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Biomedical subjects

L Borgström

Publications and source records attributed to L Borgström.

51 records · Page 3Linked to original sources
PubMed1986

Pharmacokinetics of N-acetylcysteine in man.

N-Acetylcysteine was given intravenously and as three fast dissolving and one slow-release formulation, on separate occasions, as a single dose of 600 mg to 10 fasting (5 men and 5 women) healthy volunteers. Blood and urine were sampled for the following 12 h. Renal clearance constituted around 30% of total body clearance, which was 0.21 l/h/kg. Volume of distribution was 0.33 l/kg, consistent with distribution mainly to extracellular water. The late elimination half-life was 2.27 h and the mean residence time 1.62 h. The slow-release tablet resulted in a flattened plasma concentration-time curve typical of slow release formulations, while the other three oral formulations were rapidly absorbed. The oral availability of N-acetylcysteine varied between 6 and 10%, with the slow-release tablet having the lowest and the fast dissolving tablet the highest availability.

Acetylcysteine↗
PubMed1983

Relationship between plasma concentration and arousal in normal subjects after single oral and parenteral doses of melperone, a butyrophenone neuroleptic.

The relationship between plasma concentration and effect on arousal was studied in normal subjects after single oral and parenteral doses of melperone. A strong correlation between plasma concentration and effect was found when the effector compartment and central compartment were in equilibrium. The relationship was independent of the route of administration.

Administration, Oral↗
PubMed1983

Sedative effects and prolactin response to single oral doses of melperone.

The pharmacokinetics of melperone and the relationship between plasma concentration and the effect on arousal and prolactin secretion after single oral doses (10, 25, 50 and 100 mg) was studied in normal subjects. Dose-dependent kinetics were indicated by the fact that higher plasma concentrations than expected were demonstrated after the 100-mg dose. Melperone decreased arousal and increased prolactin secretion in a dose-dependent manner. The level of arousal was correlated to melperone plasma concentration over the entire dose range. Prolactin secretion was also correlated to melperone plasma concentration, provided the relationship was studied separately for the individual melperone doses. Thus at higher doses, higher plasma concentrations are needed to elicit the same prolactin outflow. The possibility that reduced arousal reactions might contribute in the antipsychotic action of neuroleptic drugs was discussed.

Adult↗
PubMed1982

Pharmacokinetics of parenteral and oral melperone in man.

The pharmacokinetics of melperone (Buronil, Ferrosan, Sweden) was studied after administration of various parenteral and oral doses to man. After parenteral administration, the data could be fitted to a two-compartment model, but after oral dosing the distribution phase could not be separated from the elimination phase, and so an one-compartment model gave the best fit. The half-lives were about 3-4 h, except after intramuscular injection, when the half-life was about 6 h. The bioavailability of oral doses was about 60% of the intravenous injection. After the highest oral dose of 100 mg, the pharmacokinetics, expressed as AUC or Cmax, showed non-linearity, possibly due to saturation of the hepatic elimination system.

Administration, Oral↗
PubMed1981

Plasma levels and pharmacokinetics of cyclofenil after oral administration to man.

Cyclofenil was given as a single oral dose of 200 mg, and also as 200 mg/day for eight days, to seven healthy female volunteers. Plasma was analyzed for the active metabolite and pharmacokinetic modelling was performed. A biological half life of 29 h was bound after the single dose and 18 h after the eighth day of continuous treatment. No significant difference was found in any of the calculated parameters when comparing the values from Day 1 and Day 8. The theoretically constructed steady-state curve fitted the experimented values.

Administration, Oral↗
PubMed1981

Pharmacokinetics of propranolol.

The pharmacokinetics of propranolol after the administration of 40, 80, and 120 mg p.o. and 10 mg i.v. was studied in nine healthy male volunteers. Propranolol was analyzed after extraction and derivatization by gas-liquid chromatography. A multiexponential curve-stripping program was used for the pharmacokinetic analysis. The volume of distribution was about 6 liters . kg-1, bioavailability around 25%, with a mean terminal half-life of 6 hr. There was no evidence of either dose dependent disposition kinetics or an oral threshold dose. A slight increase in urine volume was observed after propranolol administration.

Adult↗
PubMed1981

Pharmacokinetics of bendroflumethiazide after low oral doses.

The pharmacokinetics of bendroflumethiazide after oral administration of 1.25, 2.5, and 5.0 mg were studied in nine healthy male volunteers. Bendroflumethiazide was analyzed by GLC after extractive alkylation. After the lowest dose, the plasma concentration, could be followed to 14 hr, and the data were adequately fitted by a one-compartment model; the half-life was 3.1 hr. After the 2.5 and 5.0 mg doses, the plasma concentration was followed for 24 hr, and the data were fitted by a two-compartment model with half-lives of 8.9 hr. The urinary sodium concentration was doubled after bendroflumethiazide intake, but the urinary potassium concentration remained almost constant. The renal clearance of bendroflumethiazide was around 30 ml . min-1.

Bendroflumethiazide↗
PubMed1976

Glucose consumption in rat cerbral cortex in normoxia, hypoxia and hypercapnia.

Glucose consumption was measured in the cerebral cortex of rats, anesthetized with 70% N20, under normoxic conditions, as well as in hypoxia (Pao2 about 25 mmHg) and hypercapnia (Paco2 80-85 mmHg). The method used was that Hawkins et al (1974), modified to allow studies of transients in glycolytic rate. Cortical glucose consumption in normoxia was 0.77 mumol-g(-1)-min(-1). It is concluded that whereas glucose consumption in the whole brain of unanesthetized rat may be close to 0.6 mumol-g(-1)-min(-1), that of the cerebral cortex is close to 0.8 mumol-g(-1)-min(-1). During the first 2 min of hypoxia, glucose consumption was increased to twice the normal, and during the fist 2 min of hypercapnia, the corresponding value was less thane third of the normal. After 15 min of hypoxia, the glucose consumption had returned towards control values. In "steady state" hypercapnia, the glycolytic flux was higher than in the inital phase although still below normocapnic values.

Animals↗
PubMed1975

The relationship between arterial po2 and cerebral blood flow in hypoxic hypoxia.

The relationship between arterial oxygen tension (PaO2) and cerebral blood flow (CBF) in hypoxic hypoxia was studied in artificially ventilated and normocapnic rats. Changes in CBF were evaluated from arteriovenous differences in oxygen content after 2, 5, 15 and 30 min exposure to PaO2 85, 75, 55, 45, 35, and 25 mm Hg. In separate experiments the PaO2 was decreased to 25 mm Hg for 1, 2, 5, 15 and 30 min in animals in which PaCO2 was allowed to fall by 5-10 mm Hg. There was a small, gradual increase in CBF when PaO2 was lowered in steps from 130 to 55 mm Hg, and a more pronounced increase at PO2 values below 50 mm Hg. At PaO2 25 mm Hg CBF increased to values of 500% of normal. Significant increased in CBF were recorded at PaO2 values of 85 and 75 mm Hg in spite of the fact that previous studies have failed to record an elevated tissue lactate content at these po2 levels, and in spite of an unchanged cerebral venous PO2. When the PaO2 was reduced to 25 mm Hg CBF increased markedly already at 1 and 2 min, and this increase in CBF occurred even if PaCO2 was allowed to fall by 5-10 mm Hg. Previous results have shown that in such short periods enough lactic acid is not formed to induce a net tissue acidosis. The results thus give no support to the hypothesis that cerebral hyperemia in hypoxia is coupled to accumulation of lactic acid in the tissue.

Animals↗
PubMed1975

The influence of acute normovolemic anemia on cerebral blood flow and oxygen consumption of anesthetized rats.

The influence of acute normovolemic anemia on cerebral blood flow (CBF) and cerebral metabolic rate for oxygen (CMRo2) was studied in normocapnic rats under nitrous oxide anaesthesia. The arterial hemoglobin content was reduced to values of about 12, 9, 6 and 3 g.(100 ml)(-1) by arterial bleeding and substitution with equal volumes of homolgous plasma. The CBF increased in proportion to the reduction in hemoglobin content to reach values of 500-600 per cent of normal at extreme degrees of anemia, but CMR02 remained unchanged. Cerebral venous PO2 and oxygen saturation did not decrease below normal values, indicating that tissue hypoxia did not develop. However, since the increase in CBF at hemoglobin concentrations of below 9 g(100 ml)(-1) was far in excess of that expected from the decrease in viscosity the results indicate thatdilatation of cerebral resistance vessels occurred. This dilatation, which was obviously related to the fall in arterial oxygen content, cannot be explained by any of the current theories proposed to explain cerebral hyperemia in hypoxia.

Acute Disease↗
PubMedDate not supplied

In vitro and in vivo evaluation of controlled-release and enteric-coated formulations of sodium salicylate.

The bioavailability and pharmacokinetics of salicylic acid (SA) were studied after single and multiple doses of a new slow-release formulation, based on porous membrane diffusion of sodium salicylate (NaSA). A solution of NaSA and an enteric-coated tablet of NaSA were used for comparison. Dissolution rate studies were carried out at various pH values, and both solid formulations showed pH-dependent release rates. The enteric-coated tablet released its content rapidly at intestinal pH but slowly and irregularly at gastric pH. The dissolution from the controlled-release formulation at intestinal pH was completed after 6h and the drug was delivered at a constant rate. At gastric pH the release rate was lower but complete release was obtained within 24h. The novel formulation appeared to offer complete bioavailability of SA and an even and sustained release of SA, allowing twice-daily medication without increased fluctuations in SA concentrations.

Adult↗
PubMedDate not supplied

Absolute bioavailability of terbutaline from a CR-granulate in asthmatic children.

The study aimed at finding the absolute bioavailability of terbutaline of a newly developed CR-granulate. Eight asthmatic children, aged 8-13 years, were given 3 mg of terbutaline as the CR-granulate, concomitant with the intravenous administration of 0.100 mg of deuterium-labelled terbutaline. The labelling of the intravenous dose made possible a separation, in the analytical step, of terbutaline originating from the intravenous and oral administration. Maximal plasma concentration, 8.7 (range: 4.9-15.2) nmol l-1, was reached after 4.7 (2.2-6.0) h. Absolute bioavailability was 10.8 (7.63-16.4) per cent. The parameter values were similar to those found after administration of terbutaline CR-tablets to adults. The CR-formulation is easily swallowed and can be dosed twice daily. Thus it should be a good alternative to elixir or plain tablets, dosed three times a day.

Adolescent↗