Theophylline reduces contrast medium nephropathy risk

The adenosine receptor antagonist theophylline may lower the risk of acute kidney injury (AKI) induced by radiocontrast medium, according to a meta-analysis in Kidney International.

A literature review identified 16 randomized controlled trials comparing adenosine antagonists with control treatments to prevent contrast medium–induced AKI. In both arms, treatment could be with or without N-acetylcysteine. Data on 1412 participants were pooled to compare contrast medium–induced AKI rates, change in serum creatinine, dialysis requirement, and in-hospital mortality.

On the basis of data from 13 trials (1412 patients), theophylline reduced the risk of contrast medium–induced AKI by about half: risk ratio 0.48. Theophylline also had a protective effect on absolute change in serum creatinine: standardized mean difference −0.31 mg/dL, based on 13 trials (1170 patients). It did not appear beneficial in patients with serum creatinine of 1.5 mg/dL or higher.

On metaregression analysis, the risk of contrast medium–induced AKI was related to baseline serum creatinine level. There was no consistent effect on rates of dialysis or in-hospital death, both of which were infrequent.

Animal studies have suggested that theophylline and aminophylline have the potential to protect kidney function after the injection of contrast medium. However, clinical studies of adenosine receptor antagonist treatment have yielded conflicting results.

Existing data suggest that theophylline reduces the risk of contrast medium–induced AKI, with a modest but significant improvement in kidney function after exposure to contrast medium. The authors call for high-quality randomized trials, including patients at different levels of baseline risk and evaluation of long-term outcomes [Bai B, et al. Effect of theophylline on prevention of contrast-induced acute kidney injury: a meta-analysis of randomized controlled trials. Am J Kidney Dis 2012; 60:360–370].