Rosiglitazone

Rosiglitazone (Avandia®) is an antihyperglycaemic agent of the thiazolidinedione class that improves glycaemic control (as indicated by glycosylated haemoglobin [HbA_1c] and fasting plasma glucose [FPG] levels) primarily by increasing hepatic and peripheral insulin sensitivity, and in addition may help to preserve pancreatic β-cell function.

In general, rosiglitazone as monotherapy or in combination with other antihyperglycaemic agents, including metformin or sulfonylureas, improves glycaemic control in adults with type 2 diabetes mellitus and may slow disease progression associated with pancreatic β-cell function decline. Rosiglitazone is generally well tolerated; however, additional long-term and comparative studies are required to further evaluate the effects of rosiglitazone on bone and the potential cardiovascular risk of the drug, including the risk relative to pioglitazone. Thus, in light of recent cardiovascular safety concerns and the need for further long-term data to clarify the potential risk of rosiglitazone in this regard, it would be prudent to use rosiglitazone in the treatment of type 2 diabetes on a case-by-case basis, taking into account individual patient cardiovascular risk factors.

Rosiglitazone, a member of the thiazolidinedione class of antihyperglycaemic agents, is a potent agonist of the peroxisome proliferator-activated receptor-γ through which many of its effects are mediated. The drug reduces hyperglycaemia primarily by improving the insulin sensitivity of the liver and peripheral tissues, and also appears to attenuate the decline in function of pancreatic β-cells. Rosiglitazone increases subcutaneous fat levels and is generally associated with bodyweight gain, although visceral and intra-hepatic fat is reduced. Rosiglitazone may have detrimental effects on bone.

In well designed monotherapy trials of 24 weeks’ to a median of 4 years’ duration, rosiglitazone was as effective as pioglitazone, superior to metformin and noninferior or superior to both the sulfonylurea glibenclamide (glyburide) and the dipeptidyl peptidase IV inhibitor vildagliptin in improving glycaemic control in patients with type 2 diabetes. Long term, rosiglitazone was also associated with a significantly lower incidence of treatment failure than metformin or glibenclamide in patients with type 2 diabetes previously untreated with pharmacotherapy.

Rosiglitazone used in combination with metformin provided better glycaemic control than metformin alone in short-term trials in patients with type 2 diabetes inadequately controlled with metformin alone or in combination with an oral insulin secretagogue or acarbose. In addition, long term, rosiglitazone plus metformin was noninferior to or as effective as metformin plus a sulfonylurea in improving glycaemic control in patients with type 2 diabetes inadequately controlled with metformin monotherapy.

In additional short-term studies, rosiglitazone in combination with a sulfonylurea was superior to sulfonylurea monotherapy and noninferior to or at least as effective as metformin plus sulfonylurea with regard to improving glycaemic control in patients with type 2 diabetes inadequately controlled with a sulfonylurea alone. Furthermore, in a 1.5-year interim analysis of a large, randomised, multicentre study, rosiglitazone plus sulfonylurea was shown to be noninferior to metformin plus sulfonylurea in terms of improving HbA_1c levels, with both combination therapies demonstrating similar efficacy in improving levels of FPG.

In triple-therapy trials in patients with type 2 diabetes inadequately controlled with metformin plus a sulfonylurea, the addition of rosiglitazone significantly improved glycaemic control compared with metformin plus sulfonylurea combination therapy alone and produced similar improvements in glycaemic control to the addition of insulin glargine in terms of HbA_1c.

Patients with type 2 diabetes receiving rosiglitazone in combination with metformin or a sulfonylurea were more satisfied with treatment than patients receiving uptitrated metformin or sulfonylurea, in studies of 24 weeks’ and 2 years’ duration. Data from a short-term study suggest that adding rosiglitazone to metformin plus a sulfonylurea in patients with inadequate glycaemic control with this dual therapy is generally significantly less effective at improving health-related quality of life than the addition of insulin glargine.

Fully published pharmacoeconomic model analyses from a healthcare system or health insurance perspective have indicated that rosiglitazone combination therapies are generally cost-effective options compared with conventional therapies for the treatment of type 2 diabetes, although in combination with metformin, rosiglitazone appears to be less cost effective than pioglitazone in patients with inadequate glycaemic control with metformin monotherapy, according to one pharmacoeconomic model.

Rosiglitazone was generally well tolerated as monotherapy and in combination with other antidiabetic agents in adult patients with type 2 diabetes in clinical trials of up to a median of 4 years’ duration. In general, rosiglitazone therapy was associated with oedema and congestive heart failure, although the drug did not differ from pioglitazone with regard to these adverse events in a 24-week study. Rosiglitazone alone or in combination with other antidiabetic agents was associated with changes from baseline in bodyweight of +0.2 to +4.3kg in trials of 8 weeks’ to a median of 4 years’ duration. The drug was also associated with an increased incidence of bone fractures compared with metformin or glibenclamide in female patients with type 2 diabetes in one long-term study. Limited data from long-term clinical trials have not confirmed the findings of meta-analyses suggesting an increased risk of myocardial infarction with rosiglitazone.