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VICUS.COM (20 July 2000) -- Americans spent approximately $4
billion on botanical remedies in 1999, including roughly $300 million
on a short, yellow, flowering plant called St. John's wort, which is
widely used in the treatment of depression, according to
estimates from health-related publications.
Despite these sales figures -- culled from HerbalGram, the
journal of the American Botanical Council and the Herb Research
Foundation, and the Nutrition Business Journal -- it
is becoming well-established in the literature that St. John's wort
can reduce the effectiveness of or interact negatively with many
prescription drugs when taken concurrently.
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Other interactions:
Other drugs which have been known to
interact with St. John's wort:
* Cyclosporine (organ transplant rejection protection)
* Warfarin (anti-coagulant)
* Indinavir (HIV-1 protease inhibitor)
* Oral contraceptives
* Theophylline (used to treat asthma, chronic bronchitis,
bronchospasm, emphysema)
* Amitriptyline
(anti-depressant)
* Nefazodone
(anti-depressant)
* Paroxetine
(anti-depressant)
Source: The Medical
Letter. 26 June 2000; 42(1081):56.
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One of these interacting drugs is digoxin, which is commonly
prescribed for patients with congestive heart failure (Kothari, 1997).
The drug is used to strengthen the contraction of the heart muscle,
slow the heart rate and promote the elimination of fluid from body
tissues.
Almost 5 million Americans are living with CHF, according to the
American Heart Association, and the condition has become the single
most expensive health-care item in the United States and the No. 1
hospital-discharge diagnosis in the elderly (Schrier, et al.,
2000).
Digoxin is one of the oldest and most widely prescribed drugs in
medicine, with a lineage that rivals St. John's wort. Digoxin is
derived from Digitalis lanata or Digitalis
purpurea (also known as the foxglove plant) and has been used
medicinally since the days of the ancient Egyptians and the Roman
Empire.
Digoxin has been a mainstay of modern medicine during this century.
But its value, particularly for heart failure, has been hotly debated,
especially during the past two decades, as newer, more effective drugs
have become available, and clinical trials in heart failure have
failed to confirm the value of digoxin beyond a doubt (Garg, et
al., 1997; Kothari, 1997; Van Veldhuisen, et al.,
1997).
St. John's wort has been shown to lower the blood levels and,
subsequently, the therapeutic effects of digoxin, as well as many
other medications (Baede-van Dijk, et al., 2000; Fugh-Berman, 2000;
Johne, et al., 1999).
There are three scenarios in which this interaction can have
important consequences.
- Scenario 1. You add St. John's wort to digoxin therapy: If
you are already taking digoxin for heart failure or abnormal heart
rhythms and are getting a good response, adding St. John's wort
will result in lower digoxin levels.
What could happen: You may find that you are not
responding well to the digoxin and symptoms from your heart
condition are returning (e.g., breathlessness, swollen ankles and
weakness).
- Scenario 2. You stop taking St. John's wort but keep taking
digoxin: Any time you stop taking St. John's wort, but
continue to take digoxin, your digoxin levels may go up.
What could happen: This unintended increase in digoxin
blood concentrations may lead to digoxin toxicity. You could
experience abnormal heartbeats, visual disturbances
("halo," "yellow" or "snowy"
vision), lethargy and fatigue, and intestinal symptoms (anorexia,
nausea and diarrhea). Other common signs of digoxin toxicity are
crying, agitation, hallucinations, nightmares, paranoia,
drowsiness and confusion.
- Scenario 3. You take St. John's wort occasionally: If
you take St. John's wort only when you are feeling
"down," and then stop it when you feel better, your
digoxin blood levels will fluctuate each time you start or stop
St. John's wort.
What could happen: If your blood digoxin level gets
too low (after you start taking St. John's wort), there may be a
loss of effectiveness and a return of the symptoms of heart
disease. If the blood levels increase too much, it could lead to
digoxin toxicity.
What's a
patient to do?
The interaction between St. John's wort and digoxin is complex,
with potentially serious consequences. Speak with your health
practitioner if you are already taking either drug and if you think
you might want to take them together. Know the signs and symptoms
associated with digoxin blood levels that are too low or too high.
John Russo
Jr., Pharm.D., is senior vice president of medical
communications at Vicus.com. He is a pharmacist and medical writer
with more than 20 years of experience in medical education.
References:
American Heart Association: Cardiovascular diseases prevalence
http://www..americanheart.org/statistics/03cardio.html
Baede-van Dijk PA, van Galen E, Lekkerkerker JF. [Drug interactions
of Hypericum perforatum (St. John's wort) are
potentially hazardous]. [Article in Dutch]. Ned Tijdschr
Geneeskd. 2000 Apr 22; 144(17):811-2.
Brevoort P. The Booming U.S. Herb Market: A New Overview. HerbalGram.
1998 Fall; (44):33-46.
Chen SC. Recent advances in the treatment of congestive heart
failure. Indian J Pediatr. 1998 Jan-Feb;
65(1):13-20.
Cohn JN. Heart failure: future treatment approaches. Am J
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Fugh-Berman A. Herb-drug interactions. Lancet. 2000
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Garg R, Gorlin R, Smith T, et al. The effect of digoxin
on mortality and morbidity in patients with heart failure. N
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Johne A, Brockmoller J, Bauer S, et al. Pharmacokinetic
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Kothari SS. Does digoxin still have a role in congestive heart
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Linde K, Mulrow CD. St John's wort for depression. Cochrane
Database Syst Rev. 2000; (2):CD000448.
Moore LB, Goodwin B, Jones SA, et al. St. John's wort
induces hepatic drug metabolism through activation of the pregnane X
receptor. Proc Natl Acad Sci U S A. 2000 Jun 20;
97(13):7500-2.
Roby CA, Anderson GD, Kantor E, et al. St John's wort:
effect on CYP3A4 activity. Clin Pharmacol Ther. 2000
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Schrier RW, Abdallah JG, Weinberger HH, et al. Therapy
of heart failure. Kidney Int. 2000 Apr; 57(4):1418-25.
Tsen LC, Segal S, Pothier M, et al. Alternative
medicine use in presurgical patients. Anesthesiology. 2000
Jul; 93(1):148-51.
Van Veldhuisen DJ, De Graeff PA, Crijns HJ. [Digoxin in chronic
heart failure and sinus rhythm: is the end of the controversy in
sight]? [Article in Dutch]. Ned Tijdschr Geneeskd. 1997
Mar 8; 141(10):460-4.
Vorbach EU, Arnoldt KH, Wolpert E. St. John's wort: a potential
therapy for elderly depressed patients? Drugs Aging. 2000
Mar; 16(3):189-97.
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