Particle size ophthalmic formulations

The final example of a novel process development formulation involves a semi-solid ophthalmic gel containing a carbonic anhydrase inhibitor drug for the treatment of glaucoma. It is administered to the patient by extruding the gel from an ophthalmic tube into the conjunctival sac of the eye. The drug had a very low aqueous solubility. It was necessary to reduce the particle size of the drug to less than 10 pim and suspend it in a very thick carbomer gel vehicle, to increase the residence time of the gel and maximise corneal permeation. The formulation details are given below ... 

The residence time of the formulation depends both on the particle size and on the nature of the surface charge. A positively charged O/W cmul.si0n containing the antifungal agent miconazole was developed for ophthalmic use... 

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