Gamma scintigraphic study of precorneal drainage and assessment of miotic response in rabbits of various ophthalmic formulations containing pilocarpine

Meseguer, G.; Gurny, Robert; Buri, P; Rozier, Annouk; Plazonnet, Bernard

doi:10.1016/0378-5173(93)90410-h

Cited by 31 publications

(11 citation statements)

References 8 publications

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“…In the past few years, an impressive number of pH (e.g., cellulose acetate phthalate and Carbopol), temperature (e.g., Poloxamer), and ion (e.g., gellan gum and alginate) induced in situ forming systems have been reported to sustain ophthalmic drug delivery (8)(9)(10)(11). These in situ gel-forming systems could prolong the precorneal residence time of a drug (12)(13)(14)(15)(16) and improve ocular bioavailability (17). The choice of a special hydrogel depends on its intrinsic properties and envisaged therapeutic use.…”

Section: Introductionmentioning

confidence: 99%

In Situ Gelling Gelrite/Alginate Formulations as Vehicles for Ophthalmic Drug Delivery

et al. 2010

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Abstract. The objective of this study was to develop an ion-activated in situ gelling vehicle for ophthalmic delivery of matrine. The rheological properties of polymer solutions, including Gelrite, alginate, and Gelrite/alginate solution, were evaluated. In addition, the effect of formulation characteristics on in vitro release and in vivo precorneal drug kinetic of matrine was investigated. It was found that the optimum concentration of Gelrite solution for the in situ gel-forming delivery systems was 0.3% (w/w) and that for alginate solution was 1.4% (w/w). The mixture of 0.2% Gelrite and 0.6% alginate solutions showed a significant enhancement in gel strength at physiological condition. On the basis of the in vitro results, the Gelrite formulations of matrine-containing alginate released the drug most slowly. For each tested polymer solution, the concentration of matrine in the precorneal area was higher than that of matrinecontaining simulated tear fluid (STF) almost at each time point (p<0.05). The area under the curve of formulation 16 (0.2%Gelrite/0.6%alginate) was 4.65 times greater than that of containing matrine STF. Both the in vitro release and in vivo pharmacological studies indicated that the Gelrite/alginate solution had the better ability to retain drug than the Gelrite or alginate solutions alone. The tested formulation was found to be almost non-irritant in the ocular irritancy test. The overall results of this study revealed that the Gelrite/alginate mixture can be used as an in situ gelling vehicle to enhance ocular retention.

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Section: Introductionmentioning

confidence: 99%

In Situ Gelling Gelrite/Alginate Formulations as Vehicles for Ophthalmic Drug Delivery

et al. 2010

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“…Although several studies have reported data on the increase in ocular bioavailability after administration of positively charged colloidal formulations, due to interaction with the corneal epithelium, the presence of a negative charge, as in SQACV-N (mean zeta potential about −33 mV), does not seem to be a limiting factor [45] and [46]. Furthermore, it should be borne in mind that particulate systems with a size of 100-200 nm can be retained on the corneal surface, and also in the conjunctival sac, for longer times than can an aqueous solution of the drug, avoiding the loss via tear turnover, as demonstrated by the t1/2 value calculated for SQACV nanoassemblies (t1/2 = 9.29 min) [11].…”

Section: Discussionmentioning

confidence: 99%

Nonpolymeric nanoassemblies for ocular administration of acyclovir: Pharmacokinetic evaluation in rabbits

Stella

Berlier

Rocco

et al. 2012

European Journal of Pharmaceutics and Biopharmaceutics

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The aim of this study was to increase bioavailability of the antiviral drug acyclovir (ACV) when administered by the ocular route. For this purpose, a new lipophilic derivative of acyclovir was synthesized, both possessing greater lipophilicity and providing the formation of a homogeneous water dispersion with higher amount of ACV than the aqueous solution of the parent drug. This was done by chemically linking acyclovir to the isoprenoid chain of squalene, obtaining 4′-trisnorsqualenoylacyclovir (SQACV), in which squalene is covalently coupled to the 4′-hydroxy group of acyclovir. This new prodrug was then formulated as nonpolymeric nanoassemblies through nanoprecipitation; the resulting particles were characterized in terms of mean diameter, zeta potential, and stability. The pharmacokinetic profile of the prodrug in the tear fluid and in the aqueous humor of rabbits was evaluated and compared to that of the parent drug. Data showed that SQACV nanoassemblies increased the amount of ACV in the aqueous humor of rabbits compared to free ACV solution. This new amphiphilic prodrug of acyclovir is a very promising tool to increase the ocular bioavailability of the parent drug.

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“…The labeled formulations were obtained by adding a specified amount of radioactive substance 99m Tc to the formulations. 32 Exactly 30 :L of the test formulation containing radioactive materials were instilled directly into the lower fornix of the conjunctival sac of the left eye. Ten seconds after instillation, a series of dynamic frames was recorded on a gamma camera (Hawkeye; GE Healthcare, Milwaukee) to detect the radiation of 99m Tc (140 keV) for 10 min with the eyes positioned in front of the pinhole collimator at a distance of 6 cm.…”

Section: In Vivo Scintigraphy Studiesmentioning

confidence: 99%

Novel Surface-Modified Nanostructured Lipid Carriers with Partially Deacetylated Water-Soluble Chitosan for Efficient Ocular Delivery

Tian

Luo

Song

et al. 2012

Journal of Pharmaceutical Sciences

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Gamma scintigraphic study of precorneal drainage and assessment of miotic response in rabbits of various ophthalmic formulations containing pilocarpine

Cited by 31 publications

References 8 publications

In Situ Gelling Gelrite/Alginate Formulations as Vehicles for Ophthalmic Drug Delivery

In Situ Gelling Gelrite/Alginate Formulations as Vehicles for Ophthalmic Drug Delivery

Nonpolymeric nanoassemblies for ocular administration of acyclovir: Pharmacokinetic evaluation in rabbits

Novel Surface-Modified Nanostructured Lipid Carriers with Partially Deacetylated Water-Soluble Chitosan for Efficient Ocular Delivery

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