From the FDA Drug Label
2 DOSAGE AND ADMINISTRATION
- 1 Adult Dosage Metformin Hydrochloride Tablets The recommended starting dose of metformin hydrochloride tablets are 500 mg orally twice a day or 850 mg once a day, given with meals. Increase the dose in increments of 500 mg weekly or 850 mg every 2 weeks on the basis of glycemic control and tolerability, up to a maximum dose of 2550 mg per day, given in divided doses.
The recommended dosage of metformin for patients with Polycystic Ovary Syndrome (PCOS) is not explicitly stated in the provided drug label. However, based on the adult dosage information, the starting dose is 500 mg orally twice a day or 850 mg once a day, given with meals. The dose can be increased in increments of 500 mg weekly or 850 mg every 2 weeks on the basis of glycemic control and tolerability, up to a maximum dose of 2550 mg per day, given in divided doses 1.
- The dosage may need to be adjusted based on individual patient factors, such as glycemic control and tolerability.
- It is essential to note that the provided drug label does not specifically address the treatment of PCOS, and the dosage may vary depending on the clinical context and patient population.
From the Research
The recommended dosage of metformin for patients with Polycystic Ovary Syndrome (PCOS) is typically 1500-2000 mg per day, with a gradual titration starting at 500 mg once daily with a meal to minimize gastrointestinal side effects. This dosage is based on the study by 2, which found that different doses of metformin exerted the same effects on clinical, biochemical, and metabolic parameters in patients with PCOS. The study suggests that higher doses are no more effective than lower doses, and the paradigm of using the minimum effective dose of metformin could be pursued in other pathological conditions characterized by insulin resistance.
Key Considerations
- The maintenance dose is often 1500 mg daily, taken as 500 mg three times daily with meals or 850 mg twice daily 2.
- Treatment duration is usually long-term, as PCOS is a chronic condition, and benefits may take 3-6 months to become apparent.
- Metformin works in PCOS by improving insulin sensitivity, which helps reduce insulin resistance commonly found in PCOS patients, leading to decreased androgen production by the ovaries, potentially improving menstrual regularity, reducing hirsutism, and in some cases, improving fertility.
Supporting Evidence
- A study by 3 found that insulin-resistant PCOS patients with low BMI are more likely to respond to metformin, whereas CC treatment is more effective in less hyperandrogenic and insulin-resistant PCOS patients with low BMI.
- Another study by 4 compared the efficacy of clomiphene citrate and metformin as first-line approaches for treating anovulation in infertile PCOS patients and found that both treatments were effective, but there was no significant difference in ovulation, pregnancy, and abortion rates between the two groups.
- A more recent study by 5 found that letrozole is better and more acceptable than combined clomiphene citrate and metformin for inducing ovulation in patients with clomiphene-resistant PCOS, with higher clinical pregnancy rates and lower adverse effects.
Clinical Implications
- The choice of metformin dosage should be individualized based on the patient's response and tolerance to the medication.
- Patients should be monitored regularly for signs of improved insulin sensitivity, menstrual regularity, and reduced androgen production.
- Extended-release formulations of metformin may be considered to improve adherence and reduce gastrointestinal side effects.