Herbal Medications

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Chapter 8 Herbal Medications

Plants and plant-derived substances have been used as medicines for centuries. Indeed, herbal medications formed the bulk of pharmacopeias until the early twentieth century. Even currently, plants remain an important source of pharmaceuticals. Herbal medications, as defined by the World Health Organization (WHO), include plants, plant components, extracts of plants, and drinks, tablets, and capsules manufactured from plant sources. The WHO has estimated that over 10,000 species of plants have been used for medicinal purposes.

Systematic study of the use of herbals as complementary medicine is relatively sparse. Nevertheless, conservative estimates suggest that approximately 20% to 50% of the general population uses some form of herbal medicine. The prevalence of use is likely underestimated. Some surveys indicate that as many as two thirds of patients are reluctant to divulge use of herbal or complementary medicines to their physicians. Compounding the problems, many physicians fail to ask directly about herbal preparations. In addition, patients fear disapproval of their care providers because most people believe that physicians are dismissive of herbal medications. Moreover, most users of herbal medications believe that the natural sources of these preparations confer a greater degree of safety than conventional pharmaceuticals, and thus these users feel less need to discuss their use.

Regulatory Issues

Initially, in the United States, herbal medications were included with conventional pharmaceuticals for the purposes of regulation. In 1962 a distinction was made between drugs and botanicals, with botanicals assigned to the category of food supplements. As a result, herbal medications have a lower threshold of burden of evidence. Subsequently, the Dietary Supplement Health and Education Act (DSHEA; 1994) further delineated regulations pertaining to herbal medications. Herbal medications were defined as compounds containing vitamins, amino acids, herbs, botanical substances, concentrates, or extracts. However, unlike conventional pharmaceuticals, manufacturers are not required to provide the Food and Drug Administration (FDA) with data showing effectiveness and safety—nor are manufacturers required to report adverse events to the FDA. Indeed, the regulatory burden is placed on the FDA to show lack of efficacy or safety. Although manufacturers may not claim effectiveness for specific conditions (e.g., angina), they are allowed to make general claims of health benefits (e.g., promotes heart health).

The FDA has instituted new regulations that improve labeling and manufacturing specifications. The National Center for Complementary and Alternative Medicine (NCCAM) oversees research activities concerning herbal medications. Lastly, the botanical industry itself has established its own regulatory body, the American Herbal Products Association (AHPA).

Other countries also have various degrees of oversight of the marketing and use of herbal medications. European countries have a much longer history of herbal medication use and regulation. The European Union has a much more stringent oversight system. Similar to conventional drugs, herbal medications are reviewed for safety and efficacy and are licensed by the Committee on Herbal Medicinal Products (HMPC), a branch of the European Medicines Agency. Licensed herbal medications can make specific health claims. The HMPC also publishes monographs describing the applications, efficacy, and side effects for each approved herbal medication. Herbal medications appear on formularies and are prescribed by physicians as well as other healthcare providers.

Use of Herbal Medicines

Advocates of herbal medicine can find an herbal preparation applicable to virtually any condition. Several factors contribute to the more widespread use of selected herbal medications by a greater segment of the general population. The general public uses herbal medicine as a supplement or substitute for conventional pharmaceuticals most frequently for the treatment of chronic conditions for which conventional pharmaceuticals provide inadequate relief or produce undesirable side effects. The public often views herbal medication as safer than traditional pharmaceuticals because herbal medicines are derived from natural sources. Because herbal medications are available without prescription in many cases, convenience and personal control of healthcare decisions also motivate use of herbal medications. Major applications of herbal medicines include the treatment of sleep disorders, cardiovascular disorders, depression, chronic pain, prostatic hypertrophy, obesity, erectile dysfunction, and infection (e.g., the common cold). Given the reluctance of patients to share information concerning the use of herbal medications, physicians should use sound judgment and contextual suspicion to inquire about herbal medication use when treating patients with these conditions.

Practice Points

Despite the scant or contradictory evidence supporting the use of herbal medications for many indications, it is clear that the general public has embraced herbal medications. Accordingly, it is important that physicians be knowledgeable about commonly used herbal medications and ask patients about use of these preparations. Many patients are reluctant to divulge their use of alternative or complementary medicines because they fear the reaction of their physicians. Therefore it is important to inquire about herbal medications in a routine nonthreatening manner. If patients acknowledge their use of herbal medications, the physician should determine whether the patient is self-medicating or is receiving guidance from another practitioner (e.g., herbalist, pharmacist). Even if the patient does not acknowledge use of herbal medications, clinicians should proactively discuss possible herbal medication candidates. The physician should present a balanced picture regarding herbal medications by indicating that there is evidence both supporting and refuting their use.

Reliability of Herbal Products

There is a great deal of variability in the safety and efficacy of herbal medications. A number of factors contribute to variability in herbal medications, including the following:

Garlic Odor, diaphoresis, bleeding Ginger No major adverse effects Potential potentiation of anticoagulant antiplatelet drugs (controversial) Ginkgo No major adverse effects Synergistic interaction with other stimulants (e.g., caffeine) Ginseng No major adverse effects No consistent reports Kava Hepatotoxicity St John’s wort Soy Gastrointestinal disturbance Inhibition of actions of tamoxifen Saw palmetto None No major interactions reported

CNS, Central nervous system.