Secobarbital
 NAME OF DRUG: Secobarbital (quinalbarbitone, Seconal) |
| PHYSICAL CHARACTERISTICS: Secobarbital is available as either a free acid or a sodium salt. The free acid is a white amorphous powder that slightly soluble in water and very soluble in ethanol. The salt is a white hygroscopic powder that is soluble in water and ethanol. |
| DOSAGE/OCCURRENCE/USAGE: Secobarbital is a barbiturate derivative that is short acting. It is used mainly as sedative. It is available in concentrations of 8-250 mg. It is available either alone or in combination with other drugs. It may be administered orally, intravenous injection, intramuscular injection, or rectally. |
| BLOOD CONCENTRATIONS VS. DOSAGE: The average peak blood concentration from a single oral dose of 244 mg given to 6 subjects was 2000 ng/mL (range 1800-2200) after 3 hours. The levels declined to 1300 ng/mL (range 1200-1600) at 20 hours and 800 ng/mL at 40 hours. When five subjects were given an oral dose of 600 mg over a three hour period, the blood concentration averaged 4300 ng/mL (range3400-5300) at 0.5 hours; 3500 ng/mL (range 2900-4500) at 4.5 hours; and 2700 ng/mL (range 2100-3300) at 18 hours. |
| URINE EXCRETION RATE: Due to extensive biotransformation, only about 5% of secobarbital is excreted unchanged in the urine within 2 days. Following a single 600 mg dose of secobarbital, concentrations in urine ranged form 700-1800 ng/mL in a 21 hour period. |
| METABOLITES: secodiol (5-(2,3-dihydroxyporopyl)-5-(1-methylbutyl) barbituric acid)), 3'-hydroxysecobarbital, 5-(1-methylbutyl) barbituric acid. |
| TOXICITY: Blood concentrations of 5000-12000 ng/mL were observed in cases of mild toxicity (ataxia, slurred speech, and drowsiness) in barbiturate abusers who were given 100-200 mg oral doses of secobarbital each hour until mild toxicity was achieved. The blood concentrations in 498 conscious secobarbital abusers were 2000-11000 ng/mL (average 6000). The concentrations in 25 comatose patients were 3000-12000 ng/mL (average 7000). As little as 2 g of secobarbital was ingested in documented fatal cases. Blood concentrations averaged 21000 ng/mL (range 5000-52000). |
| REFERENCES: Baselt, R C. Disposition of Toxic Drugs and
Chemicals in Man, Second Edition. Davis, Calif.: Biomedical Publications, 1982. Clarke, E.G.C. Isolation and Identification of Drugs. London: The Pharmaceutical Press, 1969. Shaw, Richard F., Finkle, Bryan S. Barbiturates Abused Drugs Monograph Series. Ed. Caplan, Yale H. Irving: Abbott Laboratories, 1994. |