5-Aminosalicylates and Effects on Renal Function in Patients with Crohnʼs Disease :

A formula has been developed to predict creatinine clearance (C cr ) from serum creatinine (S cr ) in adult males: Ccr = (140 – age) (wt kg)/72 × S cr (mg/100ml) (15% less in females). Derivation included the relationship found between age and 24-hour creatinine excretion/kg in 249 patients aged 18–92. Values for C cr were predicted by this formula and four other methods and the results compared with the means of two 24-hour C cr’s measured in 236 patients. The above formula gave a correlation coefficient between predicted and mean measured Ccr·s of 0.83; on average, the difference between predicted and mean measured values was no greater than that between paired clearances. Factors for age and body weight must be included for reasonable prediction.

Sulphasalazine (S.A.S.P.) is of proven value in the treatment of ulcerative colitis, but its mode of action is unknown. When it is taken by mouth, nearly all the dose reaches the colon intact, where it is split by bacteria into sulphapyridine (S.P.) and 5-aminosalicylic acid (5-A.S.A.). An experiment was devised to determine whether the therapeutic property of S.A.S.P. is a function of the parent molecule or of these two principal metabolites. Retention enemas of S.A.S.P., S.P., and 5-A.S.A. were administered to volunteer patients with sigmoidoscopic evidence of active ulcerative colitis. The experiment was conducted as a blind controlled therapeutic trial, each patient having one of the test enemas daily for two weeks. Pronounced histological improvement was observed in approximately 30% of the patients receiving S.A.S.P. or 5-A.S.A., and in only 5% of those receiving S.P. It is concluded that the active therapeutic moiety of S.A.S.P. IS 5-A.S.A. and that the S.P. functions as a carrier ensuring that the 5-A.S.A. is liberated within the colon.

5-aminosalicylates are extensively prescribed for the treatment of ulcerative colitis but have a wide range of described adverse effects. To determine whether serious adverse effect profiles differ for sulphasalazine and mesalazine. Analysis of suspected serious adverse reactions reported to the Committee on Safety of Medicines of the UK in 1991-1998. Adverse effect profiles were categorised for interstitial nephritis, pancreatitis, serious skin reactions, hepatitis and hepatic failure, and blood dyscrasias. Report rates were calculated using prescribing data from the Department of Health and compared for mesalazine and sulphasalazine. Further analysis was undertaken for sulphasalazine according to disease indication of inflammatory bowel disease or rheumatoid arthritis. A total of 4.7 million prescriptions were dispensed for sulphasalazine compared with 2.8 million for mesalazine. Interstitial nephritis was only described for mesalazine, with 11.1 reports per million prescriptions. Pancreatitis was reported seven times as frequently for mesalazine (7.5 per million prescriptions) compared with sulphasalazine (1.1 per million prescriptions) (odds ratio (OR) 7.0; 95% confidence interval (CI) 2.6-18.6; p<0.001). There were no reports of serious skin disorders in patients prescribed sulphasalazine for inflammatory bowel disease. Blood dyscrasias were reported significantly more often in patients receiving sulphasalazine for rheumatoid arthritis than for inflammatory bowel disease (OR 5.31; 95% CI 2.6-11.0; p<0.001), and there was a similar trend for hepatic disorders. Spontaneous reports suggest that within the five sets of disorders considered, there is no evidence to indicate a safety advantage of mesalazine over sulphasalazine in the treatment of inflammatory bowel disease. Pancreatitis and interstitial nephritis appear significantly more common with mesalazine, and advice on renal monitoring in patients who receive mesalazine may need reinforcing.