Intraocular Microdialysis

Sammanfattning: The method of microdialysis has been adapted for ocular use. It is a technique for monitoring concentrations of different molecules in a tissue in vivo. It is based on the principle of diffusion through a semipermeable membrane. The membrane is mounted on a soft plastic shaft, connected to an inlet and an outlet tube. The whole device, called microdialysis probe, was implanted into the vitreous body of rabbits. When a fluid is pumped through the inlet tube molecules that surround the membrane cross it and can be collelcted in the outlet tube. The concentration of these molecules is proportional to the concentration surrounding the membrane, i. e. the tissue where it is implanted. Thus the method can be used to investigate endogenous products as well as concentrations of e. g. drugs. It can also be used for drug delivery directly to the organ (the eye). In that case the drug molecules diffuse in to the tissue. There are several advantages with this technique when used in the eye. Only molecules cross the membrane, and no fluid is neither added nor withdrawn from the vitreous where the probe is implanted. In this study the technique has been used to deliver the drugs dexametasone, benzyl penicillin, 5-fluorouracil, daunomycin and ganciclovir and the growth factor NGF to the rabbit vitreous. Therapeutic concentrations have been achieved. It was also shown that the method can be used for continuous pharmacokinetic monitoring of systemically administered ceftazidime here used as a model substance.