[Comparison between the side-effects of fentanyl and morphine in conscious man (author's transl)]

Fentanyl citrate or morphine chlorhydrate are injected intramuscularly at increasing doses to patients suffering from intense pain in the facial or trigeminal nerves territory: --fentanyl = 0.0015, 0.003, 0.006 mg/kg; --morphine = 0.100, 0.150, 0.200 mg/kg. The clinically observed side-effects are noted at regular time during the three hours following the injection. Fentanyl induces a drop in ventilation similar in duration to that of morphine, but it is more intense. Fentanyl induces less vomiting, but more euphoria than morphine and the sedation is the same in frequency and intensity with both drugs. The only difference of clinical importance concerns the cardio-vascular effects: morphine induces a constant, dose-related hypotension as that of fentanyl, at equianalgesic doses, is negligible.