Comparison of the effects of therapeutic doses of meptazinol and a dextropropoxyphene/paracetamol mixture alone and in combination with ethanol on ventilatory function and saccadic eye movements.

The respiratory and psychomotor effects of a single oral dose of meptazinol (200 mg) and dextropropoxyphene (65 mg)/paracetamol (650 mg) mixture, was compared alone and in combination with ethanol (0.8 g kg-1). Peak saccade velocity following meptazinol or the dextropropoxyphene/paracetamol mixture was not significantly different from placebo. When each of the treatments was followed by ethanol administration, a significant decrease in saccade velocity (P less than 0.01) was seen. Given alone, neither of the analgesic drugs produced a significant change in the slope of the ventilatory response to hypercapnia. Ethanol did not affect the ventilatory response to hypercapnia when given alone or in combination with meptazinol, but when given with the dextropropoxyphene/paracetamol mixture, a significant reduction in the slope of the ventilatory response to hypercapnia occurred at 1.5 h (P less than 0.05) and 2 h (P less than 0.01) after administration of the analgesic drug. No pharmacokinetic interaction was demonstrated between ethanol and meptazinol or the dextropropoxyphene/paracetamol mixture in the doses used. In contrast to meptazinol, the dextropropoxyphene/paracetamol mixture interacts with ethanol on the ventilatory function.