Biomedical subjects

L Kangas

Publications and source records attributed to L Kangas.

At least 127 records · Page 7Linked to original sources

PubMed1979

Determination of nitrazepam and its main metabolites in urine by gas--liquid chromatography: use of electron capture and nitrogen-selective detectors.

Nitrazepam and its main urinary metabolites, 7-aminonitrazepam and 7-acetamidonitrazepam, free and conjugared, were determined from 24-h fractions of human urine after a single oral dose of 5 mg of nitrazepam. Nitrazepam and the metabolites were extracted before and after glusulase hydrolysis with benzene--dichloromethane (90:10) from a 1.0 ml sample. Methylnitrazepam and methylbromazepam served as internal standards. Recoveries were better than 90%. GLC analysis of nitrazepam was performed using a 63Ni electron-capture detector. The metabolites were measured by a dual flameless nitrogen selective detector. The detection limits were about 0.2 ng/ml for nitrazepam and 50 ng/ml for the metabolites. The nitrogen-selective detector responds similarly to all three compounds. The 63Ni electron-capture detector gives very poor response to 7-amino-nitrazepam but allows very sensitive detection of nitrazepam. Combined use of the two detectors gives valuable information about the metabolic profile of nitrazepam.

Adolescent↗

PubMed1979

Human pharmacokinetics of nitrazepam: effect of age and diseases.

Plasma concentrations of nitrazepam were measured by gas-liquid chromatography in: young healthy volunteers, in geriatric and psychiatric patients and in epileptic children. The disposition of nitrazepam was described in terms of a two-compartment open model. After a single oral dose of nitrazepam 5 mg the most prominent differences between the experimental groups were in the beta-phase half-life mean 29 h in the young volunteers and 40 h in geriatric patients , and in the apparent volume of distribution during the beta-phase of 2.4 vs 4.8 1/kg. Total plasma clearance and the average steady state concentration in both groups were equal. The plasma level rose at a rate proportional to the beta-phase half-life, and so, they were achieved more rapidly in the young than in the old subjects (3.5 vs 7.5 d). No change in steady-state level or in the half-life of nitrazepam were found during long term treatment, which indicates lack of enzyme induction or inhibition. In 95% of the epileptic children with a good to fair clinical response, the plasma concentration of nitrazepam was 40-180 ng/ml (mean 114 ng/ml). As all of the patients were on combined antiepileptic therapy, no attempt was made to correlate plasma level with therapeutic response.

Adolescent↗

PubMed1979

Effect of halothane anaesthesia on primary antibody response in the chicken.

The effect of a single anaesthesia of 2 hours' duration with 1% v/v halothane and of 1, 2, and 3 hours' duration with 2% v/v halothane was studied on the primary antibody response in line-bred chickens. In contradistinction to earlier studies, the immunisation was performed during anaesthesia to resemble antigenic exposure in surgical practice. The IgG and IgM antibodies against the antigens, bovine serum albumin (BSA) and formalin-killed Brucella abortus organisms (Brucella), were quantified by the enzyme-linked immunosorbent assay (ELISA). The halothane concentration of the blood was measured by gas chromatography at the end of anaesthesia. Anaesthesia with 1% and 2% v/v halothane given in the antigen-processing phase of humoral immune response had no effect on the concentrations of IgG-and IgM-anti-BSA and IgG-and IgM-anti-Brucella antibodies in the primary antibody response.

Anesthesia, Inhalation↗

PubMed1979

Flunitrazepam versus placebo premedication for minor surgery.

The clinical effects of oral flunitrazepam (2 mg on the night before operation followed by 2 mg on the morning of operation) and placebo as premedicants were tested in a double-blind study in 81 gynaecological patients. The separate or total concentrations of flunitrazepam and its demethylated metabolite in plasma (measured by gas chromatography) were correlated with the clinical effects of flunitrapam premedication, assessed both sugjectively and objectively. In most parameters tested (sleep on the night before operation, sedation, apprehension, headache, pulse rate), there was a positive, significant difference between the flunitrazepam group (n = 44) and the placebo group (n = 37). No significant difference was found between the two groups in emetic effect, excitement, systolic blood pressure increase, and vene-puncture, but the patients receiving flunitrazepam felt significantly more dizziness. The temperature of the left forefinger before, during and after the anaesthesia did not vary significantly between the two groups. There was no correlation between the plasma concentration of flunitrazepam and its demethylated metabolite (separate or total concentrations) and any of the parameters tested before induction of anaesthesia. Flunitrazepam is a new oral premedicant with prominent sedative and anxiolytic actions. When the drug is given as a sedative on the night before operation, followed by a second dose on the morning of operation, the beneficial effects last for at least 8 hours after the second dose.

Adult↗

PubMed1979

Antipyretic effect and plasma concentrations of rectal acetaminophen and diazepam in children.

Plasma levels of acetaminophen (paracetamol) and diazepam were measured in 9 children by gas chromatography after administering these drugs simultaneously in separate suppositories. The antipyretic effects of oral and rectal acetaminophen-diazepam combinations were also studied and compared with that of oral or rectal acetaminophen alone. Diazepam at a dose of 0.2 mg/kg did not increase the antipyretic action of acetaminophen. Acetaminophen and diazepam seemed to be well absorbed from the rectal suppositories, the maximal plasma concentration of diazepam after a rectal dose of 0.5 mg/kg just reaching the assumed anticonvulsant level in about 2 hr. In light of this study, an acetaminophen-diazepam combination in separate suppositories may be suitable for the prevention of recurrent febrile convulsions in susceptible children, but its practical value and efficacy require evaluation in clinical experiments.

Acetaminophen↗

PubMed1979

Urinary elimination of nitrazepam and its main metabolites.

Nitrazepam and its main metabolites, 7-aminonitrazepam and 7-acetamidonitrazepam, free and conjugated, were determined in the human urine after a single oral dose of 5 mg. The determinations were performed by GLC method using 63Ni-EC-detector for unchanged nitrazepam and nitrogen selective detector for the metabolites. Unchanged nitrazepam was poorly eliminated through the kidneys (about 1% of the dose). The interindividual variation of total excreted urinary metabolites was large ranging between 848-4933 microgram (17-99% of the dose during 7 days). Of this amount conjugated metabolites made up 57%. The urinary half-lives of free and conjugated-7-aminonitrazepam were (mean and ranges) 44 (23-65) and 46 (25-69) hrs, and of 7-acetamidonitrazepam 12 (5-31) and 18 (5-46) hrs, respectively. The half-lives of the excreted amounts of the metabolites did not correlate with any pharmacokinetic parameter of unchanged nitrazepam in serum.

Administration, Oral↗

PubMed1979

Pharmacokinetics of nitrazepam in saliva and serum after a single oral dose.

The pharmacokinetics of nitrazepam in saliva and serum was studied in 12 healthy volunteers after a single administration of a 5 mg nitrazepam tablet. The binding of nitrazepam to plasma proteins was determined 4 hours after the administration by ultracentrifugation. The analysis of nitrazepam concentrations was performed by 63Ni-EC-GLC. The pharmacokinetic parameters were evaluated manually or by AUTOAN-program in serum, and manually in saliva. The concentrations of nitrazepam in serum and saliva correlated significantly (r = 0.472, P less than 0.001, n = 97). The ratio saliva: serum was, however, time dependent. The protein free fraction in serum was significantly higher (P less than 0.01) than the salivary concentration at the same time (4 hours after administration). The peak concentrations in serum and saliva were 40.7 and 1.9 ng/ml (P less than 0.001) and the times to reach the peak maximum 2.4 and 2.5 hours, respectively (difference not significant). The mean half-life of nitrazepam in serum was 30.5 hrs and in saliva 39.9 hrs, the difference being significant at P less than 0.05. The distribution phase parameters, poorly described before, were calculated. The clinical value of nitrazepam analysis in saliva seems to be negligible.

Administration, Oral↗

PubMed1979

The effect of methysergide, pimozide, and sodium valproate on the diazepam-stimulated growth hormone secretion in man.

Diazepam-induced GH secretion was tested on 28 male volunteers before and after a 3-day treatment with methysergide, pimozide, or sodium valproate. Serum GH, diazepam, and blood glucose levels were determined. Without prior medication, the mean serum GH level increased 336% 1 h after diazepam administration. Treatment with the serotonin antagonist, methysergide, had no effect on the diazepam-stimulated GH secretion, whereas pimozide, the selective dopamine receptor-blocking agent, reduced the GH response to diazepam by 50% (P less than 0.05). Sodium valproate, a gamma-aminobutyric acid transaminase inhibitor, also inhibited diazepam-induced GH secretion; stimulated GH levels were 51% at 30 min (P less than 0.025), 39% at 60 min (P less than 0.025), and 46% at 90 min (P less than 0.025) relative to the stimulated levels without medication. No difference was found in blood glucose or serum diazepam levels after the drug treatments relative to the values obtained under basal conditions. It is suggested that diazepam-induced GH secretion is at least partly mediated via dopaminergic mechanisms. Serotonin does not seem to be involved. It is further proposed that gamma-aminobutyric acid plays an inhibitory role in GH secretion.

Adult↗

PubMed1979

A comparative study on the clinical effects of oxazepam and diazepam: Relationship between plasma level and effect.

The clinical effects of oxazepam and diazepam as oral premedicants were tested in a double-blind study of 60 children and 50 adults. The gas chromatographically measured concentrations of the active unconjugated forms of oxazepam and diazepam in the plasma were correlated to their clinical effects, as assessed both subjectively and objectively (sleep, sedation, apprehension, excitement, dizziness, emetic effect, headache, increase or decrease in systolic blood pressure, increase in pulse rate, venepuncture). No significant difference in the effects of these two benzodiazepine derivatives were observed, nor was there any obvious relationship between the plasma concentration and clinical effect.

Adult↗

PubMed1979

The pharmacokinetics of dapsone and acetylated dapsone in serum and saliva.

The concentrations of dapsone (DDS) and its acetylated derivatives (MADDS and DADDS) were determined in the serum and saliva after one oral dose of dapsone until 72 hr. The peak serum concentrations of DDS and MADDS were reached, on average, at 3.8--4.3 hr after the dosage. The amounts of DADDS were negligible. The elimination half-life of the first order kinetics was, on average, at 20--21 hr for both DDS and MADDS. The study group included 6 rapid acetylators and 4 slow acetylators with the mean ratios MADDS/DDS 1.0 and 0.19, respectively. No difference in the pharmacokinetics of DDS or MADDS could be seen between the rapid and slow acetylators. The protein-free fractions of DDS and MADDS were 50 and 41 per cent, respectively, of the total serum concentrations as measured at 8 and 32 hr after the dosage. The salivary concentration of DDS was, on average, 49 per cent of the total serum concentration during the whole study period. The salivary concentration of MADDS was 40 per cent, respectively. The elimination half-life of DDS and MADDS in saliva did not differ from that in serum. Between the salivary and serum protein-free concentrations a strict correlation existed (p less than 0.001). The salivary concentration of dapsone and its monoacetyl derivative reflect the protein-free, active drug in serum.

Acetylation↗

PubMed1979

Stimulation of renal tubular transport by ethacrynic acid in rats of different ages.

The transport system for organic acids in the kidney is not fully developed in the neonatal period. The effect of repeated administrations of ethacrynic acid on the renal excretion of p-aminohippurate (PAH) was studied in rats of different ages. Pretreatment with ethacrynic acid was followed by an increase in the renal excretion of PAH in 33-, 55-, 105- and 240-day-old rats but not in newborn rats. In 55-day-old rats the increase in renal excretion of PAH after pretreatment with ethacrynic acid was not associated with any consistent change of the glomerular filtration rate. It is concluded from these results that the stimulation of transport processes in the kidney by ethacrynic acid and some other drugs is linked with their affinity to tissue proteins.

Age Factors↗

PubMed1979

Oral oxazepam as a premedicant in minor surgery.

The clinical effects of oral oxazepam and placebo as premedicants were tested in a double-blind study in 40 gynaecological patients. The gas chromatographically measured concentrations of the active, unconjugated forms of oxazepam in the plasma were correlated with the clinical effects of oxazepam, assessed both subjectively and objectively. The insertion of an intravenous cannula was significantly more difficult (p less than 0.001) in the placebo premedicated group. However, there was no significant difference between the two groups in the cutaneous temperature of the left forefinger. Of the eleven parameters tested there was a significant difference between the oxazepam and placebo group in the quality of sleep on the night before operation (p less than 0.05) and in the degree of preoperative sedation (p less than 0.01). The combined results of the eleven parameters of the oxazepam group also differed positively significantly from the placebo group (p less than 0.01). There was no obvious relationship between the plasma concentration and clinical effect of oxazepam.

Abortion, Spontaneous↗

PubMed1978

Renal accumulation of amikacin, tobramycin and gentamycin in the rat.

Free and total concentrations of amikacin, tobramycin and gentamycin were measured separately in the rat kidney after equal weight by weight doses. The accumulation of aminoglycosides followed the order amikacin less than tobramycin less than gentamycin. The ratio between free and total aminoglycosides was similar (about 0.6) in all 3 aminoglycosides and independent on the length of administration.

Amikacin↗

PubMed1978

The nephrotoxicity and renal accumulation of amikacin, tobramycin and gentamycin in rats, rabbits and guinea pigs.

The nephrotoxicity and renal concentrations of amikacin, tobramycin and gentamycin were studied in rat, rabbit and guinea pig. The nephrotoxicity was estimated by histological examination and by measuring the relative weight of the kidneys (mg/100 mg body weight). These two systems had a significant correlation (r = 0.87; p less than 0.001). The concentrations of aminoglycosides were determined by the cylinder-plate method measuring free aminoglycosides. The renal toxicity of the aminoglycosides in equal doses weight by weight followed the order amikacin less than tobramycin less than gentamycin in the rat. The same order was observed in the renal accumulation of the aminoglycosides in rat, rabbit and guinea pig. The critical kidney damaging concentration of free aminoglycoside in the whole rat kidney was estimated to be 160--190 microgram/g.

Amikacin↗

PubMed1978

Effect of halothane anaesthesia on secondary antibody response and mitogen-induced lymphocyte transformation in the chicken.

The effect of a single halothane anaesthesia on the secondary antibody response and the lymphocyte response in vitro to phytohaemagglutinin (PHA) and concanavalin A(Con A) was studied. The antigens used were bovine serum albumin (BSA) and killed Brucella abortus organisms (Brucella). IgG and IgM antibodies against these antigens were quantified by solid-phase radioimmunoassay. Lymphocyte transformation was studied by a whole blood micromethod. The chickens were anaesthetised for two hours with 2% v/v halothane. The halothane concentration of the blood was measured by gas chromatography at the end of the anaesthesia. Halothane anaesthesia had no effect on the secondary antibody response against BSA and Brucella. In contrast, it caused a significant decrease in the lymphocyte response to PHA and Con A. This suppression was transient, however, and full recovery of the lymphocyte function was observed by the first day after anaesthesia.

Animals↗

PubMed1978

Estimation of pharmacokinetic parameters of digoxin from serum, saliva and urine.

The pharmacokinetics of digoxin was studied in 14 healthy volunteers using concentrations measured radioimmunologically in the serum, saliva and urine. The subjects were given 0.75 mg of digoxin intravenously. Serum and saliva were obtained over a 72 hr period and urinary excretion rates over 6 or 7 days. Binding of digoxin to serum proteins was determined by ultracentrifugalization. A linear correlation between the serum and saliva concentrations was found. Salivary levels were equal to the unbound fraction in the serum. The half-lives of distribution did not differ between the serum and saliva. An erroneously short half-life of elimination was found in the serum, but in the saliva and urine it was found to be in the range previously reported. Salivary level measurements may be useful in pharmacokinetic studies and may have important clinical implications.

Adolescent↗

PubMed1977

Transfer of nitrazepam across the human placenta.

Six women from 14 to 17 weeks pregnant, and 12 woman from 36 to 40 weeks pregnant, were given nitrazepam 5 mg orally about 12 h before legal abortion by hysterotomy in the former group and elective caesarean section in the latter group. The concentration of nitrazepam was determined by gas-liquid chromatography. Binding to plasma proteins was evaluated by separation of the protein-free fraction by ultracentrifugation. In the first group (early pregnancy) the level of nitrazepam was found to be lower in the fetal than in the maternal circulation. The concentration in amniotic fluid was still lower. In the latter group (late pregnancy) the concentration both of unbound and total nitrazepam in maternal and fetal plasma were in equilibrium, which indicated an increase in transplancental transfer in late pregnancy. The percentage of unbound nitrazepam in both cases was 12%.

Adolescent↗

PubMed1977

Comparison of two gas-liquid chromatographic methods for the determination of nitrazepam in plasma.

Nitrazepam in plasma was determined by gas-liquid chromatography with a nickel-63 electron-capture detector, unchanged by a direct method and also by a hydrolysis method. The extraction in the direct method was carried out with benzenedichloromethane (90:10) and in the hydrolysis method with diethyl ether. The hydrolysis was performed with 6 N sulphuric acid. The hydrolysis product was extracted with toluene-n-heptane-ethyl acetate (80:20:5) directly from acid. Thus the commonly used change in pH was omitted. Nitrazepam concentrations in plasma were determined in 10 healthy volunteers after two oral doses (5 and 10 mg); 0.5 ml of plasma was used for each determination and clonazepam, methylbromazepam and methylnitrazepam were used as internal standards. The recoveries of the methods are almost quantitative (greater than 96%). The two methods are clinically comparable. The high sensitivity and specificity make these methods useful in clinical determinations of nitrazepam in plasma. Advantages and disadvantages of both methods are discussed.

Adult↗