Microzide
Pharmacokinetics of a fixed combination of sotalol and hydrochlorothiazide in hypertensive patients with moderate renal insufficiency.

Kher A, Fillastre JP, Fourtillan JB, Lefebvre MA, Ingrand I.

Decreased elimination of a combined formulation of Sotalol (160 mg) and hydrochlorothiazide (25 mg) was found in patients with moderate renal insufficiency. Very slight accumulation of sotalol and hydrochlorothiazide was observed, so it appears unnecessary to reduce the dosage in patients with a creatinine clearance of 30 ml/min or more.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6510465&dopt=Abstract hydrochlorothiazide Microzide



Microzide
Liquid chromatographic determination of methyldopa and methyldopa-thiazide combinations in tablets: collaborative study.

Ting S.

A reverse phase liquid chromatographic method for the determination of methyldopa, methyldopa-hydrochlorothiazide, and methyldopachlorothiazide in tablets was collaboratively studied by 8 laboratories. Each collaborator received 20 samples that included drug substance, synthetic and commercial tablet compositions. The overall repeatability and reproducibility standard deviations for commercial tablets were 1.11 and 1.75% for methyldopa, 0.96 and 1.62% for chlorothiazide, and 1.21 and 2.15% for hydrochlorothiazide, respectively. The overall recoveries of methyldopa, chlorothiazide, and hydrochlorothiazide added to synthetic tablets were 100.78, 100.70, and 101.34%, respectively. The method has been adopted official first action.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6520085&dopt=Abstract hydrochlorothiazide Microzide



Microzide
Absence of a significant pharmacokinetic interaction between hydrochlorothiazide and triamterene when coadministered.

Upton RA, Williams RL, Lin ET, Gee WL, Blume CD, Benet LZ.

Hydrochlorothiazide, triamterene, and hydroxytriamterene sulfate were monitored in the plasma and urine of 24 healthy young men taking single doses of a liquid preparation containing both hydrochlorothiazide and triamterene, liquid preparations containing either of these drugs alone, and a combination tablet recently formulated with a dose ratio of hydrochlorothiazide : triamterene (1 : 1.5) found to give optimal potassium-sparing effect. In contradiction to a recent publication, no interaction between the drugs affecting the bioavailability or renal clearance of either could be demonstrated. The previous report of drug-drug interaction probably arose from formulation-related problems with bioavailability from the two capsule and two tablet products which had been studied. A well-formulated hydrochlorothiazide-triamterene combination tablet promotes plasma concentrations and urinary excretion of hydrochlorothiazide, triamterene, and hydroxytriamterene sulfate which are virtually identical to those seen after either a combination liquid dosage form or simple liquid forms containing only one of the two drugs.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6533293&dopt=Abstract hydrochlorothiazide Microzide



Microzide
Physicochemical model for dose-dependent drug absorption.

Dressman JB, Fleisher D, Amidon GL.

A two-tank perfect-mixing tank model was used to stimulate GI absorption. The effect of drug parameters (pK alpha, solubility, and intrinsic wall permeability) and system parameters (pH profile, volume of intestinal contents, and intestinal flow rate) on drug absorption were studied by numerical data stimulation. When the dose did not exceed the solubility of the drug in the intestinal lumen, the fraction absorbed depended on the transit rate relative to the absorption rate and the pK alpha relative to the pH profile, but was independent of drug dose. Saturation of one or both tanks led to dose-dependent absorption. The model was used to simulate absorption of chlorothiazide. Good agreement between simulated and experimental data led to the conclusion that the physical characteristics of chlorothiazide, rather than a saturable transport mechanism at the intestinal wall, may be responsible for the dose-dependent absorption observed for this drug. The model was also used to simulate hydrochlorothiazide absorption. By applying the same system parameters used for chlorothiazide, the model simulation correctly predicted the dose proportionality of hydrochlorothiazide absorption. The lack of dose dependency in this case may be attributed to the higher solubility and pK alpha of hydrochlorothiazide compared with chlorothiazide.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6548523&dopt=Abstract hydrochlorothiazide Microzide



Microzide
Effect of diuretics and calcium antagonists on circulatory parameters and plasma catecholamines during mental stress.

Heidbreder E, Schafferhans K, Kirsten R, Heidland A.

In a model of mental stress the influence of nifedipine and hydrochlorothiazide on stress-induced changes in blood pressure, heart rate, and plasma catecholamines was studied in normal persons. The drugs were used to investigate whether substances with antihypertensive but no particular sympatholytic properties were capable of suppressing emotionally induced stress reactions. In all subjects blood pressure and heart rate increased significantly during mental stress, and this effect was not inhibited either by nifedipine or hydrochlorothiazide. In the hydrochlorothiazide group plasma noradrenaline levels were significantly higher than in controls in the resting state and during the stress reaction, whereas in the nifedipine group no difference was observed. It is concluded that nifedipine or hydrochlorothiazide do not inhibit emotional stress reactions in normotensive persons.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6617720&dopt=Abstract hydrochlorothiazide Microzide