Potassium Magnesium Citrate Is Superior to Potassium Chloride in Reversing Metabolic Side Effects of Chlorthalidone.

BACKGROUND: Thiazide diuretics (TD) are the first-line treatment of hypertension because of its consistent benefit in lowering blood pressure and cardiovascular risk. TD is also known to cause an excess risk of diabetes, which may limit long-term use. Although potassium (K) depletion was thought to be the main mechanism of TD-induced hyperglycemia, TD also triggers magnesium (Mg) depletion. However, the role of Mg supplementation in modulating metabolic side effects of TD has not been investigated. Therefore, we aim to determine the effect of potassium magnesium citrate (KMgCit) on fasting plasma glucose and liver fat by magnetic resonance imaging during TD therapy. METHODS: Accordingly, we conducted a double-blinded RCT in 60 nondiabetic hypertension patients to compare the effects of KCl versus KMgCit during chlorthalidone treatment. Each patient received chlorthalidone alone for 3 weeks before randomization. Primary end point was the change in fasting plasma glucose after 16 weeks of KCl or KMgCit supplementation from chlorthalidone alone. RESULTS: The mean age of subjects was 59±11 years (30% Black participants). Chlorthalidone alone induced a significant rise in fasting plasma glucose, and a significant fall in serum K, serum Mg, and 24-hour urinary citrate excretion (all P<0.05). KMgCit attenuated the rise in fasting plasma glucose by 7.9 mg/dL versus KCl (P<0.05), which was not observed with KCl. There were no significant differences in liver fat between the 2 groups. CONCLUSIONS: KMgCit is superior to KCl, the common form of K supplement used in clinical practice, in preventing TD-induced hyperglycemia. This action may improve tolerability and cardiovascular safety in patients with hypertension treated with this drug class.

Pairwise comparison of hydrochlorothiazide and chlorthalidone responses among hypertensive patients.

This study conducted a pairwise comparison of antihypertensive and metabolic effects of hydrochlorothiazide (HCTZ) and chlorthalidone (CTD) at 25 mg/day in the same individuals to address the clinical dilemma on preferred thiazide for hypertension (HTN) management. We included 15 African American (AA) and 35 European American (EA) patients with HTN treated with HCTZ and CTD as part of the Pharmacogenomic Evaluation of Antihypertensive Responses (PEAR) and PEAR-2 trials, respectively. Mean reduction in systolic/diastolic blood pressure (SBP/DBP) with HCTZ versus CTD was 8/5 versus 16/8 mmHg among EA patients (p < 1.0e-5 SBP, p = 0.002 DBP) and 11/8 versus 20/11 mmHg among AA patients (p = 0.03 SBP, p = 0.22 DBP). While CTD showed clinically meaningful benefit over HCTZ in two-thirds of participants with respect to SBP reduction and half of EA patients with respect to DBP reduction, a majority of AA patients (53%) showed similar DBP reduction with both thiazides. Sixty percent of AA patients and 29% of EA patients attained blood pressure (BP) <140/90 mmHg with both thiazides. Mean potassium (K+) reduction was greater with CTD compared to HCTZ both in EA patients (mean difference = 0.35, p = 0.0002) and AA patients (0.49, p = 0.043). While 31% of AA patients developed severe hypokalemia on CTD, <5% of others developed severe hypokalemia. Although 46% of AA patients on CTD required K+ supplementation, only 6%-11% of others required supplementation. Overall, in the majority of EA patients, CTD was superior to HCTZ, whereas among AA patients, it was superior in a minority, and was associated with significant potassium-related risk, suggesting that guideline preferences for CTD over HCTZ are reasonable in EA patients but may be less reasonable in AA patients, particularly if the target is <140/90 mmHg.

Race-Specific Comparisons of Antihypertensive and Metabolic Effects of Hydrochlorothiazide and Chlorthalidone.

BACKGROUND: Chlorthalidone is recommended over hydrochlorothiazide (HCTZ) as the preferred thiazide, but the supporting evidence is not robust at routinely used doses, or in whites vs blacks, in whom differences in response to thiazides are well known. We compare the efficacy and safety of HCTZ and chlorthalidone as first-line therapies for white and black hypertensive patients. METHODS: We compared treatment-related outcomes between the HCTZ arm (12.5 mg for 2-3 weeks; 25 mg for additional 6 weeks) of the Pharmacogenomic Evaluation of Antihypertensive Responses (PEAR, n = 376) and chlorthalidone arm (15 mg for 2 weeks; 25 mg for additional 6 weeks) of PEAR-2 (n = 326) clinical trials, in 17-65-year-old mild-moderate uncomplicated hypertensive whites and blacks. RESULTS: Mean systolic/diastolic blood pressure (SBP/DBP) reduction with HCTZ vs chlorthalidone: 8 ± 8/4 ± 5 vs 12 ± 9/7 ± 5 mm Hg in whites (P < 10-6 SBP and DBP); 12 ± 10/7 ± 6 vs 15 ± 10/9 ± 6 in blacks (P = .008 SBP, P = .054 DBP). Treatment with HCTZ vs chlorthalidone in whites resulted in significantly fewer patients achieving target BP (<140/90 mm Hg) (44% vs 57%, P = .018) and clinical response rate (≥10 mm Hg DBP reduction); and significantly higher nonresponse rate (<6 mm Hg DBP reduction); but no significant differences in rates among blacks (eg, target-BP rate: 56% vs 63%, P = .31). HCTZ treatment led to significantly lower rates of hypokalemia and hyperuricemia in whites and blacks, vs chlorthalidone, and significantly lower odds of requiring potassium supplementation among blacks (odds ratio 0.16; 95% confidence interval, 0.07-0.37; P = 3.4e-7). CONCLUSION: Compared with HCTZ, chlorthalidone showed greater blood pressure lowering and adverse metabolic effects in whites, but similar blood pressure lowering and greater adverse effects in blacks; suggesting that the recent guideline recommendations to choose chlorthalidone over HCTZ may not be warranted in blacks.

Changes in serum potassium mediate thiazide-induced diabetes.

Thiazides, recommended as first-line antihypertensive therapy, are associated with an increased risk of diabetes. Thiazides also lower serum potassium. To determine whether thiazide-induced diabetes is mediated by changes in potassium, we analyzed data from 3790 nondiabetic participants in the Systolic Hypertension in Elderly Program, a randomized clinical trial of isolated systolic hypertension in individuals aged >or=60 years treated with chlorthalidone or placebo. Incident diabetes was defined by self-report, antidiabetic medication use, fasting glucose >or=126 mg/dL, or random glucose >or=200 mg/dL. The mediating variable was change in serum potassium during year 1. Of the 459 incident cases of diabetes during follow-up, 42% occurred during year 1. In year 1, the unadjusted incidence rates of diabetes per 100 person-years were 6.1 and 3.0 in the chlorthalidone and placebo groups, respectively. In year 1, the adjusted diabetes risk (hazard ratio) with chlorthalidone was 2.07 (95% CI: 1.51 to 2.83; P<0.001). After adjustment for change in serum potassium, the risk was significantly reduced (hazard ratio: 1.54; 95% CI: 1.09 to 2.17; P=0.01); the extent of risk attenuation (41%; 95% CI: 34% to 49%) was consistent with a mediating effect. Each 0.5-mEq/L decrease in serum potassium was independently associated with a 45% higher adjusted diabetes risk (95% CI: 24% to 70%; P<0.001). After year 1, chlorthalidone use was not associated with increased diabetes risk. In conclusion, thiazide-induced diabetes occurs early after initiating treatment and appears to be mediated by changes in serum potassium. Potassium supplementation might prevent thiazide-induced diabetes. This hypothesis can and should be tested in a randomized trial.

Hypokalemia associated with diuretic use and cardiovascular events in the Systolic Hypertension in the Elderly Program.

The treatment of hypertension with high-dose thiazide diuretics results in potassium depletion and a limited benefit for preventing coronary events. The clinical relevance of hypokalemia associated with low-dose diuretics has not been assessed. To determine whether hypokalemia that occurs with low-dose diuretics is associated with a reduced benefit on cardiovascular events, we analyzed data of 4126 participants in the Systolic Hypertension in the Elderly Program (SHEP), a 5-year randomized, placebo-controlled clinical trial of chlorthalidone-based treatment of isolated systolic hypertension in older persons. After 1 year of treatment, 7.2% of the participants randomized to active treatment had a serum potassium <3.5 mmol/L compared with 1% of the participants randomized to placebo (P<0.001). During the 4 years after the first annual visit, 451 participants experienced a cardiovascular event, 215 experienced a coronary event, 177 experienced stroke, and 323 died. After adjustment for known risk factors and study drug dose, the participants who received active treatment and who experienced hypokalemia had a similar risk of cardiovascular events, coronary events, and stroke as those randomized to placebo. Within the active treatment group, the risk of these events was 51%, 55%, and 72% lower, respectively, among those who had normal serum potassium levels compared with those who experienced hypokalemia (P<0.05). The participants who had hypokalemia after 1 year of treatment with a low-dose diuretic did not experience the reduction in cardiovascular events achieved among those who did not have hypokalemia.

Long-term effects on sexual function of five antihypertensive drugs and nutritional hygienic treatment in hypertensive men and women. Treatment of Mild Hypertension Study (TOMHS)

Problems with sexual function have been a long-standing concern in the treatment of hypertension and may influence the choice of treatment regimens and decisions to discontinue drugs. The Treatment of Mild Hypertension Study (TOMHS) provides an excellent opportunity for examination of sexual function and effects of treatment on sexual function in men and women with stage I diastolic hypertension because of the number of drug classes studied, the double-blind study design, and the long-term follow-up. TOMHS was a double-blind, randomized controlled trial of 902 hypertensive individuals (557 men, 345 women), aged 45 to 69 years, treated with placebo or one of five active drugs (acebutolol, amlodipine maleate, chlorthalidone, doxazosin maleate, or enalapril maleate). All participants received intensive lifestyle counseling regarding weight loss, dietary sodium reduction, alcohol reduction (for current drinkers), and increased physical activity. Sexual function was ascertained by physician interviews at baseline and annually during follow-up. At baseline, 14.4% of men and 4.9% of women reported a problems with sexual function. In men, 12.2% had problems obtaining and/or maintaining an erection; 2.0% of women reported a problem having an orgasm. Erection problems in men at baseline were positively related to age, systolic pressure, and previous antihypertensive drug use. The incidences of erection dysfunction during follow-up in men were 9.5% and 14.7% through 24 and 48 months, respectively, and were related to type of antihypertensive therapy. Participants randomized to chlorthalidone reported a significantly higher incidence of erection problems through 24 months than participants randomized to placebo (17.1% versus 8.1%, P = .025). Incidence rates through 48 months were more similar among treatment groups than at 24 months, with nonsignificant differences between the chlorthalidone and placebo groups. Incidence was lowest in the doxazosin group but was not significantly different from the placebo group. Incidence for acebutolol, amlodipine, and enalapril groups was similar to that in the placebo group. In many cases, erection dysfunction did not require withdrawal of medication. Disappearance of erection problems among men with problems at baseline was common in all groups but greatest in the doxazosin group. Incidence of reported sexual problems in women was low in all treatment groups. In conclusion, long-term incidence of erection problems in treated hypertensive men is relatively low but is higher with chlorthalidone treatment. Effects of erection dysfunction with chlorthalidone appear relatively early and are often tolerable, and new occurrences after 2 years are unlikely. The rate of reported sexual problems in hypertensive women is low and does not appear to differ by type of drug. Similar incidence rates of erection dysfunction in placebo and most active drug groups caution against routine attribution of erection problems to antihypertensive medication.

[Surreptitious intake of diuretics as the cause of pseudo-Bartter's syndrome: apropos of a case and differential diagnosis]. / Ingesta subrepticia de diuréticos como causa de "Pseudo-Síndrome Bartter", a propósito de un caso y diagnóstico diferencial.

We describe a 39 years old patient with a history of chronic symptomatic hypokalemia. She denied taking any drugs. She satisfied the clinical criteria for Bartter's syndrome and more precisely for Gitelman's syndrome: hypokalemia in the presence of inappropriately high potassium excretion, metabolic alkalosis, hyperreninemic hyperaldosteronism, hypomagnesemia with inappropriately high magnesium excretion, normocalcemia, hypocalciuria and normal blood pressure. A HPLC analysis detected the presence of furosemide in urine and chlorthalidone in urine and plasma samples. After the self administration of diuretics was stopped, the above alterations came back to normality. Prior to the verification of a self administration of diuretics, the patient showed clinical and biochemical parameters that oriented to surreptitious diuretic ingestion (Pseudo-Bartter's syndrome) not to Bartter's syndrome or Gitelman's syndrome, particularly the plasma potassium readily restored to normal by the administration of potassium chloride supplements, the increased plasma uric acid with low uric acid fractional clearance, the widely different urine and plasma electrolyte levels and the presence psychiatric disorders. The literature is reviewed and differential diagnosis, among this three syndromes, is made.

Antihypertensive efficacy and tolerability of different drug regimens in isolated systolic hypertension in the elderly.

The pharmacological treatment, mainly based on diuretics, of isolated systolic hypertension (ISH) has recently been shown to reduce the risk of stroke and coronary heart disease in the elderly. The purpose of this study was to compare the antihypertensive effect and tolerability of different drug regimens in elderly subjects with ISH (systolic blood pressure--SBP-- > or = 160 mmHg and diastolic blood pressure--DBP-- < 90 mmHg). A multicentre, randomized, controlled open trial was planned in the general practice setting. Four widely used treatment schedules were tested: hydrochlorothiazide 25 mg plus amiloride 2.5 mg (H+Am), nifedipine slow release 20 mg (N), atenolol 50 mg (At) and atenolol 25 mg plus chlorthalidone 6.25 mg (At+C). After a baseline evaluation, 308 patients (76.3% female, mean age 75.3 +/- 7.1 years) were randomized and followed up for 6 months. After 3 months the drug dosage was doubled if the systolic blood pressure goal (SBP < 160 mmHg and SBP reduction of at least 20 mmHg) had not been reached. Ninety-four subjects (30.5%) presented contraindications to beta-blockers. At the 3rd- and 6th-month visits all treatment groups, except At, showed a significant reduction in SBP compared to the control group; DBP showed no significant reduction in any group at any time. At the end of the follow-up the percentage of hypertensives who had reached the BP goal was 14.6% in the control group, 52.9% in H+Am, 54.8% in N, 28.6% in At and 52.2% in At+C.(ABSTRACT TRUNCATED AT 250 WORDS)

[Comparison of chlorthalidone and sustained-action nifedipine in the treatment of mild to moderate arterial hypertension]. / Comparación de la clortalidona y nifedipina retardada en el tratamiento de la hipertensión arterial leve-moderada.

The effectiveness and safety of sustained action nifedipine (NF) were compared to those of chlorthalidone (CL) in two groups of 35 and 37 patients with mild to moderate hypertension followed up for 4 months. There was a significant reduction in blood pressure (BP) after 15 days of therapy. The degree of control was acceptable with both drugs. A second drug was required in 20% patients of the NF group and in 30.8% of CL group. The therapeutic goal (BP less than 160/95) was achieved in 86.7% of patients in CL group and in 48.4% of those in NF group. We found 48.8% of dropouts in the NF group and none in CL group. There was a significant increase in blood glucose in CL group and a reduction of uric acid and an increase of HDL-cholesterol in NF group. Both drugs are useful to treat hypertension, although NF has the drawback of a high dropout rate and CL induces abnormalities in biochemical parameters.

Relationship of diuretic therapy and serum magnesium levels among participants in the Multiple Risk Factor Intervention Trial.

Thiazide-like diuretics cause an increased excretion of magnesium in the urine. Low serum and selected tissue magnesium levels have been reported among diuretic users. Low magnesium levels have been associated with cardiac arrhythmias, neuromuscular changes, and increases in lipoprotein levels. The dietary intake of magnesium is borderline compared with the recommended dietary allowances. Water sources may therefore play an important role. Hard water contains more magnesium than soft water. The authors studied serum magnesium levels among special intervention Multiple Risk Factor Intervention Trial participants in two centers: Pittsburgh, Pennsylvania and Davis, California. These participants were men aged 35-57 years at entry to the trial in 1972-1974; the blood samples were obtained primarily in 1980-1981. Diuretic users primarily of chlorthalidone had an average 1 ppm lower serum magnesium level than nondiuretic users. About 15% of diuretic users had persistently lower magnesium levels on two samples approximately four months apart. The serum magnesium level was not correlated with the serum potassium level. This study is the first long-term follow-up of a well-defined group of hypertensives taking thiazide-like diuretics versus suitable controls. The results suggest that within similar populations, low serum magnesium levels are relatively rare even in the absence of supplementation with magnesium. Specific high-risk populations may exist in which a combination of diuretic therapy and low intake may contribute to magnesium deficiency. Further epidemiologic studies should include monitoring both serum and intracellular levels of magnesium among these potential high-risk groups on diuretic therapy. This approach may offer the best method of testing the relationship between water hardness, minerals, and cardiovascular disease.

Diuretic induced hypokalemia in the elderly.

The effects of four commonly prescribed diuretics on serum potassium were assessed. One hundred sixteen elderly clinic patients, independently living, (mean age 74.3 years, range 60 to 99 years) were taking hydrochlorothiazide (HCTZ) (n = 40; mean daily dose, 53.9 mg), a combination of hydrochlorothiazide-triamterene (HCTZ-TMTR) (n = 38; mean daily dose, 1.28 capsules), furosemide (n = 20; mean daily dose, 38.0 mg), or chlorthalidone (n = 18; mean daily dose, 55.6 mg). Patients did not take more than one diuretic. No patients received potassium supplementation or had diseases affecting potassium balance. The study design was a nonblinded, noncrossover retrospective chart audit with chi-square analysis. All patients were counseled about reducing excessive sodium intake and using potassium-rich foods and salt substitutes, although compliance concerning these dietary factors was not assessed. Even though some comparisons of diuretics showed statistical significance, these differences probably are not clinically significant because all serum potassium values were above 3.0 mEq/L and no patient was symptomatic. This study supports the use of HCTZ as an initial antihypertensive diuretic; it is as efficacious as the other diuretics in this study, is less expensive, and usually does not cause clinically significant hypokalemia more often than do the other diuretics.

Hypokalaemia and diuretics: an analysis of publications.

Published data have been used to define the characteristics of the fall in serum potassium concentration after taking diuretics and the efficacy of the various treatments given to prevent or correct it. The average fall is less after the usual doses of frusemide (about 0.3 mmol/l) than after the usual doses of thiazides (about 0.6 mmol/l) and is little influenced by the dose or duration of treatment. The fall with a given drug is the same in heart failure and hypertension, but the initial serum potassium concentration is higher in heart failure, so that the final value is lower in hypertension. In standard doses potassium supplements are less effective than potassium-retaining diuretics in correcting the hypokalaemia. The relation between the average serum potassium value and the frequency of low values (hypokalaemia) is such that very low values after taking diuretics are unusual in patients with hypertension or heart failure. Hypokalaemia would almost disappear as an important complication of diuretic treatment if it was defined as a value less than 3.0 mmol/l rather than as a value less than 3.5 mmol/l.

A comparative study of the activity of a new agent, indapamide, in essential arterial hypertension.

A single-blind crossover trial was carried out in 38 elderly, hospitalised patients with essential hypertension to compare the hypotensive activity of 5 mg. indapamide daily with 100 mg. chlorthalidone daily. After initial treatment for 10 days with placebo, patients received treatment for 45 days with either indapamide or chlorthalidone and were then crossed over to the alternative drug for a similar period. Potassium supplementation was necessary in 25 of the patients receiving chlorthalidone, but was precribed as a precautionary measure in only 1 patients whilst on indapamide. Results showed that there were significant drops in blood pressure following both active medications, but that the percentage reduction in diastolic pressure was greater after indapamide. Indapamide also proved more effective than chlorthalidone in controlling the patients' subjective and functional symptoms of their hypertension. In an overall assessment of the effectiveness of both drugs, indapamide was judged to be better tolerated as well as more effective than chlorthalidone in 18 of the 38 patients, whilst chlorthalidone was preferred in only 7 instances.