Ethanol patch test: A simple method for identifying the effectiveness of cyanamide in alcoholics

Background: To identify the pharmacological effectiveness of cyanamide, 144 alcoholics treated with cyanamide were subjected to a test that used an acetaldehyde dehydrogenase (ALDH) inhibitor, the ethanol patch test, which is considered to be a good indicator of ALDH2 phenotype. Methods: We placed 100 mu l of 70% ethanol on a lint pad and, as a control, placed the same volume of distilled water on a second pad. The ethanol patch test was performed on 144 alcoholics more than 2 weeks after abstinence from alcohol before and after treatment with cyanamide for 1 week. The dose of cyanamide was increased up to 150 mg until the patch test yielded a positive result. Results: In the ethanol patch test, 36 alcoholics (25.0%) gave a positive result before treatment with cyanamide and might have been ALDH2(1)/2(2) heterozygotes. Among 108 alcoholics who were not positive, the distribution of the cyanamide dose that yielded a positive ethanol patch test result was 30 mg in 42 cases (38.9%), 50 mg in 33 cases (30.6%), 70 mg in 5 cases (4.6%), 100 mg in 6 cases (5.6%), and 150 mg in 2 cases (1.9%). Prevalence of liver cirrhosis was significantly higher in alcoholics who showed a positive ethanol patch test result at doses of less than 50 mg cyanamide than those at doses more than 70 mg (p = 0.029). The prevalence of adverse effects was significantly higher in alcoholics who showed a positive ethanol patch test result at doses of more than 70 mg than at doses of less than 50 mg cyanamide (p = 0.002). Conclusions: The ethanol patch test is a useful method for identifying pharmacological effectiveness of cyanamide and may reduce the prevalence of side effects in cyanamide-treated alcoholics.