Quick-Release Bromocriptine for Treatment of Type 2 Diabetes

Quick-release bromocriptine (bromocriptine-QR) (Cycloset) was approved in 2009 for the treatment of type 2 diabetes. The exact anti-diabetic mechanism of action of bromocriptine-QR has not been elucidated, but the drug may help resetting the circadian dopamine signal. Randomized placebo-controlled trials showed that the mean reduction in hemoglobin A1c (HbA1c) levels by bromocriptine-QR was 0.0-0.2% when compared to baseline and 0.4-0.5% when compared with placebo after 24 weeks of therapy. Withdrawal rates due to adverse effects in patients receiving bromocriptine- QR and placebo were 24% and 11%, respectively. The most common adverse effect of bromocriptine-QR was nausea reported by 32% of patients compared with 7% of patients randomized to placebo. The advantages of bromocriptine- QR were minimal risk of hypoglycemia, neutral effect on weight, and reassuring cardiovascular safety over 1 year of use. However, the drug had multiple drawbacks including modest efficacy, high rates of nausea, lack of long-term efficacy and safety data, and considerable cost. Bromocriptine-QR may be used in patients with type 2 diabetes with mild hyperglycemia (HbA1c close to 7.5%) either as adjunctive treatment to metformin and sulfonylurea (SU) or as monotherapy in patients who are intolerant to both agents.