Lethal effects of reserpine plus physostigmine and neostigmine in mice.

1. The interaction between the reversible cholinesterase inhibitors, physostigmine and neostigmine and reserpine was studied. 2. A combination of reserpine plus a cholinesterase inhibitor significantly increased lethality in adult male Swiss-Webster mice above that caused by either neostigmine, physostigmine, or reserpine alone. 3. Methscopolamine completely reversed this effect. 4. It would appear that the presence of the antiadrenergic agent, reserpine, increases the toxicity of cholinomimetic agents. 5. The above results may have clinical significance, since reserpine and cholinesterase inhibitors are used in the practice of medicine.