A Comparative Effectiveness Study of Renal Parameters Between Imidapril and Amlodipine in Patients with Hypertension: A Retrospective Cohort Study

INTRODUCTION Imidapril is an angiotensin converting enzyme inhibitor (ACEI) that is frequently used as an antihypertensive drug in Japan. Although ACEIs are known to have adverse effects of decreasing glomerular filtration rate (GFR) and causing hyperkalemia, there are very few clinical data on the long-term effect of imidapril on glomerular function. We conducted a retrospective cohort study using a clinical database to evaluate and compare the long-term effects of imidapril and amlodipine on renal parameters in Japanese hypertensive patients in routine clinical practice. METHODS We identified cohorts of new users of imidapril (n = 57) and a propensity score-matched group with an equal number of new users of amlodipine (n = 57). We used a multivariable regression model to evaluate and compare the effects of the drugs on laboratory parameters including serum levels of creatinine, potassium, sodium, blood urea nitrogen, and estimated GFR (eGFR) between imidapril users and amlodipine users up to 12 months after the initiation of study drug administration. The mean exposure of imidapril and amlodipine was 226.2 and 235.2 days, respectively. RESULTS We found a significant increase of serum creatinine and potassium levels and a decrease of eGFR in imidapril users from the baseline period to the exposure period. The reduction of eGFR and the increase of serum creatinine and potassium levels in imidapril users were significantly greater than those in amlodipine users. CONCLUSIONS Our study showed that imidapril decreased eGFR and increases the serum levels of creatinine and potassium compared with amlodipine, at least during 1 year of administration.