Cimetidine as adjunctive treatment for acetaminophen overdose

Abstract

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 aceta minophen overdose patients with a serum level above the nomogram line, but who would not receive N-acetylcys tine therapy until at least 8 h postingestion, were prospec tively 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 fre quent or continuous intravenous administration may war rant further study.