Drug delivery and formulation

Franz diffusion cells are used to investigate drug delivery across biological barriers: the model tissue is clamped in between the donor and receiver compartments of the cell, the drug is applied to the barrier from the top cell and its permeation is monitored in the receiver compartment over time.

A special Franz cell was designed for the study of drug delivery to the whole eye.

We are currently investigating the effect of P.L.E.A.S.E.® (Painless Laser Epidermal System) pretreatment to improve transport kinetics in collaboration with Pantec Biosolution.

This device uses an Er.YAG laser to apply energy at 2.94 microns, which is one of the principal absorption bands of water molecules present in the skin. Their excitation and subsequent evaporation leads to the formation of microchannels in the skin that facilitate drug delivery. This can be used with low molecular weight therapeutics and provides a more patient friendly means of delivering therapeutic macromolecules by offering a viable alternative to parenteral administration.

Iontophoresis employs a small electric potential to increase the rate of transport of polar and charged species across the biological barrier. The current intensity and duration of current application determine the rate and extent of delivery. Iontophoresis provides tightly controlled drug delivery and as such is well-suited to the administration of peptides, and low molecular weight therapeutics whose pharmacological effects depend on their input kinetics.

A 6 Ussing chamber system is used in our group to determine intestinal drug absorption. One chamber consists of a donor and acceptor compartment as well as an insert to add the intestinal tissue between the two compartments. Each compartment is provided with a tube to add a gas mixture. On one hand, it mixes the experimental solutions and on the other hand it allows the oxygenation of the intestinal tissue. The use of two pairs of Ag/Cl electrodes for applying / measuring currents and tensions allows the constant monitoring of the tissue viability, in case of the intestinal tissue of high evidence.

In order to understand how the drug is retained and distributed within the biological membrane after a permeation experiment, we use a histological Cryoslicer in order to separate the membrane in micrometer-scale horizontal slices. Each slice is then subjected to quantification to yield high-resolution biodistribution profiles of the drug as a function of membrane depth

The Labcoater allows preparing drug delivery systems (patches) systems by coating various kinds of drug containing matrixes on backing foils. The automated process leads to optimum homogeneity and precision of drug content.

A mechanical high-shear homogenizer is used to prepare semi-solid formulations: hydrogels, emulsions, foams.

A cryogenic mill is used to micronise drugs raw material, excipients, microparticulate formulations or solid tissue samples.

Formulations need to be characterized for their drug content, physical and chemical stability, particle content, size distribution.

To perform such characterization steps we have acess to Optical microscopes, SEM and TEM, rheometers, Zetasizer, Mass, IR and NMR spectrometers.