Interactions Between Dietary Supplements And Pharmaceuticals Essay

, Research Paper

Interactions between dietary supplements and drugs will become a more serious

concern as supplement makers adopt better manufacturing practices. Some of these

interactions are positive to the patient?s health, while others are not. Mary Hardy,

M.D., is a member of the Integrative Medicine Department of Cedars-Sinai Medical

Center in Los Angeles. According to Dr. Hardy, ?Once these substances are properly

labeled, properly documented, and properly used by consumers, we can expect that

their most serious interactions are likely to involve pharmaceutical drugs.? Dr. Hardy

believes ?As pharmacists, you can look for the pharmacokinetic issues that will affect

the bioavailability or metabolism of the drug.? Also, pharmacodynamic interactions are

more individualized, less predictable, and more qualitative.

Herbs can counteract a drug?s therapeutic effect but, not all drug-herb

counteractions are negative. Two examples of positive drug-herb interactions are

seen with ginger and ginkgo biloba. Ginger is found to limit low-grade nausea related

to chemotherapy. Ginkgo biloba can be used to treat sexual dysfunctions that are

sometimes associated with the use of selective serotonin reuptake inhibitors (SSRIs).

Occasionally, herbs and drugs with entirely different mechanisms of action

reinforce each other. A study has shown that ginseng is known to be hypoglycemic.

Other high fiber hypoglycemic herbs can possibly reduce the absorption of

carbohydrates in the intestines. Dr. Hardy emphasizes that the blood sugar levels of

diabetic patients taking either type of herb and receiving insulin will need to be

monitored more closely.

According to studies, St. John?s Wort has been shown to decrease the

bioavailability of protease inhibitors. Protease inhibitors are the pharmaceuticals used

to treat AIDS patients. In one study, the trough level observed in sixteen healthy

patients declined 82% ? a level deep enough to allow for the emergence of resistant

viruses in patients with active AIDS. Dr. Hart emphasizes, ?This is a clinically

significant interaction, especially because St.John?s Wort has been shown in vitro to

be highly active against HIV. HIV patients are very likely to take it and to use high


An article printed in the August 2000 issue of Pharmacy Practice News reports

that some herbs can change the level of drug absorption, either by increasing binding

or by precipitating the drug in the gut. For example, hydrocoilldal fiber herbs such as

fenugreek, slippery elm, or even psyllium and bran can change absorption levels.

Dr. Hardy also points out the reality of ?double-dipping.? Herbs that share the same

active ingredients as a drug can enhance its therapeutic action. Combinations such as

ma huang and cold remedies containing pseudoephedrine, or foxglove and the

cardioglycoside digoxin are like ?double-dipping?.

Even if the herbs and drug do not contain the same active ingredients, doubling

can happen. A drug?s effect can be intensified if both the drug and the herb share the

same mechanism of action. If a patient is taking a barbiturate and adds valerian to the

diet, then the patient is reinforcing the drugs sedative effect. Some additive side

effects are seen between dietary supplements and drugs. If a patient is taking a

diuretic and depleting his or her potassium supply, licorice should not be consumed.

Licorice greatly increases potassium wastage. Kathryn L. Grant, Pharm D, Assistant

Professor of Pharmacy at the University of Arizona?s College of Pharmacy in Tucson

believes ?As we learn more about the pharmacodynamics and pharmacokinetics of

botanicals, we will more readily predict potential interactions.?

Some herbal therapies have normal but toxic reactions. The occurrence and

severity of these reactions depend on the dosage and preparation of the supplement.

This problem has been aggravated by the use of more concentrated preparations

based on distilled alcohol. Liver toxicities and carcinogenic properties have been

reported from this.

Adulterants have also been discovered in herbal products. Contaminants have

included diuretics, nonsteroidal anti-inflammatories (NSAIDS), benzodiazepines, and

heavy metals. In a documented case, a patient taking a protein supplement displayed

symptoms of lead poisoning. When analyzed, the supplement contained 2.88% lead.

?I believe there?s a lot to learn by taking a systematic look at case series and

cohort studies,? Dr. Hardy stresses. ?You have to know your manufacturer when you

buy these medications,? Dr. Hardy cautions. Direct research and adoption of better

manufacturing procedures are essential if pharmacists are to anticipate positive and

negative drug-herb interactions.

Gold Standard Multimedia. Clinical Pharmacology 2000. 1 November 2000

Kravetz, Shayna. ?Pharmacists Alerted to Alternative Agent Interactions With

Pharmaceutical Products?. Pharmacy Practice News August 2000: 16-17


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