[Stability of hydrochlorothiazide and cyclopenthiazide in various drug forms. 1. Stability of hydrochlorothiazide and cyclopenthiazide].
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Cyclopenthiazide↗
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The antihypertensive and metabolic effects of low and conventional dose cyclopenthiazide in type II diabetics with hypertension.
The antihypertensive efficacy and metabolic effects of cyclopenthiazide 125 micrograms were compared with cyclopenthiazide 500 micrograms in patients with non-insulin dependent diabetes and hypertension in a double blind, randomized crossover study. After a 6-week placebo period 24 patients with non-insulin dependent diabetes mellitus, stabilized on diet or oral hypoglycaemic agents, who had a mean diastolic blood pressure between 90 and 120 mmHg after receiving placebo for 6 weeks were given 125 micrograms or 500 micrograms cyclopenthiazide for 12 weeks. Patients then received placebo for a further 6-week period, following which they received the alternate treatment dosage for 12 weeks. There were no differences between doses in their antihypertensive effects. While 500 micrograms significantly reduced systolic and diastolic blood pressures, only diastolic pressure was significantly reduced by 125 micrograms from pre-treatment values. The higher dose of cyclopenthiazide had greater effects on measures of diabetic control than did the 125 micrograms dose and the rise in blood glucose after 12 weeks' treatment with 500 micrograms was significantly different from pre-treatment values. Cyclopenthiazide 125 micrograms had significantly less effect on triglycerides, potassium and urate, than did 500 micrograms. Cyclopenthiazide 500 micrograms resulted in a significant fall in serum potassium from pre-treatment values. There were no intertreatment differences in the other variables measured. Cyclopenthiazide 125 micrograms is as effective as 500 micrograms in reducing diastolic blood pressure in mildly hypertensive non-insulin dependent diabetic patients. The higher dose had more pronounced adverse effects on glucose control and serum concentrations of triglycerides, potassium and urate.
Adult↗
The case for low dose diuretics in hypertension: comparison of low and conventional doses of cyclopenthiazide.
In a double blind placebo controlled randomised parallel study the antihypertensive activity and adverse biochemical effects of three doses of cyclopenthiazide were evaluated in patients with mild essential hypertension that had been recently diagnosed or was being treated with a single drug. After a four week placebo washout period 53 patients with diastolic blood pressures between 90-110 mm Hg were randomly assigned to 50, 125, or 500 micrograms cyclopenthiazide or matching placebo for an eight week period of treatment. Blood pressure was measured in the patients' homes by the same observer every two weeks. Serum urea, electrolytes, urate, and creatinine concentrations and 24 hour urinary sodium excretion were monitored every four weeks and serum magnesium concentration and plasma renin activity at the end of the washout and treatment periods. After eight weeks of treatment systolic and diastolic blood pressures were significantly reduced in patients taking 125 and 500 micrograms cyclopenthiazide when compared with those taking placebo. The decrement in serum potassium concentration (0.6 mmol/l) and increase in serum urate concentration 0.06 mmol/l) were greatest with the 500 micrograms dose, the increase in serum urate concentration alone being significant. No change in serum magnesium concentration or 24 hour urinary sodium excretion was noted with any dose of cyclopenthiazide. Only the 500 micrograms dose of cyclopenthiazide significantly increased the mean plasma renin activity (1.8 (95% confidence interval 0.2 to 3.4)-5.4 (3.9 to 6.8) nmol angiotensin I/l/h); the other doses like the placebo had no effect. Cyclopenthiazide 125 micrograms, a dose lower than is currently marketed, produced a similar hypotensive response to 500 micrograms of the drug without upsetting the biochemical profile.
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Comparison of tienilic acid with cyclopenthiazide in hyperuricaemic hypertensive patients.
Tienilic acid, a diuretic with uricosuric properties, was compared with cyclopenthiazide, in an open, random-order, within-patient crossover study (3 months on each drug) in 36 hyperuricaemic hypertensive patients. All were on an established dose of cyclopenthiazide; most were also on a beta-blocker which they continued to take in their usual dose. A mean dose of 210 mg of tienilic acid gave the same antihypertensive and diuretic effect as a mean dose of 0.41 mg of cyclopenthiazide. Serum uric acid was very much lower when patients were on tienilic acid (0.29 mmol/l) than on cyclopenthiazide (0.50 mmol/l). Apart from slightly higher serum-chloride and serum-urea during the period on tienilic acid, no major differences in serum-electrolytes, renal-function tests, glucose tolerance, and fasting lipids were observed. Audiometric tests showed that tienilic acid was not ototoxic. S.G.O.T. and S.G.P.T. rose to pathological values in 3 women when they were on tienilic acid, to a lesser extent, in 2 men when they were on cyclopenthiazide. There is no definite evidence that the changes in the transaminases were related to tienilic acid. Some postural hypotension or slight fluid retention occurred during the initial, dose-finding period, and 3 patients had mild indigestion but no patient had to discontinue the trial because of side-effects.
Blood Pressure↗
Xipamide and cyclopenthiazide in essential hypertension--comparative effects on blood pressure and plasma potassium.
1 The blood pressure lowering effect of xipamide, a non-thiazide diuretic given for 6 weeks was compared in a randomised cross-over trial with that of cyclopenthiazide in 14 patients with essential hypertension. 2 Xipamide 10 or 20 mg given once daily was as effective in lowering supine blood pressure as daily cyclopenthiazide 0.5 mg. There was no difference in the blood pressure lowering effect of 10 mg xipamide daily for 2 weeks compared to 20 mg daily given for a further 4 weeks. 3 Plasma potassium was reduced by both drugs, but markedly more after both 10 mg and 20 mg xipamide than after cyclopenthiazide 0.5 mg. By the sixth week of treatment 13 of 14 patients on xipamide but only 6 of 14 on cyclopenthiazide has plasma potassium concentrations of, or less than, 3.5 mmol/l. The fall in plasma potassium was significantly greater and the final plasma potassium concentration was significantly lower after either dose of xipamide than after cyclopenthiazide. 4 These results suggest that 10 mg or 20 mg of xipamide daily is effective in lowering blood pressure in hypertensive patients but is associated with hypokalaemia. In view of recent evidence linking diuretic-induced hypokalaemia with cardiac dysrhythmias in patients with essential hypertension we would suggest that thiazide diuretics be used in preference to xipamide for the routine management of essential hypertension. Our results also suggest that the currently recommended dose of xipamide (20 mg) for the treatment of hypertension is excessive, and lower amounts than 10 mg per day might possibly be as effective in lowering blood pressure with less adverse metabolic consequences.
Adult↗
A comparison of the haemodynamic and hormonal effects of low and conventional dose cyclopenthiazide in normal volunteers.
In this study we compared low (125 micrograms) and conventional (500 micrograms) doses of cyclopenthiazide on the renin angiotensin system, plasma and extracellular fluid volumes and the pressor responsiveness to angiotensin II since we have previously shown that the two doses have the same antihypertensive effect but different effects on plasma renin activity. Following a two week placebo run-in period, 8 healthy male volunteers received 125 micrograms or 500 micrograms of cyclopenthiazide for 2 treatment periods of 4 weeks as part of a double blind, 2-part crossover study with treatment periods separated by a 4-week placebo washout phase. Measurements were made on two study days at the beginning and end of the active treatment periods. On the first day serum potassium, plasma renin activity and plasma angiotensin II levels were measured after a 1 h period of supine rest. Plasma and extracellular fluid volumes were also measured after appropriate equilibration times. The blood pressure responses to angiotensin II were assessed on day 2. The 500 micrograms dose of cyclopenthiazide had a greater effect than the 125 micrograms dose on plasma renin activity, serum potassium, angiotensin II levels and extracellular fluid volumes. Neither drug had any effect on plasma volume or the responsiveness to infused angiotensin II. Low dose cyclopenthiazide failed to increase angiotensin II levels, contract body fluid volumes or attenuate vascular reactivity in normotensive volunteers.
Adult↗
Low and conventional dose cyclopenthiazide on glucose and lipid metabolism in mild hypertension.
In a double-blind, placebo controlled, randomised parallel study we investigated the antihypertensive activity and metabolic adverse effects of three doses of cyclopenthiazide in 53 patients with mild hypertension. After a 4 week placebo washout period, patients with diastolic blood pressures between 90-110 mm Hg were randomly assigned to receive 50 micrograms, 125 micrograms and 500 micrograms of cyclopenthiazide or matching placebo, over an 8 week active treatment period. Blood pressure was recorded at 2 weekly intervals during the trial. Venous samples were taken for evaluation of drug effect on indices of carbohydrate and lipid metabolism just prior to, and on completion of, the active treatment period. Systolic and diastolic blood pressure decreased significantly (P less than 0.05) with the 125 micrograms and 500 micrograms doses of cyclopenthiazide. No change was apparent in any index of glucose and lipid metabolism over time. Low and conventional doses of cyclopenthiazide lower blood pressure without alteration to the metabolic profile in the short term.
Apoproteins↗
[Accumulation of p-aminohippuric acid and cyclopenthiazide in renal cortex slices from rats of various ages and their dependence on the energy supply].
The accumulation of p-aminohippuric acid (PAH) and cyclopenthiazide, two drugs of acidic character and extremely different physico-chemical properties, was determined in renal cortical slices of rats aged 5, 15, 33, 55, 105, and 240 days. PAH is accumulated in the cortical slices of 5- and 15-day-old animals to a lesser extent than in those of adult rats. Cyclopenthiazide is accumulated in much higher amounts than PAH in all age groups. The age dependence of cyclopenthiazide accumulation is not so pronounced as with PAH accumulation. There is no accumulation of PAH in the cortical slices of all age groups through active tubular transport, when the energy supply is inhibited by means of 2,4-dinitrophenol (DNP) or nitrogen 2 times bubbling (i.e. anaerobic incubation). By subsequent addition of DNP to the incubation medium or subsequent N2 atmosphere bubbling, an already existing PAH accumulation may be completely nullified. Contrary to PAH accumulation, cyclopenthiazide accumulation can be neither prevented nor abolished by inhibiting the energy supply.
Age Factors↗
Effect of slow oxprenolol and a combination of slow oxprenolol and cyclopenthiazide on plasma lipoproteins.
The effect of slow oxprenolol on plasma lipoprotein concentrations was compared to that of combined therapy with slow oxprenolol and cyclopenthiazide. The design of the study was a double blind between patient investigation in which 9 subjects with mild hypertension received slow oxprenolol and 11 slow oxprenolol and cyclopenthiazide. Plasma lipoproteins were analysed at 0, 2, 4, 8, 12 and 16 weeks. Slow oxprenolol given alone resulted in a significant rise in plasma and low density lipoprotein (LDL) cholesterol concentration whereas combined therapy with slow oxprenolol and cyclopenthiazide produced significant rises in plasma and very low density lipoprotein (VLDL) triglyceride. If one accepts that a rise in plasma or LDL cholesterol increases atherogenic risk more than a rise in plasma or VLDL triglyceride combined therapy is preferable.
Adult↗
Effect of low versus conventional dose cyclopenthiazide on platelet intracellular calcium in mild essential hypertension.
Platelet free intracellular calcium levels were measured during a double-blind, placebo-controlled parallel study to investigate the antihypertensive activity of 50 micrograms, 125 micrograms, and 500 micrograms cyclopenthiazide, in mild essential hypertension. Cytosolic free calcium levels were significantly higher in established hypertensive patients (135 +/- 28 nmol/l, P less than 0.001) but not in borderline hypertensive patients (123 +/- 26 nmol/l) compared with normotensive controls (111 +/- 9 nmol/l). A positive correlation between platelet free calcium level and systolic and diastolic blood pressure was confirmed (n = 68; r = 0.309 P = 0.01; r = 0.405 P less than 0.001, respectively). The 125-micrograms and 500-microgram doses of cyclopenthiazide produced mean decrements in blood pressure of 18/10 mmHg and 23/8 mmHg, respectively, (P less than 0.05 for both), after 8 weeks of therapy. The 50-microgram dose displayed no useful antihypertensive activity. Platelet free calcium levels fell by a similar amount in the four groups. The fall in blood pressure produced by the 125 and 500-microgram doses of cyclopenthiazide did not correlate with changes in platelet [Ca2+]i (r = 0.166 systolic and r = 0.169 diastolic). These findings do not support the hypothesis that changes in platelet cytosolic calcium levels are determined by the same factors that control blood pressure.
Blood Platelets↗
Lipids and lipoprotein fractions after cyclopenthiazide and oxprenolol: a double-blind crossover study.
A double-blind crossover study was carried out to investigate the effects of cyclopenthiazide and oxprenolol on blood lipids in 20 previously untreated patients with mild to moderate hypertension. After a 4-week placebo period, patients received at random either 8-weeks' treatment with the two drugs followed by 8 weeks on cyclopenthiazide alone, or the reversed sequence. Daily doses were 160 mg slow-release oxprenolol and/or 0.25 mg cyclopenthiazide during the first 4 weeks of each treatment period, after which the dosage was doubled. Data from 13 patients who completed the trial showed no significant changes in the blood levels of triglycerides, total cholesterol or LDL and HDL cholesterol fractions. These findings are discussed in relation to published studies on the effects of other beta-blockers on blood lipids.
Cholesterol↗
Effect of equivalent antihypertensive doses of mefruside and cyclopenthiazide on serum electrolytes, uric acid and glucose tolerance in hypertensive patients.
1. A comparative cross-over trial of mefruside and cyclopenthiazide, each drug being given for 6 weeks, was conducted on thirty hypertensive patients with diabetes mellitus or impaired glucose tolerance. Other antihypertensive therapy, any antidiabetic therapy and potassium supplementation were kept constant throughout the trial. Dosages of mefruside and cyclopenthiazide were adjusted to give approximately equal blood pressure levels in the two drug periods. 2. There was no significant difference in the following parameters studied during the sixth week of each of the two periods of drug therapy: serum electrolytes, total CO2, chloride, urea, amylase, haemoglobin, erythrocyte sedimentation rate, platelet and white blood cell counts, lying and standing blood pressure and pulse rate, weight, fasting and 2-h glucose and insulin levels and five-value glucose and insulin curve areas, fasting calcium and phosphate. 3. Serum creatinine and uric acid showed a small but significant fall during mefruside therapy.
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A comparative study of frusemide-amiloride and cyclopenthiazide-potassium chloride in the treatment of congestive cardiac failure in general practice.
Forty-seven patients entered this comparison of frusemide-amiloride and cyclopenthiazide-potassium chloride in the treatment of congestive cardiac failure in general practice. Frusemide-amiloride was 'very satisfactory' in 92% of the patients compared to only 55% who took cyclopenthiazide-potassium chloride. Significantly more patients were free of paroxysmal nocturnal dyspnoea and orthopnoea after taking frusemide-amiloride.
Amiloride↗
Oxprenolol slow-release with cyclopenthiazide-KCl compared with methyldopa in the treatment of essential hypertension. A multicentre general practice trial.
Two hundred and thirty-eight patients with essential hypertension from 39 general practice centres were treated in a double-blind trial with either oxprenolol 160 mg in a slow-release (SR) formulation with cyclopenthiazide 0,25 mg and potassium chloride 600 mg given once daily, or methyldopa 250 mg 3 times daily. After a 2-week placebo washout period, each patient was treated for 10 weeks. Both treatments significantly reduced blood pressure. Oxprenolol SR plus cyclopenthiazide-KCl was shown to possess significantly superior antihypertensive activity to methyldopa. Pulse rate, as expected, was significantly decreased by the beta-blocker and virtually unaffected by methyldopa. The overall incidence of side-effects was low. The incidence of sleepiness and dry mouth was significantly higher in the methyldopa group, and erythema in the oxprenolol group. The principle of general practitioners conducting multi-centre double-blind trials for research purposes, on drugs which are predominantly given to ambulatory patients, has been established for the first time in South Africa. Virtually no difficulty was encountered in getting patients' consent in the general practice milieu.
Adult↗
A study comparing indapamide with cyclopenthiazide in geriatric patients.
The efficacy of indapamide was compared with cyclopenthiazide in geriatric hypertensive patients. On admission to the study patients were randomly allocated following a placebo run-in period before therapy commenced. Indapamide produced a greater fall in blood pressure which was well maintained in contrast to cyclopenthiazide. Both drugs were well tolerated.
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Comparison of the antihypertensive effects of indapamide and cyclopenthiazide.
The antihypertensive effects of indapamide, 2.5 mg, and cyclopenthiazide, 0.5 mg daily were compared over a two week period. The falls in both diastolic and systolic blood pressure were greater with indapamide than with cyclopenthiazide reaching statistical significance for the supine diastolic values. This difference was still seen when matching patient groups of similar age, sex or severity of blood pressure were compared.
Antihypertensive Agents↗
Different inhibitory effects of 2,4-dinitrophenol, iodoacetate, and probenecid on renal excretion of p-aminohippurate, cyclopenthiazide, and sulfamethoxypyridazine in rats.
The present study was undertaken to determine whether the renal excretion of drugs can be modified by inhibition of the carrier system for organic acids in vivo. The renal excretion of p-aminohippurate is not influenced by 2,4-dinitrophenol but is reduced by iodoacetate and probenecid. The renal excretion of cyclopenthiazide is decreased by all inhibitors. Rats excrete only a very small portion of the administered dose of sulfamethoxypyridazine. Renal sulfamethoxypyridazine excretion is 3 times higher when the tubular reabsorption is blocked by simultaneous administration of NaHCO3. However, even then only a small portion of the injected dose is excreted. Renal sulfamethoxypyridazine excretion is only reduced by probenecid. This finding can be explained by the reduction of the urine volume. It can be concluded that p-aminohippurate and cyclopenthiazide are renally excreted by tubular secretion, whereas sulfamethoxy-pyridazine is excreted by glomerular filtration.
Aminohippuric Acids↗
Steady-state pharmacokinetics and pharmacodynamics of cilazapril in the presence and absence of cyclopenthiazide.
Twenty-two patients with essential hypertension received a single dose of 2.5 mg cilazapril and were then randomised into a double-blind parallel group study to receive either placebo, 1.25 mg cilazapril + 0.5 mg cyclopenthiazide (CPTZ), 2.5 mg cilazapril + 0.5 mg CPTZ, or 2.5 mg cilazapril alone for 1 month. After oral administration of a single dose of 2.5 mg cilazapril, the active diacid cilazaprilat appeared rapidly in the plasma (Tmax 2.0 +/- 0.2 h). With the radioinhibitor assay used in this study, a single elimination phase of cilazaprilat was evident, with a half-life (t1/2) of 2-3 h. At steady state, the pharmacokinetics of cilazaprilat were similar to single-dose administration and were not altered by CPTZ. The Cmax and area under the curve (AUC) of cilazaprilat were directly proportional to dose. Cilazapril administration in the dose range of 1.25-2.5 mg produced a dose-proportional inhibition of angiotensin-converting enzyme (ACE) activity that was maximum 2 h after drug administration. The degree of ACE inhibition correlated with the plasma concentration-time profile of cilazaprilat and the maximum decrease in blood pressure (BP). The EC50 for ACE inhibition by cilazaprilat was 7.7 ng/ml after acute treatment and was not significantly altered during chronic administration or by concomitant administration of CPTZ. There was no evidence of a dose-related antihypertensive effect of cilazapril at steady state and, with the small numbers of subjects used in this study, there was no evidence of 24-h BP control with monotherapy.
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