What exactly does bioidentical mean for hormones?
Mary Heim, RPh, FAAFM
The FDA still classifies “bioidentical hormone” as a marketing term but the purpose of the phrase is to identify those hormones that have the same chemical and molecular structure as hormones that are produced in the human body. For treatment of menopausal symptoms or hormone imbalance, those hormones could be estrone, estradiol, estriol, progesterone, and testosterone. The chemical structure of these hormones can be reproduced in a laboratory starting with plant phytoestrogens like yam or soy.
The term bioidentical is used to differentiate from synthetic derivatives such as conjugated equine estrogens, medroxyprogesterone, norethindrone, levonorgestrel, and methyltestosterone. Many physicians and pharmacists strongly believe the bioidentical hormones have less side effects and metabolism issues over synthetic alternatives. A literature review addressing this subject was completed by Dr. Kent Holtrof and published in Postgraduate Medicine in January 2009. A more intense review concerning progestogens in menopausal therapy was published in Endocrine Reviews in 2012 by Frank Stancyk.
Many FDA approved commercial products contain bioidentical hormones. Estradiol is available commercially as topical patches, oral tablets, vaginal cream, vaginal tablets, topical gels and in a cypionate salt for intramuscular injection. Progesterone is available in capsule form but does contain peanut oil as an inactive ingredient. Testosterone is available in male doses in topical gels and in a cypionate salt form for intramuscular injection.
The FDA has not yet approved a commercial product containing estriol, a weaker estrogen used often for vaginal dryness or combined with estradiol. They also have not approved a female dosage or female indication for testosterone. When a physician wants to prescribe the estriol, a low testosterone dosage for women, or some combination not yet commercially available, they will utilize a compounding pharmacy. A compounding pharmacy can mix together the exact dosages and combination desired for a specific patient based on the physician’s instructions.
Compounded is not interchangeable with bioidentical. A compounded hormone replacement product could be considered bioidentical if it contains certain hormones (estrone, estradiol, estriol, progesterone, and/or testosterone) or it could be synthetic if contained other hormones (norethindrone or methyltestosterone). Bioidentical hormones could be either compounded or an FDA approved commercial product.
Stanczyk, F et al. Progestogens Used in Postmenopausal Hormone Therapy: Differences in Their Pharmacological Properties, Intercellular Actions, and Clinical Effects. Endocrine Review. 34(2) 2013
Holtorf, K. The Bioidentical Hormone Debate: Are Bioidentical Hormones (Estradiol, Estriol and Progesterone) Safer or More Efficacious than Commonly Used Synthetic Versions in Hormone Replacement Therapy? Postgraduate Medicine. 121(1) 2009
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