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Biomedical subjects

L Paalzow

Publications and source records attributed to L Paalzow.

17 recordsLinked to original sources
PubMed1979

Morphine kinetics in children.

The kinetics of morphine in the plasma of children (0 to 15 yr) can in most cases be adequately described by a triexponential function. When the dosage in children receiving morphine as premedication before surgery is based on kilograms of body weight, there are only minor differences in the kinetic patterns of morphine at different ages (0 to 1, 1 to 7, and 7 to 15 yr). No significant difference in the morphine kinetics was observed between patients (7 to 15 yr) receiving the drug only as premedication and those who also received doses during surgery. The minimum morphine concentration in plasma necessary to suppress the clinical signs of pain during surgery was found to be 65 ng/ml (95% confidence limits of 46 to 83 ng/ml). Based on these minimum effective plasma levels of morphine, there does not seem to be any difference between children of different ages in their sensitivity to morphine. No difference was found in the minimum effective level of morphine when clinical signs of pain were observed by different anesthesiologists.

Adolescent↗
PubMed1979

Pharmacokinetics of theophylline in young children with asthma: comparison of rectal enema and suppositories.

Six children, aged 2 months - 4 years, received theophylline 5-6 mg/kg intravenously. Its disposition could be described by a two-compartment open model, the mean serum half life (t 1/2 beta) was 3.75 h, i.e., shorter than in adults, but there was a considerable interindividual variation (1.8-7.0 h, in one patient 13.3 h). Thirteen children (2 months - 4 years) received theophylline suppositories in a dose of 3.8-5.0 mg/kg, and ten (6 months - 4 years) in a dose of 8.4-14.5 mg/kg. Absorption was slow (mean half-time 43 min), incomplete and variable (biological availability 8-100%, mean 80%). Only four of the patients given the higher dose and none given the lower dose reached a therapeutic serum concentration (10-20 microgram/ml). Nine children (6 months - 4 years) received rectal enemas of theophylline 4.1-9.2 mg/kg. Absorbtion was rapid (mean half-time 5.5 min) and biological availability averaged 100%. Six patients reached a serum concentration within the therapeutic range. Using the mean values of the calculated pharmacokinetic parameters, rectal enemas providing a dose of theophylline of 6-8 mg/kg t.i.d. were computed to give serum concentrations between 8-20 microgram/ml, without producing too high a level during the absorption phase.

Age Factors↗
PubMed1978

Pharmacokinetics of clonidine and its relation to the hypotensive effect in patients.

1 The kinetics of clonidine and its relation to the blood pressure response after single intravenous doses of 75 micrograms--275 micrograms in hypertensive patients were determined. 2 Clonidine disposition could be described by a two compartment open model and pharmacokinetic parameters show a rapid distribution phase of 20--30 min and a mean plasma clearance of 4.6 ml min-1 kg-1 (75--200 microgram). The half-life of the beta-phase was found to be in the range of 7.4--11.4 h. Indications of dose dependent kinetics were obtained. 3 A dose-dependent decrease in blood pressure was obtained. 4 The maximal reduction in MAP (mean arterial blood pressure) was significantly (P less than 0.01) related to plasma concentrations of clonidine. 5 The reduction in MAP was always related to plasma concentrations of clonidine (r = 0.88, P less than 0.01) when pseudoequilibrium of distribution of the drug was achieved.

Adult↗
PubMed1977

Simultaneous determination of codeine and morphine in biological samples by gas chromatography with electron capture detection.

A sensitive gas chromatographic method for the simultaneous determination of codeine and morphine in plasma and brain samples is described. The method involves solvent extraction of the compounds from plasma, derivatization with pentafluoropropionic anhydride and subsequent separation on a 3% OV-17 column. The quantification is performed with electron capture detection. The sensitivity of the method (0.75 ng of morphine and 7.5 ng of codeine in a sample) makes it especially useful for pharmacokinetic investigations. The method was successfully applied to determine the time course of codeine and its metabolite morphine after intravenous administration of codeine to the rat.

Animals↗
PubMed1976

Clonidine antinociceptive activity: effects of drugs influencing central monoaminergic and cholinergic mechanisms in the rat.

Clonidine is able to increase the threshold for vocalisation during stimulation and the threshold for vocalisation after withdrawal of stimulus (vocalisation afterdischarge). These effects of clonidine were investigated after treatment of rats with drugs influencing central monoaminergic and cholinergic mechanisms. Chlorpromazine, atropine and p-chlorophenylalanine increased the activity of clonidine at both thresholds while phenoxybenzamine and reserpine pretreatment increased the activity at the thresholds for vocalisation only. Yohimbine decreased clonidine activity at both thresholds while 5-HTP and alpha-methyl-p-tyrosine decreased the effects at the threshold for vocalisation afterdischarge. Naloxone did not change the activity of clonidine at either pain response studied. It is concluded from the present findings that influence from several neuronal systems modulate the antinociceptive action of clonidine. The inhibition of the medullary nociceptive response after clonidine might be connected to a decreased activity of noradrenergic neurons. Endogenous noradrenaline seems to be of minor importance in mediating this effect. It is moreover shown that decreased cholinergic receptor activity enhances clonidine antinociceptive action on both medullary and diencephalic-rhinencephalic pain responses. The possible involvement of serotonin these functional responses after clonidine is also discussed.

5-Hydroxytryptophan↗
PubMed1976

Evaluation of the antinociceptive effects of 4, alpha-dimethyl-m-tyramine (H 77/77) in the rat.

4, alpha-Dimethyl-m-tyramine (H 77/77) has been shown to induce dose dependently antinociceptive activity against 3 parameters: (1) the motor (M), (2) the vocalisation during stimulation (V) and (3) the vocalisation after withdrawal of stimulation (VA) responses. The effect of H 77/77 upon the V and VA pain responses was abolished or reduced by prior treatment with phenoxybenzamine, chlorpromazine, H 44/68, FLA 63, reserpine and protriptyline, and was potentiated by atropine sulphate. It is suggested that H 77/77 may exert is inhibitory effect on painful stimulation predominantly by inhibiting spinal sensory input.

Amines↗
PubMed1975

Antinociceptive action of oxotremorine and regional turnover of rat brain noradrenaline, dopamine and 5-HT.

In the rat, oxotremorine increases the threshold for vocalisation after-discharge (affective component of pain reactions) dose dependently at subtremor doses (30-67 mug/kg s.c.). Doses of 225-506 mug/kg were needed to elevate the thresholds for vocalisation and motor response. 1-Tryptophan, PCPA, alpha-methyl-p-tyrosine, 1-Dopa, pimozide and LSD-25 did not affect the antinociceptive activity of oxotremorine, while phenocybenzamine slightly increased the threshold for vocalisation. Oxotremorine did not change the endogenous brain concentrations of noradrenaline and dopamine or 5-HT but decreased that of 5-HIAA in all brain regions at the time of maximal analgesia. The decrease of 5-HIAA was still present after pretreatment with probenecid. After inhibition of tyrosine hydroxylase, oxotremorine accelerated the depletion of dopamine in telencephalic cortex during maximal antinociceptive activity and of noradrenaline in all brain regions at a time when this activity had vanished. Atropine significantly antagonized the analgesic activity of oxotremorine. It is concluded that oxotremorine antinociceptive activity in the rat is related to a cholinergic compoent, while a monoaminergic component is not directly involved.

Analgesics↗
PubMed1975

Effect of stress on the pharmacokinetics of sodium salicylate and quinidine sulphate in rats.

Studies on the influence of foot shock stress on the absorption, distribution and overall serum elimination of sodium salicylate and guinidine sulphate were performed in rats. Foot shock stress was produced by grid floor electrical stimulation. The animals were stressed 1 hr before administration of the drugs and then throughout the experimental period. A significant induced stress was demonstrated by increased blood glucose levels and increased whole brain turnover of noradrenaline. Gastric emptying and intestinal transit as well as tissue levels of the drugs in the serum, heart, brain, liver, muscle and fat were determined. Results were obtained indicating that stress produced a significant increase in the gastro-intestinal absorption of quinidine sulphate while no change in the distribution pattern of overall elimination was noted. On the other hand, sodium salicylate did not show any marked change in the pharmacokinetic parameters during a stressful situation.

Animals↗
PubMed1975

Quantitative determination of morphine in biological samples by gas-liquid chromatography and electron-capture detection.

A highly sensitive method for the determination of morphine in plasma and brain samples down to 500 pg ml-1 in plasma and 100 pg in 30 mg of brain tissue is described. This sensitivity is in the range of that described for radioactive and radioimmunological tehcniques. The samples (50-500 mu-l) are extracted with toluene-butanol (9:1) at pH 8.9 and then re-extracted into 0.1 N sulphuric acid and back extracted to a toluene-butanol phase at pH 8.9. The pentafluoropropionic anhydride derivatives of morphine and the internal standard nalorphine were quantitatively determined by gas-liquid chromatography with a 3-H electron capture detector.

Animals↗