Post-marketing studies of subjective side effects; a case for strict methodological criteria and careful analysis of data

Zofenopril and incidence of cough: a review of published and unpublished data

OBJECTIVE

Cough is a typical side effect of angiotensin-converting enzyme (ACE) inhibitors, though its frequency quantitatively varies among the different compounds. Data on the incidence of cough with the lipophilic third-generation ACE inhibitor zofenopril are scanty and never systematically analyzed. The purpose of this paper is to give an overview on the epidemiology, pathophysiology, and treatment of ACE inhibitor-induced cough and to assess the incidence of cough induced by zofenopril treatment.

METHODS

Published and unpublished data from randomized and postmarketing zofenopril trials were merged together and analyzed.

RESULTS

Twenty-three studies including 5794 hypertensive patients and three studies including 1455 postmyocardial infarction patients exposed for a median follow-up time of 3 months to zofenopril at doses of 7.5-60 mg once-daily were analyzed. The incidence of zofenopril-induced cough was 2.6% (range 0%-4.2%): 2.4% in the hypertension trials (2.4% in the double-blind randomized studies and 2.4% in the open-label postmarketing studies) and 3.6% in the doubleblind randomized postmyocardial infarction trials. Zofenopril-induced cough was generally of a mild to moderate intensity, occurred significantly (P < 0.001) more frequently in the first 3-6 months of treatment (3.0% vs 0.2% 9-12 months), and always resolved or improved upon therapy discontinuation. Zofenopril doses of 30 mg and 60 mg resulted in significantly (P = 0.042) greater rate of cough (2.1% and 2.6%, respectively) than doses of 7.5 mg and 15 mg (0.4% and 0.7%, respectively). In direct comparison trials (enalapril and lisinopril), incidence of cough was not significantly different between zofenopril and other ACE inhibitors (2.4% vs 2.7%).

CONCLUSION

Evidence from a limited number of studies indicates a relatively low incidence of zofenopril-induced cough. Large head-to-head comparison studies versus different ACE inhibitors are needed to highlight possible differences between zofenopril and other ACE inhibitors in the incidence of cough.

ACE inhibitor- versus angiotensin II blocker-induced cough and angioedema

OBJECTIVE

To compare the tolerability of angiotensin-converting enzyme (ACE) inhibitors with that of angiotensin II (AII)-receptor blockers and the incidence of cough and angioedema associated with their use through review of published data.

DATA SOURCES

References were identified through a MEDLINE search of articles published between January 1975 and April 1997. Bibliographies of pertinent references were also reviewed.

RESULTS

Results of placebo-controlled and comparative trials of the AII blockers demonstrate that they are at least as effective as ACE inhibitors for hypertension, but exhibit an incidence of cough and absent or rare angioedema like that of placebo.

CONCLUSIONS

In the 10 comparative trials described, all reported a lower incidence of cough with AII blockers than with ACE inhibitors. Angioedema was not reported in the comparative trials described.

Cough due to ACE inhibitors: a case-control study using automated general practice data

OBJECTIVES

To determine the risk of coughing as an adverse reaction to ACE inhibitors under everyday circumstances in a large population, and to study whether this adverse effect was duration or dose dependent.

DESIGN

A population-based case-control study.

SETTING

Ten general practices of 14 Dutch general practitioners (GP), in which all consultations, morbidity and medical interventions, including drugs prescribed, were registered over the 18 month period from 1st September, 1992 to 1st March, 1994.

SUBJECTS

1458 patients with incident coughing and up to four controls per case were obtained (total 4182 controls), matched for GP. All cases and controls were 20 years or older and had no record of respiratory infection, influenza, tuberculosis, asthma, chronic bronchitis, emphysema, congestive heart failure, sinusitis, laryngitis, haemoptysis or respiratory neoplasms during the study period.

RESULTS

Cases were 2.1-times more likely than controls to have been exposed to ACE inhibitors (95% CI 1.5-3.1), but after adjustment the odds ratio was 1.4 (95% CI 0.9-2.1). The crude odds ratio for captopril was 1.3 (95% CI 0.7-2.5), for enalapril 2.6 (95% CI 1.6-4.2) and for lisinopril 2.0 (95% CI 0.5-9.3). The adjusted odds ratio for captopril was 0.9 (95% CI 0.4-1.7), for enalapril 1.7 (95% CI 1.03-2.8) and for lisinopril 1.7 (95% CI 0.4-7.9). For patients who had been on ACE inhibitor treatment for no longer than 2 months the odds ratio was 4.8 (95% CI 1.7-13.3). The odds ratio declined to 2.0 (95% CI 1.1-3.8) for those who had taken an ACE inhibitor for 2-6 months, and to 1.6 (95% CI 0.9-2.7) for those on ACE-inhibitors for more than 6 months.

CONCLUSION

The risk of coughing was increased twofold among ACE inhibitor users, but the odds ratios were no longer significant after controlling for several confounding factors. The risk of developing cough due to ACE-inhibitors declines with the duration of treatment, possibly due to depletion of susceptible persons.

Angiotensin converting enzyme inhibitor associated cough: a population-based case-control study

The objectives of this study were to determine the risk for coughing as an adverse reaction to angiotensin converting enzyme (ACE) inhibitors under everyday circumstances in a large population and to study whether this adverse effect is more common in women. A population-based case-control study was used. The study was set in the practices of 161 Dutch general practitioners (GPs), in which all consultations, morbidity, mortality, medical interventions and prescriptions were registered during 4 consecutive 3-month periods in 4 consecutive groups of 40-41 GPs. The subjects were 2436 patients with incident coughing and up to 3 controls per case were obtained (total group: 7348 controls), matched for GP and a contemporary consultation in the same 3 months. All cases and controls were 20 years or older and had no notification of respiratory infections, influenza, tuberculosis, asthma, chronic bronchitis, emphysema, congestive heart failure, sinusitis, laryngitis, haemoptysis or respiratory neoplasms during the 3-month period. The results showed that cases were 3.6 times as likely as controls to have been exposed to ACE inhibitors (95% CI: 2.4-5.5) but after adjustment for potential confounders the odds ratio was 2.5 (95% CI: 1.6-3.9). The crude odds ratio for males was 2.7 (95% CI: 1.4-5.1) and for females 4.2 (95% CI: 2.4-7.5). The adjusted odds ratio for males was 1.8 (95% CI: 0.9-3.5) and for females 2.7 (95% CI: 1.5-4.8).(ABSTRACT TRUNCATED AT 250 WORDS)