Subjective side effects and antihypertensive therapy

Of 3000 general practitioners in Canada who received a questionnaire about subjective side effects of antihypertensive therapy, 679 practitioners, who saw a mean of 135 patients each completed and returned the form. The percentage of doctors who prescribed each of the antihypertensives available was as follows: thiazides 97.9%, propranolol 91.3%, methyldopa 90%, metoprolol 78.2%, chlorthalidone 67.3%, hydralazine 62.6%, prazosin 41.7% and clonidine 33.1 %.

When doctors were asked if the incidence of subjective side effects was rare, occasional or frequent the most common reply was 'occasional' for all the drugs except thiazides. 36.7% of doctors reported that subjective side effects were rare with thiazides while 35.8% said they were occasional. Similarly, 44.2 and 42.7% of practitioners said that subjective side effects in patients on methyldopa were occasional or frequent, respectively. Ranking of drugs according to the ratio of the percentage of prescribers who think side effects are frequent to those who think effects are rare showed that effects were most common with methyldopa (ratio frequent: rare = 3.26) followed by propranolol (ratio = 1.2). The remaining drugs all had a ratio < 1 and chlorthalidone and hydralazine had the lowest ratio values of 0.56 and 0.59, respectively. The most commonly reported side effects, reported with all drugs, were fatigue, weakness, dizziness, headache, constipation, dry mucosae, postural hypotension, visual symptoms, anorexia-nausea-vomiting, palpitations, dyspepsia and vertigo. Thus, these effects are not drug-specific. However, it is important to note that bronchospasm and dyspnoea were reported only with beta-blockers and nightmares were also most common with these drugs. Somnolence was associated primarily with clonidine and methyldopa; hypokalaemic symptoms with thiazides and chlorthalidone; sexual function disorders and depression most often with methyldopa; and arthralgia with diuretics and hydralazine. Laganiere S. Biron P. Current Therapeutic Research 39 970·978, Jun 1986

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