Drug penetration as studied by noninvasive methods: fourier transform infrared-attenuated total reflection, fourier transform infrared, and ultraviolet photoacoustic spectroscopy

The penetration of the drugs dithranol and methoxsalen from semisolid Vaseline formulation into an artificial dodecanol-collodion membrane was followed by three spectroscopic methods; they are, step-scan Fourier transform infrared (FTIR) photoacoustic spectroscopy (PAS) with phase modulation, FTIR-attenuated total reflection (FTIR-ATR), and ultraviolet (UV) PAS. The uptake of the drug in the membrane was quantified by monitoring the dependence of an appropriate drug band on the penetration time. The PAS experiments were carried out with various modulation frequencies for generating various sampling depths. Based on Fick's second law, the diffusion coefficient was derived by numerical fitting of the experimental data. It appears that the diffusion coefficient for the drug in the membrane depends on the distance. The comparative studies demonstrate that FTIR-ATR is favored for permeation studies, whereas the PAS techniques are capable of providing the drug penetration profile in the membrane. Thus, extended experimental data are available for new insight into the penetration process. However, because of the photacoustic cells at hand, PAS is only suitable for in vitro studies.     

Interactions between food components and drugs. Part 8: Effect of pectins and bile acid preparations forming stable mixed micelles on transport of quinine in vitro

Interactions between quinine and acetylated pectin, amidated pectin and pectin with blockwise arrangement of the free carboxyl groups as well as interactions between quinine and bile salt preparations forming stable mixed bicelles have been investigated. A diffusion cell with two compartments and an artificial lipid membrane and a filter-grown colon carcinoma cell line (Caco-2) have been used. Depending on structural parameters, pectin preparations diminished the rate of permeation of the drug. Above the critical micelle concentration, the bile salt preparations influence the quinine transport stronger than the pectin preparations. The strongest inhibition of the quinine permeation showed a stable mixed micelle preparation consisting of glycodeoxycholate, palmitic acid and lecithin. The Caco-2 cell line appears to be not as suitable as artificial lipid membranes to study drug transport in the presence of the bile salt preparations.     

BK-Anerkennung einer Echinokokkose in einer Klärschlammverbrennungsanlage

A sewage worker had a kidney removed because it was affected by an echinococcal cyst. The German law relating to occupational aspects of contact with biological substances is explained.     

Characterization of honeybee venom by MALDI-TOF and nanoESI-QqTOF mass spectrometry

The aim of the study was to comprehensively characterize different honeybee venom samples applying two complementary mass spectrometry methods. 41 honeybee venom samples of different bee strains, country of origin (Poland, Georgia, and Estonia), year and season of the venom collection were analyzed using MALDI-TOF and nanoESI-QqTOF-MS.     

Principles and problems in assessing prenatal toxicity

(1) The terminology to be used in reproductive (or in prenatal) toxicology has to be in accord with other fields and principles of toxicology; the reasons are briefly discussed. In addition it is essential to assess prenatal toxicity in comparison to adult (maternal) toxicity. (2) Since pharmacokinetics in laboratory animals (e. g. rodents) usually differ considerably from that in man, this fact has to be considered when planning and evaluating studies on prenatal toxicity. Up till now this aspect has seldom been taken into account. (3) A special problem in prenatal toxicity is the inter- and intralitter variability of the toxic manifestation (especially in polytocal animals). This problem has to be recognized by the investigators and means of dealing with it have to be developed. (4) Like all other toxic effects, embryo-/fetotoxic manifestations occur dose dependently. Little information is available in the literature on clean dose-response-curves for teratogenic effects. Some data from our laboratory are presented. (5) Risk assessment of teratogenic effects up till now represents a major problem. While qualitative risk assessment for man on the basis of animal data is possible, quantitative extrapolation from such data to the situation possibly existing in man is still difficult, because basic principles and strategies are largely lacking (e. g. may a “threshold” be assumed or not?). The results of some activities towards this goal are presented from our laboratory.     

Ion Pair Transport Across Membranes

The present review discusses drugs and counter ions suitable for ion pair transport (IPT). Ion pairing is shown to effectively increase the lipophilicity and transport rate of polar drugs across lipid membranes. The proposed mechanisms of IPT are discussed in detail. A marked change in drug properties upon ion pair formation is necessary to improve the bioavailability of hydrophilic ionizable drugs.