This section is from the book "Botanic Drugs Their Materia Medica, Pharmacology and Therapeutics", by Thomas S. Blair. Also available from Amazon: Botanic Drugs, Their Materia Medica, Pharmacology and Therapeutics.
Passiflora incarnata, Passion Flower. Not official, but listed in the N. F. The order of Passi-floraceae are not generally recognized as possessed of any definite activity. This drug came into vogue in America largely through proprietary medicine advertising in which unwarranted and wholly unscientific claims were made.
On the other hand, there is quite a volume of clinical evidence in favor of the drug. One article in its favor was by Prof. Solomon Solis Cohen (Critic and Guide, Jan., 1913).
My attention was first attracted to it in Homeopathic literature, in which it is commended as an efficient antispasmodic useful in insomnia, neuroses, asthma, and even in acute mania. Thirty to sixty minims, repeated several times, of the "mother tincture" (strongly alcoholic, 10 per cent tincture), and every ten minutes in asthma, were recommended, the drug being especially commended in treating children. See "Pocket Manual of Homeopathic Materia Medica," Boericke, edition of 1903. Having many cases of insomnia and asthma, and as I was a sufferer from insomnia myself at that time, I tried it out pretty thoroughly. In asthma it failed utterly; but it certainly was effective in insomnia - some cases - and I slept well under its influence. The explanation is this: It is a good "night-cap" from the alcohol contained therein. Take two teaspoonfuls of brandy (the alcoholic equivalent of Dr. Boericke's recommendations), "repeated several times," as he says of passiflora, and one is almost sure to sleep.
But Eclectic literature is more conservative. It sets up the contention that preparations made from the fresh drug are alone of value, and the Eclectic preparations are of fluidextract strength. Eclectic authorities report the finding of two glucosides in the drug. They give the dose of the fl. as 5 to 60 minims. It is not contended by them that it will relieve pain or act in sthenic conditions; but they class it as an antispasmodic and mild soporific of value in asthenic insomnia, and in some cases of infantile spasm, and the restlessness and insomnia of low fevers. They use it in numerous states dependent upon reflex nervous excitement, and in place of the bromides.
There is not available any credited scientific study of the drug; its pharmacology has not been determined; but I know reliable clinicians who much esteem passiflora on an admittedly empiric basis, as established by the Eclectics. My own use of the drug has, as with mild remedies generally, been marked by some successes, but many cases in which I was unable to determine whether Nature or passiflora was to be credited. I never employed it in serious cases of illness. Probably passiflora is worthy of further study.