Cisplatin-induced hyponatremia in malignancy: comparison between brand-name and generic formulation

Abstract

Introduction

Widespread use of generic drugs is considered to be indispensable if reductions in total health care costs are to be achieved, but the market share of such drugs remains low. In general, generic drugs have the same active ingredients as brand-name drugs, but this is not always the case. Thus, toxicity profiles may vary when brand-name and generic drugs are compared. We retrospectively investigated the incidence of hyponatremia in patients receiving brand-name cisplatin (CDDP) and a generic counterpart thereof.

Methods

We reviewed the medical records of patients treated with brand-name CDDP (n=53) and a generic formulation (n=26), and compared the incidences of hyponatremia and renal toxicity. Toxicities were graded using the Common Terminology Criteria for Adverse Events, version 4.0. Differences between groups were evaluated using the Student’s t-test, and the odds ratio for hyponatremia was estimated via logistic regression analysis.

Results

Serum creatinine levels after chemotherapy increased significantly in both the brand-name and generic CDDP groups; no significant difference was evident between the two groups. Hyponatremia of grade 3 or above developed in 30.7% of the generic CDDP group compared to 15.1% of the brand-name CDDP group (P=0.011). Multivariate analysis showed that the use of generic CDDP increased the incidence of hyponatremia (odds ratio =5.661, 95% confidence interval =1.403–22.839; P=0.015).

Conclusion

Oncologists should be aware that use of a generic CDDP might be associated with more hyponatremia than would use of brand-name CDDP.

Keywords:

• cisplatin
• hyponatremia
• brand-name
• generic drug

Acknowledgments

We thank Dr Yasumasa Monobe, Department of Pathology 1, Kawasaki Hospital, Kawasaki Medical School, Okayama, Japan, who confirmed the diagnoses of malignancies.

Disclosure

KH has received honoraria from Eli Lilly Japan, Taiho Pharmaceutical, Chugai Pharmaceutical, and Sanofi-Aventis. KK has received honoraria from Eli Lilly Japan, Nihon Kayaku, AstraZeneca, Daiichi-Sankyo Pharmaceutical, Chugai Pharmaceutical, Taiho Pharmaceutical, and Sanofi-Aventis. NT has received honoraria from Eli Lilly Japan, Nihon Kayaku, AstraZeneca, Daiichi-Sankyo Pharmaceutical, Chugai Pharmaceutical, Taiho Pharmaceutical, Pfizer Inc. Japan, Boehringer–Ingelheim in Japan, and Sanofi-Aventis. The authors report no other conflicts of interest in this work.