No abstract

Volunteer subjects with previous histories of cocaine use were administered cocaine hydrochloride intravenously or intranasally. There was a positive relationship between peak plasma concentration, physiological and subjective responses, and dose administered. The rate of cocaine disappearance after intravenous administration paralleled the drop in physiological and subjective drug effects. After intranasal administration, blood levels remained elevated for a considerably longer period.

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Cocaine kinetics were studied in four subjects after intravenous and intranasal administration. For intravenous administration cocaine hydrochloride (32 mg) dissolved in physiological saline was injected in 1 ml volume over a 1 min period. Intranasal cocaine was administered as 100 mg powder consisting of an appropriate dose of cocaine hydrochloride (64 and 96 mg) mixed with lactose powder. Subjects were instructed to inhale the mixture through a 5 cm straw within 1 min. Cocaine kinetics, after intravenous injection, conform to a one-compartment open model with first-order elimination. After intranasal administration, cocaine kinetics conform to a one-compartment model with first-order absorption and first-order elimination. The mean half-life of cocaine for intravenous injection in four subjects was 41.4 +/- 8.2 min (mean +/- S.E.M.) and the range was 19 to 64 min. There were statistically significant differences in the mean area under the concentration-time curve (AUC) following intravenous and intranasal administration. The AUC was dose-dependent and the fraction of the dose absorbed after 64 mg intranasal cocaine was significantly lower than after 96 mg dose (p less than 0.05).

The effect of intravenously administered nicotine upon smoking behavior was studied in smokers who were unaware of the nature of the administered drug and the true purpose of the study. Smoking behavior was not altered significantly when nicotine was administered in a dose of 1 mg. per hour for 6 hours. A significant decrease in smoking frequency was obtained when nicotine was administered at the rate of 2 to 4 mg. per hour. Recordings of systolic blood pressure, heart rate, and the elect1"Ocardiogram indicate that the physiological alterations in these parameters produced by smoking can be reproduced by parenteral nicotine.