Successful Treatment of Homozygous Cystinuria with Captopril

ABSTRACT

Objective: Cystinuria is an autosomal recessive hereditary disorder associated with nephrolithiasis and its attendant complications. Traditional management using oral alkali; D-penicillamine; or mercaptopropionyglycine in an attempt to increase urinary cystine solubility is often unsuccessful due to intolerable side-effects. The aim of this study was to determine; if captopril could reduce urinary cystine excretion in homozygous cystinuric patients. Patients and methods: Three cystinuric patients with a history of multiple cystine stones despite previous traditional therapy were treated with 150 mg captopril daily for 3 years after determination of their baseline 24-hour urine cystine excretion. Cystine excretion studies were repeated subsequently at 6-month intervals. Results: The baseline 24-hour urine cystine excretion was within the expected limits for homozygous cystinuria in all patients (1072; 862 and 959 mg cystine per gm creatinine per 24 hours). After institution of captopril treatment; all patients had a significant decrease in urinary cystine levels (374; 313 and 451 mg cystine per gm creatinine per 24 hours). No patient experienced recurrent nephrolithiasis or adverse drug effects. Conclusion: We conclude that captopril can significantly decrease urinary cystine excretion in patients with homozygous cystinuria. Captopril should be considered an alternative to traditional drug management of cystinuria