Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.
Rapifen (ICI Australia Operations)
0.5 mg/mL in 2 mL and 10 mL ampoules
Alfentanil is an opioid analgesic related to fentanyl. It can be used before intubation to induce anaesthesia or to supplement analgesia.
After the drug is given intravenously, its maximum analgesic and respiratory depressant effects occur within two minutes. This onset of action is more rapid than an equianalgesic dose of fentanyl. A bolus dose is suitable for procedures lasting less than 10 minutes, but the drug can be given by infusion for longer procedures. The drug is metabolised by the liver with a terminal elimination half-life of 1-2 hours.
The duration of analgesia may be less than the respiratory depressant effect. As respiratory depression can occur up to several hours after a dose of alfentanil, the patient must be monitored in the recovery area. Naloxone should be available.
Apart from respiratory depression and apnoea, there are other adverse effects on heart rate, blood pressure and muscle rigidity. The most common adverse effects are nausea and vomiting.