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Biomedical subjects

K Haglund

Publications and source records attributed to K Haglund.

At least 37 records · Page 2Linked to original sources
PubMed1982

Prazosin first dose phenomenon during combined treatment with a beta-adrenoceptor blocker in hypertensive patients.

1 The antihypertensive effect of prazosin has been studied in three groups of hypertensive patients. 2 The drug caused a significant reduction of blood pressure both as monotherapy and combined with alprenolol. 3 The effect of prazosin on blood pressure was more marked at the first dose and especially in combination with alprenolol. 4 No pharmacokinetic interaction between prazosin and alprenolol was observed. 5 Prazosin exhibits an exaggerated first dose effect together with alprenolol. Smaller starting doses of prazosin in combination therapy with beta-adrenoceptor blockers are warranted.

Adult↗
PubMed1982

Additive intraocular pressure reducing effect of topical timolol during systemic beta-blockade.

The effect on intraocular pressure (IOP) of topical timolol was studied in 30 patients with arterial hypertension treated with oral alprenolol, metoprolol or timolol. No patient had any known eye disorder. Topical administration of timolol induced a significant reduction of IOP regardless if the patients had systemic beta-blockade or not. Treatment with topical timolol alone was equally effective in reducing IOP as combined topical and oral therapy. Patient compliance was checked with plasma concentrations of the different beta-blockers.

Administration, Oral↗
PubMed1981

Prazosin kinetics in hypertension.

Prazosin kinetics were studied after single doses (intravenous and oral, 0.5 mg) and after increasing multiple doses (0.5 to 5 mg three times daily) in eight patients with hypertension. After intravenous administration the kinetics could be described by a linear two-compartment open model. Terminal half-life (t1/2 beta) was about 3 hr and apparent volume of distribution (Vd beta) about 0.6 l/kg. After oral doses bioavailability ranged between 55% and 82%. Since total plasma clearance was low (0.14 l/kg x hr) incomplete bioavailability was the result of incomplete absorption rather than of first-pass liver metabolism. The estimated extraction ratio was about 14%. Renal clearance was negligible; only 1% to 2% of the dose was recovered unchanged in urine. Binding to plasma proteins to both albumin and alpha 1-acid glycoprotein was substantial (97%), with albumin being most important. Increasing multiple doses showed that prazosin followed first-order kinetics with a linear correlation between dose and steady-state plasma concentration (P less than 0.001). There were substantial variations in plasma concentrations between patients and there were also day-to-day variations in concentration within the same patient.

Adult↗
PubMed1981

Prazosin dynamics in hypertension: relationship to plasma concentration.

The antihypertensive effects of prazosin in relation to its kinetics were studied after single doses (intravenous and oral, 0.5 mg) and during increasing multiple doses (0.5 to 5 mg three times a day). There was a fall in systolic and diastolic blood pressures of 10% to 14%, which was greater in the standing than in the sitting position. Prazosin plasma concentrations correlated with dose (P less than 0.001). After intravenous prazosin the fall in systolic and diastolic blood pressure and prazosin plasma concentration correlated (P less than 0.01) during the beta-elimination phase in all patients. In only five of eight patients, however, did mean plasma concentration and antihypertensive effect during continuous treatment with different doses correlate. The maximal fall in systolic blood pressure correlated (P less than 0.01) with that after the first oral steady-state dose (0.5 mg three times daily), which indicates limited possibility of early identification of prazosin responders. There were no signs of overshoot of blood pressure when prazosin was withdrawn for a week. On rechallenge with a single oral dose of 2.5 mg prazosin there were no signs of enhanced hypotensive effect.

Adult↗
PubMed1980

Time course of blood pressure, pulse rate, plasma renin and metoprolol during treatment of hypertensive patients.

Eleven patients were treated for essential hypertension with metoprolol (Selokén) for more than three months. The time course of changes in blood pressure, pulse rate and plasma renin activity was studied during treatment with an oral maintenance dose of 100 mg twice daily. Significant decreases in pulse rate, diastolic blood pressure and plasma renin activity were observed even after the first dose. The plasma concentration of metoprolol reached equilibrium after the second dose. After the third dose there was no further significant change in blood pressure. There was a significant correlation (p < 0.001) between the initial (after three doses) and final (after > 90 days) effect of metoprolol on blood pressure (r = 0.86 and 0.91 for systolic and diastolic blood pressure change, respectively).

Adult↗
PubMed1980

Monoamine metabolites in cerebrospinal fluid during treatment of hypertension with prazosin.

Six hypertensive patients were treated with prazosin up to a final dose of 3-4.5 mg/day. There was a significant reduction of blood pressure. The cerebrospinal fluid (CSF) concentrations of the major metabolites of noradrenaline, dopamine and serotonin were unchanged. This indicates that the antihypertensive effect is not mediated via central monoaminergic neurons as suggested by animal studies.

Biogenic Amines↗
PubMed1980

Plasma levels and effects of metoprolol after single and multiple oral doses.

Five patients with moderate hypertension were given placebo and at least 3 single oral doses (25, 50, 75, 100, or 150 mg) of metoprolol as well as multiple doses at at least 2 dose levels (25, 50, or 100 mg thrice daily). Blood pressure, pulse rate at rest, plasma renin activity, and drug plasma concentration were intensively monitored during 7.5 hr after each dose. Pulse rate, systolic blood pressure, and plasma renin activity decreased after the single oral doses, but diastolic blood pressure did not decrease consistently. The correlation coefficients between percentage decrease in systolic blood pressure and pulse rate and total plasma concentrations were higher individually than in the group. The corresponding regression equations were different between individuals and for systolic blood pressure there was a 700% difference in regression coefficients. The acute changes in diastolic blood pressure and plasma renin activity were not related to metoprolol plasma concentrations. The decrease in systolic blood pressure and pulse rate on multiple doses could not be predicted from the response after single doses.

Administration, Oral↗
PubMed1979

Influence of pentobarbital on effect and plasma levels of alprenolol and 4-hydroxy-alprenolol.

Six healthy subjects were given placebo and a single oral 0.2-gm dose of alprenolol (Aptin) before and after 0.1 gm pentobarbital at bedtime for 10 days. The plasma concentrations of alprenolol and its metabolite 4-hydroxy-alprenolol and the inhibition of exercise tachycardia were studied for 7 hr after the alprenolol. Alprenolol and 4-hydroxy-alprenolol plasma levels were decreased by about 40% by pentobarbital but plasma half-lives were unchanged. The inhibition of exercise tachycardia during a 7-hr period was reduced from 14.0% to 10.7% by pentobarbital. The reduction was proportional to the decreased drug plasma levels. There was a significant contribution of the metabolite to alprenolol effect. The estimation of relative potency of metabolite against parent compound was 0.9 before pentobarbital and 1.9 after pentobarbital.

Adult↗
PubMed1979

Influence of pentobarbital on metoprolol plasma levels.

Induction of microsomal enzymes with barbiturates in rats has little effect on the metabolism of metoprolol, compared with propranolol and alprenolol, which undergo extensive hepatic extraction in animals and man. Our study was designed to examine whether the metabolism of metoprolol is inducable by barbiturate in man. In 8 healthy subjects the area under the plasma concentration/time curve after 0.1 gm metoprolol was reduced by a mean of 32% after treatment with 0.1 gm pentobarbital at bedtime for 10 days. There was considerable interindividual variability in the reduction after pentobarbital treatment (2% to 46%).

Adult↗