Brand versus generic alendronate: gastrointestinal effects measured by resource utilization.
BACKGROUND
Adverse reactions related to the upper gastrointestinal tract (UGIT) that are associated with generic alendronate formulations may differ from those associated with the brand drug.


OBJECTIVE
To test the hypothesis that adverse UGIT effects of alendronate formulations may differ between generic and brand products.


METHODS
We conducted a database health resource utilization analysis of UGIT outcomes in patients who started treatment with generic or brand alendronate formulations during 2001-2005. We included 6962 patients who were treated continuously for 3 months with 1 of 4 alendronate formulations: brand 10 mg/day (Merck, Sharpe & Dohme, n = 1418), generic A 10 mg/day (Teva, Israel, n = 650), generic B 10 mg/day (Unipharm, Israel, n = 628), and brand 70 mg/wk (n = 4266). In these patients, who had neither filled a prescription for alendronate nor had any gastrointestinal problems in the year preceding the study, we compared incidence rates of new use of gastric medications (H2-blockers, proton-pump inhibitors, or antacids), gastroenterology visits, endoscopies, and hospital admissions.


RESULTS
Incident rate ratios (IRR) for treatment discontinuation were higher with both daily generic products (IRR 1.3; 95% CI 1.04 to 1.63). Adherence (medication possession ratio [MPR] >80%) was better with brand 10 mg/day (IRR 1.19; 95% CI 1.11 to 1.27). All comparisons were adjusted for use of concurrent corticosteroids, nonsteroidal antiinflammatory drugs, and potassium supplements. Hospitalization rates (2.7-3.2%) were similar in all groups. New use of gastric medications (3.4-4.9%) was lower with brand 10 mg/day (IRR 0.71; 95% CI 0.53 to 0.95). Rates of UGIT endoscopy (n = 49) in patients receiving 10 mg were 0.6% (brand), 1.1% (generic A), and 1.6% (generic B), with generic B higher (IRR 2.88; 95% CI 1.14 to 7.29) in the entire cohort, but not among new users (n = 273) of gastric drugs (IRR 2.46; 95% CI 0.55 to 11.05). Endoscopic findings were normal in 22 patients, hiatal hernia with no mucosal lesion was present in 10 patients, and there was mild-to-moderate esophagitis or gastritis in 17 patients; there were no significant differences among the formulations.


CONCLUSIONS
We found insufficient evidence to indicate major differences in UGIT adverse effects related to use of daily generic, as compared with brand, alendronates.
Halkin
Hillel
H
Chairman, Formulary Committee, Maccabi Healthcare Services, Tel Aviv, Israel; Sackler School of Medicine, Tel Aviv University.
Dushenat
Marina
M
Silverman
Barbara
B
Shalev
Varda
V
Loebstein
Ronen
R
Lomnicky
Yosef
Y
Friedman
Nurit
N
D000368:Aged; D019386:Alendronate / Q000009:adverse effects* / Q000191:economics / Q000627:therapeutic use; D002626:Chemistry, Pharmaceutical; D015331:Cohort Studies; D016568:Drugs, Generic / Q000009:adverse effects* / Q000191:economics; D005260:Female; D005767:Gastrointestinal Diseases / Q000139:chemically induced* / Q000175:diagnosis / Q000188:drug therapy / Q000191:economics; D005773:Gastroscopy; D006760:Hospitalization; D006801:Humans; D015994:Incidence; D008297:Male; D012189:Retrospective Studies
D016568:Drugs, Generic; D019386:Alendronate