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Biomedical subjects

P L Sharma

Publications and source records attributed to P L Sharma.

At least 145 records · Page 8Linked to original sources
PubMed1979

Comparative bioavailability of sustained-release and conventional tablets of hydroxyethyltheophylline in man.

The comparative bioavailability of sustained-release and conventional tablets of hydroxyethyltheophylline was studied in normal subjects. In a single dose study on 7 subjects, 3 conventional tablets or 2 sustained-release tablets were administered orally after a light breakfast and blood samples taken for 6 and 12 hours respectively. With conventional tablets the mean peak concentration (8.10 +/- 0.751 microgram/ml) was reached at 3 hours and concentrations less than 5 microgram/ml were observed in 4 out of 7 subjects at 6 hours. In contrast, with sustained-release tablets of theophylline and hydroxytheophylline complex the mean peak concentration (8.90 +/- 0.88 microgram/ml) was reached at 6 hours and levels above 5 microgram/ml were observed in 4 out of 7 cases at 12 hours. Administration of 2 sustained-release tablets twice a day produced trough plasma concentrations varying between 6.9-13.8 microgram/ml, i.e. within the therapeutic range in all the 5 subjects. It is concluded that this new oral sustained-release preparation provides therapeutic plasma theophylline concentration on a 12 hourly dosage schedule.

Biological Availability↗
PubMed1978

The effect on myocardial contractility of a new beta-adrenergic receptor blocking drug, penbutolol.

1 The inotropic effect of penbutolol, a new beta-adrenergic receptor blocking drug, has been compared with that of propranolol in two similar groups of six subjects each. 2 Inotropic changes were assessed from changes in myocardial contractility index [LV dp-dt/11 T] as well as the slope of the regression line relating LV dp/dt to LVED during incremental pacing. 3 Penbutolol was found to have a significant negative inotropic effect of an order similar to that of propranolol in the respective doses studied.

Adult↗
PubMed1978

Comparative potency of intravenous penbutolol and propranolol in man.

A study on the comparative potency of intravenously administered penbutolol, a new non-selective beta adrenoceptor antagonist, on the resting and post-exercise heart rate and rate-pressure product was carried out in 5 normal human subjects. The effects produced by 0.1, 0.2 and 0.3 mg of penbutolol and of 0.025 mg/kg (mean dose 1.28 mg) of propranolol was recorded. The dose of penbutolol producing an effect equivalent to that of propranolol was calculating from the log dose-response curve of penbutolol. In these tests, penbutolol was 7.90 and 7.66 times more potent than propranolol on a weight to weight basis. Penbutolol was well tolerated and no side-effects were observed.

Adrenergic beta-Antagonists↗
PubMed1978

Comparative effects of placebo and plain and slow-release tablets of xanthinol nicotinate on exercise tolerance in normal human subjects.

The effects of placebo and plain and slow-release xanthinol nicotinate on exercise tolerance were studied in 6 normal human subjects. Placebo administration had no significant effect on exercise tolerance. Administration of plain and slow-release xanthinol nicotinate significantly increased exercise tolerance at 1 hour and 1--9 hours respectively from ingestion of the drug. The intensity and duration of action correlated well with the blood levels of nicotinic acid reported earlier. Four subjects experienced moderate to severe side-effects with plain xanthinol nicotinate. Only 1 subject experienced mild side-effects with slow-release xanthinol nicotinate. Slow-release tablets of xanthinol nicotinate may prove useful in the treatment of angina pectoris.

Adolescent↗
PubMed1977

Potentiating effect of (+)-sotalol and deoxysotalol on prostaglandin-evoked contractions of the isolated rat uterus.

The effect of (+)-sotalol and deoxysotalol on prostaglandin (PGF2a and 15-methyl PGF2alpha)-evoked contractions was studied using the isolated rat uterus. After control responses to prostaglandins had been obtained the uterus was exposed to the nutrient fluid containing 10 microgram/ml of (+)-sotalol, deoxysotalol or (--) sotalol. 30 min later the responses to prostaglandins were again recorded. Both (+)-sotalol and deoxysotalol potentiated PGF2alpha as well as 15-methyl PGF2alpha-induced contractions. (--)-Sotalol did not potentiate the PGF2alpha-evoked contractions of the isolated rat uterus. The possible clinical significance of the results is discussed.

Animals↗
PubMed1977

Quantitative study of alpha-adrenergic receptors in circular and longitudinal muscle of isthmus of rabbit fallopian tube and in rabbit aorta.

The affinity of phenylephrine (pD2 value) and KB value for phentolamine for the alpha-adrenergic receptors of circular and longitudinal muscle of isthmus of rabbit fallopian tube and rabbit aorta have been estimated. The affinity of both phenylephrine and phentolamine was significantly more for the alpha adrenoceptors of the longitudinal muscle of isthmus of rabbit fallopian tube and rabbit aorta than circular muscle of isthmus of fallopian tube. The results of this investigation suggest that alpha adrenoceptors of circular muscle of isthmus are atypical. If this holds good for the human fallopian tube, the development of selective alpha-adrenergic-receptor agonists and antagonists may be of potential practical application for the control of fertility.

Animals↗
PubMed1977

The effect of beta-adrenoceptor antagonists on the alpha-adrenoceptor blockade produced by phenoxybenzamine.

The effect of beta-adrenoceptor antagonists on the irreversible alpha-adrenoceptor blockade produced by phenoxybenzamine was studied in dogs. The pressor effects of adrenaline were revived after the inhibition by the alpha-receptor block by (+/-) propranolol, (-) INPEA, (+/-) MJ 1999 and (+/-) butoxamine. The enantiomers (+) propranolol and (+) INPEA were ineffective in this regard. (+/-) Practolol also did not revive the pressor effect of the amines. The alpha-receptor mediated effect of the amines, in the nictitating membrana-receptor blockade. It is concluded that (1) blockade of the peripheral (beta-2) receptors is essential for the revival of the pressor effects, (2) local anesthetic effect of the beta-antagonists is not involved. Further work using a series of doses of agonists and antagonists of alpha-and beta-receptors is indicated to clarify the nature of this drug-interaction.

Adrenergic beta-Antagonists↗
PubMed1977

Comparative effect of intravenous administration of atenolol and practolol on resting and exercise-evoked increase in heart rate and cardiac work load in normal human subjects.

A comparative study of the intensity and duration of action of intravenously administered single doses of atenolol and practolol on the resting and exercise-evoked increase in heart rate and rate-pressure product was carried out in six normal human subjects. On a weight to weight basis, atenolol was 8 times more potent than practolol. There were only marginal differences in the intensity and duration of action of the two drugs. Atenolol, like practolol, was well-tolerated and no side effects were observed. If found safe on longterm use, atenolol may be a suitable alternative to practolol. The daily administration of atenolol in two divided doses should suffice for therapeutic purposes.

Adult↗
PubMed1976

Effect of acebutolol, a new beta-receptor antagonist on heart rate and rate-pressure product in normal subjects.

A study on the effect of acebutolol, a new beta receptor antagonist, on the resting and post-exercise heart rate and rate-pressure product was carried out in 8 normal volunteers. Intravenous administration of 10 and 20 mg acebutolol was compared with 10 and 20 mg practolol administered at weekly intervals. In the oral study, increasing doses of acebutolol were administered over a period of 20 days. The heart rate and blood pressure was recorded before and at the completion of 4-minute exercise period. The exercise was carried out on a bicycle ergometer at 150 watt per minute for 4 minutes. In a dose to dose comparison, the potencies of acebutolol and practolol administered intravenously were of the same order, in decreasing the resting and post-exercise heart rate and rate pressure product. Their duration of action was also similar. In the oral study, the peak effect was achieved at a dosage of 200 mg per day (100 mg twice daily) of acebutolol. Acebutolol decreased the resting as well as post-exercise rate-pressure product (cardiac work load). This may be the mechanism for the reported beneficial effect in angina pectoris. Acebutolol was well tolerated and no serious side-effects were observed.

Acebutolol↗
PubMed1976

A phase II study of prazosin hydrochloride in hypertensive subjects.

The antihypertensive action of Prazosin was studied in 20 hypertensive patients. Sixteen patients completed the 36-week treatment period. The drug produced a gradual and sustained fall in both systolic and diastolic blood pressure. The dosage used was 1 mg TDS. Only 2 patients required 2 mg TDS of Prazosin combined with 1 mg per day of polythiazide, and one of these did not respond. No postural hypotension or weight gain was observed. Side-effects were mild and were not troublesome.

Adult↗