Ophthalmic inserts

An erodible insert developed as a potential ocular drug-delivery system is marketed as a prescription drug for the lubricant properties of the polymer base. Lacrisert is a sterile ophthalmic insert used in the treatment of moderate to severe dry eye syndrome and is usually recommended for patients unable to obtain symptomatic relief with artificial tear solutions. The insert is composed of 5 mg of hydroxypropylcellulose in a rod-shaped form about 1.27 mm diameter by about 3.5 mm long. No preservative is used, since it is essentially anhydrous. The quite rigid cellulose rod is placed in the lower conjunctival sac and first imbibes water from the tears and after several hours forms a... 

Chetoni, P., Di-Colo, G., Grandi, M., Morelli, M., Saettone, M.F., and Darougar, S., Silicone rubber/hydrogel composite ophthalmic inserts preparation and preliminary in vitro/in vivo evaluation, Eur. J. Pharm. Biopharm., 46 125-132 (1998). 

Sasaki et al. [151] prepared nondegradable disc-type ophthalmic inserts of P- blockers using different polymers. They found that inserts made from poly(hydroxypropyl methacrylate) were able to control the release of tilisolol hydrochloride. 

Saettone, M. F.,Torracca, M. T., Pagano, A., Giannaccini, B., Rodriguez, L., and Cini, M. (1992), Controlled release of pilocarpine from coated polymeric ophthalmic inserts prepared by extrusion, Ini. J. Pharm., 86(2-3), 159-166. 

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. 

Insoluble inserts are polymeric systems into which the drug is incorporated as a solution or dispersion. Ophthalmic inserts (ocuserts) have been reported using alginate salts, poly(A-vinyl pyrrol-idone), modified collagen, and hydroxyl propyl methyl cellulose. Ocufit is a silicone elastomer-based matrix that allows for the controlled release of an active ingredient over a period of at least 2 weeks. Osmotically controlled inserts have also been described, where release is by diffusion and is osmotically controlled. 

Ophthalmic inserts are sterile, solid or semisolid preparations of suitable size and shape, designed to be inserted in the conjunctival sac, to produce an ocular effect. They generally consist of a reservoir of active substances embedded in a matrix or bounded by a rate-controlling membrane. The active substance, which is more or less soluble in the lachrymal liquid, is released over a determined period of time. Ophthalmic inserts are individually distributed into sterile containers. 

Vijay DW, Kalpana VW, Beena I, Malay KS (2009) The effect of forskolin ophthalmic inserts on intraocular pressure in rabbit eyes. Int J Pharm Pharm Sci 1(2) 146-155... 

S.E. Bloomfield, T. Miyata, M.W. Dunn Buese, N. Bueser, K.H. Stenzel, and A.L. Rubin, Soluble gentamicin ophthalmic inserts as a drug dehvery system, Ophthalmol, 96,885-887,1978. R.E. Ros, J.W. Tijl, and J.A.J. Faber, Bandage lenses Collagen shield vs. hydrogel lens, CLAOJ., 17,187-190,1991. 

Hamcerencu M, Popa M, Costin D, Bucatariu P, Desebrieres J, Riess G. New ophthalmic insert. 

Ophthalmic inserts are solid devices, intended to be placed in the conjunctival sac and to deliver the drug at a comparatively slow rate. These devices might present valuable assets, such as ... 

Ophthalmic inserts are generally classified according to their solubility behavior and their possible biodegradability. 

Soluble inserts are the most frequently investigated class of ophthalmic inserts. Their main advantage relies on their complete solubility compared with then-insoluble counterparts, so that they do not need to be removed from the eye after deposition. The major problems of these soluble inserts are the rapid penetration of the lacrimal fluid into the device, the blurred vision caused by the solubilization of insert components and the glassy constitution of the insert increasing the risk of expulsion. They are usually divided into two categories according to their polymer composition. The first type is based on natural polymers whereas the second is derived from synthetic or semisynthetic polymers. 

Synthetic and semisynthetic polymers. Ophthalmic inserts containing synthetic, i.e. PVA [107, 108] and sanisynthetic, i.e. cellirlose based [108-110] polymers, are extensively desalbed in the literature. This stems in part from then-advantage of being based in products well adapted for ophthalmic use and then-ease of manufacture by conventional methods, including extrusion [110], compression [111] and compression molding [112]. Ethylcellulose, a hydrophobic polymer, can be incorporated in the formulation to deaease insert deformation, and therefore prevent blurred vision [113]. Regarding the risk of expulsion, several authors have incorporated carbomer, which, at low concentrations, is strong, but well-tolerated bioadhesive polymer. 

Guttler, R, Gurny, R. Patent literature review of ophthalmic inserts. Drug. Dev. Ind. Pharm. 21, 1-18 (1995)... 

Katz, I.M. Shaped ophthalmic inserts for treating dry eye syndrome, Google Patents (1982)... 

Bloomfield, S.E., et al. Soluble gentamicin ophthalmic inserts as a drug delivery system. Arch. Ophthalmol. 96(5), 885-887 (1978)... 

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