[Ampicillin ion pair transport in comparison with the transport of other penicillins].
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Ampicillin↗
Biomedical subjects
R Neubert
Publications and source records attributed to R Neubert.
[Synthesis, detection and pharmacokinetic behavior of pholedrine sulphate esters. 7. Comparison of free- and sustained-release tablets in vivo and in vitro].
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Amidines↗
[Bronchoalveolar lavage in patients with sarcoidosis--methodologic aspects of the collection, immunologic characterization of lymphocytes and studies of immunoglobulin content].
The activity of alveolitis in 25 patients with pulmonary sarcoidosis was determined by analysis of T-Lymphocytes and their subpopulations collected by broncho-alveolar lavage. The characterization of the lymphocytes was performed with monoclonal antibodies (BL-series). An amount of T-lymphocytes higher than 28% of all cells and a proportion of T4/T8-lymphocytes of 8:1 and over are signs of the activity of the alveolitis and an indication for corticoid therapy.
Antibodies, Monoclonal↗
[Drug transport through artificial lipoid membranes. 22. Amplitude of ultrasonicated liposomes as a model system for investigations of drug transport].
The use of sonicated liposomes for the characterization of the transport behaviour of basic drugs is described. The rate of permeation depends mostly on the lipophilic character of the drugs.
Chemical Phenomena↗
Influence of ion-pair-formation on the pharmacokinetic properties of drugs. Part 3: Influence of hexylsalicylic acid on the pharmacokinetics of pholedrine.
Based on previous in vitro studies it could be shown that ion-pair-formation with the lipophilic hexylsalicylic acid (1) influences the pharmacokinetics of the hydrophilic drug pholedrine (2) which is ionized in all physiological media. After oral combination with 1 an increase of the AUC of 2 could be observed. This finding is due both to the increase of the absorption of 2 and to the decrease of the elimination of 2. After i.v. application the high biotransformation rate of 2 prevents an influence of 1.
Administration, Oral↗
Influence of ion-pair-formation on the pharmacokinetic properties of drugs. Part 4: Influence of hexylsalicylic acid on the pharmacokinetics of bretylium.
Based on in vitro results it was found that the pharmacokinetic parameters of the hydrophilic drug bretylium (2) can be influenced by an ion-pair-formation with the lipophilic hexylsalicyclic acid (1). After simultaneous i.v. application of 1 and 2 on rabbits a significant increase of the AUC of 2 was observed. Under these conditions a marked increase of the AUC and the MRT of 1 was also obtained, since the blood levels of 2 are high enough for such an influence. A combined rectal application of 1 and 2 causes an increase of the AUC of 2.
Administration, Oral↗
[Production, analysis and pharmacokinetic behavior of pholedrin sulfuric acid esters. 1. Production and analysis of pholedrin sulfuric acid esters].
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Chemical Phenomena↗
[The effect of ion pair formation on the pharmacokinetic properties of drugs. 1. The effect of alpha-methylpalmitic acid on the pharmacokinetics of quinine in rabbits].
The transport of quinine through artificial lipid membranes is significantly increased by use of alpha-methylpalmitinic acid (alpha-MPS). Using rabbits it could be shown that the alpha-MPS causes a significant increase of the mean resistance time (MRT) of quinine. Besides the alpha-MPS causes an increases Cmax and a shorter tmax of the quinine blood levels.
Animals↗
[Drug permeation through artificial lipoid membranes. 20. The effectiveness of multiple-lamellar liposomes for evaluating drug transport].
The use of stable liposomes for distribution experiments with some drugs is described. Great differences between distribution coefficients liposomes/water and n-octanol/water were found.
Liposomes↗
[Drug transport through artificial lipoid membranes. 21. Ion pair transport with alkyl salicylic acids].
Using hexylsalicylic acid it was demonstrated that alkylated derivatives of salicylic acid are able to increase partition and transport of ionized basic drugs across lipophilic membranes. The influence of different donor concentrations on the relation of transport was studied by means of pholedrine in combination with hexylsalicylic acid. In order to explain the mechanism of the ion-pair-transport experiments were carried out which show beside the mentioned increase of transport the occurrence of a countertransport of protons and lithium-ions, respectively. The lipophilic counterion hexylsalicylate acts inside of this mechanism as a carrier for the ionized drugs.
Chemical Phenomena↗
[The effect of ion pair formation on the pharmacokinetics of drugs. 2. The effect of hexylsalicylic acid on the pharmacokinetics of quinine].
The influence of the hexylsalicylic acid (2) on the pharmacokinetic of the quinine (1), was studied using rabbits. It could be observed that after i.v. application the mean resistance time (MRT) of 1 was increased by means of ion-pair-formation with 2. But the AUC of 1 was not influenced. After rectal application of the combination 1/2 an acceleration of the 1 absorption could be pointed out. The kinetic parameters of 2 were not increased significantly if 1 was applicated simultaneously.
Administration, Rectal↗
[A new experimental design for the in vitro evaluation of drug absorption in topical forms. 1. Design and model calculation].
An in-vitro model is presented which consists on several membrane Layers. The penetration of drugs from the ointment bases into these membrane Layers is observed. By combination of different membranes this system can be varied. In model calculations the resulting conditions are demonstrated.
Administration, Topical↗
[Possibilities for the in vitro evaluation of bioavailability. 5. Compact peroral agents with basic drugs].
Lipophilic, basic drugs can be transported across lipoid-membrane even if the part of the substance being not ionized in the solution is very low. Therefore the resorption model can be used for the control of drugs containing the substances as salts. In the case of 4 substances no differences could be found concerning half transport time between the aqueous solutions and the drugs.
Administration, Oral↗
[Action of [3,14-L-selenocysteine, 8-D-tryptophan]-somatostatin on insulin and glucagon secretion of the isolated perfused pancrease of the Wistar rat].
By isolated perfused pancreas of Wistar rats the glucose (11 mmol/l) and arginine (10 mmol/l) stimulated insulin (IRI) and glucagon (IRG) secretion was measured in order to investigate the inhibitory activities of somatostatin-14 (SS 14) and the somatostatin analogue [3,14-L-seleno-cysteine, 8-D-tryptophan]-somatostatin (SeSS). SS-14 or SeSS (152.8 nmol/l) inhibit the glucose stimulated IRI secretion by 75 and 65%, respectively. Only the second phase of the biphasic arginine stimulated insulin secretion pattern by 40%. SeSS has under these conditions no effect, whereas 58 nmol/l SS-14 or SeSS show a suppressing effect on the first (20 and 55%, respectively) and second phase (65 and 85%, respectively) of the insulin secretion. Using 5.8 nmol/l SS-14 or SeSS the arginine stimulated IRG secretion was inhibited only in the second phase of the biphasic glucagon secretion pattern by about 40%. 58 nmol/l SS-14 or SeSS show an inhibiting effect on the first and on the second phase of secretion, in both cases about 50%. It is concluded that in the SS-14 molecule the sulfur of cysteine in position 3 and 14 can be exchanged by selenium without modifying the biological activities measured in the glucose or arginine stimulated IRI and IRG secretion in vitro. The D-Trp8 in the SeSS analogue does not show the typical better inhibitory action of D-Trp8-SS-14 on insulin and glucagon secretion compared with SS-14. Possibly the selenium in the SeSS analogue abolishes this effect.
Animals↗
[Improvement of the solubility behavior of problem drugs. 9. In vitro absorption studies using melting solidification products of iomeglamic acid].
By means of the absorption apparatus according to Fürst and Neubert the solid dispersions of the iomeglamic acid were studied with regard to their in vitro absorption properties. All products showed better half lives of transport in relation to the pure compound. This was in correlation to the solubility parameters.
Absorption↗
[Resistance behavior of atypical mycobacteria to antibiotics and sulfonamides].
In the work presented here a simple method is described for sensitivity testing of atypical mycobacteria against antibiotics and sulphamerazin. The sensibility is tested with susceptibility discs in the liquid medium (culture medium 66 without agar) against Amikacin, Ciprofloxacin, Erythromycin, Gentamycin, Lincomycin, Sisomicin and Sulphamerazin. Following strains of atypical mycobacteria were examined: M. kansasii, M. xenopi, M. avium-complex, M. fortuitum. The aminoglycosides, Ciprofloxacin and Erythromycin show a wide spectrum of effects. We state a good sensibility of M. kansasii and M. fortuitum towards lincomycin and of M. kansasii and M. xenopi towards Sulphamerazin. The heterogeneity in sensibility of the single strains of some species already described is confirmed. This fact makes it necessary to carry out a sensitivity test of each strain of atypical mycobacteria before therapy.
Anti-Bacterial Agents↗
[Comparison of various methods for the identification of pneumococci based on optochin sensitivity].
The sensitivity against optochin of 491 strains of Streptococcus pneumoniae respectively alpha-haemolytic Streptococci was tested in optochin-plate-method and in the diffusion-test. Discs impregnated and used in wet condition and dry discs prepared in one of the participating laboratories were equal in their efficiency. The differentiation of Streptococcus pneumoniae and alpha-haemolytic Streptococci is possible by the disc-diffusion method using the following limit of inhibition zone. Streptococcus pneumoniae diameter of inhibition zone greater than 15 mm alpha-haemolytic Streptococci diameter of inhibition zone 0-15 mm The industrial production of optochin-discs can be recommended.
Bacteriological Techniques↗
[Dissolution processes and surface changes. 3. Determination of the surface with the BET process].
Two methods are demonstrated for the determination of the surfaces of solid substances by the BET-method. Using a newly constructed apparatus substances with high specific surfaces can be determined by the two-point-method with a good precision. For the determination of pulverous drugs we used the one-point-method proposed by Haul and Dümbgen [2] improving it in calibration und practicability.
Chemistry, Pharmaceutical↗