Differential effects of di-isopropylfluorophosphate poisoning and its treatment on opioid antinociception in the mouse.

Compounds which enhance cholinergic activity have been reported to interact with opioid drugs. We have shown, using the hot-plate test in mice that di-isopropylfluorophosphate potentiates the antinociceptive activity of alfentanil but has no effect on the activity of morphine or fentanyl. Administration of atropine and pralidoxime as a treatment for DFP poisoning does not reverse this effect, and itself potentiates morphine antinociception. The results suggest that a cholinergic/opioid interaction is dependent on the opioid studied, and may have clinical importance when opioid drugs are required in patients poisoned by irreversible anticholinesterases.