Role of nephrotoxic drugs in contrast-induced nephropathy.

Background: Elevation of serum creatinine (SCr) more than 0.5 mg/dl or 25% or more of the baseline value in 3 days after contrast administration is considered as contrast-induced nephropathy (CIN). Contrast material (CM) used in the radiological studies like contrast-enhanced computed tomography (CECT) and intravenous urogram (IVU) are nephrotoxic and their ability to cause renal damage is increased when other potential nephrotoxic drugs are given simultaneously. The present study aimed to demonstrate the effects of CM on patients who are on nephrotoxic drugs by studying the incidence of CIN in patients who are on nephrotoxic drugs and need a CECT or IVU (cases presenting with an emergency). The study compares the incidence of CIN in patients on nephrotoxic drugs with that in those not on nephrotoxic drugs and evaluates the importance of withdrawal of nephrotoxic drugs (3 days) in non-emergency contrast studies. Methods: The study population is divided into three groups. Group A consists of 40 cases undergoing emergency CECT or IVU, who are on nephrotoxic drugs. 40 cases undergoing CECT or IVU after 3 days of holding of nephrotoxic drugs are included in Group B. Group C consists of 40 cases undergoing CECT or IVU who are not on any nephrotoxic drugs. Patients with parenchymal renal disease, renal injury, and renal mass are excluded from the study. All cases having SCr <1.4 mg/dl are included in the study. SCr investigation is repeated 3 days after the contrast study. Results: The incidence of CIN is more in the patients who are on nephrotoxic drugs (15%) than in those who are not on nephrotoxic drugs (5%). There is no significant difference in the incidence of CIN between Groups B and C. p=0.045 between Groups A and B was noted showing the significance of waiting period in reducing the incidence of CIN. Conclusions: The incidence of CIN is more in patients who underwent contrast studies without stopping nephrotoxic drugs and stoppage of nephrotoxic drugs for 3 days prior to the procedure is beneficial by reducing the incidence of CIN among them.