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Biomedical subjects

M Schürer

Publications and source records attributed to M Schürer.

At least 19 recordsLinked to original sources
PubMed2004

Effects of buffered and plain acetylsalicylic acid formulations with and without ascorbic acid on gastric mucosa in healthy subjects.

BACKGROUND: The most frequently reported adverse events associated with acetylsalicylic acid intake are minor gastrointestinal complaints. Galenic modifications, such as buffered formulations with or without ascorbic acid, may improve the benefit-risk ratio by decreasing the local mucosal side-effects of acetylsalicylic acid. AIM: To assess endoscopically-proven gastrointestinal lesions and the amount of gastric microbleeding of four different buffered and plain acetylsalicylic acid formulations, one containing paracetamol. METHODS: A randomized, four-fold cross-over study was performed in 17 healthy subjects who underwent serial oesophago-gastro-duodenoscopy before and after each course of 4-day dosing. Gastric aspirates were collected for the determination of haemoglobin concentrations to detect microbleeding. RESULTS: Buffered acetylsalicylic acid plus ascorbic acid yielded the lowest Lanza score, the lowest increase in the number of mucosal petechiae and the lowest increase in the amount of gastric microbleeding. Subjects receiving acetylsalicylic acid plus paracetamol plus caffeine showed the highest Lanza score of all treatments, and a considerably greater sum of petechiae in the oesophagus, stomach and duodenum compared with those receiving buffered acetylsalicylic acid plus ascorbic acid. CONCLUSIONS: The trial confirms that buffering of acetylsalicylic acid improves local gastric tolerability. Acetylsalicylic acid in combination with ascorbic acid shows significantly fewer gastric lesions and the lowest increase in gastric microbleeding compared with the other tested formulations.

Adult↗
PubMed2004

Effects of acetylsalicylic acid on ascorbic acid concentrations in plasma, gastric mucosa, gastric juice and urine--a double-blind study in healthy subjects.

OBJECTIVE: This study investigated concentrations of ascorbic acid (ASC) in gastric mucosa, gastric juice, urine and plasma in healthy subjects under steady state and fasted conditions with and without concomitant administration of acetylsalicylic acid (ASA). MATERIAL AND METHODS: This was a prospective, randomized, double-blind, parallel-group study in healthy subjects. It has assessed the effects of a 6-day administration of 0.8 g ASA or 0.48 g ASC, 3 times daily and the combination of both on concentrations of ASC in gastric mucosa, gastric juice, urine and plasma. Treatments were switched after 6 days without any washout for assessment of compartment sensitivity to changes in study medication resulting in an overall 14-day study period. Each of the 3 treatment groups consisted of 15 subjects. RESULTS: ASC concentrations were highest in the gastric mucosa (251+/-11 microg/g), followed by gastric juice (29+/-6 microg/ml), plasma (10+/-0.2 microg/ml), and urine (5+/-1 microg/ml). On day 7, ASC concentrations in gastric mucosa, plasma and urine had increased in those groups receiving ASC and decreased in the group receiving ASA only. All differences were statistically significant and indicate an interaction with ASA. In gastric juice, differences in ASC concentrations between the treatment groups were not statistically significant between baseline and day 7. ASC concentrations in plasma were strongly correlated with corresponding ASC concentrations in gastric mucosa (r = 0.34) and urine (r = 0.83), as were ASC concentrations in gastric mucosa with ASC in urine (r = 0.28). CONCLUSIONS: The gastric mucosa is the largest depot of ASC in the human body with ASC concentrations 25 times higher than in plasma. In healthy subjects, clinically relevant doses of ASA reduced ASC concentrations in gastric mucosa by about 10% within 6 days resulting from antioxidative defense mechanisms. In patients with long-term ASA treatment or conditions with additional risks such as elderly subjects with unfavorable dietary conditions and impaired antioxidative protection, a protective adjunct administration of ASC appears to be beneficial.

Adolescent↗
PubMed1999

Pharmacokinetic properties of tramadol sustained release capsules. 1st communication: investigation of dose linearity.

The relationship between the dose and the pharmacokinetic characteristics. AUC(0-infinity) and Cmax was investigated with respect to linearity in 12 healthy male volunteers. Single doses of 50 mg, 100 mg and 200 mg tramadol (CAS 27203-92-5) hydrochloride were administered as sustained release capsules in an open, randomized three-period crossover study. Tramadol plasma concentrations were determined by a validated gas chromatography method. Statistical analysis after logarithmic transformation of the dose-adjusted characteristics mentioned above yielded bioequivalence for all doses applied. Therefore, dose linearity for the range investigated could be concluded.

Adult↗
PubMed1999

Pharmacokinetic properties of tramadol sustained release capsules. 2nd communication: investigation of relative bioavailability and food interaction.

In an open, randomized four-period crossover study in 24 healthy male volunteers a newly developed tramadol (CAS 27203-92-5) sustained release capsule with and without concomitant food intake and an instant release formulation were administered. Additionally, a sustained release tablet was applied as further reference substance. Statistical analysis of AUC(0-infinity) and Cmax after logarithmic transformation yielded bioequivalence of tramadol sustained release capsules with and without concomitant food intake. Therefore, lack of food interaction could be concluded. The investigation also showed an only slightly diminished bioavailability of the tramadol sustained release capsules compared to the instant release formulation. Furthermore, the sustained release capsules investigated showed enhanced retardation at almost identical bioavailability compared with the sustained release competitor drug.

Adult↗
PubMed1999

Pharmacokinetic properties of tramadol sustained release capsules. 3rd communication: investigation of relative bioavailability under steady state conditions.

In an open, randomized two-period crossover study in 24 healthy male volunteers multiple doses of tramadol (CAS 27203-92-5) test and reference medication were administered as follows: Test: sustained release capsules containing 100 mg tramadol hydrochloride, a total of 6 capsules at intervals of 12 h; Reference: instant release capsules containing 50 mg tramadol hydrochloride, a total of 12 capsules at intervals of 6 h. As a result of the statistical analysis of AUCss(48-72 h) after logarithmic transformation a bioavailability of 100% for the sustained release capsules compared with the instant release capsules was obtained. As expected statistical analysis of the peak trough fluctuation at steady state PTFss(48-72 h) yielded a distinct diminution of the fluctuation.

Adult↗
PubMed1998

[The plasma level of the neurotoxin 1-trichloromethyl-1,2,4,5-tetrahydro-beta-carboline (TaClo) in man after oral administration of chloral hydrate].

Chloral hydrate (CAS 302-17-0) is a widely used hypnotic and sedative agent. It was recently reported in the literature that a neurotoxin, TaClo (1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline), may be formed in vitro from tryptamine (Ta) and chloral (Clo). Intraperitoneal administration of TaClo led to parkinson-like symptoms in the rat. Hence, the plasma levels of TaClo were determined at various time-points in 18 healthy volunteers in two periods each during a bioavailability study of several chloral hydrate preparations. The limit of quantitation for TaClo was 5 ng/ml. No TaClo could be determined in the plasma of the various volunteers following administration of human therapeutic doses of chloral hydrate. Hence, it is unlikely that TaClo will be formed in man after application of therapeutic doses of chloral hydrate to patients.

Adult↗
PubMed1997

Influence of food on the bioavailability of a carbamazepine slow-release formulation.

The pharmacokinetics of a multiple-unit carbamazepine slow-release preparation were studied after a 12-hour fast and after a standardized breakfast in 24 healthy male volunteers. There was a small increase in mean values of AUC0-infinity and Cmax when the drug was given with food. The rate of absorption of slow-release carbamazepine, as reflected by HVD, appeared to be unchanged in the presence of food. Bioequivalence was concluded for the AUC0-infinity and HVD ratios applying the inclusion rule, thus demonstrating the lack of food interaction. The results indicate that administration of the investigated carbamazepine slow-release formulation to patients in the fasting or nonfasting state seems not to be a major consideration when deciding on the regimen.

Adult↗
PubMed1995

New injectable aqueous carbamazepine solution through complexing with 2-hydroxypropyl-beta-cyclodextrin: tolerability and pharmacokinetics after intravenous injection in comparison to a glycofurol-based formulation.

The poor water solubility of the antiepileptic drug (AED) carbamazepine (CBZ) is generally considered an absolute contraindication to parenteral administration in epileptic patients. However, the water solubility of CBZ can be largely enhanced through formation of an inclusion complex with an amorphous cyclodextrin derivative, 2-hydroxypropyl-beta-cyclodextrin (HP beta CD). We studied tolerability and pharmacokinetics of an aqueous CBZ:HP beta CD solution after intravenous (i.v.) administration in dogs. For comparison, a conventional glycofurol-based solution of CBZ was used. We also administered a commercial liquid formulation of CBZ orally (p.o.). Infusion of CBZ:HP beta CD solutions or HP beta CD "placebo" formulations i.v. was well tolerated by the animals. In contrast, infusion of CBZ:glycofurol solutions and glycofurol placebo solutions induced marked behavioral and cardiovascular adverse effects. Pharmacokinetic studies indicated that glycofurol inhibited CBZ metabolism by decreasing formation of the major CBZ metabolite CBZ-10,11-epoxide (CBZ-E). With infusion of CBZ:HP beta CD 10 ml/min for 12-15 min, resulting in a CBZ dose of CBZ 5 mg/kg body weight, peak CBZ plasma levels of approximately 3.6 micrograms/ml were obtained. This relatively low peak concentration is primarily due to the rapid elimination of CBZ in dogs [half-life (t1/2) < 1 h]. Comparison of peak plasma levels determined after p.o. administration of CBZ to dogs with peak CBZ levels previously determined after p.o. administration in humans indicated that about four times higher doses are needed in dogs to attain the same peak plasma levels as in humans.(ABSTRACT TRUNCATED AT 250 WORDS)

2-Hydroxypropyl-beta-cyclodextrin↗
PubMed1995

[The solubility and bioequivalence of silymarin preparations].

Seven silymarin products (pharmacies only), two of them with two batches each, were analysed for their ingredients, in particular silibinin (CAS 22888-70-6) and tested in vitro for their liberation of active agents. Founded on the results of these tests three products were checked for bioequivalence. Therefore, a typical phase I 3 fold crossover study was performed showing one product (Legalon) to be qualified by an approx. 2 fold higher silibinin availability compared to the two other preparations.

Adult↗
PubMed1990

[A densitometric method for the assessment of myocardial perfusion using digital subtraction angiography].

The aim of the method presented is the quantitative description of the perfusion of the myocardium. In the framework of the invasive diagnostics of the coronary heart disease with catheterization of the left heart, ventriculography and coronarography in Seldinger's technique in 50 patients (35 of them well to be evaluated) subsequently DSA-investigations of the left coronary artery (LCA) were performed by means of the DVI-2 CV system (Philips) and densitometrically evaluated with the help of the analytic processing unit (APU). In injection by hand of 4 and 6 ml, respectively, visotrast 370 in each case 10-15 DSA-pictures in LAO 60 degrees-projection were possible. For a differentiated evaluation the total myocardium was subdivided into 12 partial areas. The densitometric analysis consisted in the calculation of time-density curves over all areas and their description by suitable parameters: density maximum (DMAX) and its moment TMAX, elevation of the curve SLOPE at 50% of DMAX, the elevation time AZEIT as well as measure for the exponential decrease of the curve after the maximum LAMBDA. For special questioning the parameters of the 12 areas were concentrated according to the main supply areas of the anterior interventricular branch (RIVA), the circumflex branch (RCX) and the apex of the heart, respectively. In the interobserver comparison the statistical analysis of the results showed deviations lower than 10% (except LAMBDA). Significant correlations were found between the body-weight and the applied quantity of contrast remedies, respectively, and the parameters DMAX and AZEIT.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[Kidney function in the course of compensatory hypertrophy following unilateral nephrectomy in the Wistar rat].

Unilateral nephrectomy was performed in 109 male Wistar rats, 35 animals served as controls. Determinations of glomerular filtration rate (GFR) using slope clearance of 99mTc-DTPA and of tubular function using an orally water-loading test were made. The tests were performed 2 and 5 days as well as 2, 4, 5 and 6 weeks after nephrectomy. In all examinations the GFR was more than 50% of the level of two-kidney control animals. Fractional maximum diuresis was increased in the first 2 examinations after nephrectomy from 8.9 +/- 2.1 to 15.4 +/- 4.2% of the GFR and fractional clearance of osmotically free water from 6.8 +/- 1.9 to 10.9 +/- 3.5%. In the fourth and sixth week the proximal tubular reabsorption was increased and the glomerulo-tubular balance had been recovered. However, the minimal urine osmolarity was increased to 107.8 +/- 17.7 mmol/l and the osmotic load of the nephrons remained elevated. Possible clinical implications of the results are discussed.

Animals↗
PubMed1987

[Kidney function in spontaneously hypertensive rats under minoxidil treatment].

In 25 spontaneously hypertensive rats the blood pressure was lowered from 192 +/- 11.6 to 130 +/- 11.7 mm Hg and in 26 normotensive Wistar rats from 129 +/- 9.1 to 107 +/- 6.7 mm Hg by applying 1 mg/kg body weight minoxidil twice a day orally. 19 spontaneously hypertensive and 21 normotensive rats served as untreated control groups. During the treatment the glomerular filtration rate, determined by the slope clearance of Tc-99m-DTPA, remained unchanged. Under maximal water diuresis the excretion fraction of sodium was diminished compared with the control data. The Na+ and water reabsorption was increased in the proximal tubules (not an aldosterone effect) only in the treated spontaneously hypertensive rats. The potassium clearance was increased in this group, but decreased in the treated normotensive group. The different reactions of the renal tubular function to the treatment with minoxidil in spontaneously hypertensive compared with normotensive rats were discussed in connection with changes of membrane transport in essential hypertension.

Animals↗
PubMed1985

Scintigraphy of lymphatic vessels in malignant melanoma of the skin before operation (en bloc excision).

An injection of 99mTc-labelled antimony sulphide colloid was used to show the lymphatic pathways in patients with malignant melanoma of the trunk skin. Using a gamma camera, optimal visualisation was obtained 15-30 min postinjection. Surprising deviations of the lymphatic pathways were found; therefore, this method makes it possible to plan continuity dissection appropriate to individual cases. Two examples are presented.

Antimony↗
PubMed1985

[Bacteriologic, histologic and functional studies of the kidney in 5 days' therapy of experimental E. coli pyelonephritis with gentamycin. Comparison with 9 days' therapy].

Short-term antibiotic treatment is recommended in infections of the lower urinary tract but its effectiveness is questioned in the upper urinary tract infections. We compared a 5 and a 9 day treatment of experimental E. coli 022 pyelonephritis after unilateral nephrectomy in 127 mal Wistar rats. We used 9 mg gentamycin per kg b.w. twice daily. I131 hippurat excretion was not decreased during the 5 day treatment but was only temporarily diminished during the 9 day treatment. Histologically the severe acute pyelonephritis was decreased after the 9 day treatment but not after 5 days of treatment. Bacteriologically almost all the kidneys were sterile after the 9 day treatment but the majority of the kidneys showed the injected strain of E. coli after the 5 day treatment. The results indicated that the shortened treatment was much less effective in our acute experimental pyelonephritis.

Animals↗