Direct demonstration of small intestinal secretion and site-dependent absorption of the beta-blocker talinolol in humans.

OBJECTIVE: To examine the relevance of site-dependent small intestinal absorption for incomplete intestinal absorption of the poorly metabolized beta 1-adrenergic receptor antagonist talinolol. METHODS: The intestinal steady-state perfusion technique (triple lumen tubing system with a 30 cm test segment) for intraluminal measurements was combined with simultaneous determination of talinolol serum concentrations. Dissolved talinolol was perfused over 160 minutes into different parts of the small intestine. The middle of the test segment was located between 25 and 235 cm beyond the teeth. Each of the six healthy subjects was studied twice with a proximal and a more distal site of perfusion to allow for comparisons within an individual subject. RESULTS: The area under the curve for serum concentrations from 0 to 480 minutes [AUC(0-480 min)] and the maximum serum concentration after distal perfusions corresponded to only 15% to 73% and 7% to 90% of the proximal values, respectively. AUC decreased with increasing distance from the teeth. The mean amount of talinolol absorbed from the test segment per unit time (intestinal transport rate) corresponds to only one-tenth of the amount of drug offered to the test segment (perfusion rate). There was a direct correlation between the perfusion rate of talinolol and its transport rate for both regions and in all subjects investigated. However, to achieve the same transport rate in the distal region a higher perfusion rate is required, compared to the proximal small intestine. At perfusion rates lower than 600 micrograms/min, net secretion of talinolol into the intestinal lumen occurred against a steep concentration gradient blood: lumen of about 1:4200. CONCLUSION: Talinolol oral bioavailability of 55% is due to a low absorption rate and a decrease of absorption capabilities along the small intestine. Net absorption of talinolol is reduced by the involvement of active intestinal secretion.

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.

[The concentration of local anesthetics in the dental alveolus. Comparative studies of lidocaine and articaine in the mandible and maxilla]. / Die Konzentration von Lokalanästhetika in der Zahnalveole. Vergleichende Untersuchungen von Lidocain und Articain im Unter- und Oberkiefer.

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)

Propiverine hydrochloride immediate and extended release: comparison of efficacy and tolerability in patients with overactive bladder.

INTRODUCTION: This study aims to compare the efficacy of propiverine hydrochloride immediate release (IR), propiverine hydrochloride extended release (ER) and placebo for the treatment of overactive bladder syndrome. The primary outcome measure is incontinence episode frequency, with secondary outcome measures including mean volume per void and quality of life as assessed on King's Health Questionnaire. MATERIAL AND METHODS: The double-blind, double-dummy, randomized study compared IR 15 mg twice daily, ER 30 mg once daily and placebo in 3 parallel groups. After a run-in period of 7 days, the patients were treated for 32 days. Nine hundred and eighty-eight patients were randomized, and 910 patients completed the protocol without major violations. RESULTS: The number of incontinence episodes/24 h decreased by 2.26 in the IR group (p < 0.001 vs. placebo), by 2.46 in the ER group (p < 0.0001 vs. placebo) and by 1.75 in the placebo group. The most frequent adverse event was dry mouth with 22.8% of the patients in the IR group, 21.7% in the ER group and 6.4% in the placebo group. The overall tolerability was rated 'very good' or 'good' by more than 80% of the investigators and patients in all 3 groups. CONCLUSIONS: Propiverine ER 30 mg once daily and propiverine IR 15 mg twice daily significantly reduce the number of incontinence episodes/24 h within a treatment period of 32 days. Both formulations are safe and well tolerated. The extended release formulation of propiverine is a suitable new option for the treatment of the overactive bladder.

Griseofulvin absorption from different sites in the human small intestine.

The site-dependent small-intestinal absorption pattern of griseofulvin was investigated in man. Griseofulvin was chosen as a model substance having extremely low water solubility and moderate lipid solubility. A conventional steady-state perfusion technique (triple-lumen tubing system with a 20 cm test segment) was applied. Dissolved griseofulvin (10.0 mg L-1) was perfused (10 mL min-1) during 160 min into different parts of the small intestine with the middle of the test segment between 85 cm and 270 cm beyond the teeth. Each of the ten healthy volunteers was examined twice with the test segment localized in different regions to allow for intraindividual comparisons. Mean drug absorption rates calculated from intestinal aspirate concentrations were similar in the two intestinal parts (proximal, 15.0 +/- 5.9 micrograms (20 cm min)-1; distal, 16.2 +/- 4.3 micrograms (20 cm min)-1; mean +/- SD). Absorption rate was strongly correlated to the amount of griseofulvin offered to the test segment per unit time. Extrapolating these findings it follows that an amount of griseofulvin, once dissolved, would be absorbed completely (> 99%) along 100 cm of the small intestine. A significant, positive correlation between the rate of transmucosal fluid transport and the absorption rate of griseofulvin was observed in the distal parts investigated.

Paracetamol absorption from different sites in the human small intestine.

Site-specificity in the small intestinal absorption of paracetamol was investigated using a segmental intestinal steady state perfusion technique (triple-lumen tubing system) combined with simultaneous measurements of serum drug concentrations. Dissolved paracetamol was perfused over 160 min into different parts of the small intestine (65-210 cm beyond the teeth). Each of the four healthy subjects was studied twice with a proximal and a more distal site of perfusion. Serum drug concentrations were similar after proximal and distal perfusions. Mean drug absorption rates calculated from intestinal aspirate concentrations were similar in both parts of the intestine--proximal: 869 micrograms 30 cm-1 min-1 (95% CI: 659-1079) vs distal: 941 micrograms 30 cm-1 min-1 (794-1088). The absorption rate was related directly to the amount of paracetamol perfused per unit time as well as to the rate of transmucosal water fluxes.

[Clinico-pharmacologic studies with a M1 receptor antagonist (substance AWD 26-06) in a phase I clinical trial]. / Klinisch-pharmakologische Untersuchungen mit einem M1-Rezeptor-antagonisten (Substanz AWD 26-06) in der Stufe I der klinischen Erprobung.

The tolerability of the compound AWD 26-06 (which is to classify as a M1-antagonist in consequence of the pharmacological investigations) was investigated in 11 healthy male persons with increasing dosage from 5 to 150 mg. Dryness of the mouth and scratch in the throat were observed by a dosage of 50 mg onwards, a diminuation of the flow of saliva and the accommodation were observed by a dosage of 100 and 150 mg, respectively. The frequency of the heart, but not the blood pressure, is increased by 150 mg of AWD 26-06. The influence on the secretion of the gastric juice was investigated in normal conditions and after stimulation by Pentagastrin with a dosage of AWD 26-06 of 25 mg in comparison with a placebo on 7 healthy male persons. The volume of gastric juice was diminished by 35% in all fractions, but the secretion of HCl, measured as basal acid output and peak acid output, was diminished in 5 of the 7 persons by 20%. A further investigation in order to check the therapeutic effect in patients with ulcus ventriculi and ulcus duodeni, respectively, is necessary and useful.

Site-dependent small intestinal absorption of ranitidine.

The site-dependent, small intestinal absorption characteristics of ranitidine were estimated by the intestinal steady state perfusion technique (triple lumen tubing system) combined with simultaneous measurement of serum concentrations of ranitidine. Ranitidine 150 mg.l-1 was perfused at 10 ml.min-1 for 180 min in different sites of the small intestine between 65-250 cm beyond the teeth. Each of 9 healthy, male volunteers was examined twice, using perfusion sites in different regions of the small intestine to permit intraindividual comparisons. The absorption rates (micrograms.30 cm-1.min-1) calculated from intestinal samples showed distinct site-dependence; the highest rates (medians 160-923 micrograms.30 cm-1.min-1) were found in the most proximal region (duodenojejunal junction), and the most distal perfusion sites (distal jejunum/ileum) showed median rates from 193 to 265 micrograms.30 cm-1.min-1. In both of these regions there was a significant positive correlation between the net intestinal water flux and the movement of ranitidine. Within the mid-jejunum, every subject showed marked secretion of ranitidine into the gut lumen (medians -338 to -124 micrograms.30 cm-1.min-1), and in this region there was no influence of water flux on ranitidine movement. The intraluminal results were confirmed by the corresponding site-dependent areas under the serum concentration-time curves (AUC), which decreased with the distance of the perfusion site from the teeth. After the more distal perfusions individual AUCs amounted to 64-16% of the AUCs obtained after more proximal applications. The results demonstrate the small intestine as the site of a gradient of absorption of ranitidine.(ABSTRACT TRUNCATED AT 250 WORDS)