Self-association of analgesics in aqueous solution: association models for codeine, oxycodone, ethylmorphine and pethidine.

Light scattering, vapour pressure osmometry, conductivity and surface tension techniques have been used to examine aqueous solutions of several narcotic analgesics for evidence of association. Contrary to a previous report, no significant association could be detected in solutions of morphine sulphate and codeine phosphate. Other drugs which showed no evidence of aggregation in water included morphine hydrochloride, ethylmorphine hydrochloride, oxycodone hydrochloride and dihydrocodeine tartrate. Self-association of ethylmorphine hydrochloride, oxycodone hydrochloride and codeine phosphate was observed in the presence of 0.5 mol dm-3 electrolyte, the pattern of association conforming to that of a stepwise association process with all association constants of equal value. The association of pethidine hydrochloride in 0.5 mol dm-3 sodium chloride could be represented by an association scheme in which association constant KN increased sequentially with aggregation number N according to the relation KN = K(N - 1)/N.

Self-association of analgesics in aqueous solution: micellar properties of dextropropoxyphene hydrochloride and methadone hydrochloride.

The solution properties of several analgesics including dextropropoxyphene hydrochloride, methadone hydrochloride, dextromoramide acid tartrate and dipipanone hydrochloride have been examined using light scattering, conductivity, vapour pressure osmometry and surface tension techniques. A micellar pattern of association was established for dextropropoxyphene hydrochloride and methadone hydrochloride and critical micelle concentrations and aggregation numbers are reported. The hydrophobic contribution to the free energy of micellization of dextropropoxyphene was determined from measurement of the critical micelle concentration in the presence of added electrolyte.

Carotid artery occlusive disease. Clinical considerations in surgical revascularization.

In clinical evaluation and analysis of 85 consecutive carotid endarterectomies in 74 consecutive patients, the operation was shown to be an effective and safe method of treating cerebral vascular insufficiency. It must be properly timed and performed, and excellent results may be expected, particularly in comparison with nonoperatively treated patients with the same disease.