Passion Flower - Medicinal Uses, Interactions, Side Effects, Dosage

Passion Flower

There are over 400 species of passion flower (genus Passiflora), which are also known as maypop, apricot vine, or passion vine. The dried, leafy, aerial parts of the P. incarnata species have been most frequently used medicinally.

Uses and Benefits:

Passion flower is promoted as a mild herbal anxiolytic, sedative, and hypnotic. It is a popular ingredient in many European sedative-hypnotic herbal combination products (often with valerian, lemon balm, and other herbs). Herbalists have also used passion flower for neuralgia, seizures, hysteria, and various physiologic disorders of presumed nervous origin-whenever a "calming" action is desired. Passion flower was included in over-the-counter (OTC) sedative and sleep aids in the United States until 1978, when the FDA banned it due to lack of proven effectiveness.

Pharmacology:

P. incarnata contains flavonoids (e.g., vitexin and isovitexin), small amounts of indole or harmala alkaloids (harman and related compounds), and maltol, all of which have pharmacologic activity in animal models. In most rodent studies, herbal extracts administered orally and by injection have sedative or hypnotic activityHarmala alkaloids have CNS activity (includ�ing psychedelic properties when given in large amounts); interact with a variety of neuroreceptor systems; and are inhibitors of the monoamine oxidase (MAO) enzyme. Chrysin, thought to be a flavonoid component of a related Passiflora species (P. coerulea), binds to benzodiazepine receptors and has anxiolytic actions in mice. however, chrysin may not be found in P. incarnata.

Clinical Trials:

Passion flower has only been studied in combi�nation products with other potentially sedative-hypnotic herbs or drugs; thus, the efficacy of passion flower itself is unknown. Euphytose, a European product that combines P. incarnata with several other herbal sedatives (including valerian), was found to have statistically beneficial anxiolytic properties in a double-blind, placebo-controlled study. In contrast, a European controlled study comparing a single oral dose of Valverde (P. incarnata, va�lerian, balm, and pestilence wort) with 3 mg of bromazepam found that both were no more effective than placebo.

Compoz, formerly a popular U.S. OTC product that contained P. incarnata (as well as scopolamine and antihistamines), was found to have equivalent anxiolytic effects to placebo in one study; however, the amount of Passiflora in 3 tablets of Compoz was 22.5 mg, a daily dose that was probably negligible. Compoz has been removed from the market.

Despite having CNS effects in rodents, an aqueous extract from a related Passiflora species, P. edulis, had no sedative-hyp�notic effects in nine healthy volunteers.

Adverse Effects:

In general, passion flower is considered to be safe and nontoxic, and dependence and withdrawal have not been reported. However, there are isolated case reports of adverse reactions. Five patients required hospitalization due to unresponsiveness or altered consciousness associated with overdoses (100-600 ml) of a P. incarnata product (Relaxir; usual dose 2 teaspoons) used in Norway. One patient appeared to respond to flumazenil. In Australia, a 34-year-old female developed severe nausea, vomiting, drowsiness, prolonged QTc on EKG, and episodes of nonsustained ventricular tachycardia associated with initiation of a P. incarnata product (Sedacalm) at therapeutic doses. Lastly, a patient with rheumatoid arthritis developed a cutaneous hypersensitivity reaction associated with the use of an oral extract. Product adulteration or contamination may have been responsible for these disparate reactions.

Other species of Passiflora have been implicated in toxicities. An aqueous extract of P. edulis caused abnormal elevations of aspartate aminotransferase (AST) and amylase in several healthy volunteers. Old reports that passion flower contains toxic cyanogenic glycosides are probably referring to the ornamental blue passion flower, P. coerulea, and not to P. incarnata.

Side Effects and Interactions:

Although pure harmala alkaloids have MAO inhibitor activity in animal experiments, adverse reactions or interactions in humans using passion flower have not been reported. Newer studies have shown that only trace amounts of the alkaloids are contained in the herb ( <0.1 ppm), and thus doses used clinically should not have MAO inhibitor activity.

Cautions:

Safety in pregnant and breast-feeding women hafl not been evaluated.

Preparations & Doses:

The usual recommended dose is about 500-2000 mg of dried herb, or 300-400 mg of commonly prepared extracts, 3-4 times daily, or as needed.

Summary Evaluation :

Passion flower is commonly used as a mild anxiolytic, sedative, and hypnotic herb, properties which have been demonstrated only with large doses in animal studies. Beneficial activity in humans has not been adequately evaluated at therapeutic doses, and evidence-based recommendations cannot be made. Avail�able information suggests that effects are likely to be mild in usual doses, and can only be regarded as possibly beneficial for minor problems of anxiety or insomnia