Rivastigmine does not alter cocaine-induced subjective effects or self-administration

Area of Science:

• Neuroscience
• Pharmacology
• Addiction Research

Background:

• Acetylcholinergic (ACh) neurons interact with the mesolimbic dopamine pathway, which is involved in addiction.
• Acetylcholinesterase inhibitors (AChEis) have demonstrated potential in reducing cocaine's immediate effects and overall usage.
• Rivastigmine is a safe AChEi with low drug interactions, making it a candidate for addiction treatment research.

Purpose of the Study:

• To investigate whether rivastigmine alters the subjective effects of cocaine administration.
• To evaluate the impact of different rivastigmine dosages on cocaine's psychoactive properties.
• To compare rivastigmine's effects with placebo in cocaine-dependent individuals.

Main Methods:

• Cocaine-dependent subjects were randomized to placebo, rivastigmine 3 mg, or rivastigmine 6 mg daily for 10 days.
• Intravenous cocaine (40 mg) or placebo was administered on days 1 and 9, with subjective effects assessed using visual analog scales (VAS).
• On day 10, participants received a reduced cocaine dose (20 mg) and could purchase additional doses, with effects and purchasing behavior recorded.

Main Results:

• No significant pharmacokinetic differences in cocaine blood levels were observed between treatment groups.
• Rivastigmine treatment did not significantly alter any VAS subjective effect ratings following cocaine administration.
• No significant effect of rivastigmine was found on subjective effects or subsequent cocaine purchases on day 10.

Conclusions:

• Rivastigmine at 3 mg or 6 mg daily for 9 days did not significantly affect the subjective experience of cocaine.
• The lack of effect contrasts with findings from other acetylcholinesterase inhibitors like donepezil and Huperzine A.
• Differences in receptor specificity and pharmacokinetic profiles may explain rivastigmine's distinct outcomes compared to other AChEis.