Interaction between cigarettes and propranolol in treatment of angina pectoris

Enalapril versus atenolol in the treatment of hypertensive smokers

A randomised crossover study has been done to compare the antihypertensive efficacy of enalapril and atenolol in 45 smoking, hypertensive men. Treatment was started with enalapril 20 mg/d or atenolol 50 mg/d and, if necessary, the doses were doubled after 4 weeks to achieve a sitting diastolic blood pressure < or = 95 mm Hg, after which hydrochlorothiazide was added, if necessary. Both drugs lowered blood pressure significantly. However, enalapril was more efficient in lowering both systolic and diastolic blood pressure; the mean difference was significant after both 4 and 8 weeks in the sitting systolic (11.6 mm Hg and 7.9 mm Hg) and diastolic (3.3 mm Hg and 3.0 mm Hg) pressures and in the erect systolic pressures (8.2 mm Hg and 7.2 mm Hg), and after 8 weeks in the supine systolic pressure, too (8.9 mm Hg). The effect on enalapril was especially marked in moderate (< 20 cigarettes/day) smokers. The need for diuretics was also significantly less in the enalapril group. It appears that angiotensin-converting enzyme inhibitors may be superior to beta-adrenoceptor blockers in the treatment of hypertensive smoking patients.

The health consequences of smoking. Cardiovascular diseases

Cigarette smoking is a major cause of atherosclerotic diseases. Cardiovascular diseases (CVD) remain the leading disease cause of death and disability in the United States. Smoking contributes to much of the premature and overall disease burden from CVD. Smoking affects the physiologic, pathologic, hematologic, and metabolic factors that lead to the initiation, progression, and sequelae of atherosclerosis. Smoking cessation reduces the progression of atherosclerosis and the subsequent morbidity, mortality, and years of productive life lost from CVD.

Decreased beta-adrenergic receptor density and catecholamine response in male cigarette smokers. A study of monozygotic twin pairs discordant for smoking

The effect of long-term cigarette smoking on beta-adrenoceptor density and catecholamine response was studied in 10 monozygotic male twin-pairs discordant for smoking, with an average discordance time for smoking of 23 years (range, 12-35 years). The density of beta-adrenergic receptors was 40% lower in the lymphocytes of smoking twins compared with their nonsmoking cotwins (beta-receptor density, 6.7 +/- 1.2 and 11.1 +/- 1.8 fmol/10(6) cells, respectively; p less than 0.05). The corresponding apparent Kd values were 31.7 +/- 5.5 and 26.7 +/- 5.4 pM, respectively. Stimulation of the lymphocyte beta-receptors resulted in significantly lower levels of cyclic adenosine monophosphate in the smokers compared with the nonsmokers (16.2 +/- 3.3 vs. 29.2 +/- 6.5 pmol/10(6) cells, p less than 0.05). When subjected to submaximal exercise, the smokers had a lower level of cyclic adenosine monophosphate in plasma (25.9 +/- 1.2 vs. 28.6 +/- 1.0, p less than 0.05) and a net decrease was seen in plasma free fatty acids in the smokers compared with a net increase in the nonsmokers (-15% vs. +19%, p less than 0.01). The total plasma catecholamine level was, in the basal state, significantly higher in smokers compared with nonsmokers (74.8%, p less than 0.05). The intrapair difference in plasma norepinephrine predicted well the intrapair difference in beta-receptor density (r = -0.84, p less than 0.001). We conclude that the autonomic neurohumoral response evoked by cigarette smoking results in downregulation of beta-adrenergic receptors in long-term smokers.

Acute elevation of blood carboxyhemoglobin to 6% impairs exercise performance and aggravates symptoms in patients with ischemic heart disease

Acute exposure to carbon monoxide has the potential to impair exercise capacity in patients with ischemic heart disease. The effect of sufficient inhalation of this compound to gradually produce a level of 6% carboxyhemoglobin was studied in 30 nonsmoking patients with obstructive coronary artery disease and evidence of exercise-induced ischemia. After an initial training session, subjects were exposed to air or carbon monoxide on successive days in a randomized double-blind crossover fashion. Cardiac function and exercise capacity were assessed during symptom-limited supine radionuclide ventriculography. On the carbon monoxide day, mean postexposure carboxyhemoglobin was 5.9 +/- 0.1% compared with 1.6 +/- 0.1% (p less than 0.01) after air exposure. The mean duration of exercise was significantly longer after air compared with carbon monoxide exposure (626 +/- 50 s for air versus 585 +/- 49 s for carbon monoxide, p less than 0.05). Actuarial methods suggested that subjects were likely to experience angina earlier during exercise on the day of carbon monoxide exposure (p less than 0.05). Both the level (62 +/- 2.4 versus 60 +/- 2.4%, p = 0.05) and change in left ventricular ejection fraction at submaximal exercise (1.6 +/- 1.6 versus -1.2 +/- 1.6%, p = 0.05) were greater on the air exposure day compared with the carbon monoxide day. The peak exercise left ventricular ejection fraction was not different for the two exposures (57 +/- 2.5% for both). These results demonstrate earlier onset of ventricular dysfunction, angina and poorer exercise performance in patients with ischemic heart disease after acute carbon monoxide exposure sufficient to increase blood carboxyhemoglobin to 6%.

Impact of smoking on heart attacks, strokes, blood pressure control, drug dose, and quality of life aspects in the International Prospective Primary Prevention Study in Hypertension

Effects of smoking are highlighted in a posthoc analysis of this randomized, double-blind International Prospective Primary Prevention Study in Hypertension (IPPPSH). At the time of entry, 37% of the men and 23% of the women were smoking cigarettes, and only 537 patients changed their smoking status during the trial. In men and women, smoking doubled cardiac and cerebrovascular event rates. Nonsmoking men had fewer myocardial infarctions and sudden deaths when treated with oxprenolol. Smoking status did not affect in-study blood pressure control, the type of drugs, or the combinations used, but smokers were given higher doses of oxprenolol. For a given blood pressure during antihypertensive treatment, rates for cardiac and cerebrovascular events were higher in smokers. Heart rates were higher in both oxprenolol and non-beta-blocker-treated smokers. Smoking dose dependently increased hematocrit level. Among physician-elicited symptoms, dyspnea and cold extremities were more frequent in smokers, whereas dyspnea, headaches, impotence, dizziness, and anxiety states were common, with unsatisfactory blood pressure control (diastolic blood pressure greater than 95 mm Hg). Quality of life may be more jeopardized by smoking, poor blood pressure control, or diuretic use than by beta-blocker-based therapy. In the IPPPSH, the patient who smoked had double the cardiovascular complication rates without cardiac benefit from the beta-blocker despite higher doses given; the higher heart rate and hematocrit level may have been contributing factors.

The effects of cigarette smoking on plasma concentrations of gastric antisecretory drugs

Plasma concentrations of cimetidine and ranitidine were measured after oral administration (n = 5 for cimetidine, n = 5 for ranitidine) or intravenous administration (n = 6 for cimetidine, n = 4 for ranitidine) in habitual smokers, once when cigarettes were smoked and again on a separate day when cigarettes were prohibited. After oral administration plasma concentrations of both drugs rose more rapidly and peak plasma concentrations were achieved earlier when cigarettes were smoked. However, plasma concentrations of the drugs subsequent to the peak were significantly lower when cigarettes were smoked. Cigarette smoking had no effect on plasma blood concentrations of either drug when administered intravenously. In eight healthy smokers cigarette smoking increased the gastric emptying of a liquid test meal by 28% compared with non-smoking control rates. In habitual smokers cigarette smoking alters the blood concentrations of antisecretory drugs in a manner which appears attributable to an increase in the rate of gastric emptying. The observed changes in drug disposition may contribute to the loss of gastric secretory inhibition observed in duodenal ulcer patients who are smokers.

Cardiorespiratory response to exercise before and after acute beta-adrenoreceptor blockade in nonsmokers and chronic smokers

To evaluate the effects of chronic smoking on exercise performance we studied 5 smokers and 7 nonsmokers of comparable age and physical characteristics. The resting heart rate in smokers (75 +/- 3 beats/min; mean +/- SD) was significantly (P less than 0.01) higher than in nonsmokers (64 +/- 5). During exercise on a bicycle ergometer the heart rate remained significantly (P less than 0.01) higher in smokers than in nonsmokers. After exercise, the heart rate in nonsmokers settled to 78 +/- 9 beats/min at 10 minutes compared with 105 +/- 11 (P less than 0.01) in smokers. Oxygen consumption was similar in both groups throughout. Beta-adrenergic blockade reduced the exercise tachycardia in both groups but the heart rate for the same workload remained significantly (P less than 0.01) higher in smokers. Beta-blockade significantly reduced (P less than 0.05) oxygen consumption in nonsmokers but not in smokers who also incurred a significantly (P less than 0.05) greater oxygen debt and had higher serum lactate levels. These differences were attributed mainly to carboxyhaemoglobinaemia and partly to the effect of prolonged smoking on the heart and on intermediary metabolism.

Cigarette smoking and the treatment of angina with propranolol, atenolol, and nifedipine

To determine whether cigarette smoking affects the results of drug treatment for angina, we studied 10 cigarette smokers with angina who were given placebo, nifedipine (60 mg per day), propranolol (240 mg per day), and atenolol (100 mg per day), each for one week. The four-week double-blind study was repeated with the same randomly determined order of drug sequences, after all 10 subjects had stopped smoking. Before and after the subjects stopped smoking, all three drugs significantly reduced the frequency of angina, as measured with angina diaries, and improved the results of maximal exercise testing and 48-hour ambulatory monitoring of ST segments (P less than 0.01). However, during the nonsmoking phase of the study, there was an overall decline in the frequency of angina and an improvement in performance on exercise testing (P less than 0.05) as compared with the smoking period, although the results of 48-hour ambulatory monitoring remained unchanged. The improvement after patients stopped smoking was greater during treatment with nifedipine than during administration of the other two drugs or placebo. Blood levels of propranolol were increased when patients stopped smoking; levels of nifedipine and atenolol were unchanged. Our data show that smoking had direct and adverse effects on the heart and interfered with the efficacy of all three anti-anginal drugs, but with nifedipine the most.

Acute coronary hemodynamic response to cigarette smoking in patients with coronary artery disease

The acute changes in coronary blood flow and coronary resistance that occur in response to cigarette smoking have not been accurately determined. To define the factors that affect this response, coronary sinus blood flow was measured in 16 patients (group I) with coronary artery disease and in 6 patients (group II) without angiographically detectable coronary disease. Seven patients (group IA) had severe (greater than or equal to 75%) proximal left coronary lesions and nine patients (group IB) had significant distal lesions with 50% or less proximal stenoses. Group I had a smaller overall increase (increases 1.6 +/- 5.3%) in coronary sinus blood flow than did group II (increases 7.7 +/- 6.1%) (p less than 0.05). Coronary resistance increased overall (increases 2.7 +/- 5.3%) in group I but decreased (decreases 2.4 +/- 3.4%) in group II (p less than 0.05). Patients in group IA had a highly significant increase in coronary resistance as compared with group IB (increases 7.0 +/- 4.2% versus decreases 0.9 +/- 2.6%) (p less than 0.001). Coronary sinus flow tended to decrease (decreases 1.2 +/- 4.6%) in group IA but to increase (increases 3.8 +/- 5.1%) in group IB (p = 0.06). It is concluded that smoking increases coronary resistance in patients with coronary artery disease. A greater impact is observed in patients with a severe proximal stenosis than in those with a distal stenosis. It is proposed that smoking increases coronary artery tone at the site of the stenosis, limiting the coronary flow response proportionally to the size of the affected vascular bed.

Tobacco smoking and drugs: a clinically important interaction?

Tobacco smoking may interact with the metabolism of a number of drugs. This has been demonstrated clearly in pharmacokinetic studies in animals and man. HOwever, tobacco smoking as a variant has been studied with relatively few clinically essential drugs and these studies do not always demonstrate a consistent effect of smoking. This review therefore not only records what data have emerged from pharmacokinetic or other studies, but it also attempts to determine whether such interactions have clinical significance. The main finding of this review is that, in the majority of examples, there is little evidence that there is a recognizable hazard from the interaction per se. The exceptions to this general conclusion are limited to four drugs: insulin, propoxyphene, propranolol, and theophylline preparations. With these drugs, there is some evidence of clinical importance of an interaction with tobacco smoking.

The interaction of cigarette smoking and beta-adrenoceptor blockade

The importance of the interaction between smoking and propranolol (metabolised in the liver) and atenolol (excreted almost entirely in the urine) was investigated in a double-blind placebo-controlled trial. Resting and exercise heart rates were significantly greater during smoking than no-smoking phases. Atenolol and propranolol significantly improved ST segment response after exercise whether or not the patients were smoking. Plasma propranolol significantly increased when patients stopped smoking whereas there was no such change in atenolol levels.

Study of smoking habits in hospital and attitudes of medical staff towards smoking

Most hospital policies place little or no restriction on patients' smoking in hospital. In this study patients were surveyed to determine if they smoked and if their doctors advised or ordered them to stop smoking in hospital. As well, the smoking habits and attitudes towards smoking of the medical staff and other hospital workers were explored. Of 741 patients 37% were smokers, and those who responded fully to a questionnaire 86% continued to smoke in hospital. Patients who were advised or ordered not to smoke (59%) were no more likely to stop smoking than those who were not so advised or ordered. Physicians were less likely to smoke than other hospital staff, and those who did smoke were much more likely not to smoke while in the hospital. Physicians appear to have a reasonable appreciation of the health hazards of smoking, and almost two thirds are in favour of stricter restrictions on patients' smoking in hospital. The ineffectiveness of their efforts is primarily due to hospital policies that are not in keeping with physicians' standards of practice and with established knowledge of the deleterious effects of smoking on health.