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PubMed1976

Beta1-blocker (practolol) and exercise in patients with chronic obstructive lung disease.

Ventilatory and circulatory data from 20 patients suffering from chronic obstructive lung disease have been obtained before, during and after exercise at 600 kpm/min for 5 min on a bicycle ergometer. The patients had been given intravenously practolol, 15 mg, or saline alternatively, using a double-blind cross-over technique. A slight postexercise reduction of FEV1 (8%) was noted after practolol medication as compared to placebo, with an accompanying decrease in PaCO2; PaO2 did not differ substantially. No wheezing or inappropriate dyspnea attributable to the medication was noted in any of the patients. The well known beta1-blocking effects on the circulation were confirmed, with maintained Q and reduced HR, together with a lowered systemic BP during and after exercise. There was a significant positive relationship between the postexercise reduction of FEV1 and the concomitant fall in HR. It is concluded that practolol in doses with near maximal circulatory effects had a slight, but clinically insignificant effect on the ventilatory parameters.

Adult↗
PubMed1975

Comparison of the effects of acebutolol (Sectral) and practolol (Eraldin) on airways obstruction in asthmatics.

The effects of oral practolol (Eraldin, I.C.I. Ltd) (300 mg) and acebutolol (Sectral, May & Baker Ltd) (300 mg) were compared in a placebo-controlled, crossover study in ten asthmatics. 2. Pulse rate, forced expiratory volume in one second (FEV1) and specific airways conductance were measured before and after a bronchodilator and the same procedure was repeated after taking acebutolol, practolol or placebo. 3. A mean increase in resting airways obstruction and reduction in bronchodilator response were evident with both drugs. The differences were statistically significant only after acebutolol for the logarithm of specific conductance. Mean plasma levels of the two drugs were similar. The response to both drugs was similar in the same patient and unrelated to severity of asthma. Mean reduction in resting pulse rate was statisitcally greater after acebutolol compared with placebo but not after practolol compared with placebo. 4. In any individual the beta-adrenoceptor blocking response is unpredictable and any beta-adrenoceptor blocking drug must be used with extreme caution in asthmatics.

Acebutolol↗
PubMed1975

Beta-adrenoceptors in the human dorsal hand vein, and the effects of propranolol and practolol on venous sensitivity to noradrenaline.

1 Infusion of isoprenaline into dorsal hand veins preconstricted with noradrenaline produced vasodilatation in four subjects out of five which was reversed by addition of propranolol. It is confirmed that beta-adrenoceptors are present in the hand veins of most subjects. 2 Addition of either propranolol or practolol to infusions of vasoconstrictor doses of noradrenaline potentiated the vasoconstriction in the hand vein. 3 After systemic administration of propranolol (0.3 mg/kg) or of practolol (1.0 mg/kg) intravenously, the sensitivity of the hand vein to the vasoconstrictor activity of noradrenaline was increased by 7.5 times and 2.9 times respectively. Significant reductions in hand skin temperature and resting pulse rate occurred after propranolol only. 4 It is suggested that this may be a useful method for the quantitative estimation of peripheral vascular beta-adrenoceptor blocking activity in man. At the doses used, significant beta-adrenoceptor blockade appears to occur at this site with practolol as well as propranolol.

Adult↗
PubMed1976

Comparison of propranolol and practolol in the management of hyperthyroidism.

Twenty-one hyperthyroid patients participated in an 8-week double-blind crossover trial of propranolol and practolol, and the effecte of these drugs on the clinical and metabolic features of the disease were studied. Propranolol was marginally more effective than practolol, as measured by the hyperthyroid diagnostic index and anxiety scale. Propranolol produced a significant reduction in the serum concentration ratio of tri-iodothyronine to thyroxine, compatible with partial inhibition of peripheral deiodination of thyroxine. Adverse reactions occurred more frequently with propranolol than with practolol. In veiw of the efficacy of practoloo, further trials in hyperthyroid patients of newer beta1-adrenoceptor antagonists, preferably without partial agonist activity, are indicated.

Adult↗
PubMed1986

Electrocardiographic changes during microlaryngoscopy in practolol-pretreated patients under balanced anaesthesia.

Electrocardiographic (ECG) changes were studied in 82 adult patients with a mean age of 49 years undergoing microlaryngoscopy. The patients were pretreated with practolol 0.15 mg/kg i.v. 5 min before induction of anaesthesia with thiopental. Anaesthesia was maintained with nitrous oxide in oxygen, fentanyl and suxamethonium-infusion. ECG changes occurred in 49% of the patients before anaesthesia and procedure. Pre-existing ECG changes increased or new changes occurred in 39% of the patients during intubation and in 38% during the procedure. The most common preanaesthetic ECG changes were flat or negative T-wave (18%), sinus tachycardia (13%), ischaemic S-T segment depression (8.5%) and intraventricular conduction disturbance (8.5%). ECG changes during intubation were sinus tachycardia (16%), ventricular ectopic beats (12%), supraventricular ectopic beats (10%) and ischaemic S-T segment depression (10%). The most common changes during microlaryngoscopy were supraventricular ectopic beats (16%), T-wave flattening or inversion (15%), ischaemic S-T segment depression (11%) and sinus bradycardia (10%). In all patients ECG changes disappeared without any special treatment. Unlike our earlier identical study without practolol pretreatment, neither sinus tachycardia nor junctional rhythm occurred during microlaryngoscopy in the present study. The results suggest that practolol pretreatment before microlaryngoscopy is especially useful when sinus tachycardia and junctional rhythm should be avoided.

Adult↗
PubMed1973

Isoprenaline- and exercise- induced tachycardia in the assessment of beta-adrenoceptor blocking drugs; a comparison between tolamolol, practolol and propranolol.

The effects of tolamolol, propranolol and practolol on both isoprenaline- and exercise-induced tachycardia have been studied in conscious dogs. Tolamolol was approximately equipotent to propranolol and 50 times more potent than practolol in antagonizing exercise-induced tachycardias, but was approximately 12 times less potent than propranolol and 8 times more potent than practolol in blocking isoprenaline-induced tachycardia. It is suggested that antagonism of the tachycardia induced by exercise affords a more meaningful assessment of the possible therapeutic potential of beta-adrenoceptor blocking drugs than does that induced by isoprenaline.

Adrenergic beta-Antagonists↗
PubMed1980

Test and teach. Number twenty-one. Diagnosis: practolol induced sclerosing peritonitis.

A relatively uncommon but unique and life threatening iatrogenic condition is described. There are few aids to diagnosis but once it is known that the patient has been on practolol the surgical and pathological findings are pathognomonic. Other practolol related side effects are usually present in the patient. The conditions may develop months or possibly years after cessation of intake of the drug and further cases may occur, although practolol has been withdrawn from use. Awareness of the condition is therefore of continuing importance.

Angina Pectoris↗
PubMed1976

The effect of propranolol, prindolol, practolol and verapamil versus placebo on exercise induced tachycardia in patients with ventricular preexcitation.

Propranolol, prindolol, practolol and verapamil have been given orally in a fixed dose to subjects with preexcitation syndrome in a cross over study. The effect on exercise induced tachycardia, prevention of tachyarrhythmias and normalization of heart rate after exercise was investigated. Propranolol, practolol and prindolol significantly (p less than 0.01-0.05) reduced the heart rate at rest and during exercise and favourably influenced the normalization of the heart rate after exercise. The effect on effort tolerance (work done till the submaximal heart rate was reached) was significantly better after propranolol (versus prindolol and verapamil) and practolol (versus verapamil) only. Verapamil showed a consistent effect only given intravenously in paroxysmal tachycardia while in the majority of patients there was no difference between oral verapamil and placebo.

Adult↗
PubMed1999

Nonspecific membrane effects of CH-103: hydrophobicity, surface activity and membrane fluidity studies in comparison with propranolol and practolol.

The partition coefficient, surface activity and membrane fluidizing/disordering effects of CH-103, a beta-adrenergic receptor antagonist, were compared to those of propranolol and practolol as reference compounds. Changes in membrane fluidity were followed by measuring the steady-state fluorescence anisotropy of bull sperm cells with 1-[4-(trimethylammonium)-phenyl]-6-phenyl-1,3,5-hexatriene (TMA-DPH) as a fluorescence probe. The octanol/buffer (pH 7.0) partition coefficients for CH-103, propranolol and practolol were 32.9, 5.08 and 0.013, respectively; the surface activity of the compounds decreased in the same order. CH-103 and propranolol significantly increased the fluidity of the membrane in a concentration-dependent manner, whereas practolol reduced fluidity. These physicochemical parameters correlated with the effects of these drugs on rat sarcolemmal Ca2+, Mg(2+)-ATPase, a manifestation of their nonspecific membrane activity. Our results suggest that the physicochemical properties of CH-103, similarly to those of propranolol, are the main determinants of its nonspecific membrane activity.

Adrenergic beta-Antagonists↗
PubMed1976

Hemodynamic effects of verapamil and practolol in man.

The hemodynamic effects of verapamil and practolol were investigated in a group of 10 selected patients (7 with coronary artery disease) undergoing cardiac catherization. The drugs were given i.v. in a dose of 0.1 mg/kg, alone or in combination, before and after controling the heart rate by atrial pacing. Measured hemodynamic parameters included aortic and left ventricular pressure and its first derivative, cardiac output, and echocardiographically derived left ventricular dimensions. Each drug given individually caused minor hemodynamic changes, but the combination of practolol and verapamil when the heart rate was fixed by atrial pacing invaribly caused a reduction in LV dp/dt max which was independent of preload and afterload. It is concluded that both drugs have a mildly negative inotropic effect when administered at this dose intravenously to patients with normal or mildly impaired left ventricular function. The myocardial depression was more apparent when practolol preceded verpamil. Caution must be exercised when using these drugs in combination in patients with impaired myocardial function.

Adult↗
PubMed1977

Effects of beta-adrenoceptor blocking agents, pindolol, alprenolol and practolol on blood pressure and heart rate in conscious renal hypertensive dogs.

The effects of pindolol, 10 mg/kg, alprenolol, 50 mg/kg, and practolol, 50 mg/kg, given by mouth, on blood pressure and heart rate were investigated over a 24-hr period in 5 conscious renal hypertensive dogs, using a cross-over design. Pindolol and alprenolol caused significant falls in blood pressure which averaged 22 mm Hg (at 3-hr after p.o. administration) and 20 mm Hg (at 3-hr). However, practolol failed to produce any significant changes in blood pressure. Heart rate increased by 67 beats/min (at 1-hr) and 39 beats/min (at 3-hr) after pindolol and alprenolol, respectively, but did not show any significant increase when practolol was given orally. The pindolol-induced tachycardia and hypotension were not suppressed significantly by propranolol (1 mg/kg i.v.) which blocked completely the tachycardia and hypotension induced by isoprenaline (3 mg/kg p.o.). The hypotension and tachycardia observed after oral administration of D-32 (50 mg/kg) or after intravenous infusion of p-OH D-32 (1 mg/kg per min for 5 min) were also not modified significantly by propranolol (1 mg/kg i.v.). Based on these results and other published data, mechanisms pertaining to the hypotension exerted by beta-adrenoceptor blocking agents were discussed.

Administration, Oral↗
PubMed1978

Immune reactions associated with practolol therapy.

A review of adverse reactions following practolol therapy is presented. The appearance of antinuclear antibodies seems to herald the clinical manifestations. Antinuclear antibodies were found in 30% of patients treated with practolol for prolonged periods. It is suggested that patients who develop an immune reaction following practolol metabolize the drug differently than those who do not.

Antibodies, Antinuclear↗
PubMed1975

[Experimental findings on tyramine-dependent release of noradrenaline in various parts of the heart under the influence of practolol].

Determinations of Noradrenaline-concentrations (NA) in the myocardium of the atria and ventricles of rats were performed and the influences of Practolol and Tyramine were controlled. Following Tyramine, NA was decreased significantly in all specimens. After preinjection of Practolol, NA depletion was considerably less in the right and left atria compared to control values. By these results, the clinical observation of a preferential antiarrhythmic action of Practolol on atrial extrasystoles and tachycardias may be supported.

Animals↗
PubMed1976

Aggravation of psoriasis and occurrence of psoriasiform cutaneous eruptions induced by practolol (Eraldin).

Twelve patients with cutaneous and/or eye symptoms caused by practolol have been studied. The morphological appearance of the skin eruptions was psoriasiform in 5, vesiculo-papular in one, and exfoliating dermatitis was seen in 2 patients. Keratoconjunctivitis sicca was the only adverse reaction to practolol in one and was present in 3 additional patients. Practolol was found to aggravate existing psoriasis in 3 patients and render it extremely refractory to therapy.

Adult↗
PubMedDate not supplied

[Effects of metoprolol, practolol, and propranolol after isoprenaline injections in asthmatic patients (author's transl)].

The effects of two beta-blockers, one non-selective, propranolol, the other beta 1 selective, metoprolol, were studied in 8 asthmatic patients. Practolol and a placebo were used as reference products. Heart rate, blood pressure, MEV, and muscle tremor were measured at rest and after isoprenaline infusions at different concentrations. In patients receiving placebo, isoprenaline caused an increase in heart rate, MEV, systolic BP, and muscle tremor, and a reduction in diastolic BP. After propranolol, the effects of isoprenaline on heart rate, MEV, and muscle tremor were almost completely blocked, and modifications in systolic and diastolic BP were only slightly affected. Metoprolol and practolol did not inhibit the increase in MEV induced by isoprenaline, but they reduced the increase noted in the heart rate. These results demonstrate the beta 1 selectivity of these two beta-blockers. Contrary to propranolol, metoprolol and practolol did not block the increased muscle tremor provoked by isoprenaline: muscle tremor must be dependent on beta 2-receptor activity. As the effect of isoprenaline on the MEV was not inhibited by beta 1-selective beta-blockers, these can be prescribed for asthmatic patients in association with beta 2 stimulants.

Adult↗
PubMed1983

Treatment of hypertension following endotracheal intubation. A study comparing the efficacy of labetalol, practolol and placebo.

Labetalol, a new adrenergic receptor antagonist, has both alpha- and beta-blocking properties. Intravenous labetalol (0.25 and 0.5 mg/kg), practolol (0.4 mg/kg) and saline (1 ml), injected prior to anaesthesia, were compared with respect to their effect on the haemodynamic consequences of direct laryngoscopy followed by the passage of an endotracheal tube. When compared with intravenous saline injection, both labetalol and practolol obtunded the tachycardia induced by endotracheal intubation. The higher dose of labetalol was more effective in reducing the hypertensive response than the lower dose of practolol. However, none of the regimens completely abolished the adverse haemodynamic consequences of laryngotracheal manipulations.

Blood Pressure↗
PubMed1983

Mechanism of the hypotensive action of practolol in the anesthetized rat.

Cardiovascular effects of acute administration of practolol were studied in groups of normotensive and spontaneously hypertensive rats. In some of these animals a strong and long-lasting hypotension was shown, resulting from a decrease in the total peripheral resistance. This hypotension was impaired by preventive propranolol administration, and did not result from a direct vascular effect. Moreover, it was previously reported that practolol induced a strong and long-lasting hypotension in all normotensive and hypertensive rats after blood-brain barrier disruption. From these experiments it is suggested that the blood pressure decrease observed in some groups of Okamoto rats may be due to a practolol action on central beta-receptors. The intensity of hypotension depends on the molecule penetration in the central nervous system, and seems to be related to blood-brain barrier lesions induced by genetic hypertension.

Animals↗
PubMed1980

Studies of practolol on mitochondrial metabolism.

The possible effect of practolol (ICI 50,172) on mitochondrial metabolism was studied. The drug inhibited the oxidation of glutamate, alpha-ketoglutarate and succinate by heart mitochondria. The polarographic determinations showed that practolol is an inhibitor of the oxidative phosphorylation. The activity of NADH-oxidase, NADH-ferricyanide reductase, NADH-cytochrome c redutase was inhibit by the drug; no effect was observed on the succinate dehydrogenase. The electron microscopy of isolated mitochondria treated with practolol showed that the drug promote conformational changes of the mitochondrial membrane, probably concerning with the detergent characteristics of the drug.

Animals↗