Bioadhesion: The effect of polyacrylic acid on the ocular bioavailability of timolol

Thermes, Florence; Rozier, Annouk; Plazonnet, Bernard; Grove, Jeffrey

doi:10.1016/0378-5173(92)90043-2

Cited by 35 publications

(13 citation statements)

References 14 publications

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“…Thermos et al evaluated ocular bioavailibity of timolol in isoviscous solution of PVA (PAA and timolol PAA salt). The result suggested that PAA polymer produce lower ocular concentration that those after PVA and slower the release of timolol and resulting in longer retention of vehicle in cunjuctivital sac by mucoadhesion 33 .…”

Section: Mucoadhesive Polymersmentioning

confidence: 80%

Untitled

2014

IJPSR

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Section: Mucoadhesive Polymersmentioning

confidence: 80%

Untitled

2014

IJPSR

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“…Several ways of prolonging the presence of drugs in precorneal area consist of increasing the viscoisty of the dosage form by adding a number of water soluble or insoluble, natural, synthetic, and semisynthetic polymers (El-Kamel, 2002;Felt et al, 1999;Lin & Sung, 2000;Thermes et al, 1992;Xu et al, 2002;Yie et al, 2000). However, these polymers explicit characteristics such as high viscosity, ensuring prolonged retention and a better miscibility with the lacrymal fluid, which helps in release of water soluble drugs.…”

Section: Introductionmentioning

confidence: 97%

A Long Acting Ophthalmic Gel Formulations of Atenolol

Hassan

2007

Drug Development and Industrial Pharmacy

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The main aim of pharmacotherapeutics, is the attainment of an effective drug concentration at the intended site of action for a sufficient period of time to elicit the response. In this study a trial was made to formulate atenolol, which is a beta-adrenergic blocker in a topical ophthalmic gel. Two polymers were used in this study, carboxymethylcellulose and sodium alginate in different concentrations. Atenolol was used in concentrations 0.5, 1, and 1.5% w/v. The in vitro release study was carried out. The results showed that the release rate of atenolol from gel preparations decreased as an inverse function of polymer concentration, while the release rate of the drug increased as the initial concentration increased. The data of drug release from the two polymers in different concentrations was plotted against the square root of time, and the diffusion coefficients (D), were calculated from the slope of the equation. Intra-ocular pressure (IOP) measurements of the rabbit's eye treated with 1% w/v atenolol solution, and 1% w/v atenolol in two gel formulations with different concentrations of the polymer were determined. The two gel formulations showed that these polymers extended the duration of pressure reducing effect to 8 hr, when compared with atenolol solution. Area above the curve (AAC), maximum response, maximum time of response (t(max)), and the duration of action were calculated. The overall results of this study indicated that the gel formulations of atenolol could be used for the development of a long-acting ophthalmic formulation.

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“…Mucoadhesion is an important feature of topical sustained-release dosage forms which may increase the duration or intensity of contact between drug molecules and the epithelium, thus provide control over the site and duration of drug release (Park and Robinson 1987, Gu et al 1988, Thermes et al 1992a, b, BlancoFuente et al 1996, Peppas and Sahlin 1996, Ahuja et al 1997, Genta et al 1997, Jones et al 1997, Tur and Chang 1998, De et al 2003. Thermes et al (1992b) have shown that the mucoadhesive polymer, PAA, modified the kinetic release profiles of timolol in the albino rabbit eye. This formulation resulted in higher timolol concentrations in the iris and ciliary body at later sampling times as compared to equal viscosity solutions of the drug in polyvinyl alcohol.…”

Section: Introductionmentioning

confidence: 98%

Polycarboxylic acid nanoparticles for ophthalmic drug delivery: anex vivoevaluation with human cornea

Bergey

Chung

et al. 2004

Journal of Microencapsulation

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In ophthalmic drug delivery, a major problem is retaining an adequate concentration of a therapeutic agent in the pre-corneal area. Polycarboxylic acid carriers such as polyacrylic acid and polyitaconic acid in sub-colloidal, nanoparticulate hydrogel form have a strong potential for sustained release of a drug in ocular delivery. Formulations have been prepared of brimonidine loaded in polycarboxylic (polyacrylic and polyitaconic) acid nanoparticles for potential ophthalmic delivery. These particles were prepared by a reverse micro-emulsion polymerization technique with sizes in the range of 50 nm. The loading efficiencies of the drug brimonidine in the particles were shown to be between 80-85% for polyacrylic acid nanoparticles and between 65-70% for polyitaconic nanoparticles. The loading efficiency was also found to be pH dependent. In a preliminary biocompatibility test, human corneal epithelial cells incubated with polyacrylic acid nanoparticles were found to retain their viability, whereas polyitaconic acid nanoparticles were found to be toxic. Two-photon laser scanning microscopic studies of the fluorescently labelled polyacrylic acid nanoparticles and human cornea shows that they are adhesive on the corneal surface. The polyacrylic acid nanoparticles demonstrated a controlled release of the opthalmological drug (Brimonidine) through the human cornea as compared to that of the commercial formulation, Alphagan.

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Bioadhesion: The effect of polyacrylic acid on the ocular bioavailability of timolol

Cited by 35 publications

References 14 publications

Untitled

Untitled

A Long Acting Ophthalmic Gel Formulations of Atenolol

Polycarboxylic acid nanoparticles for ophthalmic drug delivery: anex vivoevaluation with human cornea

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