Ocular inserts

Collagen, because of its unique structural properties, has been fabricated into a wide variety of forms including crosslinked films, meshes, fibers, and sponges. Solid ocular inserts have also been prepared from purified animal tissues. 

Intra-ocular insertion occasionally results in visual acuity loss, vitreous hemorrhage, and retinal detachment. 

In addition to the use of penetration enhancers in eye solutions, both for improving the corneal and the conjunctival (systemic) delivery of drugs, the use of these agents has also been extended to their incorporation into other ocular delivery systems. For example, solid ocular inserts made of polyvinylalcohol (PVA) containing sulfadicramide and some absorption promoters, e.g., polyoxyethylene-9-lauryl ether, L-(lysophosphatidylocholine), and deoxy-cholic acid sodium salt, have been reported. Such inserts showed an increase in the penetration of the drug through the animal cornea in in vitro studies [108]. 

Grzeskowiak, E. 1998. Technology and biopharmaceutical availability of solid ocular inserts containing sulfadicramide and some promoters. Acta Pol Pharm 55 205. 

Timolol Ocular inserts HPC, coated with Eudragit RS [150]... 

Tilisolol Ocular inserts Poly(hydroxypropyl-methacrylate) [151]... 

Ciprofloxacin Ocular inserts Sodium alginate, Eudragit, [153]... 

Pradofloxacin Ocular inserts Hydrogel coating on thin metallic [154]... 

Fluorescein Ocular inserts FLPMC lyophilisate on carrier [155]... 

Ocular inserts (epinephrin prodrug) Alginic acid Ocusert Alza... 

Ocular Inserts Solid ocular dosage forms such as films, erodible and nonerodible inserts, rods, and shields have been developed to overcome the typical pulse-entry-type drug release associated with conventional ocular dosage forms. This pulse entry... 

Ocular inserts probably represent one of the oldest ophthalmic formulation approaches. In 1948 the British Pharmacopoeia described an atropine-in-gelatin wafer and ever since then numerous systems have been developed applying various polymers and different release principals. However, the difficulty of insertion by the patient, foreign-body sensation, and inadvertent loss of inserts from the eye make these systems less popular, especially among the elderly. Furthermore, the high cost involved in manufacture prevented the insert market from taking off [197],... 

A number of ocular inserts using different techniques, namely soluble, erodible, nonerodible, and hydrogel inserts with polymers such as cellulose derivates, acrylates, and poly (ethylene oxide), have been investigated over the last few decades. 

Sultana,Y.,Aqil,M.,and Ali,A. (2005), Ocular inserts for controlled delivery of pefloxacin mesylate Preparation and evaluation, Acta Pharma., 55(3), 305-314. 

Di Colo, G., and Zambito, Y. (2002), A study of release mechanisms of different ophthalmic drugs from erodible ocular inserts based on poly(ethylene oxide), Eur. J. Pharm. Biopharm., 54(2), 193-199. 

Hornof, M., Weyenberg, W., Ludwig, A., and Bernkop-Schnurch, A. (2003), Mucoadhe-sive ocular insert based on thiolated poly(acrylic acid) Development and in vivo evaluation in humans, /. Controlled Release, 89(3), 419 428. 

In this controlled-release ocular insert, the drug reservoir is a thin disc of pilocarpine-alginate complex sandwiched between two transparent discs of micro-porous membrane fabricated from ethylene-vinyl acetate copolymer (Fig. 5). The microporous membranes permit the tear fluid to penetrate into the drug... 

A recent approach to ocular inserts was presented by Chetoni et in a study of cylindrical devices for oxytetracycline, made from mixtures of silicone elastomer and grafted on the surface of the inserts with an interpenetrating mueoadhesive polymeric network of polyacrylic acid or polymethacrylic acid. The inserts were tested for drug release and retention at rabbit eyes. It was shown that some of the inserts are able to maintain prolonged oxytetracycline concentrations in the lacrimal fluid for 36 h. 

Hosaka, S. Ozawa, H. Tanzawa, H. Kinitomo, T. Nichols, R.L. Vivo Evaluation of Ocular Inserts of Hydrogel Impregnated with Antibiotics for Trachoma Therapy, Basic Research Laboratories and the Department of Microbiology Harvard School of Public Health, 1982. 

IVIVCs are often indicated only for obtaining oral formulations. Various data have been presented in the cases of less-classical formulations such as intrauterine devices, chewing gums, ocular inserts, suppositories, etc. For example, for suppositories two main types of formulations exist one based on hydrophilic excipients and the second on lipophilic excipients. The first step is the dissolution of the mass. This means a fusion of the lipophilic base at human body temperature (36-39.5°C) or dissolution for the water-soluble base (even with a high melting point) in the rectal fluid. 

Hydroxypropyl cellulose is generally regarded as an essentially nontoxic and nonirritant material. However, the use of hydroxypropyl cellulose as a solid ocular insert has been associated with rare reports of discomfort or irritation, including hypersensitivity and edema of the eyelids. Adverse reactions to hydroxypropyl cellulose are rare. However, it has been reported that a single patient developed contact dermatitis due to hydroxypropyl cellulose in a transdermal estradiol patch. ... 

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