New cutaneous toxicities with generic docetaxel: are the excipients guilty?

Docetaxel is one of the most widely used anticancer drugs and an ideal candidate for the development of generic formulations to reduce the economic cost. However, the use of generic drugs is an issue of debate because studies of their safety and efficacy in comparison with the original drug are not required for approval. The aim of this study is to determine whether the change in the formulation of the original drug is responsible for the toxicity changes observed.

A retrospective study contrasts the incidence of acute infusion reactions and skin reactions to four different presentations of docetaxel including the original drug. These drugs differ in the amounts of excipients.

1.031 doses of docetaxel were administered to 268 patients. A total of 26 grade 3/4 infusion reactions were detected. Compared to the original formulation, the relative risk of acute infusion reaction was 3.74 (1.52-9.18, p = 0.002), 0.57 (0.19-1.64, p = 0.288) and 0.37 (0.1-1.34, p = 0.117) for the patients treated with drugs 2, 3 and 4. For the dermal toxicity, 9 % of patients suffered a clinically significant skin reaction. The relative risks of clinically significant dermal toxicity for the different formulations of docetaxel versus the original formulation were as follows: 6.15 (2.78-13.58) and 7.13 (3.24-15.69) for drugs 3 and 4 (p < 0.001).

Our study suggests that some toxic effects of docetaxel may be related to the excipients used in different formulations of the drug.