Metformin for PCOS symptoms: 5 challenging cases
This inexpensive and versatile drug broadens the choices for treating polycystic ovary syndrome. An expert describes its efficacy for common manifestations of PCOS.
The incidence of newly diagnosed diabetes was 11, 7.8, and 4.8 cases per 100 person-years in the placebo, metformin, and lifestyle groups, respectively. Compared with placebo, lifestyle changes reduced the risk of developing diabetes by 58%, while metformin reduced it by 31%.
Obese women with PCOS may want to try to achieve the goals established in this study: weight loss of 7% of body weight and at least 150 minutes of exercise weekly. If lifestyle change alone is not effective for achieving a desired target weight, then metformin 500 mg 3 times daily or 850 mg twice daily could be prescribed.
Metformin for hyperglycemia, type 2 diabetes. Metformin also may be helpful in patients with type 2 diabetes; it is approved as monotherapy for hyperglycemia in patients in whom disease has not been controlled with diet and exercise alone.
Unlike sulfonylureas, metformin does not cause the body to make more insulin and hence does not produce hypoglycemia in normal subjects or patients with type 2 diabetes.
Generic metformin is available as 500-, 850-, and 1,000-mg tablets. The target dose is in the range of 1,500 mg to 2,550 mg, which can be achieved by doses of 500 mg 3 times daily, 850 mg 2 or 3 times daily, or 1,000 mg 2 times daily. The maximum dose of metformin is 850 mg 3 times daily (2,550 mg daily). Significant responses to metformin are not regularly observed at total doses lower than 1,000 mg daily. The cost of 1,500 mg of generic metformin is about $1.75.
Metformin is taken with meals to reduce gastrointestinal side effects and is usually initiated at a dose of 500 mg, administered at the largest meal. If the patient tolerates this initial dose, metformin can then be increased to 500 mg at the 2 largest meals and then to 500 mg at breakfast, lunch, and dinner. It may take the patient 1 to 2 weeks to adapt to the gastrointestinal effects of an increase in dose.
Extended-release metformin is available as 500- and 750-mg tablets (Glucophage XR). The entire daily dose is taken at dinner. The initial dose is 500 mg or 750 mg daily, with escalation to a maximum of approximately 2,250 mg. Many authorities believe that extended-release metformin is associated with fewer gastrointestinal side effects than generic metformin.
Side effects. The most common side effects are diarrhea (10% to 53% of patients), nausea or vomiting (6% to 26%), flatulence (12%), indigestion, and abdominal discomfort. Weakness has been reported in 9% of patients. In 1 clinical trial at a dose of 2,550 mg daily, treatment was associated with diarrhea in 53% of the patients, compared with 12% of patients taking placebo.49 In the same study, nausea or vomiting was reported in 26% of those taking metformin and 8% of those taking placebo.
A small percentage of women discontinue the medication because of side effects.49,50 Occasionally, the onset of side effects begins well after the patient has begun taking the medication.51
Clinical courseKey element: Lifestyle changes
The patient decides to use metformin plus lifestyle changes in her weight-loss plan, even though you recommend first trying lifestyle changes alone.
Over 6 months she loses 35 lb and reports being satisfied with her treatment. She believes that metformin was largely responsible for her weight loss. However, it is likely that her commitment to diet and exercise were the key to her success.
Dr. Barbieri reports no financial relationship with any companies whose products are mentioned in this article.
