Читать книгу Complementary and Alternative Medicine (CAM) Supplement Use in People with Diabetes: A Clinician's Guide - Laura Shane-McWhorter - Страница 7

A primary reason to address CAM use by diabetes patients is that they are 1.6 times more likely than people without diabetes to use these treatments and hence may be more vulnerable to problems resulting from CAM supplement use.¹⁰ Two potential concerns immediately emerge: side effects and drug interactions. Other concerns include variability of products, lack of standardization, contamination, and misidentification. Confusion regarding product content and labeling is another issue. A recent concern is whether clinical investigations actually verify the content of CAM supplements being studied.¹¹ Of equal concern is that there may be additional costs associated with CAM supplement use and may be delays in initiation of proven treatments.

A clinician may not even be aware that a patient is using CAM supplements. Less than 40% of patients tell their health care provider they are using CAM treatments.^6,12 A patient may experience a side effect that the provider may attribute to another medication, when in fact it could be due to a CAM supplement. Many serious side effects have been experienced by patients taking complementary therapies.^13,14 In individuals with diabetes, some products have caused irreversible hypoglycemia (Amanita phalloides) and critical hepatic glycogen depletion (unripe Ackee fruit).⁸ Unorthodox practices to treat diabetes, such as urine treatment, have also been reported.¹⁵ Clinicians should note that certain ethnic groups may be more reticent about reporting CAM supplement use to their health care providers.¹⁵

Potential drug interactions are another concern.^16,17 Since people with diabetes often have to take other medications, concomitant use of CAM supplements may result in toxicity secondary to exaggerated or subtherapeutic effects from their medications. For instance, ginseng may be used to treat diabetes, but may interfere with the ability of warfarin to produce its anticoagulant effect.¹⁸ Alternatively, a product may produce a drug-disease interaction. For instance, ginseng may increase blood pressure.¹⁹

Another potential problem is untoward reactions during surgery, secondary to CAM supplement use. Some products may cause excessive bleeding during surgery or interact with anesthetics, and patients may experience increases or decreases in blood pressure.^20,21 Because patients do not normally consider CAM supplements to be actual drugs, they may not tell providers they are taking them, and therefore providers may not ask the patients to stop use before surgery.^20,21

Product variability is another reason for caution. CAM supplements are available in a variety of forms, including tablets, capsules, or liquid extracts (if water-based they are called decoctions or infusions; if hydroalcoholic they are called tinctures). Alcohol-free glycerin-extracted preparations are called glycerites. The quality of a botanical product may depend on what part of the plant was used, how it was grown and stored, how long it was stored, how it was processed, and how the extract was prepared.¹⁴ A group of investigators assessed 59 products containing Echinacea, as a single ingredient, available in a retail setting.²² The investigators” intent was to determine whether the Echinacea species used was consistent with the labeled content. The researchers found that 52% (31 of 59) of products accurately reported the content, while 10% (6 of 59) contained no measurable Echinacea. For 18 samples where actual content differed from labeled content, 39% (7) contained more species than were listed on the label and 56% (10) contained fewer species. This is a prime example of product content variability. Hence it becomes very confusing for clinicians to determine which brand is most or least acceptable and what dose should be used.

Some products are available in standardized forms or standardized extracts. Ideally, standardization should guarantee consistency in each product batch as well as stability of the active ingredients. However, the active constituents are unknown for many agents, making standardization a difficult process. Furthermore, a botanical standardized constituent may show consistency between products, but may not necessarily be the active ingredient.²³ For instance, St. John’s wort has two main marker constituents, hypericin and hyperforin. Many researchers believe that hyperforin may be the more active species in providing therapeutic effects.²⁴ But should the results of well-designed studies where hypericin was the standardized extract in a clinical investigation be ignored? Pharmacological action of CAM supplements may be due to combined effects of several ingredients, and the individual ingredients may not produce the same effects as the whole plant.²⁵ Active botanical constituents may vary because of differences in geographic location or soil conditions, exposure to rain or sun, harvest time, and processing methods (drying and storage). Thus, pharmacological activity may be affected.²⁶

Other factors include potential misidentification, mislabeling, addition of unnatural toxic substances, such as heavy metals or steroids, and contamination with microbes, pesticides, fumigants, or radioactive products.²⁶ One example of contamination was the inadvertent substitution of Aristolochia serpentaria for Stephania tetranda in a weight-loss product, which resulted in Chinese herb nephropathy.²⁷ Another example was a dietary supplement available in American stores and by mail order, that was found to contain an unlabeled ingredient, glyburide, a prescription sulfonylurea.²⁸ Lead contamination of CAM products used to treat diabetes has also been reported.^29,30

There are wide variations in CAM supplement product labels, which may also be very confusing. This issue has been addressed in different investigations. In one study the investigators assayed six bottles each of two different supplement lots from nine different manufacturers containing Echinacea, kava, saw palmetto, ginseng, and St. John’s wort.³¹ Labels for the same product from different manufacturers were inconsistent in recommended daily amounts and botanical information regarding species, plant part used, and marker compounds. The greatest variability in that study was found in products containing Echinacea and ginseng. For example, the Echinacea contained the purpurea, pallida, or angustifolia species separately or in combination. The Echinacea products may have been derived from the aerial parts or the root. For ginseng, measured amounts ranged from 44% to 261% of what was stated on the bottle. The researchers noted that products from the same manufacturer but different lots of the same plant contained different plant parts. The least bottle for bottle variability was found for saw palmetto, kava, and St. John’s wort.

Another study assessed the label information of 10 popular herbs from 20 retail settings to determine consistency of reported ingredients and recommended daily doses.³² The investigators found that labels for 43% of 880 (379) products were consistent in reported benchmark ingredients (benchmarked according to ingredients in a reputable dietary supplement text) and recommended daily doses. Only 20% (179) were consistent in ingredients but not recommended doses, and 37% (329) lacked consistency in reporting ingredients or had vague label information that rendered it impossible to assess ingredient information. These reports verify that there is great inconsistency and variability in labeled information.

Furthermore, many investigators do not evaluate the product contents when conducting a clinical study. A group of researchers analyzed randomized controlled trials published between 2000 and 2004 of singleingredient products including Echinacea, garlic, ginkgo, saw palmetto, or St. John’s wort to determine whether the investigators evaluated and verified the product content.¹¹ The investigators found that 15% (12 of 81 studies) reported performing tests to calculate actual product contents and only 4% (3 studies) provided sufficient data to compare actual and expected content values of at least one chemical ingredient. The investigators found that in those three studies actual constituent content ranged from 80% to 113% of expected values.

Yet another thing to consider is the potential increased indirect costs of diabetes, because individuals with diabetes may substitute ineffective complementary therapies or delay treatment with proven therapeutic agents. These costs may include increased hospitalizations, acute complications such as ketoacidosis or acute hyperglycemia, or chronic complications such as retinopathy.³³ Other potential costs include decreased work productivity and diminished ability to function in a social or occupational setting if patients are substituting less effective treatments for more effective therapies. Conversely, a recent study examined whether CAM users with diabetes neglected preventive health care maintenance practices. The study found that CAM use was correlated with increased preventive health practices, including pneumococcal immunizations and visits to primary care providers.³⁴