Biomedical subjects

A Schneeweis

Publications and source records attributed to A Schneeweis.

2 recordsLinked to original sources

PubMed2000

Controlled release of solid-reversed-micellar-solution (SRMS) suppositories containing metoclopramide-HCl.

The investigated drug delivery system is a solid-reversed-micellar-solution (SRMS). The composition of this solution is 70% Witepsol W35 and 30% (w/w) lecithin. 1% (w/w) metoclopramide-HCl (MCP) was solubilized in the SRMS. After melting and on contact with water or any physicological aqueous media the SRMS exhibits an application induced transformation into a semisolid system of liquid crystalline microstructure. The structure of the liquid crystal has been identified by polarized light microscopy as a lamellar mesophase. Due to a low coefficient of diffusion in this mesophase a controlled release of the drug may be possible. The release profiles of the in vitro experiments have shown zero order kinetics and a sustained release of the SRMS-suppositories (SRMS-supp.) in comparison with commercial suppositories (Gastrosil-supp.). To examine bioavailability an in vivo study with rabbits was carried out. Five SRMS-supp. (10 mg MCP) and five Gastrosil-supp. (10 mg MCP) were tested in a parallel-group study. These experiments have shown a five times longer mean residence time (parameter of sustained release) in comparison with Gastrosil-supp. In vitro and in vivo studies have shown that rectal application of SRMS-supp. provides an appropriate route for controlled release of MCP via application induced transformation into liquid crystals.

Administration, Rectal↗

PubMed1997

In vivo and in vitro diclofenac sodium evaluation after rectal application of soft gelatine capsules enabling application induced transformation (AIT) into a semisolid system of liquid crystals (SSLC) for controlled release.

PURPOSE: Reverse micellar solutions of diclofenac sodium were encapsulated in soft gelatine capsules. On contact with aqueous media they exhibited an application induced transformation (AIT) into a semisolid system of liquid crystals (SSLC) which slows down drug release. The aim of the present paper was to study in vitro and in vivo drug release from these systems after rectal application. METHODS: In vitro drug release was determined in a self-constructed dissolution apparatus to simulate rectal application. For in vivo bioavailability studies rabbits were used as animal models. In vitro release and in vivo bioavailability of the capsules was compared to Voltaren suppositories. RESULTS: The release profiles of the in vitro experiments show zero-order kinetics. The in vivo bioavailability studies show bioequivalence in terms of AUC for both formulations (capsules and Voltaren suppositories). The mean residence time (parameter of sustained release) of the capsules is three time longer in comparison to Voltaren suppositories. CONCLUSIONS: Rectal administration of capsules provides an appropriate route for controlled release via AIT-SSLC which could be clearly verified in rabbits.

Administration, Rectal↗