Studies of drugs given before anaesthesia. XIX. The opiates.

Using Ridit analysis, a comparison was made of the overall effects of what are generally considered to be equianalgesic doses of sixteen opiates, with respect to their desired and toxic effects when given as premedication to a standard population. Four mixtures of opiates, the non-opiate diazepam and saline were also included in the analysis. Results with all individual drugs have been previously reported in detail. Under the conditions of this study, pethidine 100 mg, papaveretum 20 mg and even morphine 10 mg are too toxic to warrant their present popularity. More attention should be paid to the use of levorphanol 2 mg, diamorphine 5 mg, methadone 10 mg and oxycodone 10 mg for premedication. These findings may be modified by the concomitant use of atropine or hyoscine. Papaveretum-hyoscine fully justifies its popularity, but its greater efficacy can be explained by its high morphine content and the action of hyoscine. Under appropriate conditions diazepam may be superior to any of the opiates for use in premedication.