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At least 19 recordsLinked to original sources
PubMed1979

A comparative study of the action of frusemide and methyclothiazide on renin release by rat kidney slices and the interaction with indomethacin.

1 The effects of frusemide (a diuretic acting on the loop of Henle) and methyclothiazide (a thiazide diuretic) on renin release were studied on rat kidney slices. 2 Frusemide at concentrations of 1.5 and 7.5 mmol/l produced significant increases in renin release but had no effect at 0.15 mmol/l. 3 Methyclothiazide in a similar concentration range did not increase renin release; instead, at the highest concentration used, methyclothiazide (3.5 mmol/l) inhibited renin release. 4 Indomethacin (25 mumol/l) did not inhibit the increase of renin induced by frusemide. 5 Our limited study in vitro is consistent with the findings of other workers who have shown in vivo, in the absence of systemic electrolyte depletion, that only "loop diuretics" increase renin secretion. Under our experimental conditions, it is suggested that frusemide exerts a direct action either upon the epithelioid cells or upon the macula densa since the renal prostaglandin system does not intervene.

Animals↗
PubMed1977

Failure of methyclothiazide to lower home blood pressure level in "essential" hypertensive and normotensive young men, despite significant plasma volume contraction.

Home blood pressure measurements were used to assess the effect of methyclothiazide in young essential hypertensive and normotensive males. Although plasma volume was reduced by approximately 10 percent, blood pressure was not reduced in either group. The lack of effect on blood pressure was probably not attributable to dosage employed, as doubling the dose (5 to 10 mg) in the normal subjects (who were equilibrated on constant diet) did not significantly increase changes in plasma volume, plasma renin activity, aldosterone excretion, urine sodium or blood pressure. The higher dose did result in greater changes in plasma potassium and uric acid. Homeostatic mechanisms which limit the volume mediated and other antihypertensive effects of methyclothiazide apparently achieved complete compensation in these young males. This suggests that thiazide diuretics may not be the drug of first choice in the treatment of hypertension in young adults. Further studies with other diuretics are clearly necessary before the significance of these findings can be fully assessed.

Adolescent↗
PubMed1999

Effect of powder substrate on the dissolution properties of methyclothiazide liquisolid compacts.

The effects of powder substrate composition on the in vitro release properties of methyclothiazide liquisolid compacts were evaluated. The dissolution patterns of this water-insoluble drug formulated in liquisolid tablets were also compared to those of commercial products. According to the new liquisolid technique, liquid medications such as solutions or suspensions of water-insoluble drugs in suitable nonvolatile liquid vehicles can be converted into acceptably flowing and readily compressible powders by a simple admixture with certain powder substrates, which are selected powders referred to as the carrier and coating materials. Enhanced release profiles may be exhibited by such systems due to the increased wetting properties and surface of drug available for dissolution. Liquisolid tablets of methyclothiazide containing a 5% w/w drug solution in polyethylene glycol 400 were prepared using powder substrates of different excipient ratios. The release rates of such products were assessed using the USP dissolution test and were compared to those of their commercial counterparts. It was observed that maximum drug dissolution rates can be exhibited by systems that have powder substrates with optimum carrier-to-coating ratios. In addition, liquisolid tablets displayed significantly enhanced dissolution profiles compared to those of marketed products.

Chemistry, Pharmaceutical↗
PubMedDate not supplied

Methyclothiazide attenuates salt-induced hypertension without affecting sympathetic responsiveness in Dahl rats.

Methyclothiazide added for 7 weeks to the drinking water of weanling Dahl rats attenuated development of hypertension in salt-sensitive (DS) rats, but did not affect blood pressure in salt-resistant (DR) ones. There were no appreciable effects on heart rate, body weight, or sympathetic nerve activity. Cardiovascular responses to electrical stimulation of the ventromedial hypothalamus, or to intravenous injections of norepinephrine, tyramine, or vasopressin, were likewise unaffected. These results indicate that the antihypertensive effect of methyclothiazide in DS rats does not depend on sympathetic inhibition.

Animals↗
PubMedDate not supplied

Direct vascular actions of methyclothiazide and indapamide in aorta of spontaneously hypertensive rats.

In vitro experiments were designed to assess the inhibitory effect of the thiazide diuretics methyclothiazide (MCTZ), the hydrochlorothiazide (HCTZ), and the thiazide-related diuretic indapamide (IND) on contractile responses to norepinephrine (NE) and arginine vasopressin (AVP) of aortic rings from spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY). Changes in the tension of aortic ring preparations were measured isometrically. MCTZ (10(-4) M) induced endothelium-dependent inhibition of the vasoconstrictor responses to NE and AVP only in aortas from SHR, and the maximal vasoconstrictive effect of NE and AVP was decreased by 59 +/- 11% and 32.3 +/- 13%, respectively. Indapamide (10(-4) M) also induced endothelium-dependent inhibition of the contractile response to AVP in aortic rings from SHR, and the maximal vasoconstrictive effect of AVP was decreased by 33 +/- 5%. In contrast, HCTZ did not inhibit the contractile response to either NE or AVP, even at the highest concentration. This study provides evidence that methyclothiazide and indapamide inhibit the contractile response induced by norepinephrine and/or arginine vasopressin on SHR aortic preparations via an endothelium-dependent mechanism.

Animals↗
PubMed1977

Influence of dosage and duration of therapy on the rate of response to methyclothiazide in essential hypertension.

One hundred twenty patients with essential hypertension were studied to determine whether patients who had not responded to the usual dose of a thiazide (methyclothiazide, 5 mg daily during a six-week drug trial) would respond to a higher dose (10 mg daily). The 14-week study was divided into three periods: (1) a two-week placebo period; (2) a six-week single-blind trial; and (3) a six-week period for double-blind dose comparison. Among the 77.3 percent of patients who responded to the drug, diastolic blood pressure was reduced to 90 mm Hg or lower. Two types of thiazide responders were identified-early and late. The early responders (50 percent of study patients), showed a significant reduction in diastolic blood pressure within four weeks; the late responders (27.3 percent) showed a modest reduction in diastolic blood pressure during the first four weeks of therapy, followed by a plateau lasting about two weeks, then a further significant reduction in blood pressure during the ensuing six weeks. Hypokalemia was more common in early responders. There were no significant differences in late response among patients who continued on the usual dose of methyclothiazide compared to those whose dosage was doubled, suggesting that the late response was not due to increasing the dose of the drug.

Adult↗
PubMed1978

Methyclothiazide in hypertension. A report from the General Practitioner Research Group.

In view of the statistically significant falls in blood pressure achieved at the end of two weeks only, it would seem that methyclothiazide is an effective antihypertensive agent, at least in the new cases of mild hypertension treated in this trial. The results are, perhaps, particularly impressive in view of the fact that the majority of patients were treated with the smaller dose of 5mg daily. In this trial, postural hypotension was of no importance whatsoever, and the incidence of side effects was minimal. Methyclothiazide would seem to be a suitable choice for the treatment of mild hypertension in general practice.

Humans↗
PubMed1992

Antihypertensive and metabolic effects of concomitant administration of terazosin and methyclothiazide for the treatment of essential hypertension.

The efficacy and safety of once-daily 2.5- or 5.0-mg methyclothiazide (MCTZ) added to once-daily 5.0-mg terazosin (TRZ) versus 5.0-mg TRZ alone was evaluated in this double-blind, multicenter study. All patients received TRZ during a 6-week titration period. Hypertensive patients (222) (mean blood pressure of 159/104 mm Hg) were randomized to one of three treatment groups: TRZ alone (N = 76); TRZ+MCTZ-2.5 mg (N = 74); and TRZ+MCTZ-5.0 mg (N = 72) for the 8-week double-blind period. Changes in the supine and standing SBP/DBP from preTRZ period were: TRZ alone (-4.8/-8.1 and -2.6/-6.1 mm Hg); TRZ+MCTZ-2.5 mg (-17.3/-12.4 and -16.0/-11.2 mm Hg); and TRZ+MCTZ-5.0 mg (-20.6/-14.4 and -23.3/-14.6 mm Hg). Blood pressure changes in the combination groups were significantly greater than those in the TRZ alone group. However, there were no statistically significant differences between the TRZ+MCTZ-2.5-mg and TRZ+MCTZ-5.0-mg groups. The combination of TRZ and MCTZ tends to mitigate the adverse effects on serum glucose, uric, potassium and lipids usually associated with thiazide diuretics. Thus, combination treatment that begins with TRZ and adds MCTZ is effective in lowering blood pressure without any significant adverse metabolic effects.

Adrenergic alpha-Antagonists↗
PubMed1989

The effects of terazosin and methyclothiazide on blood pressure and serum lipids.

This study compared the antihypertensive efficacy and the effects on serum lipids of terazosin, a new selective alpha 1-adrenergic antagonist, of methyclothiazide (MCTZ), and of the two drugs used as combination therapy. Adult patients with supine diastolic blood pressure ranging from 95 to 120 mm Hg were eligible to enter this double-blind, randomized, parallel-group study. Analyses of the blood pressure data from the 194 evaluable patients revealed that all three treatments produced significant (p less than 0.001) reductions in supine and standing systolic and diastolic blood pressures from baseline values. Moreover, combination therapy resulted in significantly greater mean blood pressure reductions than were observed with either drug used as monotherapy. In the group receiving terazosin monotherapy, the total serum cholesterol level, low-density lipoprotein plus very-low-density lipoprotein cholesterol fraction, and triglyceride level fell significantly (median changes of 3.7%, 5.0%, and 16.3%, respectively, p less than 0.05). However, in the group receiving MCTZ monotherapy, the total serum cholesterol level, low-density lipoprotein plus very-low-density lipoprotein cholesterol fraction, and triglyceride level increased significantly (4.7%, 7.1%, and 12.5%, respectively, p less than 0.001). In contrast, no significant changes from baseline values were observed for any lipid variable in the group receiving terazosin/MCTZ combination therapy. We conclude that terazosin is effective antihypertensive therapy that has a potentially beneficial effect on the serum lipid profile when used as monotherapy and that it counteracts the negative impact of MCTZ monotherapy on the serum lipid profile when used concurrently with this thiazide diuretic.

Adrenergic alpha-Antagonists↗
PubMed1996

Statistical optimization of a reversed-phase liquid chromatographic method for the determination of amiloride and methyclothiazide in tablets.

A quantitative high-performance liquid chromatographic method in which amiloride is separated from methyclothiazide on a C18 column with detection at 286 mm was developed with the aid of the 'window diagram' technique of Laub and Purnell. The effect of simultaneously varying the pH and methanol to water ratio in the mobile phase were studied to optimize the separation. The method was applied to the quantitative analysis of Lometazid tablets. The powdered tablets were extracted with methanol, containing phenacetin as the internal standard, and assayed by comparison of peak heights after liquid chromatography.

Amiloride↗
PubMed2000

Mechanisms of methyclothiazide-induced inhibition of contractile responses in rat aorta.

Methyclothiazide (MCTZ), a thiazide diuretic, inhibits the contractile response induced by norepinephrine in aortic rings from 12-week-old spontaneously hypertensive rats (SHR). Although not modified by indomethacin, this inhibition was attenuated by either mechanical removal of the endothelium or N omega-nitro-L-arginine (NOLA) treatment. These results suggest that the MCTZ effects on the norepinephrine-evoked vascular response are mediated by an endothelium-dependent mechanism involving endothelium-dependent relaxing factor (EDRF)/nitric oxide (NO) release. MCTZ was also found to alter the contractile response induced by the addition of Ca(2+) to a depolarizing solution, and this inhibitory effect was partially abolished by NOLA application. Our data led us to propose that MCTZ relaxes aortic rings, resulting in an endothelium-dependent relaxation phenomenon that could even be reinforced under high-K(+) depolarizing conditions.

Animals↗
PubMed2001

Direct vascular actions of methyclothiazide in remodeled mesenteric arteries from hypertensive patients.

In vitro experiments were designed to assess the inhibitory effect of the thiazide diuretic methyclothiazide (MCTZ) on contractile responses to norepinephrine (NE) of mesenteric rings from hypertensive patients and normotensive controls. Arteries were taken from portions of mesocolon from 24 patients: 13 hypertensives and 11 normotensives. Changes in the tension of mesenteric ring preparations were measured isometrically. Histologic studies showed that the arteries from hypertensive patients exhibited 1) a greater media thickness-to-lumen diameter ratio, 2) a smaller lumen diameter, and 3) identical media cross-sectional area as those of normotensive controls. At the physiologic level, the hypertensive and normotensive arteries display similar contractile responses to KCl and NE. Furthermore, our results indicate that MCTZ induces concentration-dependent inhibition of the vasoconstrictor responses to NE. This study provides evidence that hypertension is associated with the remodeling of the human mesenteric artery and that MCTZ is as efficient in inhibiting the contractile response induced by NE on hypertensive than on normotensive arteries.

Adult↗
PubMed1966

Effect of antihypertensive (pargyline hydrochloride-methyclothiazide) therapy in three types of hypertension: preliminary report after one year of observation.

Fifty patients with elevated blood pressure were classified according to 3 sub-groups as follows: 11 with borderline hypertension, 8 with systolic hypertension, and 31 with diastolic hypertension. So far, they have been observed for one year while being treated with an antihypertensive preparation containing pargyline hydrochloride and methyclothiazide. Response to treatment depended in large measure upon the type of hypertension; the borderline type was virtually unchanged; in the systolic type there was some diminution in the systolic, but less in the diastolic pressure; and in the diastolic type there was a reduction in both systolic and diastolic pressures. Side effects (faintness, nervousness, mouth dryness, insomnia, genitourinary disturbances and elevated blood uric acid level), when they occurred, were usually relieved by appropriate alteration of the antihypertensive drug dosage, by a change in the time of administration, or by adding medication directed at treatment of the side effect. Evaluation of cardiac output before and after therapy showed no change in this parameter. The results suggest: (a) that the antihypertensive effect probably was achieved by diminishing the peripheral resistance rather than by reducing the cardiac output, and (b) that there was no deterioration of myocardial efficiency, as measured by cardiac output, during the one-year period of antihypertensive therapy. More knowledge of the natural history of hypertension in each of the 3 sub-groups is required for better assessment of the influence of antihypertensive therapy on the outcome of the disease. Judgment as to the desirability of initiating therapy can in some measure be based on the classification of patients into appropriate sub-groups.

Antihypertensive Agents↗
PubMed2000

[Effect of methyclothiazide on the entry of calcium into vascular smooth muscle cells].

The possible involvement of calcium and potassium channels in mediating the vascular actions of methyclothiazide (MCTZ), a thiazide diuretic, was investigated in isolated aortic rings from 12 week-old hypertensive rats. MCTZ (10(-4) M) inhibits the contractile response induced by addition of Ca2+ to a depolarizing solution, the maximal contracture is reduced by 87.16 +/- 6.4%. Furthermore this inhibitory effect was unaffected by charybdotoxine a selective blocker of calcium-activated K+ channels (Kca). This suggesting that MCTZ inhibits voltage-gated Ca2+ channels and blunts the Ca2+ entry into vascular smooth muscle cells. This inhibition was partially attenuated by either mechanical removal of the endothelium or N omega-nitro-L-arginine (NOLA) treatment, suggesting that MCTZ effects are also mediated by an endothelium-dependent mechanism involving endothelium-dependent relaxing factor (EDRF)/nitric oxide (NO) release. Taken together, these observations could point to a role of voltage-gated Ca2+ channels and endothelial release of EDRF/NO in the antihypertensive action of MCTZ.

Animals↗