OPTICAL ISOMERS VII. HYOSCINES AND HYOSCYAMINES

¹ Pharmacological Laboratory, University of Edinburgh

1. Two hyoscines, each of them racemised in the oscine component, but opposed in the direction of rotation of the tropyl radicle, were examined and it was found that the laevorotary hyoscine is fifteen to eighteen times as powerful as the dextrorotary in action on the terminations of the nerves in the salivary glands and in other "specific" atropine effects.

2. D-hyoscine and d-hyoscyamine are more slowly destroyed in the tissues than l-hyoscine and l-hyoscyamine.

3. The action of the hyoscines on the nerve ends in striated muscle, on unstriated muscle, and on the central nervous system is identical.

4. Similar results were obtained in comparing the two hyoscyamines, except that d-hyoscyamine possesses a late stimulant effect on the spinal cord, which may be ascribed to the presence of some decomposition product rather than to the alkaloid itself.

5. It is suggested that the "specific" effects of the atropine group arise from the physical properties of some chemical compound formed with an optically active substance in the tissues, while the less specific effects may be explained by the properties of the uncombined alkaloid.