PASSION FLOWER

Fetal Risk Summary

The herbal product used for medicinal purposes usually refers to the plant, Passiflora incarnata, but the common name, passion flower, may refer to many of the approximately 400 species of the genus Passiflora (1,2). Some species are grown for their flowers. In addition, some species produce edible fruit, such as P. incarnata, P. edulis, and P. quadrangularis. The plant is a perennial vine that may reach 10 meters in length. It is indigenous to the southeastern United States to South America. The medicinal parts include the whole or cut dried herb and the fresh aerial parts (1,2). In this review, the term passion flower will only refer to P. incarnata, the product used in herbal medicine.

Commercial products of passion flower are available for both oral and topical administration. A number of indications have been claimed for passion flower, including nervousness (e.g., hysteria, nervous exhaustion, pediatric nervousness and excitability), neuralgia, insomnia, pain, asthma and other bronchial disorders, generalized seizures, compresses for burns, hemorrhoids (externally), and for menopausal complaints (1,2,3 and 4) .

As with most herbs, a relatively large number of chemical compounds are contained in the commercial product: flavonoids (content 2.5%; includes flavone di-C-glycosides shaftoside, isoshaftoside, isovitexin, iso-orientin, vicenin, lucenin, saponarin, and passiflorine), maltol (0.05%), cyanogenic glycosides (gynocardine [less than 0.1%]), and indole alkaloids (harman, harmine, harmaline, harmalol, and harmin) are the primary constituents (1,2,3 and 4) . The alkaloids, however, are reportedly present in subtherapeutic amounts (5). Other constituents include free flavonoids (apigenin, luteolin, quercetin, and campherol), several acid compounds (phenolic, linoleic, linolenic, palmitic, oleic, myristic, formic, and butyric acids), coumarins, phytosterols, and essential oil (1).

The pharmacologic activity of passion flower apparently derives from the flavonoids and alkaloids (1,3). A few studies have apparently documented the sedative action of passion flower in animals and humans. The FDA prohibited the use of passion flower in over-the-counter (OTC) products in 1978 because it had not been proven to be safe and effective (5), but the product is apparently available as a herbal remedy.

No reports have been located describing the use of passion flower in human pregnancy. However, two sources have cited reports that the herb is contraindicated during pregnancy because of the uterine stimulant action of the harman (harmala) alkaloids (harman, harmaline) shown in animals and because of the presence of cyanogenic glycoside gynocardine (1,3). In contrast, the German Commission E monographs states there are no contraindications (4).

In summary, the use of passion flower has apparently not been reported during human pregnancy. Typically with herbal products, a large number of chemicals have been identified from this herb and none have undergone reproductive testing. Because passion flower has been in use for hundreds of years or longer, it is doubtful that a major teratogenic effect or other significant reproductive toxicity would have escaped notice. More subtle or low-incidence effects, however, including structural and behavioral teratogenicity, the induction of abortions due to its uterine stimulant properties, and infertility, may have escaped detection, and further study is required before human reproductive risk or safety can be assessed.

In addition to the above concerns, standardization of any herbal product is often questionable (6). As such, the presence of therapeutic or subtherapeutic amounts of active ingredients, or their complete absence, in a given preparation cannot be predicted. Commercial herbal products may also be adulterated with unlabeled ingredients (6). Because of these uncertainties, the consumption of passion flower during gestation should be avoided.

Breast Feeding Summary

No reports describing the use of passion flower during lactation have been located. Because of the large number of chemical compounds in the herb, the lack of standardization of commercial products, and the complete lack of information on the effects of exposure to these substances in a nursing infant, the use of passion flower during breast feeding should be avoided.

References

1. Passion Flower. The Review of Natural Products. St. Louis, MO: Facts and Comparisons, March, 1999.
2. Passiflora Incarnata. PDR for Herbal Medicines. Montvale, NJ: Medical Economics, 1998:1015–16.
3. Passion Flower. Natural Medicines Comprehensive Database. Stockton, CA: Therapeutic Research Faculty, 1999:645–6.
4. Passionflower Herb. Blumenthal M, Senior Editor. The Complete German Commission E Monographs. Therapeutic Guide to Herbal Medicines. Austin, TX: American Botanical Council. 1998:179–80.
5. Robbers JE, Tyler VE. Tyler's Herbs of Choice. The Therapeutic Use of Phytomedicinals. Binghamton, NY: Haworth Press, 2000:159–60.
6. Miller LG, Hume A, Harris IM, Jackson EA, Kanmaz TJ, Cauffield JS, Chin TWF, Knell M. White paper on herbal products. American College of Clinical Pharmacy. Pharmacotherapy 2000;20:877–91.