed and symptomatic therapy given. Should respiration or blood pressure become compromised, respiratory assistance, central nervous system stimulants, and pressor agents should be administered cautiously as indicated. Meprobamate is metabolized in the liver and excreted by the kidney. Diuresis, osmotic (mannitol) diuresis, peritoneal dialysis, and hemodialysis have been used successfully. Careful monitoring of urinary output is necessary and caution should be taken to avoid overhydration. Relapse and death, after initial recovery, have been attributed to incomplete gastric emptying and delayed absorption. Meprobamate can be measured in biological fluids by two methods: colorimetric (Hoffman, A.J. and Ludwig, B.J.: J Amer Pharm Assn 48: 740, 1959) and gas chromatographic (Douglas, J.F. et al: Anal Chem 39: 956, 1967).