Methamphetamine
 NAME OF DRUG: Methamphetamine (Desoxyephedrine, Desoxyn, Methedrine) |
| PHYSICAL CHARACTERISTICS: Pure methamphetamine as a free base is a colorless or straw-colored oil with a mild “fishy” ammoniacal odor. Methamphetamine is usually found as a hydrochloride or sulfate salt. These are white, odorless crystalline powders that are freely soluble in water and alcohol and have a bitter taste. Illicit methamphetamine may be off-white in color. |
| DOSAGE/OCCURRENCE/USAGE: The hydrochloride salt of the d-isomer is used in the treatment of obesity in single oral doses of 2.5-15 mg. Methamphetamine is available as conventional tablets of 2.5 -5 mg and prolonged release tablets of 5-15 mg. The l-isomer is used as a decongestant in some non-prescription inhalers. Illicit methamphetamine is synthesized from phenylacetone and N-methylformamide. |
| BLOOD CONCENTRATIONS VS. DOSAGE: After the administration of a single dose of 10 mg of methamphetamine, a maximum blood concentration of 30 ng/mL was observed at one hour. A 12.5 mg dose produced as average peak blood level of 20 ng/mL at 2.5 hours, 16 ng/mL at 6 hours, and 10 ng/mL at 24 hours. |
| URINE EXCRETION RATE: Some methamphetamine is metabolized into amphetamine. Under normal conditions, up to 43% of the dose is eliminated unchanged in 24 hours with 4-7% as amphetamine. In acidic urine up to 76% is unchanged drug an 7% is excreted as amphetamine in 24 hours. While in basic urine only 2% is unchanged drug and less than 0.1% is amphetamine at 24 hours. Methamphetamine concentrations after the administration of 10 mg are typically 500-4000 ng/mL during the first 24 hours. It has been reported that the methamphetamine concentration of methamphetamine abusers is 2400-33300 ng/mL (average 14200) and amphetamine concentrations of 1000-9000 ng/mL. (Average 1800). |
| METABOLITES: Amphetamine |
| TOXICITY: Symptoms of methamphetamine overdose include restlessness, confusion, anxiety, hallucinations, cardiac arrhythmias, hypertension, hyperthermia, circulatory collapse, convulsions, and coma. Chronic abusers may develop paranoid psychosis. The estimated lethal dose is 100 mg in children and 1 g in adults. |
| REFERENCES: Baselt RC. Disposition of Toxic Drugs and Chemicals in Man, Second Edition.
Davis, Calif.: Biomedical Publications, 1982. Clarke E.C. Isolation and Identification of Drugs. London: The Pharmaceutical Press, 1969. Roche Online package inserts. |