Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Practolol”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed1985

Practolol and its metabolites: tissue localization and retention in the hamster.

The disposition of [14C]practolol and its tissue association in the male Syrian hamster were investigated after p.o. administration. After an acute dose of 400 mg/kg, there was a marked persistence in the eye of total radioactivity (primarily practolol; approximate T 1/2 = 7 days) and nonextractable radioactivity which showed minimal decay over 7 days. Nonextractable radioactivity was also found in other tissues (liver, skin, small intestine and skeletal muscle examined). The level of total and nonextractable radioactivity was linearly related to dose (800 mg/kg highest dose examined). There was a marked accumulation of total and nonextractable radioactivity in the eye (7- and 14-fold, respectively) and skin (6- and 7-fold) after daily administration of 400 mg/kg for 22 days. The association of practolol metabolites with tissue macromolecules might explain the immunological changes in patients with the practolol-induced oculomucocutaneous syndrome. The adverse effects of practolol in humans have not yet been reproduced in any laboratory species and so the results must be interpreted with caution in relation to the toxicity of compound.

Animals↗
PubMed1978

Intravenous and oral practolol in the acute stages of myocardial infarction.

The influence of routine administration of the beta adrenoceptor blocking drug practolol on the outcome of acute myocardial infarction has been studied in 94 patients. The study was restricted to patients under the age of 70 experiencing their first myocardial infarction and in whom there was no contraindication to beta blockade. In the treated group an initial dose intravenous practolol 15 mg was followed by five oral doses of practolol 200 mg at 12 h intervals. A significant reduction in heart rate and systolic blood pressure was apparent in the treated group within 2 h. No difference was detectable in the course of the acute stage of the illness between treated and control patients, apart from a significant reduction in the incidence of atrial fibrillation among those receiving practolol. Patients with inferior infarctions showed a tendency to develop potentially harmful bradycardia and hypotension on receiving practolol which lead to withdrawal of the drug in many cases. At regular review over 7 mth no detectable difference emerged between the treated and control groups in the incidence of cardiac failure, death or reinfarction.

Acute Disease↗
PubMed1970

Clinical evaluation of practolol, a new cardioselective beta-blocking agent in angina pectoris.

In a controlled double-blind study practolol, a new cardioselective beta-blocking drug, was given to 15 patients with angina pectoris, and compared with propranolol 80 mg. q.d.s. The dose of practolol ranged from 200 to 600 mg.b.d. and was decided by initial open titration in individual patients. Though practolol did not influence the incidence of angina or glyceryl trinitrate consumption, it increased the duration of exercise possible in exercise tests and reduced the amount of ischaemic S-T depression in the radiocardiogram during exercise. Propranolol reduced the incidence of angina and, in the exercise tests, increased the amount and duration of exercise but did not affect the degree of S-T depression. Unlike propranolol, practolol did not produce any adverse effects on bronchial smooth muscle. Hence it is concluded that practolol is an effective drug in treating angina, and in the dosage used is of potential value in patients with asthmatic bronchitis and angina. It should, however, be used cautiously in anginal patients with heart failure.

Acetanilides↗
PubMed1983

Divergent effects of atenolol, practolol and propranolol on the peripheral metabolic changes induced by dynamic exercise in healthy men.

A study has been made of the effects of intravenous atenolol, practolol and propranolol on the changes induced by exhaustive dynamic physical exercise in blood pressure, heart rate and blood levels of lactate, glucose, insulin, free fatty acids and potassium. The mean endurance of dynamic exercise was reduced by all three beta-blockers, most markedly by propranolol. After all the beta-blockers heart rate showed a similar decrease during the first 60 min of exercise; atenolol caused the smallest reduction at exhaustion. All three beta-blockers lowered the systolic blood pressure during exercise; propranolol was the most active agent both during exercise and during recovery. The diastolic pressure was higher during exercise after treatment with the beta-blockers, especially propranolol. The beta-blockers did not markedly affect the elevation of blood lactate induced by exercise. The increase in blood glucose was abolished by atenolol. Plasma insulin was reduced by exercise after beta-blockade, most markedly after propranolol and practolol. All the beta-blockers were equipotent in reducing up to 60 min the exercise-induced increase in plasma free fatty acids, although at exhaustion propranolol had a significantly greater effect than atenolol or practolol. Serum potassium was higher after propranolol and atenolol than after practolol during exercise and recovery.

Adult↗
PubMed1975

[The influence of propranolol, practolol and theophylline on the plasma renin activity (author's transl)].

The stimulating effect of theophylline on the plasma renin activity (PRA) under beta-receptor blockade by propranolol or practolol was investigated in 27 patients with essential hypertension of degree I-II. After propranolol and also practolol PRA decreased about thirty per cent of the basal value, increased however by the factor of 2 to 3 after application of theophylline, in spite of the blockade of the beta-receptors indicated by a slight decrease of systolic blood pressure and heart rate. The effect of propranolol and practolol on the basal PRA was not different. Our results show the possibility, to stimulate renin secretion despite blockade of beta receptors by propranolol or practolol, respectively.

Adult↗
PubMed1987

Practolol inhibits human skin fibroblast cell mat hydroxyproline accumulation.

Despite being poorly absorbed practolol (N-4-2-hydroxy-3-(1-methyl-ethyl)-amino propoxy phenyl acetamine) inhibited the accumulation of cell mat hydroxyproline, a measure of collagen synthesis, by human skin fibroblasts (DT2PH) in vitro, (ID50 0.8 X 10(-3) M). The degree of inhibition was dependent on the concentration of practolol used and the incubation time. Neither preinitiation of collagen synthesis nor omitting ascorbic acid from the incubation medium modified this inhibitory action. In contrast, in vitro generated metabolites of practol, using normal and aroclor induced hamster liver preparation, and structural analogues of practolol had no effect on cell mat hydroxyproline levels. Related compounds, propranolol, (1-(isopropylamino)-3(1-naphthyl-oxy)2-propranolol), and paracetamol, (N-(4-hydroxyphenyl)acetamide), both inhibited hydroxyproline levels. Fibroblasts derived from uninvolved skin of a psoriasis patient (PS1) were several fold more sensitive to practolol and propranolol than cells derived from normal skin but showed little change in sensitivity towards paracetamol.

Cells, Cultured↗
PubMed1975

Effect of practolol on left ventricular dimensions during coronary occlusion.

Beta adrenergic blockade has been suggested to improve the myocardial oxygen balance during ischemic conditions. This investigation was undertaken to examine the effects of practolol, a relatively cardiospecific beta adrenergic blocking agent, on regional myocardial dimensions and shortening during acute coronary arterial occlusion in dogs. Local myocardial dimensions were measured ultrasonically in ischemic and nonischemic regions of the left ventricle. Myocardial dilatation and marked reduction in systolic shortening occurred in ischemic regions after occlusion, whereas nonischemic regions were only moderately dilated. Administration of 10 to 20 mg of practolol exerted different effects in the two ventricular regions; myocardial dilatation was reduced and the systolic shortening increased by practolol in ischemic regions, whereas further dilatation and diminished shortening occurred in nonischemic control regions. Similar results were obtained when heart rate was kept constant by atrial pacing during beta adrenergic blockade. Thus, practolol improved the function in ischemic ventricular regions, and restored ventricular stroke volume to preocclusion levels, probably as a result of improved myocardial oxygen balance.

Animals↗
PubMed1978

Superiority of practolol versus propranolol in protection against ventricular fibrillation induced by coronary occlusion.

The ability of practolol and propranolol of prevent ventricular fibrillation in experimental anterior myocardial infarction was compared in dogs subjected to ligation of the left anterior descending and first septal coronary arteries. This procedure, which causes ventricular fibrillation in 90 percent of animals within 30 minutes, was performed in control dogs and in dogs pretreated with propranolol (0.5 mg/kg body weight) or with practolol (1.5 to 2.5 mg/kg). These doses produced nearly equivalent shifts in isoproterenol-induced chronotropic dose-response curves, indicating equivalent degrees of beta adrenergic blockade. In 21 dogs with confirmed ligation, cardiogenic shock did not develop. Six of seven control dogs died with ventricular fibrillation. Six of seven dogs pretreated with propranolol also had fibrillation, whereas only one of the seven dogs pretreated with practolol manifested ventricular fibrillation during the 45 minute postligation observation period. Practolol afforded significant protection compared with no treatment or treatment with propranolol (P less than 0.05).

Animals↗
PubMed1975

Differential blockade of guinea-pig atrial rate and force responses to (--)-noradrenaline by practolol - an uptake phenomenon.

The relative blockade of rate and force responses of guinea-pig isolated atria to catecholamines by practolol was compared. pA2 determinations revealed that with (--)-noradrenaline as the agonist, practolol was more effective in antagonizing rate (pA2, 6.99) than force (pA2, 6.44). This difference was absent in either atria from reserpinized animals incubated with phenoxybenzamine and tropolone or atria incubated with cocaine. Similarly, when (--)-isoprenaline was the agonist, force and rate pA2 values were identical, suggesting that rate and force beta1-adrenoceptors do not differ. The preferential blockade of (--)-noradrenaline-induced rate responses in untreated atria was attributed to the operation of a saturable neuronal uptake mechanism which differs between left and right atria. To avoid high (--)-noradrenaline concentrations encountered during pA2 determinations, the % reduction of responses to single doses of (--)-noradrenaline by practolol were measured in untreated atria. Far from confirming the lack of receptor differentiation indicated by the pA2 determinations, this study revealed force to be more practolol sensitive. The relative merits of the two methods are discussed in an attempt to resolve the question whether rate and force beta1-adrenoceptors differ.

Animals↗
PubMed1982

Inotropic beta-blocking potency (pA2) and partial agonist activity of propranolol, practolol, sotalol and acebutolol.

The beta-blocking potencies (pA2 values) and cumulative dose responses of the direct effects of dl-propranolol, practolol, acebutolol and sotalol have been characterised in respect of the mechanical performance of isolated cat papillary muscle preparations. pA2 values calculated from antagonism of each of the drugs to the inotropic effect of isoprenaline at 29 degrees C were: dl-propranolol 8.3, practolol 5.6, acebutolol 7.5 and sotalol 4.8. The responses in reserpinized muscles were similar to those in non-reserpinized preparations. dl-Propranolol at concentrations of 10(-5) and 10(-4) M depressed peak developed force (DF) and rate of force development (+dF/dt) by 20% and 60% respectively, with similar but smaller changes in maximum unloaded shortening velocity ('Vmax'). Practolol and sotalol increased DF and +dF/dt by less than 10% at 10(-5) M and by 10-20% at 10(-4) M, with similar but smaller changes in Vmax. Sotalol induced prolonged biphasic contractions at 10(-4) M. Acebutolol had no effect on DF, +dF/dt, or Vmax. Time to peak force and half isometric relaxation time were not altered by any drug. Practolol and acebutolol, generally considered to have partial agonist activity, exerted this to a negligible degree in respect of inotropic effect at less than or equal to 10(-5) M.

Acebutolol↗
PubMed1989

Accumulation of pigment granules in lacrymal gland epithelium in practolol-treated beagle dogs.

A 6-month oral toxicity test of practolol was carried out in beagle dogs as a reference control for a newly developed beta blocker. No significant drug-induced changes were detected in any animals by various ophthalmological examinations such as ERG, tear flow, lysozymal activity in tears, etc. However, an unusual pathological change was detected in the lacrymal gland of all five dogs treated with practolol and not in control animals. Macroscopically, the lacrymal glands assumed a blackish brown to deep black colour on both the outside and the cut surface. Microscopically, fine, dark-brown pigment granules were present in the apical and supra-nuclear portion of the cytoplasm of predominantly serosal type epithelial cells. These pigments reacted positively to Schmorl's method for lipofuscin, but gave a negative PAS reaction for polysaccharide, Prussian blue for iron and Ziehl-Neelsen method for ceroid pigment. They were detected as membrane-bound electron-dense bodies by electron microscopy. Similar pigments were also deposited in the cytoplasm of the apocrine sweat gland. Although the mechanism of the accumulation of these granules is far from clear, concentration of practolol in the lacrymal gland is considered to be very closely related to the presence of these granules. A possible mechanism for ocular toxicity by practolol, involving this change, is discussed.

Animals↗
PubMed1980

I.V. practolol during microlaryngoscopy. Effect on arterial pressure, heart rate, blood glucose and lipolysis.

Twenty-five patients undergoing microlaryngoscopy were anaesthetized with thiopentone and nitrous oxide with suxamethonium as a muscle relaxant. Thirteen received practolol 0.4 mg kg-1 and atropine 1.5 mg i.v. shortly before anaesthesia. During anaesthesia practolol 0.2 mg kg-1 was given. Twelve (control) received atropine 0.5 mg before anaesthesia. Practolol reduced the frequency of tachycardia and arrhythmia. The treatment group had a greater reduction in systolic arterial pressure during induction. The hypertensive response to laryngoscopy was not significantly attenuated by practolol. A weak hyperglycaemic response to microlaryngoscopy was not affected, nor was the plasma concentration of glycerol.

Aged↗
PubMed1975

The effect of age on plasma levels of propranolol and practolol in man.

1. Plasma levels of propranolol and practolol were measured in groups of elderly and young subjects, after the oral administration of propranolol (40 mg) and practolol (200 mg) on separate occasions. 2. At all sampling times the mean plasma propranolol level in the group of elderly subjects was substantially greater than the corresponding level in the group of young subjects, there being a significant difference between the two, and a fourfold difference in the mean peak levels. 3. After practolol, there was no significant difference between the mean plasma concentrations of the drug in the two groups for the first 2 hours. Subsequently, the mean plasma levels in the group of elderly subjects were somewhat higher than the corresponding levels in the young group, the differences between the two reaching significance. 4. It is suggested that there is a need to substantially reduce the dose of propranolol given to elderly patients. With practolol, however, no reduction is necessary providing renal function is normal for the patient's age.

Administration, Oral↗
PubMed1986

Influence of the beta-adrenergic antagonists propranolol, practolol and oxprenolol on the proliferation of rat jejunal crypt cells.

Beta-adrenergic blockade by quite large doses of propranolol, practolol and oxprenolol, once or continuously applied, does not influence jejunal crypt-cell proliferation in the rat. After a single i.p. injection of 20 mg/kg propranolol or practolol and even of 100 mg/kg practolol, the mitotic index, the labelling index and the duration of the S phase do not differ between treated and untreated control animals nor between animals treated with the different drugs. Continuous application of 30 mg/kg/d propranolol, practolol or oxprenolol for 7 or 14 days does not affect the mitotic and labelling indices either, nor does it change the duration of the cycle of the jejunal crypt cells and its phases as determined by the percent labelled mitoses method. These results are in contrast to those reported previously by Tutton & Helme (1974).

Adrenergic beta-Antagonists↗
PubMedDate not supplied

A study of the interaction of practolol with acetylcholine, histamine, serotonin and bradykinin in the guinea-pig, and with bean-sprout juice in the mouse.

1. The interactions of practolol with acetylcholine, histamine, serotonin and bradykinin were studied on the trachea and lung of the guinea-pig, an animal whose sensitivity to bronchoactive endogens is known to be similar to that of human asthmatic bronchi. 2. Practolol, like propranolol, potentiated the action of the first three agonists mentioned above, but, unlike propranolol, it did not potentiate the bronchospastic effect of bradykinin. 3. Practolol, in fact, antagonized the action of bradykinin, but this effect was unlike that produced by nonsteroidal anti-inflammatory drugs. 4. The possibility that beta-adrenoreceptor antagonists might show adverse interactions with certain foodstuffs was investigated, an is discussed. 5. It is suggested that the feasibility of the continued use of practolol (or the newer cardioselective beta-blockers) in asthmatics necessarily depends on the type of allergic reaction involved, and so it is not possible to generalize. Any drug or food that might cause a bronchospastic effect synergistically in the presence of a beta- adrenoreceptor antagonist, even a cardioselective one, should be regarded with suspicion.

Acetylcholine↗
PubMed1973

The beta-adrenoceptor blocking properties of the alpha-methyl analogues of propranolol and practolol in the anaesthetized dog.

1. The beta-adrenoceptor blocking properties of alpha-methyl propranolol and alpha-methyl practolol were determined in anaesthetized dogs according to their abilities to modify the isoprenaline-induced effects on diastolic pressure, heart rate, myocardial contractile force, femoral arterial blood flow and pulmonary airway resistance.2. alpha-Methyl propranolol shifted the isoprenaline dose-response curves for the fall in diastolic pressure and the positive inotropic and chronotropic responses to the right in a parallel manner yielding pA(2) and slope values of 6.66 (0.92), 6.34 (0.77) and 6.59 (0.61) respectively. The slopes of the graphs for determining pA(2) values for the cardiac beta-adrenoceptor blocking properties of alpha-methyl propranolol were significantly less than 1 and indicated a mechanism other than simple, competitive, reversible antagonism.3. alpha-Methyl propranolol exerted a much weaker blockade of respiratory smooth muscle beta-adrenoceptors than has been reported for propranolol.4. alpha-Methyl practolol exerted a weaker blocking effect on myocardial beta-adrenoceptors than has been reported for practolol. No significant blockade of vascular or respiratory smooth muscle beta-adrenoceptors occurred after a total cumulative dose of 10 mug/kg of alpha-methyl practolol.5. alpha-Methyl substitution of propranolol and practolol reduces the potency but increases the selectivity of their beta-adrenoceptor blocking properties.6. The beta-adrenoceptors subserving cardiac stimulation, vasodilatation and bronchodilatation are representative of three different beta-adrenoceptor sub-types in the dog.

Airway Resistance↗
PubMed1974

A comparison of the experimental anti-arrhythmic properties of acebutolol (M and B 17,803), propranolol and practolol.

1 The beta-adrenoceptor blocking agent, acebutolol (M & B 17,803), has been compared with propranolol, practolol, lignocaine and quinidine for its ability to revert or prevent various types of experimental arrhythmias.2 By intravenous infusion, acebutolol had one half the potency of propranolol in reverting an established ouabain-induced ventricular arrhythmia in the anaesthetized dog. Practolol was ineffective in the conditions used.3 High oral doses of acebutolol or propranolol significantly increased the arrhythmic dose of ouabain in the conscious rabbit. Similar doses of practolol produced a significant decrease (i.e. potentiation) in the dose of ouabain required to produce arrhythmia. Lignocaine and quinidine showed no or little activity in this test.4 Propranolol, acebutolol and practolol were all effective in decreasing the frequency of ectopic beats induced by adrenaline and methylchloroform in the anaesthetized cat. Lignocaine and quinidine were only weakly effective.5 Acebutolol and propranolol were equally effective either intravenously or orally in reducing the incidence of ventricular fibrillation produced by chloroform in mice.6 It is suggested that the wide spectrum of experimental anti-arrhythmic activity of acebutolol coupled with its cardioselectivity may make it an interesting compound in the treatment of cardiac arrhythmias in man.

Administration, Oral↗
PubMed1975

Double-blind comparison of tolamolol, propranolol, practolol, and placebo in the treatment of angina pectoris.

Forty-two patients with angina pectoris have completed a randomized, double-blind trial comparing tolamolol 100 mg and 200 mg with propranolol 80 mg, practolol 100 mg, and placebo, all given three times a day. Tolamolol 200 mg thrice daily was found to be equivalent to propranolol 80 mg thrice daily in anti-anginal efficacy. Anginal attack rates and trinitrin consumption were significantly reduced by all active treatments as compared with the placebo but tolamolol and propranolol were the most effective. Tolamolol 200 mg thrice daily was most effective in reducing blood pressure, while propranolol was most effective in reducing the resting heart rate. All treatments except the placebo significantly increased the amount of exercise which could be performed before angina appeared (exercise work), while tolamolol 200 mg thrice daily significantly reduced Robinson's index when compared with all other active agents. The degree of S-T segment depression induced by exercise was significantly lessened by both tolamolol and propranolol but not by practolol or placebo. There was no difference in patient preference between tolamolol and propranolol but tolamolol at both dose levels was preferred to practolol. Both tolamolol and propranolol are potent adrenergic beta-receptor antagonists and equal in anti-anginal efficacy but tolamolol has the advantage of being cardioselective. It is superior to practolol.

Adult↗