Topogaraphical, clinical and therapeutic ophthalmology

 I-    ROUTES OF ADMINISTRATION OF OCULAR DRUGS

The main factors governing choice of the route of administration are as follows

1-      Inherent properties of the drug.

2-      Site of desired action (surface or intraocular structures.

3-     Frequency of administration possible.

4-      Drug concentration required at target tissue.

5-     Vascularity of the target tissue.

Sites of drug administration

1-     Topically applied ointments

 Suspensions and solutions achieve high drug concentrations on the corneal and conjunctival surface.

2-      Subconjunctival injections

 Facilitate high drug concentrations at the ocular surface and provide a variable-duration depot effect.

3-      Intraocular (intracameral or intravitreal)

 Injection of drugs is used rarely because general anesthesia is needed, serious ocular risks are associated with this route of therapy.

4-     Systemically administered drugs (oral or parenteral)

Reach all vascular ocular structures but are not delivered in useful concentration.

Fig.31: Sites of drug administration. A, Topically applied ointments,   B, Subconjunctival   C, Intraocular (intracameral or intravitreal) injection.    D, Systemically administered drugs (oral or parenteral). (Budras  et al.,2002).