[Factors contributing to increases in serum creatinine following treatment with a sulfamethoxazole-trimethoprim combination product: retrospective analysis of Japanese patients with normal renal function].

  Japanese patients with normal renal function were retrospectively analyzed to characterize increases in serum creatinine (SCr) observed following the use of a sulfamethoxazole-trimethoprim (SMX-TMP) combination product and identify factors affecting these increases. In the patients studied (n=49), an individual comparison was conducted for the three factors of age group [≤74 years (n=21) vs. ≥75 years (n=28)], sex [male (n=24) vs. female (n=25)], and total dose throughout the treatment period [≤7 g (n=24) vs. ≥8 g (n=25)] to determine the extent of SCr increase following SMX-TMP combination product use. SCr increased significantly following SMX-TMP combination product use in patients ≤74 years of age and ≥75 years of age, in both males and females, and in patients with a total dose of ≥8 g (8 to 96 g) (p<0.05). Multivariate logistic regression analysis was used to determine the independence of these factors. Total dose was identified as an independent factor and had an odds ratio of 6.571 [95% confidence interval=1.735-24.882, p=0.006]. Post-treatment percent increases in SCr were compared using pre-treatment levels as the baseline. The group with a total dose of ≥8 g (mean 29.8 g) had a significant SCr increase of 18.4% (p=0.002), while the increase in the ≤7 g (mean 5.3 g) group was only 4.5%. The data showed that SCr increased by about 20% when the total dose taken over the treatment period was around 30 g (about 2.4 g as TMP) and indicated that total dose contributes more than age and sex to the post-treatment increase in SCr.