Pilocarpine alginate

Nondegradable polymers are also useful as matrices for ocular implants. This application requires the polymer to be hydrophilic, to minimize local tissue irritation. Need for ocular implants stems from the challenges posed to conventional ocular medicines (i.e., eye drops) such as rapid dilution, tear washout, poor patient compliance, and limited bioavailability. Ocular implants from hydrophilic polymer matrices that provide localized sustained release may overcome the above limitations. The first polymeric sustained release product to reach the market was Ocusert , a pilocarpin sustained release ocular implant developed by Alza. Ocusert has the drug reservoir as a thin disc of pilocarpine-alginate complex sandwiched between two transparent discs of microporous membrane fabricated from ethylene-vinyl acetate copolymer. The microporous membranes permit the tear fluid to penetrate into the drug reservoir compartment to dissolve pilocarpine from the complex. Pilocarpine molecules are then released at a constant rate of 20 or 40 pg/hr for a four- to seven-day management of glaucoma. 

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... 

Pamoic acid and alginic acid have also been used to prolong the action of basic drugs (e.g., streptomycin, pilocarpine) by forming salts of low solubility. 

Ocusert provides uniform controlled release (20 or 40 pg/h for 7 days) of pilocarpine as an ocular hypotensive drug and has been commercialized in 1974. Ocusert consists of two outer layers of ethylene-vinyl acetate copolymer (EVA) and an inner layer of pilocarpine in alginate gel within di-(ethylhexyl) phthalate for a release enhancer, sandwiched between EVA layers. ... 

C, is the saturated pilocarpine concentration in the lachrymal fluid within the alginic acid matrix, and... 

The latter device, developed by Alza Corp., Palo Alto, California, is a diffusion unit consisting of a drug reservoir (e.g., pilocarpine HCl in an alginate gel) enclosed by two release-controlling membranes made of ethylene-vinyl acetate copolymer, and enclosed by a white ring which Slows positioning of the system in the eye. The Pilo-20 Ocular Therapeutic System has a release rate of 20 mg/hr for 7 days, and the Pilo-40 system a release rate of 40 mg/hr for 7 days. The former releases a total of 3.4 mg in 7 days, the latter 6.7 mg. In order to maintain constant release of tog, and in accordance with the principles of diffusion, there... 

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