Background: Pioglitazone, an oral antidiabetic agent in the class of thiazolidinediones (TZDs), was widely used in the case of insulin tolerance as it provided more benefit to patients with type 2 diabetes. However, the original product is costly while some generic products are available at the substantial lower cost in Thailand. The objective of the present study was to assess bioequivalence in terms of efficacy between generic and original pioglitazone products.
Material and Method: A randomized double blind, crossover controlled trial was performed on 60 patients with type 2 diabetes at the Endocrine Unit, Department of Medicine, Phramongkutklao Hospital, Thailand. All subjects were randomly selected for group A and B (30 volunteers in each group). Duration of observation for efficacy of treatment with pioglitazone (both generic and original products) was totally 24 weeks. The dose of pioglitazone was 15 mg once daily.
Results: Finally, 22 males and 37 females remained in the trial. The reduction in means of HbA1c in group A and group B were 0.7% and 0.6% respectively. The least squares means of the HbA1c reduction of the generic and original group were 0.75% and 0.79%, respectively. There was no significant difference in HbA1c reduction between both groups. The average equality of HbA1c in all subjects in both groups was 100.7% (87.9-113.5%) at 90% confidence interval.
Conclusion: These findings indicated that both formulations were bioequivalent as their efficacy or therapeutic effects in reduction of HbA1c in the type 2 diabetic subjects were statistically the same.

Keywords: Pioglitazone, Test product, Reference product, HbA1c, Clinical efficacy