Risk of gynaecomastia associated with cimetidine, omeprazole, and other antiulcer drugs.
OBJECTIVE
To study the risk of gynaecomastia associated with cimetidine, misoprostol, omeprazole and ranitidine.


METHODS
Open cohort study with nested case-control analysis.


METHODS
General practices in United Kingdom that had computerised offices, 1989-92.


METHODS
81,535 men aged 25-84 years who received at least one prescription for cimetidine, misoprostol, omeprazole, or ranitidine during the study period.


METHODS
New occurrences of idiopathic gynaecomastia diagnosed by general practitioner.


RESULTS
The relative risk of gynaecomastia for current users of cimetidine compared with non-users was 7.2 (95% confidence interval 4.5 to 11.3). Relative risks for misoprostol, omeprazole, and ranitidine were 2.0 (0.1 to 10.7), 0.6 (0.1 to 3.3), and 1.5 (0.8 to 2.6), respectively. Current users of cimetidine on a daily dose > or = 1000 mg had more than 40 times the risk of developing gynaecomastia than non-users. The period of highest risk was seven to 12 months after starting cimetidine treatment. Spironolactone (relative risk 9.3 (3.3 to 26.1)) and verapamil (9.7 (2.6 to 36.0)) were associated with a relative risk of gynaecomastia comparable to one for cimetidine.


CONCLUSIONS
Use of cimetidine, but not the three other antiulcer drugs, is associated with a substantially greater risk of gynaecomastia in men. A strong dose-response relation was present among cimetidine users.
García Rodríguez
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Boston Collaborative Drug Surveillance Program, Boston University Medical Center, Lexington, MA 02173-5207.
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D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000897:Anti-Ulcer Agents / Q000009:adverse effects*; D016022:Case-Control Studies; D002927:Cimetidine / Q000009:adverse effects; D015331:Cohort Studies; D004305:Dose-Response Relationship, Drug; D004739:England / Q000453:epidemiology; D006177:Gynecomastia / Q000139:chemically induced* / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009853:Omeprazole / Q000009:adverse effects; D012307:Risk Factors; D013997:Time Factors
D000897:Anti-Ulcer Agents; D002927:Cimetidine; D009853:Omeprazole