Method ocular route

Similar to the ocular route, CNS delivery is concerned with localized drag delivery, in this case to the central nervous system, rather than achieving the systemic delivery of a drag. The primary challenge here is to penetrate the permeability barrier comprising the brain capillary endothelium, known as the Blood-Brain-Barrier (BBB). Various methods are under investigation, as described in Chapter 13. 

Different ocular drug delivery routes are schematically shown in Fig. 21.2. For a thorough review on this field, several articles are available [7—13]. Topical or systemic administration of drugs is preferred over all other delivery methods since these techniques are cost-effective, non-invasive and easy to administer. However, systemic delivery is extremely inefficient for ocular drugs due to the separation of ocular tissues from the systemic circulation of the body [14,15]. A study has shown that systemic administration of a radiolabeled protein to healthy rats led to the accumulation of high radioactivity in blood, liver, and spleen, but no radioactivity could be detected in the ocular tissues [16]. 

In order to understand the mechanisms of steroid induced cataract, the route of the administered steroid into the crystalline lens should be clarified. Although intralenticular corticosteroid penetration studies have been performed the methodologies applied were different from those of the authors. This study aimed to investigate topographic lenticular dmg distribution together with the route of dmg penetration into the ocular tissues by using a convenient HPLC technique combined with a newly applied microsectioning method. 

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