Antiemetic activity of N-methyllevonantradol and nabilone in cisplatin-treated cats

The comprehensive emetic response to xenobiotics can be quantified by monitoring the physiological forces which effectuate vomiting. A unique sequence of thoracic pressure pulses, generated by the somatic muscles of ventilation, can be measured by means of a central venous catheter. This unambiguous emetic endpoint is used to record emetic latency, repetitions and duration of action, all on an established time base and dependent of stomach content. Deslanoside (160 micrograms/kg) produced emesis in 15 cats beginning in 4.4 +/- 1.9 min (mean +/- S.D.). Subsequent emetic episodes were related in time in a log-linear but biphasic manner. Cisplatin (7.5 mg/kg) had an emetic latency of 71 +/- 18 mn in 7 cats. Additional events also had a long-linear temporal relationship for up to 400 min. This quantified emetic profile of cisplatin served as a measure for assessing antiemetic activity of N-metyllevonantradol (Pfizer), nabilone (Lilly) and prochlorperazine. The cannabinoids all evinced dose dependent antiemetic activity in terms of either complete protection, or increased latency to the first emetic episode and reduced number of episodes in those animals not completely protected. By comparison prochlorperazine afforded only minimal protection.