Reversal or prevention of diuretic-induced alterations in serum lipoproteins with betablockers

A lifestyle program for treated hypertensives improved health-related behaviors and cardiovascular risk factors, a randomized controlled trial

OBJECTIVE

To assess effects of a cognitively based program on health-related behaviors and cardiovascular risk factors in overweight drug-treated hypertensives.

STUDY DESIGN AND SETTING

In a clinical trials center, volunteers, recruited by advertisement, were randomized to usual care (N=118) or to a 4-month program (N=123) incorporating weight loss; a low-sodium diet, high in fruit, vegetables, and fish; and increased physical activity. Diet, physical activity, weight, blood lipids, glucose, and insulin were measured at 4 and 16 months.

RESULTS

Ninety-eight usual care and 106 program participants completed the 4-month assessment; 90 and 102, respectively, completed follow-up. Using intention-to-treat analysis, relative to usual care, net changes with the program at 4 months were as follows: dietary fat (-2.6% energy; P<0.001); sodium (-290mg/d; P=0.004); energy (-313mJ/d; P=0.005); fish (+2.1 serves/wk; P<0.001); vegetables (+3.0 serves/wk; P<0.001); physical activity (+37min/wk; P=0.004); weight (-2.8kg; P<0.001); waist girth (-3.1cm; P<0.001); total cholesterol (-0.2mmol/L; P=0.017); and triacylglycerols (-0.12mmol/L; P=0.002). One year later, net changes included dietary fat (-2.2% energy; P<0.001); sodium (-150mg/d; P=0.029); fish (+2.0 serves/wk; P<0.001); vegetables (+4.3 serves/wk; P<0.001); weight (-2.5kg; P=0.001); waist girth (-3.1cm; P<0.001); high-density lipoprotein cholesterol (+0.03mmol/L; P=0.031).

CONCLUSION

Improvements in behaviors and risk factors, several maintained long term, suggest the potential for long-term benefits in hypertensives.

The relevance of plasma lipid changes with cardiovascular drug therapy

Evidence is reviewed that thiazide diuretics increase plasma levels of triglycerides and LDL-cholesterol, and that most beta-blockers increase triglycerides and depress HDL-cholesterol. By contrast, indapamide, pindolol, and calcium channel blockers have little effect, and alpha 1-blockers and alpha 2-stimulants may improve the HDL- to LDL-cholesterol ratio.

Effect of pindolol on changes in serum lipids induced by hydrochlorthiazide

Forty-two patients with essential hypertension, WHO I-II, and a diastolic blood pressure greater than or equal to 100 mm Hg, were initially given 25 mg hydrochlorthiazide alone. After treatment for 3 months 10 mg pindolol was also given to 16 of them as the diastolic blood pressure had not been reduced to less than or equal to 90 mm Hg. After 3 months treatment on hydrochlorthiazide alone there was a significant increase in serum cholesterol, low density lipoprotein cholesterol and triglyceride concentrations, and a decrease in high density lipoprotein cholesterol concentration, and this pattern persisted after a further 3 months on the single drug regimen. In contrast, in those patients who received additional treatment with pindolol after the first 3 months, there was a significant decrease in the low density lipoprotein cholesterol and an increase in high density lipoprotein cholesterol during the following 3 months. Thus, the addition of pindolol to hydrochlorthiazide therapy appeared to reverse the negative effects on the lipid profile induced by the diuretic alone.

The influence of non-beta-blocking drugs on the lipid profile: are diuretics outclassed as initial therapy for hypertension?

Diuretic drugs, when used in the treatment of hypertension, raise the blood concentrations of total cholesterol and low-density or very low-density lipoprotein cholesterol. Triglycerides often increase as well. Thiazide, phthalimidine, loop, potassium-sparing, and methylindoline drugs produce a similar effect. Only indapamide, a methylindoline agent with vasodilator activity, has been free of adverse lipid effects. It remains unclear whether it is the low dose of indapamide or some other quality that frees it of this effect. In long-term diuretic therapy, total cholesterol returns to, or below, baseline values, suggesting that the lipid elevations are transitory. However, in studies with adequate control groups, total cholesterol declines below baseline valves in control subjects such that an adverse differential in lipid values persists in long-term treatment. Selective alpha-1-adrenoceptor-blocking drugs cause no change or favorable alterations in lipid concentrations in short-term and long-term (1 year) treatment. Among all antihypertensive drugs, this class of agents, and especially prazosin, has produced the most consistently salutary lipid and metabolic effects. Although less well examined, guanabenz, clonidine, guanfacine, and diltiazem have been associated with favorable lipid changes. Captopril and nifedipine have caused no change in lipid-lipoprotein values in limited investigations. These agents are preferable to diuretics and certain beta blockers with respect to short-term effects on lipids and lipoproteins. Their ultimate superiority as monotherapy depends on whether they lower blood pressure equally well. Lowering of the probability of coronary heart disease in hypertensive patients depends as much on blood pressure control as on lipid effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular toxicity of diuretics related to magnesium depletion

The chronic administration of common loop or distal tubular diuretics may lead to somatic depletion of Mg2+. The resultant deficiency of this cation causes an increase in intramyocardial cytosolic Ca2+ and aggravates the decrease in intramyocardial K+ provoked by diuretics through their hyperkaliuretic effect. Thus the myocardium is electrically destabilized and cardiac arrhythmias may develop. Mg2+ deficiency positively contributes to the development of atherogenic alterations in lipid metabolism, vasospastic phenomena in the coronary and cerebrovascular territories, myocardial infarction and to the retardation of infarct healing and the occurrence of ventricular arrhythmias during the acute phase of infarction.

Increased serum high-density lipoprotein cholesterol in hypertensive men treated with the potent vasodilator carprazidil

The effects of the potent arteriolar vasodilator carprazidil on serum lipoproteins and various clinical, biochemical and endocrine parameters were assessed in 15 men with mild to moderate essential hypertension. Following a carprazidil monotherapy (average dose 50 to 60 mg/d) of 8 weeks (N = 15) or 16 weeks (N = 12) duration, blood pressure was decreased significantly (P less than 0.01), while serum high-density lipoprotein cholesterol (+ 26% and + 24%, respectively; P less than 0.01) and the alpha-lipoprotein fraction (+ 26% and + 41%) were increased. Low- and very low-density lipoprotein cholesterol, triglycerides, as well as mean body weight, blood and plasma volume, heart rate, and plasma renin, aldosterone, norepinephrine, and epinephrine were not consistently altered. These results indicate that treatment of hypertensive men with carprazidil in modest dosage may have a favorable influence both on blood pressure and serum lipoproteins.

Effects of antihypertensive therapy on serum lipoproteins

Several drugs used for standard antihypertensive therapy may also interact with the lipoprotein metabolism. The following has been observed after 1 to 12 months of treatment. Various thiazide-type diuretics may significantly increase the potentially atherogenic serum low-density-lipoprotein cholesterol (LDL-C) and/or very-LDL-C-fractions, while the antiatherogenic high-density-lipoprotein cholesterol (HDL-C) is largely unchanged. Certain loop-diuretics also increase the LDL-C/HDL-C ratio and both types of diuretics elevated serum triglycerides (Tg) in some but not all studies. LDL-C was increased in diuretic-treated men and in chlorthalidone-treated postmenopausal women, but not in chlorthalidone-treated premenopausal women. The latter may be protected from this effect. Only two diuretics evaluated, namely indapamide and spironolactone, had no apparent influence on lipoproteins. Beta-blocker monotherapy may often increase Tg and slightly decrease HDL-C. The magnitude of these changes did not distinctly differ between highly cardioselective and nonselective beta-blockers, but it was less pronounced on beta-blockers than on those without intrinsic sympatholytic activity. Other sympatholytics such as reserpine, methyldopa, clonidine, debrisoquine, the alpha-beta-blocker labetalol, or the postsynaptic alpha-blocker, prazosin, did not affect or even slightly decrease Tg or total C, LDL-C, and very-LDL-C values. With combinations, a tendency for increased Tg and lower HDL-C was also apparent during thiazide-type diuretic-beta-blocker therapy. However, diuretic-induced increases in LDL-C were prevented or reversed by concomitant beta-blockade, but not by reserpine, methyldopa, or clonidine. Monotherapy with the potent direct vasodilator, carprazidil, improved blood pressure and significantly increased HDL-C. Prospective long-term studies are needed to clarify the course and the pathogenic and prognostic relevance of lipoprotein changes induced by certain diuretics or beta-blockers.

Thiazides, beta blockers and lipoproteins

Some of the more important recent studies on the effect of thiazides and beta-adrenoceptor blocking agents is conflicting, possibly because of differences in patient compliance and in lipoprotein methodology and quality assurance between studies. It is likely that in the short-term, thiazide diuretics produce an increase in plasma triglyceride and cholesterol and in LDL-cholesterol. No consistent effect of monotherapy with beta-adrenoceptor blocking agents was seen. Further long-term studies of monotherapy with both of these classes of drugs are required. Combined therapy with thiazides or beta-adrenoceptor blocking agents consistently increased plasma triglyceride concentrations, but their effect on VLDL, LDL and HDL concentrations is uncertain. Further research required into the effect of these drugs on apolipoproteins which may be useful discriminators for patients with coronary heart disease (Avogaro et al., 1979) and on HDL subfractions.

Effects of indapamide and various diuretics alone or combined with beta-blockers on serum lipoproteins

A prospective evaluation was started in 1976 to study the influence of diuretics alone or combined with beta-blockers on serum lipoproteins in normal or hypertensive subjects. Compared to placebo conditions, 4 or 6-weeks' monotherapy with various diuretics significantly (p less than 0.05) increased the beta-lipoprotein fraction (furosemide, 80 mg/day or chlorthalidone, 100 mg/day; n = 16) or low-density lipoprotein-cholesterol (LDL-C) (chlorthalidone, 100 mg/day, n = 27 men; tienilic acid, 250 mg/day, n = 16 men, clopamide, 5 mg/day, n = 17 men; or muzolimine, 20 to 40 mg/day, n = 13 men or post-menopausal women). No increase in LDL-C was noted in 43 men (32 normal, 11 with mild hypertension) treated with indapamide, 2.5 mg/day. Serum high-density lipoprotein-cholesterol and apoproteins A1, A2 and B were not consistently changed by any of these agents. In women, chlorthalidone (100 mg/day) significantly increased LDL-C in the (100 mg/day) significantly increased LDL-C in the post-menopausal (n = 18) but not in the pre-menopausal (n = 22) state. Increases in LDL-C caused by chlorthalidone monotherapy were prevented or reversed by the addition of a beta-blocker, usually propranolol or atenolol (n = 18); increases in LDL-C during clopamide monotherapy were reversed after the addition of the beta-blocker pindolol (10 mg/day, n = 17). In all studies, variations in beta-lipoprotein or LDL-C levels could not be explained by changes in blood volume, serum glucose or insulin and did not correlate with alterations in blood pressure, plasma potassium, renin, aldosterone, adrenaline or noradrenaline. These observations indicate that various diuretics may increase serum LDL-C in men or post-menopausal women. Pre-menopausal women may often be protected from this side-effect. Long-term studies are now needed to clarify the pathogenic and prognostic relevance of lipoprotein changes induced by diuretics. In the meantime, it is of clinical interest that indapamide had no significant effect on serum lipoproteins and that certain beta-blockers appear to prevent or reverse increases in LDL-C during diuretic treatment in men and post-menopausal women.

Serum lipoproteins in patients with mild renal disease treated with the diuretic muzolimine

Patients with renal functional impairment are prone to develop hypertension and hyperlipidemia, and both abnormalities tend to occur already at an early stage of kidney disease. In 18 patients with mild renal disease (glomerular filtration rate 65 +/- 5 ml/min) and hypertension (mean blood pressure 126 +/- 4 mm Hg), the effect of six weeks of treatment with the loop-diuretic muzolimine on serum lipoproteins was assessed. Compared to placebo values, the diuretic significantly increased serum low-density lipoprotein cholesterol (LDL-C) and apoprotein B (+ 18 and 11%, respectively, P less than 0.005) in 13 men or postmenopausal women, but not in 5 premenopausal women. Serum high-density lipoprotein cholesterol (HDL-C), and total triglycerides or lipoprotein triglyceride fractions were not consistently changed in both subgroups. Thus, the ratio LDL-C/HDL-C was increased from 3.2 +/- 0.3 to 3.9 +/- 0.3 (P less than 0.05) in the men or postmenopausal women, while no such tendency occurred in the premenopausal women (4.1 +/- 0.6 to 3.7 +/- 0.6). Changes in serum LDL-C were not associated with hemoconcentration or alterations in carbohydrate metabolism and were not related to variations in serum potassium or blood pressure. Increased serum levels of the atherogenic LDL-C fraction during diuretic treatment in men or postmenopausal women with renal disease may represent a potentially undesirable effect, particularly since such patients may tend to have hyperlipidemia in the untreated state.