[Influence of substitution of brand name for generic drugs on therapeutic compliance in hypertension and dyslipidemia].
OBJECTIVE
To determine therapeutic compliance when brand name amlodipine and simvastatin are substituted for generic drugs, and to determine patients' and physicians' opinions of this substitution.


METHODS
We performed an observational study with a control group, based on a review of the medical records in six primary care centers. Participants consisted of patients ≥ 40 years old initiating treatment with a brand name drug (initial period), which was later substituted by a generic drug (final period). The study subgroups consisted of patients with hypertension (amlodipine) or dyslipidemia (simvastatin). The main measures were comorbidity, compliance, treatment length, biochemistry determinations, and patients' and physicians' opinions (interviews). All patients received a brand name drug for a minimum of 1 year followed by a generic drug for a minimum of 1 year (minimum continuation/patient: 24 months).


RESULTS
There were 1,252 patients (groups: 49.5% amlodipine; 50.5% simvastatin). Patients treated with amlodipine (period comparison) showed better compliance (65.8 vs. 61.3%; p=0.037) and blood pressure control (48.5 vs. 45.8%; p=0.039) with the brand name drug. The percentages with simvastatin were 62.8 vs. 58.4% (p=0.041), respectively. A total of 73.6% of the physicians interviewed prescribed generic drugs and 59.2% believed that both types of drug had the same efficacy. Most of the patients interviewed (79.8%; CI: 74.3-85.3%) accepted the substitution; 55.3% (CI: 48.5-62.1%) received the appropriate information but 61.5% were confused by the different products. Lack of compliance was reported by 18.2%.


CONCLUSIONS
In patients receiving amlodipine or simvastatin, compliance decreased with time, independently of the change from a band name to a generic drug.
Dirección de Planificación, Badalona Serveis Assistencials S.A., Badalona, Barcelona, España. asicras@bsa.cat
Antoni Sicras
AS
Mainar
Ruth Navarro
RN
Artieda
D000328:Adult; D000368:Aged; D017311:Amlodipine / Q000627:therapeutic use*; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D057915:Drug Substitution / Q000706:statistics & numerical data*; D016568:Drugs, Generic / Q000627:therapeutic use*; D050171:Dyslipidemias / Q000188:drug therapy*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D000960:Hypolipidemic Agents / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D019821:Simvastatin / Q000627:therapeutic use*; D016903:Drug Monitoring
D000959:Antihypertensive Agents; D016568:Drugs, Generic; D000960:Hypolipidemic Agents; D017311:Amlodipine; D019821:Simvastatin