Ocusert system

Fig. 2. Ocusert ocular therapeutic system. The Ocusert system releases pilocarpine at a controUed rate to treat glaucoma. In this schematic representation, the three disks and the ring are shown two-dimension ally. The patient inserts the Ocusert system under the eyeUd, where it releases pilocarpine for seven...

The Ocusert system illustrated in Figure 12.7 is one example of a diffusion-controlled reservoir device. Another is the steroid-releasing intrauterine device (IUD) shown in Figure 12.9. Inert IUDs of various shapes were widely used for... 

Armaly and Rao examined the clinical effects of the Pilocarpine Ocusert systems with different release rates. The systems exhibited a dose-response relationship such that increases in the release rate above 50 pg/h resulted in increased ocular hypotensive effects with no appreciable change in ocular pressure. The reduction in pressure observed at the 50 pg/h rate was comparable with the changes seen after the administration of 4-8% of pilocarpine solutions. 

Fig. 5 Diagrammatic illustration of a unit of Ocusert system, showing various structural components, and the ocular release rate profile of pilocarpine from the Ocusert pilo-20 system. (From Ref. l)...

Figure 8.34 Examples of drug-delivery systems employing polymeric membranes, (o) Ocusert system for the eye with two rote-controlling membranes, (b) Tronsiderm system for transdermal medication with one rote-controlling layer, (c) The Progestasert device for intrauterine insertion in which the body of the device serves as the rote-controlling barrier, (d) The oral Oros device in which the membrane is o semipermeable membrane which forbids drug transport, allowing water ingress only.

Figure 19 Exploded view of the pilocarpine Ocusert system (AJD) Transparent rate-controlling membranes. (B) Plastic ring, opaque white for visibUity in handling and insertion. (C) Drug reservoir. Total thickness of the assembled system is 0.3 mm. Major and minor axes of the ellipsoidal device are 13.4 and 5.7 mm, respectively.

Figure 9.1 Schematic diagram of the Ocusert reservoir delivery system. The figure shows an exploded view of the different elements of the Ocusert system. Two rate-controlled membranes composed of poly[ethylene-co-(vinyl acetate)] enclose a drug reservoir. An opaque ring is added for ease of handling and visibility.

The client with glaucoma is using an Ocusert system when applying pilocarpine, a miotic ophthalmic medication. Which intervention should the nurse discuss with the client ... 

In clinical studies the Oeuserl system has been shown to lower intra-ocular pressure, the main (and sight threatening) symptom of glaucoma, for periods up to one week (a.47). Furthermore, there were fewer side effects associated with this system and patient compliance was improved in comparison with the conventional pilocarpine eye drop formulation. One disadvantage of the Ocusert system was the discomfort to some patients and potential retention problems within the eye (a.43). 

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. 

Ophthalmic dmg dehveiy systems (qv) have been developed to dehvei controlled dmg quantities for a prolonged time (up to seven days) to the eye, eg, pilocarpine [92-13-7J (17). Alza Corp. in conjunction with Ciba-Geigy Corp. originally marketed such a product known as Ocusert to treat glaucoma. 

Fig. 1. Ocusert Pilo-20 and Ocusert Pilo-40 therapeutic systems, (a) Dimensions of the P20 system P40 systems are 5.5 mm and 13.0 mm, respectively (b)...

Fig. 2. In vivo release rate of pilocarpiae from the Ocusert Pilo-40 ocular therapeutic system where (—) represeats the calculated rate, and (—...

The Ocusert Pilo-20 and Pilo-40 Ocular Therapeutic System is an elliptical membrane that is soft and flexible and designed to be placed in the inferior cul-de-sac between the sclera and the eyelid and to release pilocarpine continuously at a steady rate for 7 days. The design of the dosage form is described by Alza in terms of an open-looped therapeutic system, having three major components (a) the drug, (b) a... 

Initiation of therapy - It has been estimated that 20 meg Ocusert is roughly equal to 0.5% or 1 % drops and 40 meg is roughly equal to 2% or 3% drops. Therapy may be started with the 20 meg system, regardless of the strength of pilocarpine solution the patient previously required. Because of the patient s age, family history, and disease status or progression, however, therapy may be started with the 40 meg system. 

Pilocarpine ocular therapeutic system (Ocusert) Carefully consider and evaluate patients with acute infectious conjunctivitis or keratitis prior to use. 

Ocusert - [CONTROLLED RELEASE TECHNOLOGY - PHARMACEUTICAL] (Vol 7) - [PHARMACEUTICALS] (Vol 18) -use m drug delivery [DRUG DELIVERY SYSTEMS] (Vol 8)... 

Figure 12.7 The Ocusert pilocarpine system is a thin multilayer membrane device. The central sandwich consists of a core containing the drug pilocarpine. The device is placed in the eye, where it releases the drug at a continuous rate for 7 days. Devices with release rates of 20 or 40 p,g/h are used. Controlled release of the drug eliminates the over- and under-dosing observed with conventional eyedrop formulations, which must be delivered every 4-6 h to maintain therapeutic levels of the drug in the eye tissue [18]...

The Ocusert (pilocarpine) Pilo-20/Pilo-40 Ocular Therapeutic System, Alza Corporation, Palo Alto, CA (1974). 

Diffusion-controlled membranes exist in two categories depot systems, in which the drug is totally encapsulated within a reservoir, and monolithic systems, where the drug is dispersed in a rate-controlling polymer matrix [25]. One commercially successful depot device is the Alza Ocusert for ocular delivery of pilocarpine in the treatment of glaucoma [25]. 

An alternative system, manufactured as a wafer-like insoluble implant, has been developed (Ocusert). The system is preprogrammed to release pilocarpine at a constant rate of 20 or 40 / g/hr for a week to treat chronic glaucoma however, release from inserts may be incomplete and approximately 20% of all patients treated with the Ocusert lose the device without being aware of the loss. The device also presents problems including foreign-body sensation, expulsion from the eye, and difficulty in handling and insertion. An alternative to the advanced non-erodible systems is an erodible insert for placement in the cul-de-sac. 

Two major types of advanced drug release systems have been designed on the basis of insertion of a solid device in the eye.The first is a device of low permeability filled with drug (Ocusert), which has been discontinued. The second is a polymer that is completely soluble in lacrimal fluid, formulated with drug in its matrix (Lacrisert). Both systems can be made to approach zero-order kinetics. However, patient acceptance has been poor. 

Controlling the release of medication at the site of action is often desirable, especially for compounds that are absorbed rapidly through mucous membranes or are removed rapidly from the site of action. The approach normally reduces the systemic side effects of the agent. The application of this approach can be illustrated with the Progestasert and Pilocarpine Ocusert dosage forms. 

Distinct from the development of contact lens materials or the Ocusert in the 1970s, additional promising delivery systems and materials have emerged with the more recent focus on development of intraocular applications for treatment of macular degeneration, cataract, retinopathy, and inflammation. 

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