Intraocular dosage forms

Intraocular Dosage Forms. For orientation, readers are encouraged to familiarize themselves with the anatomical structures of the eye (Table 1), some of which are shown in Figure 3. 

Very few injectable dosage forms have been specifically developed and approved by FDA for intraocular use. However, the ophthalmologist uses available parenteral dosage forms to deliver antiinfectives, corti-costerioids, and anesthetic products to achieve higher therapeutic concentrations intraocularly than can ordinarily be achieved by topical or systemic administration. These unapproved or off-label uses have developed over time as part of the physician s practice of medicine. However, these drugs are usually administered by subconjunctival or retrobulbar injection and rarely are they injected directly in the eye [301]. 

Ocular topical drug delivery is particularly challenging because of the inherent difficulties associated with absorption of topically applied drugs into the eye. Ophthalmic dosage forms are administered via the topical route to treat both surface and intraocular conditions. Consideration of the anatomical and physiological features of the eye, as well as the physicochemical properties of the drug, are all important when developing a topical ophthalmic delivery system. 

Pilocarpine is a drug commonly used in glaucoma therapy to relieve intraocular pressure (lOP), which is a cause of great discomfort to the patient. Piloplex is a sustained-release product based on an emulsion system of pilocarpine bound to a polymeric carrier [87,88]. Piloplex was shown to prolong a reduction in lOP as compared to standard pilocarpine hydrochloride drops. This is attributed to its bioadhesive properties, which keep the drug in the precorneal area longer than do conventional ocular dosage forms. 

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