CIMETIDINE AS ADJUNCTIVE TREATMENT FOR ACETAMINOPHEN OVERDOSE

The aim of this study was to determine if cimetidine in addition to N-acetylcysteine and standard supportive care provide additional hepatoprotection following acute acetaminophen poisoning. It was designed as a prospective study with alternate month treatment protocol, and the work was carried out at a regional certified poison information centre. For a 2-year period, consultations received by the Rocky Mountain Poison Center involving acute acetaminophen overdose patients with a serum level above the nomogram line, but who would not receive N-acetylcystine therapy until at least 8 h postingestion, were prospectively evaluated for adjunctive treatment with cimetidine. All patients received standard supportive therapy and N-acetylcysteine treatment. During odd numbered months, cimetidine 300 mg was administered intravenously every 6 h for the duration of N-acetylcysteine therapy. Forty-one cimetidine treated patients were compared to 66 patients in the control group. The peak measured AST levels (+/- s.e.) were 1259 +/- 330 and 1301 +/- 451 for the control and cimetidine treatment groups, respectively (P = 0.94), Fourteen of 64 patients (21%) in the control group and 8/41 patients (20%) in the cimetidine group developed an AST > 1000 IUL(-1). There were no statistical differences between the cimetidine-treated and control groups when classified by AST<100IUL(-1), 100- 1000IUL(-1), or >1000IUL(-1). The addition of cimetidine therapy to standard N-acetylcysteine treatment did not provide additional hepatoprotection in acutely acetaminophen poisoned patients when treatment was started later than 8 h post overdose. Larger doses of cimetidine along with more frequent or continuous intravenous administration may warrant further study.