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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It has been suggested that a diuretic added to a calcium antagonist may not reduce blood pressure further in patients with hypertension. Bendroflumethiazide 5 mg was given to 17 patients with essential hypertension who had persistent mild to moderate hypertension despite treatment with nifedipine slow-release tablets 20 mg bid. One group received bendroflumethiazide before (N = 8) and the other after placebo (N = 9) in a double-blind, randomized cross-over trial. Supine blood pressure following active bendroflumethiazide administration was significantly reduced in both groups compared with trial entry (166/105 to 150/96 mm Hg, P less than .01; 170/108 to 156/98 mm Hg, P less than .01). A reduction in serum potassium level and a rise in serum uric acid concentration were seen with combined treatment. We cannot substantiate theoretic arguments for the ineffectiveness of a bendroflumethiazide-nifedipine combination on blood pressure.
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PMID:The effects of bendroflumethiazide added to nifedipine in patients with hypertension. 331 3

In a double-blind study 30 patients with mild or moderate (World Health Organization classification I or II) hypertension were treated with either nifedipine, 20 mg twice a day, or bendroflumethiazide, 2.5 mg (+0.57 g KCl) twice a day for 24 weeks. All patients were then given a combination of half the initial dosage of both drugs for an additional period of 6 weeks. Nifedipine caused a significant reduction of both supine and standing blood pressures (16/10 and 11/5 mm Hg, respectively). Bendroflumethiazide also reduced both recumbent and standing blood pressures significantly (15/10 and 11/10 mm Hg, respectively). Combined treatment with nifedipine and bendroflumethiazide caused a further reduction of both supine and standing blood pressures. The total reduction compared with placebo was 23/12 mm Hg (p less than 0.001) and 17/11 mm Hg (p less than 0.001), respectively. There was no significant correlation between antihypertensive effect and age of patient.
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PMID:Controlled trial of nifedipine and bendroflumethiazide in hypertension. 619 58

Hydrochlorothiazide has been shown to exert direct vasodilator effects by activation of calcium-activated potassium (KCa) channels in human and guinea pig isolated resistance arteries. Since hydrochlorothiazide binds to and inhibits the enzyme carbonic anhydrase and because KCa channel activation is pH sensitive, we investigated the role of intracellular and extracellular carbonic anhydrase in the vascular effects of thiazide diuretics. Small arteries were isolated from guinea pig mesentery and studied by use of a microvascular myograph technique. In some experiments, tone and intracellular pH (pHi) were measured simultaneously with 2', 7'-bis(2-carboxyethyl)-5(6)'-carboxyfluorescein (BCECF-AM). Bendroflumethiazide, a thiazide diuretic with minimal inhibitory effects on carbonic anhydrase, had little effect on noradrenaline-induced tone (16+/-8% relaxation) compared with hydrochlorothiazide (74+/-12% relaxation). In contrast to hydrochlorothiazide, the action of bendroflumethiazide was unaffected by 100 nmol/L charybdotoxin, a selective blocker of KCa channels. All inhibitors of carbonic anhydrase relaxed noradrenaline-induced tone in a concentration-dependent manner, and this effect was blocked by charybdotoxin. Hydrochlorothiazide and the inhibitors of carbonic anhydrase failed to relax tone induced by a depolarizing potassium solution. Acetazolamide and hydrochlorothiazide increased pHi by 0.27+/-0.07 and 0.21+/-0.04, respectively, whereas bendroflumethiazide had a much smaller effect: 0.06+/-0.03. The rise in pHi induced by any agent was not inhibited by charybdotoxin. The vasorelaxant effect of hydrochlorothiazide is shared by other inhibitors of carbonic anhydrase. Inhibitors of carbonic anhydrase, but not bendroflumethiazide, cause intracellular alkalinization, which is associated with KCa channel opening. These data suggest that the vasodilator effect of thiazide diuretics results primarily from inhibition of vascular smooth muscle cell carbonic anhydrase, which results in a rise in pHI, leading to KCa channel activation and vasorelaxation.
Hypertension 1999 Apr
PMID:Inhibition of carbonic anhydrase accounts for the direct vascular effects of hydrochlorothiazide. 1020 45

A 31-year-old hypertensive woman was admitted to hospital with palpitations. Her hypertension was treated with bendroflumethiazide, which had been increased from 2.5 to 5 mg daily by her general practitioner about 18 months prior to her admission. She was also on ramipril 10 mg once daily. There were no abnormal findings on examination, and a 12-lead ECG showed sinus rhythm, rate 75, with Q waves in leads V1-V2. Telemetry (over 24 h) showed ventricular bigeminy when she had her typical palpitations. Her admission serum sodium and potassium concentrations were 132 and 3.4 mmol/l, respectively. Immediately prior to planned discharge the following day, she experienced paraesthesiae, weakness, confusion and seizures accompanied by 10 s asystole on the ECG monitor. Her serum sodium had fallen to 120 mmol/l and potassium to 2.3 mmol/l. Bendroflumethiazide and ramipril were discontinued and the patient was restricted to fluids of 1.5 l/24 h. She also received potassium supplements. Her serum sodium concentration rose to normal over 6 days, and she was discharged on feeling well.
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PMID:Life-threatening hyponatraemia. 2269 60

Thiazide diuretics have been the cornerstone of hypertension treatment for >5 decades. Most recent European and American guidelines recommend both thiazide-type and thiazide-like diuretics as first-line drugs for all patients with hypertension. In contrast, diuretics are not regarded as first-line treatment in the UK and in patients who are to be initiated on a diuretic treatment, thiazide-like molecules, such as chlortalidone and indapamide are the preferred option. This review examines the prescribing trend of the 4 most commonly prescribed thiazide diuretics for the treatment of hypertension in the UK. Prescription cost analysis data were obtained for both 2010 and 2016/2017 for each region of the UK to analyse the impact of the 2011 National Institute for Health and Care Excellence hypertension guidelines on the trend in thiazide diuretic prescribing. Overall, the prescriptions of thiazide diuretics declined over the years. Bendroflumethiazide is the most commonly prescribed diuretic in the UK and despite some geographical differences, thiazide-type diuretics are more widely used than thiazide-like. The use of indapamide increased significantly between 2010 and 2016/2017 while chlortalidone was rarely employed. Of the many factors affecting trends in prescriptions, clinical inertia, treatment adherence, availability of the products and the lack of fixed dose combinations may play a role.
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PMID:A review of the prescribing trend of thiazide-type and thiazide-like diuretics in hypertension: A UK perspective. 3147 72