Depressive States Induced by Drugs of Abuse: Clinical Evidence, Theoretical Mechanisms and Proposed Treatment Part II

Chronic imipramine does not block cocaine-induced increases in brain stimulation reward

Self-stimulating rats implanted with ventral tegmental area electrodes were tested with 15 mg/kg cocaine HCl before and after chronic imipramine treatment. Chronic imipramine had no influence on cocaine's ability to lower brain stimulation reward thresholds, suggesting that tricyclic antidepressant treatment does not block cocaine-induced euphoria.

Histories of substance abuse in patients with postpsychotic depressions

Forty-six schizophrenic or schizoaffective patients with operationally defined episodes of postpsychotic depression were assessed for previous histories of substance abuse. Thirty-five percent had histories of previous cannabis (marijuana) abuse. Additionally, 13% had also abused cocaine, 13% amphetamines, 11% hallucinogens, 4% sedatives, and 2% opiates. Patients with histories of substance abuse were younger and showed higher index ratings on a subscale of endogenous depressive features. These findings are considered in the context of a possible self-medication hypothesis of substance abuse. A history of substance abuse did not appear to be a contraindication to a therapeutic trial of adjunctive imipramine (Ciba Geigy Corp., Summit, NJ) for postpsychotic depression.

The interactive effects of cocaine and imipramine on self-stimulation train-duration thresholds

The present experiment examined the ability of the tricyclic antidepressant imipramine to influence cocaine's effect on intracranial self-stimulation. Following a predrug, saline injection period, cocaine hydrochloride (10, 20 or 30 mg/kg) was injected (IP) in 19 rats implanted with ventral tegmental area electrodes. Cocaine treatment uniformly decreased self-stimulation train-duration thresholds. In the next phase, the subjects were divided into two groups. One group received cocaine (as in the previous phase) and the other received cocaine plus imipramine (10 mg/kg, IP). Imipramine doubled cocaine's effect on self-stimulation train-duration thresholds. In addition, several other effects of cocaine (e.g., bradycardia, rear-limb dyskinesia) were potentiated by imipramine treatment. The results suggest that care must be exercised when treating cocaine abuse with tricyclic antidepressants since coadministration of these drugs intensifies cocaine's effects.

An overview of cocaine use and abuse

Use of cocaine is traced from South American Indians through 19th century European patterns into 20th century United States. Different methods of using cocaine produce effects with different potencies; the free-basing method is most potent and potentially most lethal and addictive. Addiction to cocaine has a different pattern than the physiological effects of heroin but is no less real, perhaps even more dangerous.