Renal failure after omeprazole.

SIR,-An 86-year-old woman had a 10 year history of oesophagitis and had been treated intermittently with cimetidine or ranitidine. Because of progression in symptoms in 1989, omeprazole 40 mg daily was started. At that time the patient had normal serum creatinine concentration. 2 months later she was admitted with renal failure: maximum serum creatinine 858 pmol/L (normal < 120). A renal needle biopsy revealed interstitial inflammation, with plasma cells, lymphocytes, and eosinophils and patchy tubulitis but no effect on glomeruli, which is characteristic of acute interstitial nephritis.1 2 weeks before admission the patient had been treated with erythromycin for suspected pneumonia. Both drugs were withdrawn, and the patient regained normal renal function on treatment with diuretics. Erythromycin was suspected of being the drug causing the renal failure. In 1992, during cimetidine treatment, the patient had a peptic stricture of the oesophagus and omeprazole was given with surveillance of renal function. Within a week the patient developed high temperature, a rash, eosinophilia, and diminishing renal function. The patient did not receive any other drugs, and omeprazole was withdrawn after 9 days. The renal failure progressed to anuria, and necessitated haemodialysis for a week. The renal function remained severely affected, and after 3 months serum creatinine had declined from 810 to 396 mmol/L. Our patient had typical acute interstitial nephritis, with the triad of high temperature, rash, and eosinophilia.1 The pathophysiology remains unclear, but cell-mediated immunity is probably important in most cases The allergic nature of our patient's disease is favoured by the fact that she had previously reacted with rashes to other drugs (amiloride with hydrochlorthiazide, phenylbutazone, and penicillin), and in 1972 she had had sarcoidosis (verified by mediastinal gland biopsy) that spontaneously subsided. Patients with sarcoidosis react with an enhanced T-lymphocyte-mediated immune response to various antigens. This is the second case of acute interstitial nephritis due to omeprazole, and the diagnosis was confirmed by renal biopsy. The first case was a 74-year-old woman with oesophagitis who twice had increased serum creatinine and eosinophilia/eosinophiluria for weeks after treatment with omeprazole.3