Reference Range
Barbiturates are sedatives/hypnotics used mainly for anesthesia and epilepsy treatment. They affect the gamma-aminobutyric acid (GABA) system and cause a CNS suppressive effect, which ranges from anxiolysis, sedation, and coma to fatal cardiovascular and respiratory arrest upon overdose.
They are classified as short-acting, intermediate-acting, and long-acting. See Table 1 for classification and properties.
Table 1. Classification and Properties of Barbiturates (Open Table in a new window)
|
Drug |
Half-life (h) |
Duration of Effect (h) |
Hypnotic Dose, mg |
Minimum Toxic level, mg/L |
|
Ultra–short-acting |
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|
Methohexital |
3-5 |
< 0.5 |
50-120 |
>5 |
|
Thiopental |
8-10 |
< 0.5 |
50-75 |
>5 |
|
Short-acting |
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|
Secobarbital |
15-40 |
>3-4 |
100-200 |
>10 |
|
Intermediate-acting |
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|
Amobarbital |
10-40 |
>4-6 |
65-200 |
>10 |
|
Butabarbital |
35-50 |
>4-6 |
100-200 |
>10 |
|
Long-acting |
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|
Mephobarbital |
10-70 |
>6-12 |
50-100 |
>30 |
|
Phenobarbital |
80-120 |
>6-12 |
100-320 |
>30 |