Rosiglitazone is an oral drug that reduces the amount of sugar (glucose) in the blood. It is used for treating patients with type 2 diabetes and is in a class of anti-diabetic drugs called thiazolidinediones. The other member of this class is pioglitazone (Actos). Insulin is a hormone produced by the pancreas that is important for controlling the levels of glucose in the blood. Insulin stimulates the cells of the body to remove glucose from the blood and thereby lowers the level of glucose in the blood. Patients with type II diabetes cannot make enough insulin. As a result, the cells in their bodies do not remove enough glucose from the blood, and the level of glucose rises. Rosiglitazone often is referred to as an “”insulin sensitizer”” because it attaches to the insulin receptors on cells throughout the body and causes the cells to become more sensitive (more responsive) to insulin and remove more glucose from the blood. At least some insulin must be produced by the pancreas in order for rosiglitazone to work). Rosiglitazone was approved by the FDA on May 28, 1999.
PREPARATIONS: Tablets: 2, 4, and 8 mg.
STORAGE: Tablets should be kept at room temperature, 15-30°C (59-86°F).
PRESCRIBED FOR: Rosiglitazone, combined with diet, exercise, weight control and cessation of smoking is used for treating type II diabetes. Rosiglitazone may be used alone or in combination with other types of anti-diabetic drugs such as metformin or sulfonylureas as well as insulin. Since it requires naturally-secreted insulin to be effective, rosiglitazone is not recommended for use in type I diabetes where the amount of insulin is very low or absent.
DOSING: Rosiglitazone may be taken once or twice daily, with or without meals. Daily doses range from 4 to 8 mg either with or without other antidiabetic medications. Studies do not demonstrate additional effects when more than 8mg per day are taken.
DRUG INTERACTIONS: Rifampin decreases the blood concentration of rosiglitazone by increasing its breakdown in the liver. Therefore, use of rifampin may decrease the effect of rosiglitazone.
Gemfibrozil increases the concentration of rosiglitazone in the blood by reducing its breakdown. Therefore, rosiglitazone may increase the side effects of rosiglitazone.
PREGNANCY: There are no adequate studies of rosiglitazone in pregnant women.
NURSING MOTHERS: It is unknown if rosiglitazone is secreted in breast milk. Therefore, the safety of rosiglitazone to nursing infants also is unknown.
SIDE EFFECTS AND PRECAUTIONS: The most common side effects seen with rosiglitazone alone or in combination with metformin are upper respiratory tract infection, headache, back pain, hyperglycemia, fatigue, sinusitis, diarrhea, and hypoglycemia. Rosiglitazone has been shown to cause mild to moderate accumulation of fluid (edema) and can lead to heart failure. Patients who already have heart failure may develop worsening symptoms with rosiglitazone. In addition, anemia may occur with rosiglitazone alone or combined with metformin. Rosiglitazone also causes increasing amounts of weight gain with increasing doses.
A review of the studies of rosiglitazone led the FDA to conclude that the medication might increase the risk of heart attacks and angina, but left the association as inconclusive. Additionally, there isn’t enough evidence that the risk of heart attack and angina is any greater with rosiglitazone than with other oral medicines used in the treatment of diabetes.
Since troglitazone, a related drug, was associated with liver injury, it is recommended that liver tests be obtained before starting therapy and periodically thereafter. Side effects which may suggest liver injury include unexplained nausea, vomiting, abdominal pain, fatigue, anorexia (loss of appetite), or dark urine.
Rosiglitazone may cause ovulation in premenopausal women who have stopped ovulating because they are resistant to insulin. Rosiglitazone may improve insulin sensitivity sufficiently to cause ovulation. Therefore, there is the potential for rosiglitazone to lead to pregnancy.
Studies testing rosiglitazone excluded New York Heart Association Class III and IV patients who have more serious heart disease. Therefore, it is not known how these classes of patients will respond to treatment. The concern is that fluid accumulation may lead to heart failure in these patients.
Rosiglitazone alone or combined with metformin has demonstrated various effects on blood lipids. Studies have shown elevated total and low-density cholesterol (LDL) levels within the first two months of rosiglitazone therapy with or without metformin, while high-density cholesterol (HDL) levels increase and free fatty acids decrease with continued therapy.
Two large studies have shown increased upper and lower extremity fractures in women taking rosiglitazone.