Ocular pharmacodynamics

The inherent pharmacologic properties of a drug determine its pharmacodynamic effects, and drug absorption, distribution, metabolism, and excretion are determined by the pharmacokinetic effects. The ease with which a drug passes into the systemic circulation and its ability to penetrate the blood-brain, blood-aqueous, or blood-retinal barriers determines the propensity to affect ocular tissues and functions. 

Chien DS, Schoenwald RD. Ocular pharmacokinetics and pharmacodynamics of phenylephrine and phenylephrine oxazoli-dine in rabbit eyes. Pharm Res 1990 7 476-483. 

Schoenwald RD. Ocular pharmacokinetics/pharmacodynamics . In Mitra AK, ed. Ophthalmic Drag Delivery Systems. New York Marcel Dekker, Inc., 1993 83-110. 

For all routes of administration, the absorption, distribution, and elimination kinetics are important for obtaining the desired therapeutic effect. For drugs expected to act in the eye after ocular absorption, pharmacokinetic parameters are difficult to obtain in both animals and humans. Accordingly, it has been proposed to rely essentially on pharmacodynamic measurements by use of a specific biological response after topical administration (258,259). For example, the apparent absorp-... 

We used 20 eyes of 20 pigmented rabbits to study in vivo release of BP from the implant and to evaluate pharmacodynamics in the ocular tissues after implantation. A scleral pocket was made at a depth of about one-half the total scleral thickness with a crescent knife 2 mm from the limbus. The scleral implant was inserted in the scleral pocket. At one, two, four, and eight weeks after implantation, animals were killed and four eyes were immediately enucleated at each time point. The concentrations of BP in the implants and samples of ocular tissues (aqueous humor, vitreous, and retina/choroid) were determined by HPLC. 

Rnpenthal ID, Green CR, Alany RG (2011) Comparison of ion-activated in situ gelling systems for ocular drag delivtay. Part 2 precomeal retention and in vivo pharmacodynamic study. Int J Pharm 411 78-85... 

Singh, J., Chhabra, G., Pathak, K. Development of acetazolamide-loaded, pH-triggered polymeric nanoparticulate in situ gel for sustmned ocular delivery in vitro, ex vivo evaluation and pharmacodynamic study. Drug Dev. Ind. Pharm. 40(9), 1223-1232 (2014)... 

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