Amphetamine
 NAME OF DRUG: Amphetamine (Benzadrine, Dexedrine, Obetrol) |
| PHYSICAL CHARACTERISTICS: Pure amphetamine free base is a colorless or straw-colored oil that has a mild “fishy” ammoniacal odor. Amphetamine is usually found in the hydrochloride or sulfate salt form. These are white odorless crystalline powders that are freely soluble in water and alcohol and have a bitter taste. Illicit forms of amphetamine may be off-white in color and appear as powder or crystalline chunks, loosed wrapped in foil or paper, as capsules, or illicitly-manufactured tablets. |
| DOSAGE/OCCURRENCE/USAGE: Amphetamine was first synthesized in 1887. Since 1935 it has been used in treatment of obesity, narcolepsy, hypotension, and hyperactivity and attention deficit disorder in children. It is commonly administered as the sulfate salt in single oral doses of 5-15 mg. It is frequently abused for its stimulant effect. Amphetamine may be administered either orally or intravenously in amounts up to 2000 mg per day by addicts. |
| BLOOD CONCENTRATIONS VS. DOSAGE: Blood concentration peaked at 35 ng/mL at 2 hours following a single oral dose of 10 mg (half-life 11-13 hours). The l-isomer is metabolized more slowly; it may take up to 39% longer. Following the oral administration of 30 mg of amphetamine, an average peak plasma level of 111 ng/mL was observed at 2.5 hours. After 4.5 hours, the level dropped to 84 ng/mL. After oral ingestion of amphetamine, absorption is complete in 4-6 hours. Concentration in blood or plasma following a therapeutic dose is low because of the large volume of distribution. A steady-state blood level of 2000-3000 ng/mL has been observed in addicts who orally consume an average of 1000 mg per day of amphetamine. |
| URINE EXCRETION RATE: Amphetamine is largely unaffected during metabolism. The entire dose is probably eliminated in the urine over a period of several days. About 30% is excreted unchanged in 24 hours in normal urine. In acidic urine, the amount excreted increases up to 74% and decreases to 1% in basic urine. |
| METABOLITES: Phenylacetone, benzoic acid, and hippuric acid less than 25%; 4-hydroxyamphetamine, 4-hydroxynorephedrine, and norephedrine less than 10%. |
| TOXICITY: In a study of the effects of Benzedrine, 10-30 mg was administered to 20 healthy subjects. Almost all of the subjects exhibited pallor, flushing, palpitations, and an increase in pulse rate and blood pressure. Six subjects exhibited more severe effects. The CNS (central nervous system) effects include restlessness, dizziness, tremor, hyperactive reflexes, talkativeness, tenseness, irritability, weakness, insomnia, fever, and euphoria. Other effects can include confusion, combativeness, increased libido, anxiety, delirium, paranoid hallucinations, panic states, and suicidal or homicidal tendencies. These symptoms occur more often in mentally ill persons. Fatigue and depression usually follow. Symptoms of chronic use include anorexia with weight loss, nausea, vomiting, diarrhea, and sleep disturbances. Chronic users more frequently exhibit abnormal mental conditions such as psychotic reactions with vivid hallucinations and paranoid delusions. At blood plasma levels of 5 ng/mL, changes in the amplitude and frequency of the electroencephalographic alpha-rhythm pattern appear. At 20 ng/mL, peripheral effects such as increased heart rate and blood pressure occur. Tolerance develops rapidly with high dose intravenous use. In the case of fatal overdoses, the amphetamine dosage has not been determined. Death does not occur immediately but after several hours. The subject experiences agitation, hyperthermia, convulsions, unconsciousness, and respiratory and/or cardiac failure. |
| REFERENCES: Baselt RC. 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. Osterloh, John D. Amphetamines Abused Drugs Monograph Series. Ed. Caplan, Yale H. Irving: Abbott Laboratories, 1994. |