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Biomedical subjects

F Andreasen

Publications and source records attributed to F Andreasen.

At least 109 records · Page 6Linked to original sources
PubMed1979

Determination of thiopental by high pressure liquid chromatography.

A specific and rapid reverse phase HPLC-method for the determination of thiopental in serum and in protein free solutions is described. No extraction is used. The detection limit is about 0.090 microgram/ml for serum and about 0.030 microgram/ml for buffer solutions. The retention time is 3.80 min. No interference is found with drugs commonly used in patients with heart diseases. The method was used to follow the serum concentrations in 7 patients who were given thiopental as an introduction to general anaesthesia.

Adult↗
PubMed1979

The determination of naproxen by spectrofluorometry and its binding to serum proteins.

A fluorometric method for the determination of naproxen in serum, albumin solutions and protein free buffer solutions is described. The detection limit is about 10 ng/ml. Furosemide, thiopental and salicylic acid did not show any disturbing fluorescence while phenprocoumon did. The in vitro binding of naproxen in albumin solutions and serum was studied by equilibrium dialysis. A small but significant increase was found in the percentual binding in albumin solutions as compared to serum. The percentual binding was not affected by changes in the pH from 5--8. By fitting the binding data to a model assuming two classes of binding sites, association constants and binding capacities were determined. A very high affinity and a high capacity were found. The association constant for the first class of binding sites was higher for human serum albumin than for serum (8.5 versus 5.3 . 10(6) M-1). The difference in the protein binding to the first class of binding sites in human serum albumin and serum can be explained by the existence of a competitive inhibitor in serum.

Albumins↗
PubMed1979

The binding of phenprocoumon to human plasma proteins.

By in vitro experiments with equilibrium dialysis and 5 micrograms PPC per ml an average of 99.7 +/- 0.2% was bound to serum proteins. The binding in a solution with the albumin concentration which was present in the serum samples did not differ from this binding or from the binding in plasma where coagulation was prevented with either heparin or citrate. The binding constant in albumin solutions at 37 degrees was 4.5 +/- 0.31/mol x 10(-5) and an average of 1.16 +/- 0.04 primary binding sites was found. The association constant for the PPC albumin interaction was temperature dependent and the results of thermodynamic calculations suggested a combined ionic and non-polar type of binding as the change in enthalpy contributed with 40% of change in free energy. A large positive entropy change was found (15.79 Kcal/mol/degree K). The addition of phytomenadione to albumin solutions and of menadione to plasma caused a considerable decrease in the protein bound fraction of PPC, indicating the relevance of a study concerning the possible clinical consequences of these interactions.

4-Hydroxycoumarins↗
PubMed1979

The effect of daily administration of naproxen on the prothrombin complex activity in patients under long-term therapy with phenprocoumon.

Out of a total of 150 patients attending an out-patient clinic for anticoagulant therapy, 12 had disorders which normally would indicate a prolonged use of an antirheumatic drug. To 6 of these patients, naproxen (1/4 g twice daily) was given while anticoagulant treatment with phenprocoumon was continued in an unchanged dosage schedule (average dose 2.1 mg/day). On the average, the prothrombin complex activity (PP%) was reduced to a stable level 10--20% below that obtained during a 2-month period before the naproxen treatment was started. No bleeding episodes or other effects were observed. Thus the simultaneous administration of naproxen caused no problems for the maintenance of a stable anticoagulant therapy.

4-Hydroxycoumarins↗
PubMed1979

Postprandial serum creatinine increase in normal subjects after eating cooked meat.

Ingestion of meals containing cooked meat caused a marked postprandial increase in serum creatinine concentration, whereas ingestion of raw meat had no effect on serum creatinine. A peak mean value was seen 3 hours after the start of meals. No change in creatinine clearance was observed. Analysis of serum creatinine by conventional autoanalyser and by an ion exchange method ('true creatinine") showed a high degree of correlation, making a possible effect of non-creatinine chromogens unlikely. It was shown that creatinine is produced from creatine when meat is boiled.

Animals↗
PubMed1978

Pharmacokinetics of sulfadiazine and trimethoprim in man.

Sulfadiazine (SDZ) 800 mg and trimethoprim (TMP) 160 mg were given orally to 10 normal subjects and the concentration of SDZ and TMP in serum and urine was followed for 24 h. Both drugs showed a significant negative correlation between individual "peak" concentrations in serum and the body weight of the subject. Twelve hours after dosing the serum concentration was 12 to 25 microgram/ml for SDZ and 0.3 to 1.1 microgram/ml for TMP. Individual concentration ratios between SDZ and TMP in serum were 4.8 (1 h)--145 (24 h), and in the urine the ratio was close to 6 throughout the 24 h collection period. The range of urinary concentrations was from 65 to 400 microgram/ml for SDZ and from 13.8 to 93.4 microgram/ml for TMP. The fraction (formula: see text) was 21% during the 0--8 h period, 33% during the 8--15 h period and 41% during the 15--24 period. The average "t1/2" was 15.2 +/- 7.4 h for SDZ and 7.4 +/- 1.9 h for TMP. Individual subjects showed a significant correlation between the serum clearance of TMP and SDZ (p less than 0.01) and also between the renal clearance of the two drugs (p less than 0.05). The serum clearance was significantly correlated with the renal clearance for TMP but not for SDZ. For SDZ Vd was significantly negatively correlated with the elimination constant; for TMP no such correlation was found. The serum clearance of SDZ was significantly correlated with the percentage of SDZ which was excreted as the (presumably) acetylated compound. The renal clearance of SDZ was independent of the serum concentration of SDZ. There was a highly significant negative correlation between the renal clearance and serum concentration of TMP, as well as for "acetylated SDZ". The renal clearance of "acetylated SDZ" averaged more than six times that of unconjugated SDZ. With increased urine flow the renal clearances of TMP and SDZ were significantly increased.

Absorption↗
PubMed1978

Pharmacokinetics of furosemide in anephric patients and in normal subjects.

The pharmacokinetics of furosemide 40 mg i.v. were compared in 7 anephric patients and in 7 normal subjects. The average serum clearance was 66 ml/min in the patients and 219 ml/min in the normal subjects, and the corresponding weight corrected clearances were 1.33 ml/min . kg and 2.96 ml/min . kg. Binding to serum proteins was significantly decreased in the anephric subjects, in whom a significant negative correlation was found between the percentage binding and the volume of distribution VDSS. In the patients, but not in the normal subjects, there was a significant positive correlation between VDSS and serum clearance. Both in normal and anephric individuals 4-chlor-5-sulphamoyl-anthranilic-acid (CSA) was found, but there was no evidence of special accumulation either of CSA or anthranilic acid in the anephric patients. In the patients the initial increase in serum concentration of sodium and protein followed by a more conspicuous decrease were more pronounced, but none of the changes were statistically significant.

Adolescent↗
PubMed1977

Distribution, elimination and effect of furosemide in normal subjects and in patients with heart failure.

After furosemide 40 mg i. v. its plasma concentration was significantly higher during an 8-hour period in 6 patients with left sided heart failure than in 8 normal subjects. The plasma clearance was significantly lower in the patients than in the normal subjects--1.23 and 2.34 ml/kg/min, respectively. The apparently smaller volume of distribution in the cardiac patients (0.140 1/kg and 0.181 1/kg, respectively) was not significantly different. In the group of normal subjects, whose ages ranged from 27 to 74 years, no correlation was found between age and either plasma clearance or volume of distribution. In all the patients, the renal clearance of furosemide rose from the first to the second hour after the injection (average +/- SD)--39 +/- 17 and 77 +/- 51 ml/min. In normal subjects, the average values did not change--116 +/- 79 and 117 +/- 54 ml/min. The urinary excretion of furosemide and a metabolite (probably a glucuronide) was measured in 16 individuals. 24-hour urines from all the subjects investigated contained between 20 and 30 mg unchanged furosemide (average 25.2 mg). In addition, between 2.7 and 11.2 mg (average 6.7 mg) furosemide was excreted as the metabolite in five patients who had been treated with furosemide for at least the preceding 6 months. An average of 0.8 +/- 0.8 mg of the metabolite was found in 11 subjects who had not previously been treated with furosemide.

Adult↗
PubMed1977

The influence of age on the response to anticoagulants.

1 A group of 114 patients on long-term anticoagulant therapy was studied. The daily maintenance dose of both phenprocoumon, bishydroxycoumarin and warfarin was found to be significantly lower in patients aged between 61 and 70 years than in the those between 50 and 60 years of age. The mean daily dose of bishydroxycoumarin, hower, when expressed on a weight basis, was not significantly lower in the elderly. 2 For bishydroxycoumarin but not for phenprocoumon and warfarin there was found a statistically significant correlation between the daily maintenance dose and the weight of the patient. 3 The mean daily dose of both bishydroxycoumarin and warfarin was 30-40% lower than that recommended in the literature. 4 'Correction' was made for potential drug interference by excluding patients in continuous medication with order drugs known to influence the treatment with orally administered anticoagulants. The interindividual variation in dosage requirements of coumarin drug was thereby reduced in the age groups above 60 years. 5 The level of vitamin-k dependent coagulation factors, measured by Owren's 'P and P' method (PP%) was significantly lower (P less than 0.001) in patients of advanced age (between 61 and 70 years) than in younger patients (between 50 and 60 years). 6 The plasma concentration of albumin was significantly lower in patients over 60 years than in those under that age. 7 Correlation (P less than 0.01) was found between the daily maintenance dose of phenprocoumon and the plasma concentraction of albumin.

Aged↗
PubMed1977

Simultaneous determination of furosemide and two of its possible metabolites in biological fluids.

By the means of thin-layer chromatography (TLC) prior to fluorometry it was possible to determine furosemide (F) in plasma and urine with improved specificity. Antranilic acid (A) and 4-chlor-5-sulphamoyl-antranilic acid (CSA) could be determined simultaneously with F in plasma. In urine, only F and A could be determined quantitatively by this method. The sensitivity is 0.1 microgram/ml for F and 0.15-0.20 microgram/ml for A and CSA. By means of TLC prior to fluorometry the blank value for F was reduced in normal subjects and in different groups of patients, and its diurnal variation was eliminated. The average values of the plasma concentrations of F after the intravenous injection of 40 mg into 12 normal subjects were at all times found to be lower by the TLC method than by the fluorometric method without TLC. A higher plasma clearance and a lower volume of distribution were found for F when the values obtained by the TLC method were used for the calculation.

Chromatography, Thin Layer↗
PubMed1976

Problems encountered in long-term treatment with anticoagulants.

The course of long-term anticoagulant therapy in 114 out-patients has been evaluated over a three-month period. The evaluation was based on the registration of information from the clinical records and from two personal interviews with each patient. The patients had attended the Anticoagulation Clinic for 141 weeks on the average. The prothrombin complex activity (PP%) level was siginificantly lower in patients with bleeding episodes. An apparently higher PP% level in patients with thromboembolic manifestations was not significant. No bleeding was observed when the PP% was above 25. Warfarin resulted in relatively bleeding episodes and more PP% values within the desired range (10-25) than phenprocoumon and bishydroxycoumarin. The role of age, but not of moderate hypertension, as a risk factor was confirmed. A probable adverse interaction of the anticoagulant and other drugs was found in 37.5% of the situations in which an interaction could be expected according to the literature.

Anticoagulants↗