COMPARISON OF "SEDATIVE" PROPERTIES OF SINGLE ALKALOIDS OF RAUWOLFIA AND THEIR MIXTURES

¹ Research Division, Riker Laboratories, Los Angeles, California

Using the "roller-cage" technique, the comparative sedative activities of orally administered Rauwolfia alkaloids (reserpine, rescinnamine and deserpidine) were measured in mice.

Solutions of reserpine and deserpidine were nearly equipotent and had identical dose-response curves. Solutions of rescinnamine were only one-third to one-fourth as effective.

Methylcellulose suspensions of deserpidine and rescinnamine had potencies and slopes of the dose-response curves similar to their respective solutions. However, in this form, the potency of reserpine was significantly lower than in solution and the curve was much flatter.

Alkaloidal mixtures (reserpine 75 per cent, rescinnamine 25 per cent; reserpine 75 per cent, deserpidine 25 per cent; reserpine 60 per cent, deserpidine 20 per cent, rescinnamine 20 per cent) either as solutions or suspensions appeared to be more potent than would be expected on the basis of a simple additive effect. This was especially true of the suspensions, wherein the dose-response curves were markedly steepened. An interaction between the alkaloids with respect to their solubility is one possible factor in this synergistic effect.