METFORMIN FOR THE TREATMENT OF POLYCYSTIC OVARY SYNDROME
The cause of polycystic ovarian syndrome (PCOS) is still not well understood. However a significant proportion of women with PCOS have resistance to the action of insulin such that they overproduce insulin. This results in higher levels of insulin in the blood after eating.
- drives the ovaries to produce testosterone and this may impair ovulation
- lowers the production of protein called sex hormone binding globulin (SHBG). SHBG binds testosterone in the blood so that testosterone cannot move freely into cells. If SHBG is low, then more testosterone in the blood can move into cells. This may result in increased body hair growth or oiliness of skin and acne.
METFORMIN is a drug that was developed to treat diabetes. Its major effect is to make the body more sensitive to the action of insulin, so that less insulin needs to be produced and then insulin levels fall. Because of this, metformin is used to lower insulin levels in women with PCOS.
Unlike other drugs used to treat diabetes, metformin does not cause low blood sugar (hypos) and therefore it is safe to use.
The target dose of metformin for effectiveness is between 1500-2500mg/day.
Metformin is used in PCOS women who have
- Infrequent menstrual cycles- in order to restore ovulation and regulate the cycles
- Infertility - to restore ovulation
- Obesity- to increase the body's response to insulin and as a result aid weight loss
Metformin may also have a slight appetite suppressant effect. Weight loss associated with the use of metformin usually involves loss of fat tissue (Stumvoll et al 1995)
The most commonly reported are nausea, vomiting, diarrhoea which may be due to build up of lactic acid in the bowel. Side effects are minimised by starting metformin at a low dose (250mg twice a day) and then gradually increase the dose every 2 weeks until the target dose is reached. Metformin should also be taken with a meal to reduce the likelihood of side effects.
Metformin may interfere with the absorption of Vitamin B12 and therefore red blood cell Vitamin B12 levels should be checked annually.
Lactic acidosis is a rare side effect and usually only seen in people with poor kidney function.
Metformin therapy should be temporarily stopped in the following situations:
- Before an X-Ray that will involve the use of iodine contrast injection
- Before any surgery that involves fasting and can be restarted when fluid intake is again normal
- If there may be a drug interaction (for example cimetidine)
The above advice is a general guide and was accurate at the time of production of this document. This information is provided to complement, not replace, the advice of your health professional.