Biomedical subjects
R Oertel
Publications and source records attributed to R Oertel.
[Relative bioavailability of the antiarrhythmia agent, tiracizine and its metabolites].
Relative bioavailability of a 100 mg tablet formulation of the antiarrhythmic agent tiracizine (CAS 78816-67-8) compared to a 50 mg formulation was assessed in a simple cross over study after single administration of a 100 mg dose to 12 healthy volunteers. Tiracizine and three of its metabolites (M1, M2 and M3) were measured in serum and urine by high pressure liquid chromatography. AUC (means after administration of the test preparation and 95% nonparametric confidence interval for the ratio test preparation/reference preparation) were 391.5 ng.h/ml and 0.87-1.11 for tiracizine, 5184.5 ng.h/ml and 0.94-1.26 for M1, and 1319.9 ng.h/ml and 0.88-1.16 for M2. Mean maximum serum concentrations after the test preparation and corresponding 95% confidence interval were 111.2 ng/ml and 0.86-1.20 for tiracizine, 301.2 ng/ml and 0.98-1.22 for M1, 54.6 ng/ml and 0.86-1.17 for M2, and 35.2 ng/ml and 0.82-1.17 for M3.tmax did not differ after the two preparations for tiracizine, M2 and M3, but was significant lower for M1 after administration of the test preparation (2.2 +/- 0.7 vs 3.0 +/- 1.2 h). Total urinary recovery (sum of parent compound and metabolite recovery) up to 32 h after intake of the test preparation was 31.2% of the administered dose. The corresponding 95% confidence interval was 0.84-1.08. Statistical evaluation of all parameters revealed bioequivalence between the two preparations if a single dose of 100 mg is administered.
[The bioequivalence of metoclopramide in two tablet formulations].
An investigation on the bioavailability of a tablet with 10 mg metoclopramide-HCl (CAS 363-62-5) Cerucal was performed in a two-way cross-over study with 12 volunteers. Metoclopramide was determined in serum by HPLC. The relative bioavailability (mean and nonparametric 95% confidence interval) with respect to a reference preparation was 0.95 (95% CI 0.88-1.02) for AUC and 0.92 (95% CI 0.79-1.07) for Cmax. A positive decision for bioequivalence was derived from the usual confidence intervals for both parameters. The tmax-values did not differ significantly. Statistical evaluation of all parameters revealed bioequivalence between the two preparations.
[The protein binding of talinolol].
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Elucidation of the structure of talinolol metabolites in man. Determination of talinolol and hydroxylated talinolol metabolites in urine and analysis of talinolol in serum.
The objective of this study was to determine the structure of talinolol metabolites formed and the amounts excreted in urine. Talinolol metabolites in urine were identified by comparing their HPLC retention times and their GC-MS profile with those of previously characterized reference compounds. The metabolites were quantified by HPLC with a normal-phase silica column, a single chloroform extraction and UV detection. Less than 1% of an administered dose was found in urine as hydroxylated talinolol. Other metabolites could be excluded. A sensitive method to determine talinolol in serum and a simple method for analysis of talinolol in urine are described. These methods were found to be precise and accurate for the measurement of talinolol in samples obtained from patients during chronic talinolol treatment as well as from healthy volunteers after a single dose of talinolol.
[Cough, vomiting, rapid weight loss].
A young male patient from Somalia presented with a productive cough since a few days, and he complained about vomiting after meals and a rapid loss of weight of 20 kg. Endoscopic, radiological and clinical examinations revealed a broncho-esophageal fistula. Further examinations showed mycobacterium tuberculosis as the underlying cause of the disease; a malignancy was excluded. Antituberculous treatment resulted in the loss of the present symptoms as well as in a clinical and endoscopic closure of the fistula.
[A quick, simple HPLC method for determination of talinolol in serum].
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[A sensitive HPLC-method for determination of triamterene in serum].
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[The concentration of local anesthetics in the dental alveolus. Comparative studies of lidocaine and articaine in the mandible and maxilla].
Lidocaine has been widely investigated as a local anaesthetic and cardiac antiarrhythmic agent. Articaine is the mostly used local anaesthetic agent in German dentistry. Blood levels of local anaesthetic agents after application in dentistry have been measured only in peripheral venous blood. Concentrations in the target region near the pain receptor have not been investigated. Therefore it seemed worth to compare the concentration of lidocaine and articaine in the upper and the lower jaw after extraction of a tooth as well as the penetration and distribution of the drug in the tissue and bone of the jaw. For this purpose a method for withdrawing blood from the alveolus after extraction of a tooth was developed. First patients were submitted to submucous injections of lidocaine (2.3 ml 2%) into the upper jaw and to mandibular block injection of lidocaine (2.0 ml 2%) into the lower jaw. Correlation between blood levels of lidocaine and the type of anaesthesia as well as the location of the extracted teeth were found. In the upper jaw very high concentrations of both anaesthetics were found and the blood levels of lidocaine in the region of incisors were higher compared to those in the region of molars. In the lower jaw the blood levels of lidocaine were on average ten times lower than in the upper jaw and the highest values were found in the region of molars. Secondly, blood samples were withdrawn from the alveolus of the upper molars 3 to 23 min after submucous injection of articaine (2.0 ml 4%) or identical injection of lidocaine (2.0 ml 2%).(ABSTRACT TRUNCATED AT 250 WORDS)
A simple method for the determination of articaine and its metabolite articainic acid in dentistry: application to a comparison of articaine and lidocaine concentrations in alveolus blood.
This study was undertaken to develop a time- and cost-effective method for the detection of articaine and articainic acid in alveolus blood by high-performance liquid chromatography with a simple method of sample pretreatment. To overcome the problem of very rapid hydrolysis a method for controlling hydrolysis in vitro after blood sampling was developed. Blood samples were withdrawn from the alveolus of the upper molars 2-14 min after submucous injection of articaine (2.0 ml 4%) or identical injection of lidocaine (2.0 ml 2%). The higher blood levels found for articaine correspond to the higher concentration of the drug in the injection solution. A relationship between the serum concentration of articaine and lidocaine, respectively, and the time between injection and blood sampling could be established.
A new method of blood sampling and determination of the local anesthetic agent lidocaine in dentistry.
Blood levels of local anesthetic agents after application in dentistry have been determined only in peripheral venous blood. A method of withdrawing blood from the alveolus after extraction of a tooth was developed. With a new simple gas chromatographic method with a low detection limit, concentration of lidocaine was determined. A correlation between the blood levels of lidocaine and the type of anesthesia and the localization of the extracted teeth was found.
Interaction of talinolol and sulfasalazine in the human gastrointestinal tract.
The absorption of talinolol (TA) 50 mg was investigated without and together with the co-administration of sulfasalazine (SASP) 4 g in 11 healthy young volunteers, in order to clarify gastrointestinal transit of TA. Without SASP, the tmax of TA was 2.8 h, Cmax was 112 ng.ml-1 and the half life was 12 h; the AUCo-t was 958 ng.ml-1.h. In the case of concomitant administration of SASP, TA was found only in serum from 3 individuals, with a Cmax of 23 ng.ml-1 and a mean AUCo-t of 84 ng.ml-1.h. TA was not detectable in 5 subjects and it was at the limit of detection (2 ng.ml-1) in 3 subjects. Pharmacokinetic analysis was not possible in any of those individuals. The reason for the interaction appears to be the adsorption of TA by SASP. An interval of 2-3 h should elapse between giving SASP and other drugs.
The biliary and renal elimination of the new muscarinic-1-antagonist AWD 26-06 in volunteers with T-tube after cholecystectomy.
The biliary and renal elimination of the new muscarinic-1-antagonist AWD 26-06 were investigated in 6 female volunteers (age: 26-69 years) 9-14 days after cholecystectomy and T-tube construction. After a single oral dose of 50 mg AWD 26-06 as an aqueous solution the amount of the unchanged substance was determined in serum, T-tube bile and urine with a special HPLC-method. The concentration maximum was reached earlier and higher in bile (60 +/- 22 min; 10.8 +/- 5.7 micrograms/ml) than in serum (73 +/- 28 min; 0.98 +/- 0.53 micrograms/ml). During the whole observation time of 24 h the AWD 26-06 concentration in bile was 2-21-fold higher than in serum. In mean 2.3 +/- 1.5% of the administered dose were eliminated unchanged by bile and 12.2 +/- 5.9% by urine. More than 70% of the dose were metabolized. The results gave a hint at active liver transport processes and an enterohepatic recirculation. A drug interaction was observed with valproic acid on the metabolic level. The great interindividual variability of pharmacokinetic data can be caused by the heterogeneity of the subject group and a genetic polymorphism in the metabolism of AWD 26-06. The bile sampling by means of a T-tube is a simple but effective method under consideration of special conditions.
[In vitro interactions of talinolol with propranolol and salazosulfapyridine].
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[Fever, productive cough, chest pain].
This 27 year old woman had thoracic pain associated with breathing and movements for 10 months. Later on she complained about productive cough and fever. A pleural effusion developed. This effusion and the other symptoms did not resolve after therapy with erythromycin. Microbiology, serology and a bronchoscopy were unrevealing. A thoracoscopy was performed yielding epithelioid granulomas in the biopsy specimen from the pleura. Mycobacterium tuberculosis was grown from the pleural fluid. Symptoms subsided rapidly and the patient became well shortly after institution of anti-tuberculous therapy with a combination of three drugs.
Effect of fish oil on blood pressure and serum lipids in hypertension and hyperlipidaemia.
We studied the antihypertensive and hypolipidaemic effects of fish oil containing eico-sapentaenoic acid and docosahexaenoic acid in a capsule preparation in patients with mild to moderate essential hypertension and in patients with hypercholesterolaemia. In addition, we used two independent procedures to analyse changes in blood pressure, casual and self-recorded blood pressure measurements. A very moderate blood pressure lowering effect of fish oil was confirmed in this study, and a slight antihyperlipidaemic effect in plasma triglycerides was demonstrated. During the fish oil treatment, casual blood pressure values were consistently lower than self-recorded values. It is assumed that this was an observer error due to knowledge of the treatment.
[When are self-recorded blood pressures pathological?].
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[Hypertension and nutrition].
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