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Biomedical subjects

A H Staib

Publications and source records attributed to A H Staib.

At least 55 records · Page 3Linked to original sources
PubMed1986

Theophylline pharmacokinetics after intravenous infusion with ethylenediamine or sodium glycinate.

Six healthy volunteers received two theophylline preparations by short intravenous infusion, at weekly intervals in a randomized cross-over design. The solubilizer was ethylenediamine or sodium glycinate. Plasma concentrations of theophylline and ethylenediamine were measured by h.p.l.c. for up to 24 h after dosing. The pharmacokinetics of theophylline did not show any significant intra-subject variation associated with the solubilizing agent used.

Adult↗
PubMed1985

[Determination of serum theophylline concentration in ambulatory practice].

Serum-theophylline concentration was measured in 486 ambulatory patients from 407 referring practitioners. They had been on maintenance treatment of 350 mg theophylline (Bronchoretard) twice daily. The concentration was within therapeutic range (8 to 20 mg/l) in 53% of patients, while it was below it in 43% and above in 4%. About half the patients receiving this dose would thus need individual adaptation of dosage, guided by clinical findings and serum concentration, in order to achieve optimal use of the drug's prophylactic and therapeutic potential. It is concluded that (1) theophylline dosage based entirely on standard dose will lead to an unacceptably high percentage of under-dosing; (2) schematic consideration of body-weight, sex, age, living habits, and accompanying diseases proved to be unreliable and insufficient for individual dose determination; (3) dose adaptation to individual clinical situations and serum concentration is necessary in theophylline treatment of ambulatory patients and, in the light of present technical facilities, is cost-effective.

Aged↗
PubMed1984

[Intravenous theophylline therapy. Effect of solubilizers on the incidence of adverse local effects in the area of infusion?].

The frequency and intensity of discomfort and pain at the site of injection during intravenous infusion of theophylline sodium glycinate and theophylline ethylenediamine were compared in a single blind crossover study on 6 healthy adult volunteers. The preparation containing theophylline sodium glycinate was significantly better tolerated than theophylline ethylenediamine.

Adult↗
PubMed1984

A cross-over study of oral and intravenous administration of theophylline in male volunteers. Absolute bioavailability of theophylline tablets.

Seven normal male volunteers each received an injection of 208 mg theophylline anhydride for 4 min, and a 185-mg single oral dose theophylline anhydride (Broncho-Afonilum) on separate occasions. The concentrations of unchanged theophylline was analyzed over a 24-h period in plasma and a 48-h period in urine after both dosage forms. A 2-compartment model was required to describe the intravenous plasma concentration-time course in all seven subjects. A 1-compartment model sufficed to account for the decay of the oral plasma concentrations in all subjects. The mean plasma t1/2 after i.v. dosing was 6.5 h (3.5-9 h), and the mean plasma t1/2 after oral doses was 5.7 h (3-12 h). The calculated total of 23% (11-70%) of the intravenous dose was excreted in urine, and the mean total excretion after the oral dose was 12% (7-19%). The absolute bioavailability of oral theophylline was 94 +/- 20%

Administration, Oral↗
PubMed1983

T4 levels in methylxanthine-treated premature newborns.

The respiratory stimulants caffeine and theophylline are able to control apneic spells in premature newborns. However both substances have goitrogenic properties in rats on low-iodine diet. They lower T4 serum levels and inhibit TSH- and GH-release probably by enhancing hypothalamic somatostatin secretion. The retrospective study described here was carried out in an attempt to clarify whether treatment of premature children with methylxanthines has adverse effects on thyroid function. The results are as follows: 1) There is no significant correlation between caffeine- and theophylline-concentrations and circulating T4 levels in single blood specimen of unselected premature infants. 2) In none of the infants was a low T4-serum value accompanied by a rise in serum TSH during methylxanthine treatment. Thus methylxanthines are not associated with the induction of primary hypothyroidism but the possibility of tertiary hypothyroidism cannot be excluded. In order to avoid adverse effects on thyroid function the lowest therapeutically active dose should be chosen.

Apnea↗
PubMed1983

[Release, absorption and elimination of theophylline from fast and slowly released oral formulations].

Each 2 tablets of four tablet formulations with 150 mg theophylline were administered to 6 and 5 volunteers, respectively, as single oral dose. 8 volunteers received 256 mg theophylline as a solution and as a sustained released formulation, as well as 176 mg theophylline as short intravenous bolus infusion. The elimination was independent of the examined formulations, but differences occurred between the experiments with the different groups of volunteers. The invasion parameters (t1/2i) of the four fast released tablet formulations corresponded to the values (t1/2a) of the oral theophylline solution. Furthermore, no difference existed concerning the mean times (Tsys). The mean time (theophylline) for the body model, Tvss, is 9.9 h; the mean time, which is attributed to the absorption process (Tabs) is 0.7 h; the mean in vivo dissolution time (Tdiss-vivo) for the sustained release formulation is 6.3 h. The mean time after oral administration of the theophylline solution (Tbiol) is 10.6 h. General conditions for a comparison between the in vitro and the in vivo release data are reported.

Administration, Oral↗
PubMed1983

A crossover study after oral and intravenous administration of theophylline in male volunteers (absolute bioavailability of Afonilum tablets).

Seven normal male volunteers received an injection of 208 mg theophylline-anhydride (Solosin) each for 4 min, and a 225-mg single oral dose (Afonilum) on separate occasions. The concentration of unchanged theophylline was analyzed over a 24-h period in plasma and over a 48-h period in urine, after both dosage forms. A two-compartment model was required to describe the i.v. plasma concentration-time course in all seven subjects. A one-compartment model sufficed to account for the decay of the oral plasma concentrations in five of the subjects. The mean plasma t 1/2 after i.v. dosing was 6.5 h (3.5-9 h), and the mean plasma t 1/2 after oral doses was 5.9 h (3-8.3 h). The calculated mean total of 23% (11-70%) of the i.v. dose was excreted in the urine, and the mean total excretion after the oral dose was 15% (7-44%). The absolute bioavailability of Afonilum was 108 +/- 11%.

Administration, Oral↗
PubMed1981

[Influence of theophylline on hexachlorobenzene induced porphyria (author's transl)].

Administration of 0.05% hexachlorobenzene (HCB) contained in the food to female (Wistar rats over a period of 60 days induced porphyria as measured by the increased urinary porphyrin excretion. One group of the rats was additionally treated with theophylline (150 mg/kg b.w./d). The concomitant theophylline application to rats with HCB induced porphyria increased their urinary excretion of porphyrin (p less than 0,1%) and its precursors (porphobilinogen and delta-aminolevulinic acid) in comparison to the HCB controls. The HCB induced increase of the hepatic cytochrome P-450 content was prevented whereas 7-ethoxycoumarine-deethylase activity was depressed concomitantly by theophylline. p-Nitro-anisole-demethylase activity was not influenced by this treatment. It is assumed that the delta-amino-levulinic acid synthase is induced by theophylline. The different behaviour of the porphyrin excretion and the cytochrome P-450 induction during this treatment leads to the conclusion that there is no direct or causal relationship between these two biochemical processes.

Animals↗
PubMed1981

Bioavailability of theophylline from a sustained-release aminophylline formulation (Euphyllin retard tablets)--plasma levels after single and multiple oral doses.

The absolute bioavailability of theophylline in two commercially available preparations of aminophylline, a sustained-release formulation (Euphyllin retard tablets) and a solution (Euphyllin solution), was determined in eight healthy volunteers following oral administration of a single dose. Percent bioavailability was obtained by comparing AUC data for theophylline concentration-time curves measured over 24 h with corresponding data following intravenous doses of theophylline. Absorption of theophylline from solution was rapid and complete. Bioavailability amounted to 111 +/- 16% (X +/- SD) compared to i. v. administration. Absorption from the sustained-release tablet appeared more erratic and less complete: the time of peak theophylline concentration varied between 2 and 14 h. The mean plasma level curve showed a plateau between 2 and 14 h bioavailability was 72 +/- 13%. In addition, the sustained-release formulation was administered twice daily (350 mg) for 4 days. Plasma concentrations during multiple dosing of the sustained release formulation were with one exception below 10 mg/l. On day 4 at steady state, peak theophylline concentrations were 8.1 +/- 0.63 mg/l, trough levels 6.2 +/- 1.4 mg/l in the morning and 5.6 +/- 0.67 mg/l in the evening.

Administration, Oral↗
PubMed1980

Exercise induced changes of catecholamines and potassium in plasma of dogs after treatment with propranolol.

Previous studies in man have shown that during beta-adrenoceptor blockade physical exercise caused a significantly greater elevation of plasma catecholamines than without blockade. After blockade of beta-adrenoceptors, increased levels of circulating catecholamines should have an unopposed effect on adrenergic alpha-receptors. In order to elucidate such an effect, experiments were performed with 7 trained dogs before and after acute beta-adrenoceptor blockade (0.1 mg/kg (-)-propranolol i. v.). Exercise was performed on a conveyor (10 min, 10 km/h, slope 10%). Besides catecholamine concentrations in plasma, as an index of alpha-receptor-stimulation potassium concentrations in plasma were determined. Immediately after exercise, plasma noradrenaline was increased from 310 to 579 pg/ml, plasma adrenaline from 136 to 222 pg/ml and plasma potassium from 4.23 to 4.6 mmol/l. After beta-adrenoceptor blockade exercise caused a significantly higher increase in plasma noradrenaline from 352 to 755 pg/ml and plasma adrenaline from 172 to 260 pg/ml. Also plasma potassium concentrations were significantly elevated from 4.03 to 5.05 mmol/l. The results indicate an enhanced reflex activation of sympatho-neuronal and sympatho-adrenal mechanisms during exercise after beta-adrenoceptor blockade; the increased concentrations of noradrenaline at the adrenoceptors might reduce the efficiency of beta-blockade. Concomitantly, increased stimulation of alpha-adrenoceptors is elicited, which becomes obvious by an increase of potassium concentration in plasma.

Animals↗
PubMed1980

Pharmacokinetics and metabolism of theophylline in patients with liver diseases.

In patients with acute hepatitis, cholestasis, and compensated or decompensated liver cirrhosis the kinetics and urinary excretion of theophylline and metabolites were investigated following intravenous administration (193 mg). Significant decreases of plasma clearance and a prolongation of the plasma elimination half-life were found only in cases with decompensated liver cirrhosis and to a lesser extent in cases of acute hepatitis. The metabolite pattern in urine was changed in all disease groups compared to controls, i.e., increased excretion of 1-methyl uric acid and a concomitant decrease of 1,3-dimethyl uric acid and particularly of 3-methylxanthine. These results allow the following conclusions. In liver disease the 1-demethylation of theophylline is inhibited; this inhibition appears to be compensated by a shift towards 1-methyl uric acid formation. The monitoring of plasma levels of theophylline is indicated, especially in therapy of patients wtih decompensated liver cirrhosis.

Cholestasis↗
PubMed1978

Asymmetric behaviour induced in caudate nucleus lesioned mice: interaction of aminergic and cholinergic agents.

Mice with unilateral caudate lesions exhibit a postural asymmetry or turning towards the lesioned side after application of apomorphine and towards the intact side after oxotremorine injections. The apomorphine effect was counteracted both by oxotremorine and by physostigmine. Both this antagonism and the oxotremorine effect itself were abolished by scopolamine. Adamantine reduced the effectiveness of oxotremorine in inducing asymmetric behaviour. The antagonism of oxotremorine and apomorphine was shifted in parachloramphetamine pretreated mice to an increased apomorphine reaction mode. The significance of lesions became apparent by a 50% decrease of dopamine content in the lesioned side. The 5-hydroxytryptamine content was unchanged. Parachloramphetamine lead to a small alteration of the 5-hydroxytryptamine and 5-hydroxyindolacetic acid content, different in normal and lesioned animals.

Animals↗
PubMed1976

[Influence of strophanthin and 2,4-dinitrophenol to the scopolamine-evoked acetylcholine release in rat cortex].

In rats narcotized by urethan we investigated the effect of 2,4-dinitrophenol and ouabain with regard to the cortical release of acetylcholine stimulated by scopolamine and to the acetylcholine content of telencephalon changed in that way. Dinitrophenol increased the liberating effect of scopolamine. In the presence of dinitrophenol and scopolamine ouabain reduced acetylcholine synthesis resulting in an strong decrease of acetylcholine content on persistent diminished increase of acetylcholine release.

Acetylcholine↗
PubMed1976

[Nigrostriatally induced motor reactions in the rat. I. Rotational behavior and posture asymetry after intracerebral injection of apomorphine and dopamine].

Using a rotameter described by Ungrstedt, the influence of pretreatment with 6-hydroxy-dopamine and transections of the Capsula interna on the asymmetry of the animal's poise and movement following systemic and intracerebral administration of dopamine and apomorphine was studied. After lesion of the nigrostriatal tract, i.p. administered apomorphine caused the animals to rotate towards the damaged side. After injection of apomorphine in the Nucleus caudatoputamen of healthy animals, initial rotations towards the injection side with subsequent opposite rotation were observed, whereas dopamine injected into the Nucleus caudatoputamen and the Substantia nigra initiated rotations in contralateral direction only. Pretreatment with haloperidole nullified the effect of apomorphine. The results have proved the effectiveness both in the Nucleus caudatoputamen and the Substantia nigra of drugs stimulating the dopamine receptors. With intact rats, the two sides of the nigrostriatal system are functionally asymmetric, which is reflected by the quantitative differences of responses following stimulation of dopamine-sensitive receptors and the individually different preference of one rotational direction. These individual behavioural patterns are modified by experimental influences.

Animals↗
PubMed1976

[Nigrostiatally induced motor reactions in the rat. II. Cholinergic effect on rotational behavior and posture asymetry].

The rotational behaviour released in rats by apomorphine (5 mg/kg i.p.) following nigrostriatal lesions with 6-hydroxydopamine can be inhibited both by oxotremorin (1 mg/kg i.p.) and by injections of carbachol (30 mug) in the Nucleus caudatoputamen or Substantia nigra of the intact side. The rotations released in healthy animals by intrastriatal injections of apomorphine or carbachol are in opposite directions. The bendings of the body towards the side of injection (posture asymmetry) also observed after apomorphine administration in the Substantia nigra are inhibited by intrastriatal injections of carbachol. The results indicate that a dopaminergic-cholinergic interplay in the Nucleus caudatus, corresponding to the control functions of this nuclear area, is involved in the animals movement and poise.

Apomorphine↗