Biomedical Engineering Reference
In-Depth Information
sclera
choroid
retina
Aqueous
humor
cornea
lens
Iris-ciliary body
Vitreous humor
Inferior rectus muscle
Optic nerve
Fig. 1 Structure of human eye
tissues [
1
]. Conventional routes of drug administration via oral or
intravenous are not efficient in delivering drugs to diseased ocular
tissues due to ocular static and dynamic barriers. Ocular static
barriers include corneal and conjunctival epithelial tight junctions,
blood-aqueous barrier, sclera, retinal pigment epithelia, and blood
capillary endothelial cells. On the other hand, ocular dynamic
barriers that impede deeper ocular drug permeation include con-
junctival and choroidal blood and lymph circulation and precorneal
barriers such as tears [
2
]. Therefore to deliver drugs in therapeutic
amounts local routes of drug administration need to be explored.
Despite precorneal, static, and dynamic barriers, local drug admin-
istration remains the mainstay routes to deliver drugs and treat
ocular pathologies. For anterior segment disease treatment topical
drop formulations are recommended. For posterior segment ocular
disease treatment, intravitreal injections are commonly used. In this
chapter, we have discussed various routes of drug administration
followed by selected drug products administered by these routes.
Moreover this chapter emphasizes drug product composition, dos-
age regimen, pharmacodynamic and pharmacokinetic profiles, and
adverse effects associated with the use of such drug products.
2 Routes of Drug Administration
Drug administration to the eye can be broadly classified into three
categories, namely, topical (drops, emulsions, suspensions, oint-
ment, and gels), systemic (oral or intravenous), and intraocular
injection/implants following periocular (subconjunctival, subtenon,
