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You searched for +publisher:"Duquesne University" +contributor:("Sachin Velankar"). Showing records 1 – 2 of 2 total matches.

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Duquesne University

1. Kotreka, Udaya Kanth. Development of Topical Ophthalmic In Situ Gel-Forming Estradiol Delivery System Intended for the Prevention of Age-Related Cataracts.

Degree: PhD, Pharmaceutics, 2011, Duquesne University

The increased risk of cataracts in aging women versus men, the reduced risk in women on hormone replacement therapy, and studies in animal models suggest that estrogen may protect lens transparency. To use estrogen for cataract prevention, we hypothesized that an ophthalmic estradiol in situ gel-forming formulation would be more effective for inducing lenticular estrogen responses without undesired uterine stimulation associated with systemic delivery. The following aims tested this hypothesis: 1) to develop an ophthalmic in situ gel-forming estradiol delivery system that is stable and safe; 2) to determine if ocular estrogen formulation was more effective than systemic therapy in inducing cataracts and activating estrogen-regulated genes in ERδ3 mice, while minimizing systemic side effects in the estrogen-responsive uterus; 3) to determine ocular safety and to estimate ocular and systemic drug bioavailability of the formulation in rabbits. An in situ gel-forming estradiol solution eye drop containing gellan gum polymer was developed as it offers a unique advantage of solution for easy handling which then undergoes a sol-gel transition in the presence of tear fluid in the eye to prolong drug contact time and enhance ocular bioavailability. Pre-formulation studies identified excipients that provided acceptable characteristics of clarity, isotonicity, and sterility to the ocular formulation. Using design of experiments approach, an optimized formulation with desirable viscoelastic and drug release characteristics was identified. In ERδ3 mice, estrogen-dependent cataracts occurred earlier at lower doses for ophthalmic versus systemic delivery. Further, gene expression and uterotrophic studies demonstrated that ocular estrogen therapy was more effective than systemic delivery in stimulating an estrogen-regulated gene in the ERδ3 lens and in minimizing systemic absorption as evidenced by little to no rodent uterine stimulation. Additionally, the in vivo studies in rabbits demonstrated that the optimized estradiol formulation was practically non-irritating to the eyes with maximal ocular drug absorption and minimal systemic drug bioavailability. Accelerated stability study indicated that the formulation was stable with a tentative shelf-life of 2 years assigned to the product. In summary, the developed ophthalmic estradiol formulation has the desired safety profile, stability, and ocular bioavailability required for future testing in animals and humans for cataract prevention. Advisors/Committee Members: Aleem Gangjee, Moji Adeyeye, Vicki Davis, Wilson Meng, Sachin Velankar.

Subjects/Keywords: Cataracts; Estradiol; Gellan gum; Ophthalmic; Stability; Viscoelasticity

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Kotreka, U. K. (2011). Development of Topical Ophthalmic In Situ Gel-Forming Estradiol Delivery System Intended for the Prevention of Age-Related Cataracts. (Doctoral Dissertation). Duquesne University. Retrieved from https://dsc.duq.edu/etd/771

Chicago Manual of Style (16th Edition):

Kotreka, Udaya Kanth. “Development of Topical Ophthalmic In Situ Gel-Forming Estradiol Delivery System Intended for the Prevention of Age-Related Cataracts.” 2011. Doctoral Dissertation, Duquesne University. Accessed July 15, 2019. https://dsc.duq.edu/etd/771.

MLA Handbook (7th Edition):

Kotreka, Udaya Kanth. “Development of Topical Ophthalmic In Situ Gel-Forming Estradiol Delivery System Intended for the Prevention of Age-Related Cataracts.” 2011. Web. 15 Jul 2019.

Vancouver:

Kotreka UK. Development of Topical Ophthalmic In Situ Gel-Forming Estradiol Delivery System Intended for the Prevention of Age-Related Cataracts. [Internet] [Doctoral dissertation]. Duquesne University; 2011. [cited 2019 Jul 15]. Available from: https://dsc.duq.edu/etd/771.

Council of Science Editors:

Kotreka UK. Development of Topical Ophthalmic In Situ Gel-Forming Estradiol Delivery System Intended for the Prevention of Age-Related Cataracts. [Doctoral Dissertation]. Duquesne University; 2011. Available from: https://dsc.duq.edu/etd/771


Duquesne University

2. Fu, Shao. Inter-Grade and Inter-Batch Variability of Pharmaceutical-Grade Sodium Alginate.

Degree: PhD, Pharmaceutics, 2011, Duquesne University

Polymeric excipients are generally the least well-characterized components of pharmaceutical formulations. The aim of this dissertation work is to facilitate the quality-by-design (QbD) approach to pharmaceutical formulation and manufacturing by evaluating the inter-grade and inter-batch variability of pharmaceutical-grade polymeric excipients. Sodium alginate, a widely used polymeric excipient, was selected for evaluation using appropriate analytical methods and test conditions, especially rheological methods. The materials used were six different grades of sodium alginate and an additional ten batches of one of the grades. To compare the six grades, steady shear measurements were conducted on solutions at 1, 2, and 3% w/w, consistent with their use as thickening or binding agents. Small amplitude oscillation (SAO) measurements were conducted on sodium alginate solutions at higher concentrations (4-13% w/w) corresponding to their use in controlled release matrices. In order to compare the ten batches of one grade, steady shear and SAO measurements were performed on their solutions at 2% w/w and 8% w/w, respectively. Results show that rheological properties of sodium alginate solutions are influenced by both molecular weight and chemical composition of sodium alginate. ¡§One-point¡¨ apparent viscosity data obtained at one low concentration and one shear rate is not representative of the complex rheological behavior of various grades of sodium alginate solutions at higher concentrations or other shear rates. The potential interchangeability of these different grades used as thickening or binding agents could be established by comparing the apparent viscosities of their solutions as a function of both alginate concentration and shear conditions. For sodium alginate used in controlled release formulations, both steady shear (at one low concentration, e.g., 2% w/w) and SAO measurements (at one high concentration indicative of polymer gel state, e.g., 8% w/w) are recommended to be performed on sodium alginate solutions to ensure interchangeability. Furthermore, among batches of the same grade, significant differences in rheological properties were observed, especially at the high solution concentration (i.e., 8% w/w). In summary, inter-grade and inter-batch variability of sodium alginate can be determined using steady shear and SAO methods. The influence of inter-grade and inter-batch variability of sodium alginate on the functionality of sodium alginate used in matrix tablets was investigated with a focus on compression properties, swelling, erosion behavior of alginate matrix tablets, and drug release from matrix tablets. The compression behavior of four grades and three batches of sodium alginate were studied by compaction energetics, out-of-die Gurnham, and out-of-die Heckel analysis. It was found that sodium alginates deform less plastically than microcrystalline cellulose (MCC PH102) but similar to lactose anhydrous. Sodium alginates also demonstrate more elastic deformations during compression than… Advisors/Committee Members: Lawrence H. Block, Peter Wildfong, Ira Buckner, Brian Carlin, Sachin Velankar, Christianah Moji Adeyeye.

Subjects/Keywords: Calcium alginate gels; Controlled release matrix; Rheology; Sodium alginate; Viscoelasticity; Viscosity

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Fu, S. (2011). Inter-Grade and Inter-Batch Variability of Pharmaceutical-Grade Sodium Alginate. (Doctoral Dissertation). Duquesne University. Retrieved from https://dsc.duq.edu/etd/557

Chicago Manual of Style (16th Edition):

Fu, Shao. “Inter-Grade and Inter-Batch Variability of Pharmaceutical-Grade Sodium Alginate.” 2011. Doctoral Dissertation, Duquesne University. Accessed July 15, 2019. https://dsc.duq.edu/etd/557.

MLA Handbook (7th Edition):

Fu, Shao. “Inter-Grade and Inter-Batch Variability of Pharmaceutical-Grade Sodium Alginate.” 2011. Web. 15 Jul 2019.

Vancouver:

Fu S. Inter-Grade and Inter-Batch Variability of Pharmaceutical-Grade Sodium Alginate. [Internet] [Doctoral dissertation]. Duquesne University; 2011. [cited 2019 Jul 15]. Available from: https://dsc.duq.edu/etd/557.

Council of Science Editors:

Fu S. Inter-Grade and Inter-Batch Variability of Pharmaceutical-Grade Sodium Alginate. [Doctoral Dissertation]. Duquesne University; 2011. Available from: https://dsc.duq.edu/etd/557

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