**4.12 ACE inhibitors and angiotensin receptor blockers**

ACE inhibitors have been identified as a risk factor for CIN because of their ability to reduce renal function. On the contrary, some small studies have shown that the inhibition of angiotensin II can decrease renal vasoconstriction following the injection of contrast media. In a randomized controlled study including 71 patients with diabetes who underwent coronary angiography and randomized to captopril (25 mg thrice daily) or control, there was a significant decrease in CIN in the patients who received captopril compared with the control group (6 vs 29%, respectively, p < 0.02) [35]. A randomized controlled study was performed on 80 patients with serum creatinine less than 2 mg/dl who underwent coronary angiography where captopril was administered in 48 patients preceding coronary angiography. CIN occurred in five patients (10.4%) in the captopril group, compared with only one patient (3.1%) in the control group (p = 0.02) [36]. We can say that holding ACE inhibitor or ARB use before coronary angiography is to be considered.
