Preparation and characterization of demeclocycline liposomal formulations and assessment of their intraocular pressure-lowering effects.
The objective of the present study is to enhance the ocular permeability and to study the ocular disposition of demeclocycline (DEM), liposomal topical formulation for treatment of elevated intraocular pressure using Male New Zealand albino rabbits as an animal model.


METHODS
Different liposomal formulations of the DEM were prepared and characterized for their drug entrapment, drug-liposome affinity and the in vivo distribution of DEM in various ocular tissues. Liposomal formulations of promising drug distribution within the various ocular tissues have been scaled up for the in vivo intraocular pressure (IOP) measurements by Pneuma-tonometer using different dosing regimens.


RESULTS
The amounts of drug entrapped in the charged liposomal formulations were comparable and lower than that entrapped with neutral ones. DEM was found to be more concentrated (69-95%) in the lipid phase of the liposome. The concentrations of DEM in the cornea, aqueous humor, and conjunctiva were 4.76, 2.18, and 23.32 microg/g of tissue, respectively. Test formulations have shown significant reductions in the IOP on using different treatment protocols.


CONCLUSIONS
Preparation of liposomal formulations of DEM has substantially enhanced its transcorneal transport. Furthermore, the test formulations have shown promising and long-lasting intraocular pressure-lowering effect comparable with that of pilocarpine formulation as a control.
Afouna
Mohsen I
MI
Department of Pharmaceutical Sciences, College of Pharmacy, King Abdul Aziz University, Jeddah, Saudi Arabia. mafonah@kaau.edu.au
Khattab
Ibrahim S
IS
Reddy
Indra K
IK