Controlled release systems ocular

Interestingly, the free base, piloearpine, is used frequently in the ocular controlled-release system, because the nonionized form may be able to diffuse readily and exclusively through the specific... 

Typical release profile of pilocarpine from the Pilo-20 Ocuserl ocular controlled release system... 

In controlled release systems, pectin can be applied as an additive, with great potential for nasal, oral [52], and ocular [88] drugs. The field of biomaterials has a very wide range of applications of nano-and microparticles of pectin. New strategies for particle are needed for better-quality production. Bioengineering, chemistry, material science and health sciences can be combined to achieve more complete and better results [93]. 

VHL Lee, S Li, MF Saettone, P Chetoni, H Bundgaard. (1991). Systemic and ocular absorption of timolol prodrugs from erodible inserts. Proc Int Symp Controlled Release Bioact Mater 18 291-292. 

Carbopol resins also have been used in controlled-release dosage forms. Especially, the resins Noven AA-1 USP and Carbopol 934P NF are being extensively developed in bioadhesive drug delivery systems for topical, bucal or nasal, ocular, and rectal applications (e.g., Fentanyl ). Noven CA-1 USP and CA-2 USP are used as oral laxative and antidiarrheal products in swallowable and chewable tablets. 

Chien, Y. W. (1982), Ocular controlled release drug administration, in Novel Drug Delivery Systems, Marcel Dekker, New York, pp. 13 18. 

Gurny, R., Boye,T., and Ibrahim, H. (1985), Ocular therapy with nanoparticulate systems for controlled drug delivery, J. Controlled Release, 2,353-361. 

Sasaki, H.,Tei,C.,Nishida,K., and Nakamura, J. (1993), Drug release from an ophthalmic insert of a beta-blocker as an ocular drug delivery system, / Controlled Release, 27(2), 127-137. 

Implants for controlled release of drugs (nonbiodegradable) Implantable biosensor-drug delivery system Microfiuidics device for drug delivery Controlled-release microchip Implants that could benefit from local drug release Vascular stents coronary, carotid, and peripheral vascular Ocular implants Dental implants Orthopedic implants... 

Kim YC, et al. Ocular dehvery of macromolecules. J Control Release 2014 190 172-81. Lavik E, Kuehn MH, Kwon YH. Novel drug dehvery systems for glaucoma. Eye (Lond)... 

Nagarwal RC, et al. Polymeric nanoparticulate system a potential approach for ocular dmg delivery. J Control Release 2009 136(1) 2—13. 

Cao YX, et al. Poly(N-isopropylacrylamide)-chitosan as thennosensitive in situ gelforming system for ocular drug delivery. J Control Release 2007 120(3) 186—94. 

Ocular systems (Figure 7.5b) with application in the lower ophthalmic conjunctival sac for the controlled release of ciprofloxacin (pre- or post-operative treatment of topical infections, as well as conjimctivitis) were obtained from polyvinyl alcohol and sodium carboxymethylcellulose linking the two polymers by an esterification reaction between the hydroxyl groups of the polyvinyl alcohol and carboxyl groups of carboxy-methyl cellulose [47]. Membranes were obtained by the incorporation of the antibiotic into the polymer solution with the addition of glycerol as a plasticizer (in order to ensure the flexibility of the membrane). The advantage of using these polymers comes from their biocompatibility and from the fact that they are water soluble as the controlled release occms, the membrane is dissolved by the tear bed at 35"C temperature. 

R.C. Nagarwal, S. Kant, P.N. Singh, P. Maiti, and J.K. Pandit, Polymeric nanoparticulate system A potential approach for ocular drug dehvery, / Control Release, 136,2-13,2009. 

Another method of pilocarpine release is the use of a thin laminate of hydrophile polymers inserted in the conjunctiva cul-de-sac. This pilocarpine Ocusert system releases pilocarpine at a constant pre-determined rate. The sustained-release system, providing such advantages as maximum duration of pressure control, less round-the-clock pressure variation, use of smaller drug concentrations with decrease of ocular and systemic side effects, also has some disadvantages one problem is the burst phenomenon, in which there is a large initial release of pilocarpine after insertion, resulting in severe miosis and ciliary body spasm. Up to the present several cases of loss of device and 8 -formation, comeal erosion, subconjunctival bleeding and displacement to the pupil have been reported. 

Figures 2 and 3 illustrate the constant release of pilocarpiae over the seven day treatment period. An initial burst of dmg iato the eye is seen ia the first few hours. This is temporary and the system drops to the rated value ia approximately six hours. The total amount of dmg released ia this transitory period is less than that normally given ia pilocarpiae ophthalmic solutions. The ocular hypotensive effect of these devices is hiUy developed within 2 hours of placement ia the conjunctival sac, and the hypotensive response is maintained throughout the therapy. This system replaces the need for eyedrops apphed four times per day to control iatraocular pressure.

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