Effects of calcium channel blockers on cardiovascular responses to smoking in normotensive and hypertensive smokers.

To evaluate the effects of short- and long-term administration of calcium (Ca) entry blockers on cardiovascular responses to cigarette smoking, 28 normotensive and 26 hypertensive smokers were studied. According to a double-blind, cross-over design, normotensive smokers were given a single dose (10 mg) of isradipine or a placebo and were checked before and after dosing. After a four-week period on a placebo, hypertensive smokers were treated with slow-release nicardipine 40 mg twice daily for six months and were checked at the end of the placebo period, after the first dose of nicardipine and at the end of six months of therapy. In both groups, blood pressure and heart rate were monitored by a Takeda TM 2420 non-invasive device every 3 min for 2 h. During the first hour patients were not allowed to smoke, during the second hour they were asked to smoke one cigarette every 15 min. In both normotensive and hypertensive smokers, calcium entry blockers produced a significant attenuation of the rise in blood pressure induced by cigarette smoking. Such effect was more evident after long-term therapy. Acceleration of the heart rate due to smoking was not significantly affected by the administration of Ca-antagonists, although a tendency towards a lesser heart rate increase was observed, particularly after long-term treatment. It was concluded that calcium entry blockers, reducing blood pressure variability, which bears a positive relationship with target organ damage, might be useful in the treatment of hypertensive smokers who were unwilling or unable to stop smoking.