Diffusional model for transport rate studies across membranes

Polymeric micelles of single and mixed poloxamines (Tetronic) were evaluated regarding their ability to host the antiglaucoma agent ethoxzolamide (ETOX) for topical ocular application. Three highly hydrophilic varieties of poloxamine (T908, T1107 and T1307) and a medium hydrophilic variety (T904), possessing a similar number of propylene oxide units but different contents in ethylene oxide, were chosen for the study. The critical micellar concentration and the cloud point of mixed micelles in 0.9 per cent NaCl were slightly greater than the values predicted from the additive rule, suggesting that the co-micellization is hindered. Micellar size ranged between 17 and 120 nm and it was not altered after the loading of ETOX (2.7-11.5 mg drug g -1 poloxamine). Drug solubilization ability ranked in the order: T904 (50-fold increase in the apparent solubility) . T1107 ffi T1307 . T908. Mixed micelles showed an intermediate capability to host ETOX but a greater physical stability, maintaining almost 100 per cent drug solubilized after 28 days. Furthermore, the different structural features of poloxamines and their combination in mixed micelles enabled the tuning of drug release profiles, sustaining the release in the 1-5 days range. These findings together with promising hen's egg test-chorioallantoic membrane biocompatibility tests make poloxamine micelles promising nanocarriers for carbonic anhydrase inhibitors in the treatment of glaucoma.

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“…Thus, the Higuchi equation was applied to the first 60 per cent drug released and plotted versus the square root of time [48]:…”

Section: In Vitro Release Studiesmentioning

confidence: 99%

Single and mixed poloxamine micelles as nanocarriers for solubilization and sustained release of ethoxzolamide for topical glaucoma therapy

Ribeiro

Sosnik

Chiappetta

et al. 2012

J. R. Soc. Interface.

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“…3 and 4 or Eqs. 8 and 9 are generally applicable for the (5)(6)(7)(8)(9)(10)(11)(12)(13)(14). However, all 0 values differ significantly from one, giving strong evidence for the validity of the diffusion models (6-12); other models (5,13,14) predict 0 = 1 for the in uitro system used by Lippold and Schneider (1-3).…”

Section: Resultsmentioning

confidence: 99%

Drug Partitioning: Relationships between Forward and Reverse Rate Constants and Partition Coefficient

Kubjnyi¹

1978

Journal of Pharmaceutical Sciences

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“…Another potentially important barrier to the intestinal absorption of rapidly absorbed compounds is an unstirred water layer adjacent to the mucosal surface (e.g., [12][13][14]. Estimates of the thickness of this layer are 50-300 pm, depending on the agitation intensity.…”

Section: And Discussionmentioning

confidence: 99%

Effects of Short and Medium Chain Fatty Acids on Absorption of Lipophilic Drugs from Perfused Rat Intestine

Ghisafe

Hayton

1978

Journal of Pharmaceutical Sciences

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Diffusional model for transport rate studies across membranes

Cited by 55 publications

References 3 publications

Single and mixed poloxamine micelles as nanocarriers for solubilization and sustained release of ethoxzolamide for topical glaucoma therapy

Single and mixed poloxamine micelles as nanocarriers for solubilization and sustained release of ethoxzolamide for topical glaucoma therapy

Drug Partitioning: Relationships between Forward and Reverse Rate Constants and Partition Coefficient

Effects of Short and Medium Chain Fatty Acids on Absorption of Lipophilic Drugs from Perfused Rat Intestine

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