Introduction: Diltiazem commonly use as  anti- hypertensive agent, also reduces  tacrolimus dose by decrease  metabolism  to achieve its therapeutic blood concentration in kidney transplant recipients (KTRs). This method has been practiced in several centers, including India, but the actual impact of diltiazem  as  tacrolimus toxicity salvage  and improvement of delayed graft function and safety aspects are unknown.
Materials and Methods: This retrospective observational  study was performed on 45 ABO compatible live related  renal transplant recipients  ≥18 years of age at our center from January 1, 2017 to December 31, 2019, who were  diagnosed as hypertensive delayed graft function with  20 of them prescribed diltiazem as antihypertensive agent  and others were on optimized dose of other class of anti -hypertensive agents . Surgical causes of DGF were ruled out. Blood  trough level of tacrolimus (TacC0) and other relevant clinical data for  these DGF patients were reviewed .The two groups were similar with respect to age of donor and recipient, sex distribution of both donor and recipient, degree of sensitization, cold ischemia time, DR matching, HLA matching, and DR mismatching , pretransplant transfusions, induction agents.
Results and Discussion: Despite similar serum creatinine levels at 3 month {diltiazem group 1.8 (1.1-2.9)mg/dl vs. no diltiazem  2.1 (1.3-3.1) mg/d, (P = 0.43)} , the diltiazem group had a significantly higher mean  serum creatinine reduction at 3 month post-transplant {delta S. Cr 1.93(1.1-3.4) vs 1.1(1.3-2.1) (p<0.001)}. The diltiazem group had a significantly higher glomerular filtration rate at 3 month (63.9 vs. 34.7, P <0.001). In diltiazem group there are significant difference in DGF response in which initial TAC trough level were >15 micro-gm/lit v/s <15 micro-gm/lit  in terms of  delta serum creatinine. These results suggest that there were short-term improvements noted in  DGF group specially in patients with high initial blood tacrolimus trough level (TacC0) .
Adverse effects reported within 3 months of diltiazem introduction were postural hypotension n=2 (10%) and bradycardia n=1 (5%)  which resolved after diltiazem dose reduction.
Conclusion: In this study , short-term (3 month post-transplant) improvements noted in ABO compatible live related  renal transplant hypertensive recipients with  non-surgical DGF with introduction of optimum dose of diltiazem , in comparison to patients on other maintenance anti-hypertensive and the result were more significant with higher initial TAC trough level.