PT - JOURNAL ARTICLE AU - J. M. Witkin AU - N. Savtchenko AU - M. Mashkovsky AU - M. Beekman AU - P. Munzar AU - M. Gasior AU - S. R. Goldberg AU - J. T. Ungard AU - J. Kim AU - T. Shippenberg AU - V. Chefer TI - Behavioral, Toxic, and Neurochemical Effects of Sydnocarb, a Novel Psychomotor Stimulant: Comparisons with Methamphetamine DP - 1999 Mar 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 1298--1310 VI - 288 IP - 3 4099 - http://jpet.aspetjournals.org/content/288/3/1298.short 4100 - http://jpet.aspetjournals.org/content/288/3/1298.full SO - J Pharmacol Exp Ther1999 Mar 01; 288 AB - Sydnocarb (3-(β-phenylisopropyl)-N-phenylcarbamoylsydnonimine) is a psychostimulant in clinical practice in Russia as a primary and adjunct therapy for a host of psychiatric disorders, including schizophrenia and depression. It has been described as a stimulant with an addiction liability and toxicity less than that of amphetamines. The present study undertook to evaluate the psychomotor stimulant effects of sydnocarb in comparison to those of methamphetamine. Sydnocarb increased locomotor activity of mice with reduced potency (∼10-fold) and efficacy compared with methamphetamine. Sydnocarb blocked the locomotor depressant effects of haloperidol at doses that were inactive when given alone. The locomotor stimulant effects of both methamphetamine and sydnocarb were dose-dependently blocked by the dopamine D1 and D2 antagonists SCH 39166 and spiperone, respectively; blockade generally occurred at doses of the antagonists that did not depress locomotor activity when given alone. In mice trained to discriminate methamphetamine from saline, sydnocarb fully substituted for methamphetamine with a 9-fold lower potency. When substituted for methamphetamine under self-administration experiments in rats, 10-fold higher concentrations of sydnocarb maintained responding by its i.v. presentation. Sydnocarb engendered stereotypy in high doses with approximately a 2-fold lower potency than methamphetamine. However, sydnocarb was much less efficacious than methamphetamine in inducing stereotyped behavior. Both sydnocarb and methamphetamine increased dialysate levels of dopamine in mouse striatum; however, the potency and efficacy of sydnocarb was less than methamphetamine. The convulsive effects of cocaine were significantly enhanced by the coadministration of nontoxic doses of methamphetamine but not of sydnocarb. Taken together, the present findings indicate that sydnocarb has psychomotor stimulant effects that are shared by methamphetamine while demonstrating a reduced behavioral toxicity. The American Society for Pharmacology and Experimental Therapeutics