"Aggregator" MAO Inhibitors
Summary
MAO (Monoamine Oxidase) Inhibitor Herbs
Compounds in these herbs have been shown experimentally to have varying degrees of monoamine oxidase (MAO) inhibition. MAO enzymes degrade catecholamine neurotransmitters, e.g., serotonin, dopamine, epinephrine and norepinephrine. MAO inhibitors directly or indirectly increase catecholamine levels. Dietary intake of amines such as tyramine must be restricted in MAOI therapy.
Physiological MAOI effects at therapeutic dose levels of herbs with
in vitro MAOI activity are unlikely. Interaction with pharmaceutical MAOI drugs, as well as other drugs affecting catecholamine metabolism can be considered at least a theoretical possibility, although in practice, adverse effects during MAOI therapy from herbs are more likely to result from concurrent use of herbs in the symapathomimetics group.
For discussion of issues surrounding putative MAOI interactions see Hypericum perforatum (St. John's
Wort).
overview of interactions:
herbs theoretically affecting drug toxicity: Monoamine Oxidase Inhibitors
herbs theoretically affecting drug toxicity: Epinephrine
herbal concerns: Sympathomimetic Herbs
herbal concerns: Vasoconstrictor Herbs
herbal concerns: Sedative Herbs
herbal concerns: Xanthine-containing Herbs
Herbs
herbs theoretically affecting drug toxicity: Monoamine Oxidase Inhibitors
mechanism: Monoamine oxidase inhibitor herbs theoretically may additively synergize with MAOI drugs which would cause further elevated catecholamine levels and possible hypertension. Conclusive evidence is lacking.
herbs theoretically affecting drug toxicity: Epinephrine
mechanism: Monoamineoxidase inhibiting herbs may theoretically potentiate adrenomimetic drugs which would cause further elevated catecholamine levels and possible hypertension.
herbal concerns:
Indirect interaction with other herbs from the following groups may take place through various physiologic mechanisms:
Sympathomimetic Herbs
Vasoconstrictor Herbs
Sedative Herbs
Xanthine-containing Herbs
Common herbs with MAO inhibitor activity according to experimental data:
Hypericum perforatum (St John's Wort)
Passiflora incarnata (Passion Flower)
Glycyrrhiza glabra (Licorice Root)
Myristica fragrans (Nutmeg)
Restricted or unusual herbs with MAO inhibitor activity:
Lophophora spp. (Peyote)
Peganum harmala (Syrian Rue)
Cytisus scoparius (Scotch Broom) contains <2% tyramine, a nutrient which is catabolized by MAO. In physiological terms, the bradycardic and hypertensive actions of sparteine in
Cytisus are more likely to interact with MAOI drugs than the tyramine content.
Pausinystalia yohimbe (Yohimbe) has a very weak
in vitro MAOI activity. It is however hypertensive due to central adrenergic antagonism, increasing peripheral sympathetic outflow, and may be contraindicated with
MAOI's.
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and limitations of the information provided here.
The information presented in Interactions is for
informational and educational purposes only. It is based on scientific
studies (human, animal, or in vitro), clinical experience, case
reports, and/or traditional usage with sources as cited in each
topic. The results reported may not necessarily occur in all
individuals and different individuals with the same medical conditions
with the same symptoms will often require differing treatments. For
many of the conditions discussed, treatment with conventional medical
therapies, including prescription drugs or over-the-counter
medications, is also available. Consult your physician, an
appropriately trained healthcare practitioner, and/or pharmacist for
any health concern or medical problem before using any herbal products
or nutritional supplements or before making any changes in prescribed
medications and/or before attempting to independently treat a medical
condition using supplements, herbs, remedies, or other forms of
self-care.
Do not rely solely on the information in this article.
References
Brinker F. Herb Contraindications and Drug Interactions. Second edition., Sandy, OR: Eclectic Institute Inc, 1998.
Hardman J, et al. (eds.) Goodman &Gilman's Pharmacological Basis of Therapeutics.
Ninth Edition. McGraw Hill, 1996.
McGuffin M, et al. (eds.) AHPA Botanical Safety Handbook . CRC Press, 1997.
Newall C, Anderson L, Phillipson JD, Herbal medicines: A Guide for Health-Care Professionals.
London: Pharmaceutical Press, 1996.