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Burhan AM, Klahan B, Cummins W, Andrés-Guerrero V, Byrne ME, O’Reilly NJ, Chauhan A, Fitzhenry L, Hughes H. Posterior Segment Ophthalmic Drug Delivery: Role of Muco-Adhesion with a Special Focus on Chitosan. Pharmaceutics 2021; 13:1685. [PMID: 34683978 PMCID: PMC8539343 DOI: 10.3390/pharmaceutics13101685] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 09/24/2021] [Accepted: 09/27/2021] [Indexed: 01/04/2023] Open
Abstract
Posterior segment eye diseases (PSEDs) including age macular degeneration (AMD) and diabetic retinopathy (DR) are amongst the major causes of irreversible blindness worldwide. Due to the numerous barriers encountered, highly invasive intravitreal (IVT) injections represent the primary route to deliver drugs to the posterior eye tissues. Thus, the potential of a more patient friendly topical route has been widely investigated. Mucoadhesive formulations can decrease precorneal clearance while prolonging precorneal residence. Thus, they are expected to enhance the chances of adherence to corneal and conjunctival surfaces and as such, enable increased delivery to the posterior eye segment. Among the mucoadhesive polymers available, chitosan is the most widely explored due to its outstanding mucoadhesive characteristics. In this review, the major PSEDs, their treatments, barriers to topical delivery, and routes of topical drug absorption to the posterior eye are presented. To enable the successful design of mucoadhesive ophthalmic drug delivery systems (DDSs), an overview of mucoadhesion, its theory, characterization, and considerations for ocular mucoadhesion is given. Furthermore, chitosan-based DDs that have been explored to promote topical drug delivery to the posterior eye segment are reviewed. Finally, challenges of successful preclinical to clinical translation of these DDSs for posterior eye drug delivery are discussed.
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Affiliation(s)
- Ayah Mohammad Burhan
- Ocular Therapeutics Research Group, Pharmaceutical and Molecular Biotechnology Research Centre, Waterford Institute of Technology, X91 K0EK Waterford, Ireland; (W.C.); (N.J.O.); (L.F.); (H.H.)
| | - Butsabarat Klahan
- Ocular Therapeutics Research Group, Pharmaceutical and Molecular Biotechnology Research Centre, Waterford Institute of Technology, X91 K0EK Waterford, Ireland; (W.C.); (N.J.O.); (L.F.); (H.H.)
| | - Wayne Cummins
- Ocular Therapeutics Research Group, Pharmaceutical and Molecular Biotechnology Research Centre, Waterford Institute of Technology, X91 K0EK Waterford, Ireland; (W.C.); (N.J.O.); (L.F.); (H.H.)
| | - Vanessa Andrés-Guerrero
- Innovation, Therapy and Pharmaceutical Development in Ophthalmology (InnOftal) Research Group, Department of Pharmaceutics and Food Technology, Faculty of Pharmacy, Sanitary Research Institute of the San Carlos Clinical Hospital (IdISSC), Complutense University of Madrid, 28040 Madrid, Spain;
| | - Mark E. Byrne
- Biomimetic & Biohybrid Materials, Biomedical Devices & Drug Delivery Laboratories, Department of Biomedical Engineering, Rowan University, Glassboro, NJ 08028, USA;
| | - Niall J. O’Reilly
- Ocular Therapeutics Research Group, Pharmaceutical and Molecular Biotechnology Research Centre, Waterford Institute of Technology, X91 K0EK Waterford, Ireland; (W.C.); (N.J.O.); (L.F.); (H.H.)
| | - Anuj Chauhan
- Chemical and Biological Engineering Department, Colorado School of Mines, Golden, CO 80401, USA;
| | - Laurence Fitzhenry
- Ocular Therapeutics Research Group, Pharmaceutical and Molecular Biotechnology Research Centre, Waterford Institute of Technology, X91 K0EK Waterford, Ireland; (W.C.); (N.J.O.); (L.F.); (H.H.)
| | - Helen Hughes
- Ocular Therapeutics Research Group, Pharmaceutical and Molecular Biotechnology Research Centre, Waterford Institute of Technology, X91 K0EK Waterford, Ireland; (W.C.); (N.J.O.); (L.F.); (H.H.)
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Toropainen E, Fraser-Miller SJ, Novakovic D, Del Amo EM, Vellonen KS, Ruponen M, Viitala T, Korhonen O, Auriola S, Hellinen L, Reinisalo M, Tengvall U, Choi S, Absar M, Strachan C, Urtti A. Biopharmaceutics of Topical Ophthalmic Suspensions: Importance of Viscosity and Particle Size in Ocular Absorption of Indomethacin. Pharmaceutics 2021; 13:pharmaceutics13040452. [PMID: 33810564 PMCID: PMC8067094 DOI: 10.3390/pharmaceutics13040452] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 03/23/2021] [Accepted: 03/24/2021] [Indexed: 11/16/2022] Open
Abstract
Eye drops of poorly soluble drugs are frequently formulated as suspensions. Bioavailability of suspended drug depends on the retention and dissolution of drug particles in the tear fluid, but these factors are still poorly understood. We investigated seven ocular indomethacin suspensions (experimental suspensions with two particle sizes and three viscosities, one commercial suspension) in physical and biological tests. The median particle size (d50) categories of the experimental suspensions were 0.37–1.33 and 3.12–3.50 µm and their viscosity levels were 1.3, 7.0, and 15 mPa·s. Smaller particle size facilitated ocular absorption of indomethacin to the aqueous humor of albino rabbits. In aqueous humor the AUC values of indomethacin suspensions with different particle sizes, but equal viscosity, differed over a 1.5 to 2.3-fold range. Higher viscosity increased ocular absorption 3.4–4.3-fold for the suspensions with similar particle sizes. Overall, the bioavailability range for the suspensions was about 8-fold. Instillation of larger particles resulted in higher tear fluid AUC values of total indomethacin (suspended and dissolved) as compared to application of smaller particles. Despite these tear fluid AUC values of total indomethacin, instillation of the larger particles resulted in smaller AUC levels of indomethacin in the aqueous humor. This suggests that the small particles yielded higher concentrations of dissolved indomethacin in the tear fluid, thereby leading to improved ocular bioavailability. This new conclusion was supported by ocular pharmacokinetic modeling. Both particle size and viscosity have a significant impact on drug concentrations in the tear fluid and ocular drug bioavailability from topical suspensions. Viscosity and particle size are the key players in the complex interplay of drug retention and dissolution in the tear fluid, thereby defining ocular drug absorption and bioequivalence of ocular suspensions.
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Affiliation(s)
- Elisa Toropainen
- School of Pharmacy, University of Eastern Finland, 70211 Kuopio, Finland; (E.T.); (E.M.D.A.); (K.-S.V.); (M.R.); (O.K.); (S.A.); (L.H.); (M.R.); (U.T.)
| | - Sara J. Fraser-Miller
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, University of Helsinki, 00014 Helsinki, Finland; (S.J.F.-M.); (D.N.); (T.V.); (C.S.)
| | - Dunja Novakovic
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, University of Helsinki, 00014 Helsinki, Finland; (S.J.F.-M.); (D.N.); (T.V.); (C.S.)
| | - Eva M. Del Amo
- School of Pharmacy, University of Eastern Finland, 70211 Kuopio, Finland; (E.T.); (E.M.D.A.); (K.-S.V.); (M.R.); (O.K.); (S.A.); (L.H.); (M.R.); (U.T.)
| | - Kati-Sisko Vellonen
- School of Pharmacy, University of Eastern Finland, 70211 Kuopio, Finland; (E.T.); (E.M.D.A.); (K.-S.V.); (M.R.); (O.K.); (S.A.); (L.H.); (M.R.); (U.T.)
| | - Marika Ruponen
- School of Pharmacy, University of Eastern Finland, 70211 Kuopio, Finland; (E.T.); (E.M.D.A.); (K.-S.V.); (M.R.); (O.K.); (S.A.); (L.H.); (M.R.); (U.T.)
| | - Tapani Viitala
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, University of Helsinki, 00014 Helsinki, Finland; (S.J.F.-M.); (D.N.); (T.V.); (C.S.)
| | - Ossi Korhonen
- School of Pharmacy, University of Eastern Finland, 70211 Kuopio, Finland; (E.T.); (E.M.D.A.); (K.-S.V.); (M.R.); (O.K.); (S.A.); (L.H.); (M.R.); (U.T.)
| | - Seppo Auriola
- School of Pharmacy, University of Eastern Finland, 70211 Kuopio, Finland; (E.T.); (E.M.D.A.); (K.-S.V.); (M.R.); (O.K.); (S.A.); (L.H.); (M.R.); (U.T.)
| | - Laura Hellinen
- School of Pharmacy, University of Eastern Finland, 70211 Kuopio, Finland; (E.T.); (E.M.D.A.); (K.-S.V.); (M.R.); (O.K.); (S.A.); (L.H.); (M.R.); (U.T.)
| | - Mika Reinisalo
- School of Pharmacy, University of Eastern Finland, 70211 Kuopio, Finland; (E.T.); (E.M.D.A.); (K.-S.V.); (M.R.); (O.K.); (S.A.); (L.H.); (M.R.); (U.T.)
| | - Unni Tengvall
- School of Pharmacy, University of Eastern Finland, 70211 Kuopio, Finland; (E.T.); (E.M.D.A.); (K.-S.V.); (M.R.); (O.K.); (S.A.); (L.H.); (M.R.); (U.T.)
| | - Stephanie Choi
- Food and Drug Administration, Rockville, MD 20993, USA; (S.C.); (M.A.)
| | - Mohammad Absar
- Food and Drug Administration, Rockville, MD 20993, USA; (S.C.); (M.A.)
- AstraZeneca Pharmaceuticals, Rockville, MD 20878, USA
| | - Clare Strachan
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, University of Helsinki, 00014 Helsinki, Finland; (S.J.F.-M.); (D.N.); (T.V.); (C.S.)
| | - Arto Urtti
- School of Pharmacy, University of Eastern Finland, 70211 Kuopio, Finland; (E.T.); (E.M.D.A.); (K.-S.V.); (M.R.); (O.K.); (S.A.); (L.H.); (M.R.); (U.T.)
- Drug Research Program, Division of Pharmaceutical Biosciences, University of Helsinki, 00014 Helsinki, Finland
- Laboratory of Biohybrid Technologies, Institute of Chemistry, St. Petersburg State University, 198504 Peterhof, Russia
- Correspondence: ; Tel.: +35-840-5402-2279
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Selvaraj S, Rajkumar P, Kesavan M, Gunasekaran S, Kumaresan S. Experimental and theoretical investigations on spectroscopic properties of tropicamide. J Mol Struct 2018. [DOI: 10.1016/j.molstruc.2018.06.097] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Sharma A, Taniguchi J. Review: Emerging strategies for antimicrobial drug delivery to the ocular surface: Implications for infectious keratitis. Ocul Surf 2017; 15:670-679. [PMID: 28602948 DOI: 10.1016/j.jtos.2017.06.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 04/06/2017] [Accepted: 06/02/2017] [Indexed: 12/27/2022]
Abstract
Infectious keratitis is a medical emergency that can cause severe visual morbidity if not treated promptly. Depending upon the causative microorganism, effective management of infectious keratitis requires frequent application of antibacterial, antifungal, or antiviral eye drops, which may have low bioavailability, undesirable side effects, and poor patient compliance. Ocular formulations of antimicrobials that can increase corneal permeation and provide extended presence on ocular surface are being developed. Such formulations include nanoparticles, mucoadhesives, in situ forming hydrogels, and contact lenses. Testing of these formulations in in vitro models and ex vivo excised corneas, and in vivo rabbit testing have demonstrated increased bioavailability and extended presence on the cornea. Many of these formulations have also demonstrated success in treating infectious keratitis in animal models. However, the majority of studies have evaluated fluoroquinolone antibacterials, and more studies are needed to test the delivery of antifungal drugs. Moreover, additional efficacy data in animal models and future studies in humans to determine the duration of inhibitory concentrations of these antimicrobials in tear fluid will be required to prove the effectiveness of these formulations for clinical management of infectious keratitis.
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Affiliation(s)
- Ajay Sharma
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Chapman University, Irvine, CA, USA.
| | - Jonathan Taniguchi
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Chapman University, Irvine, CA, USA
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Fabiano A, Chetoni P, Zambito Y. Mucoadhesive nano-sized supramolecular assemblies for improved pre-corneal drug residence time. Drug Dev Ind Pharm 2015. [PMID: 26204347 DOI: 10.3109/03639045.2015.1066798] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CONTEXT Mucoadhesive nanoparticles were compared with non-aggregated constituent polymers for effect on pre-corneal residence of dexamethasone phosphate (DP) or met-enkephalin (ME), administered by eye-drops to rabbits. OBJECTIVE Deepening the knowledge of ophthalmic nanoparticulate systems in terms of ability to prolong pre-corneal residence. MATERIALS AND METHODS Medicated nanoparticles resulted from gelation of quaternary ammonium-chitosan conjugate or its thiolated derivative with hyaluronan in the presence of drug. Particles were analyzed by light scattering. Dialysis removed non-encapsulated drug, dynamic dialysis measured drug-polymer interactions, and lyophilization-stabilized product. Dispersions were regenerated from lyophilized products. Also solutions of non-thiolated or thiolated chitosan derivative were administered. Mean drug residence time (MRT) in tears was determined by collecting samples from lower marginal tear strip of albino rabbits using capillaries. RESULTS AND DISCUSSION Nanoparticle size of regenerated dispersions was 400-430 nm (DP-systems), 360-370 nm (ME-systems); the drug content was 2.5 mg/mL (DP) or 0.3 mg/mL (ME). The MRT for DP nanoparticles from non-thiolated derivative was higher than that for non-aggregated polymer, due to stronger concurrent interactions of positively charged nanoparticles with ocular surface and drug. Thiolated polymer nanoparticles and non-aggregated parent polymer, both interacting weakly with DP, showed similar MRT values. The MRT of ME could only be enhanced by protecting drug from enzymatic hydrolysis. This was done by nanoparticle systems, whereas non-aggregated polymers were ineffective. CONCLUSION Developing a nanoparticle system rather than a solution of mucoadhesive polymer, for prolonging pre-corneal residence, is convenient, provided nanoparticles interact strongly with both ocular surface and drug, or protect drug from metabolic degradation.
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Affiliation(s)
- Angela Fabiano
- a Dipartimento di Farmacia , Università di Pisa , Pisa , Italy
| | | | - Ylenia Zambito
- a Dipartimento di Farmacia , Università di Pisa , Pisa , Italy
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Kumar A, Ahuja M. Aqueous carboxymethyl gum kondagogu as vehicle for ocular delivery. JOURNAL OF PHARMACEUTICAL INVESTIGATION 2014. [DOI: 10.1007/s40005-014-0120-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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8
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Uccello-Barretta G, Nazzi S, Zambito Y, Di Colo G, Balzano F, Sansò M. Synergistic interaction between TS-polysaccharide and hyaluronic acid: Implications in the formulation of eye drops. Int J Pharm 2010; 395:122-31. [DOI: 10.1016/j.ijpharm.2010.05.031] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Revised: 05/04/2010] [Accepted: 05/15/2010] [Indexed: 10/19/2022]
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Guillaumie F, Furrer P, Felt-Baeyens O, Fuhlendorff BL, Nymand S, Westh P, Gurny R, Schwach-Abdellaoui K. Comparative studies of various hyaluronic acids produced by microbial fermentation for potential topical ophthalmic applications. J Biomed Mater Res A 2010; 92:1421-30. [PMID: 19358259 DOI: 10.1002/jbm.a.32481] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This work presents a comparative study of various hyaluronic acids (HA) produced by fermentation of either Bacillus subtilis or Streptococcus towards the selection of an optimal molecular weight (MW) HA for the preparation of topical ophthalmic formulations. The influence of HA MW on water binding capacity, sterile filtration, rheological properties, precorneal residence time and ocular tolerance of ophthalmic solutions was investigated. Molecular weight did not affect hydration of hyaluronic acid according to differential scanning calorimetry (DSC). In general, medium MW HA (0.6-1 MDa) resulted in solutions that were superior in terms of sterile filtration and kinematic viscosity requirements compared to high MW HA (>1 MDa). Moreover, all HA-based solutions exhibited well-defined viscoelastic properties that depend on MW. Gamma scintigraphic data indicated that HA MW at 0.1% concentration (w/v) and HA origin did not significantly affect the corneal residence time on rabbit eyes. A 0.3% solution of high MW HA had a prolonged residence time in the precorneal area compared to a medium MW HA at the same concentration. Finally, an in vivo ocular irritation test based on confocal laser scanning ophthalmoscopy (CLSO) conclusively showed the excellent tolerance of both Bacillus-derived HA and Streptococcus-derived HA after topical instillation onto the corneal surface. Overall, this comprehensive work highlights the superiority of medium MW hyaluronic acid for topical ophthalmic formulations based on their physico-chemical and biological properties, tolerance and handling. Such solutions are expected to enhance tear film stability, to allow for maximum comfort, and to exhibit high residence times, while being biocompatible and easy to sterile filter.
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Affiliation(s)
- Fanny Guillaumie
- Novozymes Biopolymer A/S, Krogshoejvej 36, DK-2880 Bagsvaerd, Denmark.
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Gilhotra RM, Gilhotra N, Mishra DN. Piroxicam bioadhesive ocular inserts: physicochemical characterization and evaluation in prostaglandin-induced inflammation. Curr Eye Res 2010; 34:1065-73. [PMID: 19958126 DOI: 10.3109/02713680903340738] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE An attempt has been made in the present research to formulate piroxicam into bioadhesive ocular inserts with an objective to sustain drug release, reduce frequency of dosing, and enhance ocular bioavailability of piroxicam. MATERIAL AND METHODS Drug matrices were prepared using film forming polymer, PVP and bioadhesive polymers, HPMC, CMC, and carbopol. Ocular inserts were prepared by film casting method and prepared films were subjected to investigations for their physical and mechanical properties, swelling behaviors, ex vivo bioadhesion, and in vitro drug release. The optimized formulation was tested and compared with eye drops of piroxicam for ocular anti-inflammatory activity in rabbits against PGE(2)-induced inflammation. RESULTS The physicochemical, bioadhesive, and swelling properties of films were found to vary significantly depending on the type of the polymers and their combination. The above properties were found to be optimum for all films; however, formulation containing carbopol 0.5% and HPMC 1% was found to be the best film as it shows good adhesion, acceptable pH, and gives a reasonable drug release (99% at 12 hr). Kinetic studies indicated both diffusion and swelling as mechanism of drug release from this matrix. Further in vivo studies with this formulation indicated a significant inhibition of PGE(2)-induced lid closure and PMN migration as compared to eye drops formulation. CONCLUSION Formulation was found promising, as it sustained the drug release and enhanced the ocular bioavailability of piroxicam as compared to piroxicam eye drops.
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Affiliation(s)
- Ritu Mehra Gilhotra
- Department of Pharmaceutical Sciences, Guru Jambheshwar University of Science and Technology, Haryana, India.
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Zambito Y, Di Colo G. Thiolated quaternary ammonium-chitosan conjugates for enhanced precorneal retention, transcorneal permeation and intraocular absorption of dexamethasone. Eur J Pharm Biopharm 2010; 75:194-9. [PMID: 20171277 DOI: 10.1016/j.ejpb.2010.02.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Revised: 01/19/2010] [Accepted: 02/02/2010] [Indexed: 11/24/2022]
Abstract
Previously, a quaternary ammonium (N(+))-chitosan (Ch) conjugate (N(+)(60)-Ch) characterized by short pendant chains, made of 1.7+/-0.1 adjacent diethyl-dimethylene-ammonium groups, substituted onto the primary amino group of the chitosan repeating units (degree of substitution, 59.2+/-4.5%) was used to synthesize a multifunctional non-cytotoxic thiomer (N(+)(60)-Ch-SH(5)), carrying 4.5+/-0.7% thiol-bearing 3-mercaptopropionamide besides quaternary ammonium groups. The present work was aimed at evaluating the potential of N(+)(60)-Ch-SH(5) and N(+)(60)-Ch as bioactive excipients for dexamethasone (DMS) eyedrops. The DMS permeability across excised rabbit cornea was enhanced over the control value by the thiomer and the parent polymer to about the same extent (3.8 vs. 4.1 times). The mean precorneal retention time and AUC in the aqueous of DMS instilled in rabbit eyes via eyedrops were enhanced by the thiomer (MRT=77.96+/-3.57 min, AUC=33.19+/-6.96 microg ml(-1) min) more than the parent polymer (MRT=65.74+/-4.91 min, AUC=21.48+/-3.81 microg ml(-1) min) over the control (MRT=5.07+/-0.25 min, AUC=6.25+/-0.65 microg ml(-1) min). The quaternary ammonium ions were responsible for both permeabilization of corneal epithelium and polymer adhesion to precorneal mucus, while the thiols increased the latter. This synergistic action is the basis of the higher thiomer bioactivity in vivo. A good ocular tolerability of the chitosan derivatives resulted from in vivo experiments.
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Affiliation(s)
- Ylenia Zambito
- Department of Pharmaceutical Sciences, University of Pisa, Pisa, Italy.
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12
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Zambito Y, Di Colo G. Chitosan and its derivatives as intraocular penetration enhancers. J Drug Deliv Sci Technol 2010. [DOI: 10.1016/s1773-2247(10)50005-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Asane GS, Nirmal SA, Rasal KB, Naik AA, Mahadik MS, Rao YM. Polymers for mucoadhesive drug delivery system: a current status. Drug Dev Ind Pharm 2009; 34:1246-66. [PMID: 18720139 DOI: 10.1080/03639040802026012] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
To overcome the relatively short gastrointestinal (GI) time and improve localization for oral controlled or sustained release drug delivery systems, bioadhesive polymers that adhere to the mucin/epithelial surface are effective and lead to significant improvement in oral drug delivery. Improvements are also expected for other mucus-covered sites of drug administration. Bioadhesive polymers find application in the eye, nose, and vaginal cavity as well as in the GI tract, including the buccal cavity and rectum. This article lays emphasis mainly on mucoadhesive polymers, their properties, and their applications in buccal, ocular, nasal, and vaginal drug delivery systems with its evaluation methods.
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Affiliation(s)
- G S Asane
- Department of Pharmaceutics, Pravara Rural College of Pharmacy, Loni, M.S., India.
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14
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Di Colo G, Zambito Y, Zaino C, Sansò M. Selected polysaccharides at comparison for their mucoadhesiveness and effect on precorneal residence of different drugs in the rabbit model. Drug Dev Ind Pharm 2009; 35:941-9. [DOI: 10.1080/03639040802713460] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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15
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Le Bourlais CA, Treupel-Acar L, Rhodes CT, Sado PA, Leverge R. New Ophthalmic Drug Delivery Systems. Drug Dev Ind Pharm 2008. [DOI: 10.3109/03639049509048095] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Mundada AS, Shrikhande BK. Formulation and evaluation of ciprofloxacin hydrochloride soluble ocular drug insert. Curr Eye Res 2008; 33:469-75. [PMID: 18568884 DOI: 10.1080/02713680802023104] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
PURPOSE An attempt has been made in the present research to formulate soluble ocular inserts of ciprofloxacin hydrochloride to increase residence time and prolong drug release. MATERIAL AND METHODS Drug matrices were prepared using natural polymer. Gelatin, a biodegradable polymer, was tried for the first time in the preparation of soluble ocular drug insert matrices. The inserts were then evaluated for their physicochemical parameters. The in vitro drug release studies were carried out using a bi-chambered donor receiver compartment model. In vivo drug release was carried out using rabbits as animal models. RESULTS Formulations CF4 and CF8, which showed controlled and prolonged in vitro drug release, were subjected to in vivo study. In vitro and in vivo correlation was found to be strong, revealing the efficacy of the formulation. CONCLUSION Formulation CF8 was found promising, as it achieved the target of the present study.
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Affiliation(s)
- A S Mundada
- University Department of Pharmaceutical Sciences, R.T.M. Nagpur University, Nagpur, India.
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17
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In situ-forming hydrogels for sustained ophthalmic drug delivery. J Control Release 2007; 122:119-34. [PMID: 17719120 DOI: 10.1016/j.jconrel.2007.07.009] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Accepted: 07/19/2007] [Indexed: 10/23/2022]
Abstract
Ophthalmic drug delivery is one of the most interesting and challenging endeavors facing the pharmaceutical scientist. The conventional ocular drug delivery systems like solutions, suspensions, and ointments show drawbacks such as increased precorneal elimination, high variability in efficiency, and blurred vision respectively. In situ-forming hydrogels are liquid upon instillation and undergo phase transition in the ocular cul-de-sac to form visco-elastic gel and this provides a response to environmental changes. In the past few years, an impressive number of novel temperature, pH, and ion induced in situ-forming systems have been reported for sustain ophthalmic drug delivery. Each system has its own advantages and drawbacks. The choice of a particular hydrogel depends on its intrinsic properties and envisaged therapeutic use. This review includes various temperature, pH, and ion induced in situ-forming polymeric systems used to achieve prolonged contact time of drugs with the cornea and increase their bioavailability.
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Cao Y, Zhang C, Shen W, Cheng Z, Yu LL, Ping Q. Poly(N-isopropylacrylamide)–chitosan as thermosensitive in situ gel-forming system for ocular drug delivery. J Control Release 2007; 120:186-94. [PMID: 17582643 DOI: 10.1016/j.jconrel.2007.05.009] [Citation(s) in RCA: 213] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2006] [Revised: 04/17/2007] [Accepted: 05/05/2007] [Indexed: 12/25/2022]
Abstract
A novel copolymer, poly(N-isopropylacrylamide)-chitosan (PNIPAAm-CS), was investigated for its thermosensitive in situ gel-forming properties and potential utilization for ocular drug delivery. The thermal sensitivity and low critical solution temperature (LCST) were determined by the cloud point method. PNIPAAm-CS had a LCST of 32 degrees C, which is close to the surface temperature of the eye. The in vivo ocular pharmacokinetics of timolol maleate in PNIPAAm-CS solution were evaluated and compared to that in conventional eye drop solution by using rabbits according to the microdialysis method. The C(max) of timolol maleate in aqueous fluid for the PNIPAAm-CS solution was 11.2 microg/ml, which is two-fold higher than that of the conventional eye drop, along with greater AUC. Furthermore, the PNIPAAm-CS gel-forming solution of timolol maleate had a stronger capacity to reduce the intra-ocular pressure (IOP) than that of the conventional eye drop of same concentration over a period of 12 h. In addition, the MTT assay showed that there is little cytotoxicity of PNIPAAm-CS at concentration range of 0.5-400 microg/ml. These results suggest that PNIPAAm-CS is a potential thermosensitive in situ gel-forming material for ocular drug delivery, and it may improve the bio-availability, efficacy, and compliance of some eye drugs.
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Affiliation(s)
- Yanxia Cao
- College of Pharmacy, China Pharmaceutical University, Nanjing, PR China
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19
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Caruba T, Couffon-Partant C, Oliary J, Tadayoni R, Limelette N, Gaudric A. [Efficacy and efficiency of preoperative mydriasis: drops versus ocular insert]. J Fr Ophtalmol 2007; 29:789-95. [PMID: 16988629 DOI: 10.1016/s0181-5512(06)73848-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OBJECTIVE The primary objective of this study was to compare eye drops and inserts in terms of the quality of preoperative mydriasis. The secondary objective was to evaluate the safety and ease of use of each modality. PATIENTS AND METHODS Prospective randomized and simple blinded study. Patients were randomized into two groups: the insert protocol (atropine 1%, diclofenac 0.1% collyrium and Mydriasert) or the eye drop protocol (atropine 1%, diclofenac 0.1%, tropicamide 0.5%, and phenylephrine 10% collyrium). Fifty-one patients were included: 25 in the insert protocol and 26 in the drop protocol. Mydriasis quality was evaluated by nurses and surgeons. The ease of use was estimated by the number of gestures required to obtain mydriasis and the difficulties encountered. Safety was evaluated at the patient's bedside. RESULTS Mydriasis of at least 6 mm was obtained in 92% of the patients in the insert protocol (23/25) and 85% of the patients in the drop protocol (22/26) (NS). Four patients lost their insert during the study. Of the patients in the insert group, 16% (4/25) experienced stinging in their eyes, as did 23% (6/26) of patients in the group using drops (NS). To reach effective mydriasis, the insert protocol required fewer nurse gestures per patient than the drop protocol (3.0 versus 8.3; p<0.001). CONCLUSION With the protocol using an insert, preoperative mydriasis is not inferior to that obtained with drops only and is more efficient in terms of nurse time and number of gestures. Nurses should be trained in appropriate handling of the insert and avoiding the loss of the device.
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Affiliation(s)
- T Caruba
- Service de Pharmacie, CHU Lariboisière, AP-HP, Paris.
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20
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Mundada AS, Shrikhande BK. Design and evaluation of soluble ocular drug insert for controlled release of ciprofloxacin hydrochloride. Drug Dev Ind Pharm 2006; 32:443-8. [PMID: 16638682 DOI: 10.1080/03639040500534101] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
PURPOSE Soluble ocular inserts of ciprofloxacin hydrochloride were prepared with the aim of achieving once a day administration. DESIGN Drug reservoir was prepared using natural hydrophilic polymer viz. gelatin while rate-controlling membrane was prepared using hydrophobic ethyl cellulose. Ocular inserts were evaluated for their physicochemical parameters like thickness, weight uniformity, drug content, percent moisture loss, and percent moisture absorption. The in vitro drug release studies were carried out using Bi-chambered donor receiver compartment model. Since targeted prolong release was observed in formulation CF2 and CF5, these formulations were further subjected to in vivo drug release study using rabbits as an animal model. In vitro drug release kinetic data was treated according to Zero, First, and Higuchi kinetics to access the mechanism of drug release. RESULTS Correlation between in vitro and in vivo drug release was found to be strong revealing the efficacy of the formulation. CONCLUSION Formulation CF5 has achieved target of present study such as increase residence time, prolong drug release, reduction in frequency of administration, and, thus may improve the patient compliance.
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Affiliation(s)
- A S Mundada
- University Department of Pharmaceutical Sciences, Nagpur University Campus, Amaravati Road, Nagpur, India.
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21
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Abstract
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. A major problem being faced in ocular therapeutics is the attainment of an optimal concentration at the site of action. Poor bioavailability of drugs from ocular dosage forms is mainly due to the tear production, non-productive absorption, transient residence time, and impermeability of corneal epithelium. This article reviews: (1) the barriers that decrease the bioavailability of an ophthalmic drug; (2) the objectives to be considered in producing optimal formulations; and (3) the approaches being used to improve the corneal penetration of a drug molecule and delay its elimination from the eye. The focus of this review is on the recent developments in topical ocular drug delivery systems, the rationale for their use, their drug release mechanism, and the characteristic advantages and limitations of each system. In addition, the review attempts to give various analytical procedures including the animal models and other models required for bioavailability and pharmacokinetic studies. The latter can aid in the design and predictive evaluation of newer delivery systems. The dosage forms are divided into the ones which affect the precorneal parameters, and those that provide a controlled and continuous delivery to the pre- and intraocular tissues. The systems discussed include: (a) the commonly used dosage forms such as gels, viscosity imparting agents, ointments, and aqueous suspensions; (b) the newer concept of penetration enhancers, phase transition systems, use of cyclodextrins to increase solubility of various drugs, vesicular systems, and chemical delivery systems such as the prodrugs; (c) the developed and under-development controlled/continuous drug delivery systems including ocular inserts, collagen shields, ocular films, disposable contact lenses, and other new ophthalmic drug delivery systems; and (d) the newer trends directed towards a combination of drug delivery technologies for improving the therapeutic response of a non-efficacious drug. The fruitful resolution of the above-mentioned technological suggestions can result in a superior dosage form for both topical and intraocular ophthalmic application.
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Affiliation(s)
- Indu Pal Kaur
- University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh 160 014, India
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22
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Paulsson M, Edsman K. Controlled Drug Release from Gels Using Lipophilic Interactions of Charged Substances with Surfactants and Polymers. J Colloid Interface Sci 2002; 248:194-200. [PMID: 16290522 DOI: 10.1006/jcis.2001.8182] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2001] [Accepted: 12/10/2001] [Indexed: 11/22/2022]
Abstract
The aim of this article was to study interactions between different gel forming polymers and amphiphilic drugs and surfactants with the intention of finding interactions that can be used for designing controlled release formulations. The release from gels was measured by detecting the UV-absorbance of drugs released from 6 mL gel into 250 mL release medium in a dissolution bath. The rheological behavior of gels was characterized using a controlled rate rheometer. The diffusion coefficient of alprenolol was 6.3 x 10(-6) cm(2)/s when formulated in a 1% poly(acrylic acid) gel (PAA) and 2.8 x 10(-6) cm(2)/s in a lipophilically modified gel (LM-PAA). The addition of alprenolol to 1% LM-PAA increased the elasticity, G', from 123 to 182 Pa. Increased gel strength was also observed for a number of other amphiphilic drugs. The addition of 1% Brij 58 to LM-PAA decreased the diffusion coefficient of alprenolol to 2.3 x 10(-6) cm(2)/s. It was possible to sustain the release of charged drugs with high log P by adding surfactant micelles. However, the effect was small and only useful for drugs with adequate lipophilicity. The interaction between LM-PAA and amphiphilic drugs could be seen using rheology and was used for designing controlled release gel formulations. In this way surfactants can be avoided, thus decreasing toxicity problems.
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Affiliation(s)
- Mattias Paulsson
- Department of Pharmacy, Uppsala University, Uppsala Biomedical Centre, Box 580, Uppsala, SE-751 23, Sweden
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23
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Paulsson M, Edsman K. Controlled drug release from gels using surfactant aggregates: I. Effect of lipophilic interactions for a series of uncharged substances. J Pharm Sci 2001; 90:1216-25. [PMID: 11745775 DOI: 10.1002/jps.1075] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Gels are often used for the delivery of drugs because they have rheological properties that will give a long residence time. Most pharmaceutical gels consist of approximately 99% water and a polymer matrix that will not hinder the release of drugs with a small molecular weight. To fully take advantage of the residence time, it is necessary to have a sustained drug release. In this paper it is suggested that surfactant micelles can be used to control the release from gels. The in vitro release under physiological conditions of five parabens from four different poly(acrylic acid) gels (Carbopol 934, 940, 1342) and one gellan gum (Gelrite) gel was measured using a USP dissolution bath modified for gels, and the diffusion coefficients were calculated. The diffusion coefficient of uncharged parabens was generally lower in gels with lipophilic modifications, such as C1342, and the greatest effect was seen for butylparaben, with a diffusion that was 25% lower than that in C934 (lacking lipophilic modification). Addition of surfactant micelles to gels delayed the release of all the uncharged drugs in all types of gels studied. The slowest release was seen for butylparaben in a lipophilically modified gel with micelles present. The diffusion coefficient in such a system was almost 30 times smaller than that in C934 without micelles.
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Affiliation(s)
- M Paulsson
- Department of Pharmacy, Uppsala Biomedical Centre, Uppsala University, Box 580, SE-751 23 Uppsala, Sweden
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24
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Herrero-Vanrell R, Fernandez-Carballido A, Frutos G, Cadórniga R. Enhancement of the mydriatic response to tropicamide by bioadhesive polymers. J Ocul Pharmacol Ther 2000; 16:419-28. [PMID: 11110033 DOI: 10.1089/jop.2000.16.419] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The aim of this work was to evaluate how the addition of mucoadhesive polymers to aqueous solutions affects the ocular response of tropicamide (0.2%; w/v). The polymer solutions tested were carboxymethylcellulose sodium salt (CMC-Na; 1%; w/v), hyaluronic acid sodium salt (HA-Na; 0.1%; w/v) and polyacrylic acid (PAA; 0.2%; w/v). Polymeric solutions were compared to a nonviscous formulation (AS). In vitro mucoadhesion measurements were expressed as a percentage of the adhesion force mucin-mucin, considering this one as 100% mucoadhesion. The values ofmucoadhesion obtained were 172%, 127%, 103% and 87.6% for formulations with CMC, PAA, HA and AS, respectively. The mydriatic response of tropicamide was determined in adult male New Zealand rabbits, weighing 1.7-2 Kg, by pupil diameter measurements at different times after instillation. The area under the mydriatic response-time curve (AUC 0-6 hr) was interpreted as an indication of the bioavailability of tropicamide in each vehicle. The AUC 0-6 hr was related to the in vitro mucoadhesion for each formulation. Tropicamide solutions with CMC-Na and PAA resulted in mucoadhesion and AUC 0-6 hr values approximately 1.9 and 1.4 times higher than AS. Although the solution with HA-Na was less mucoadhesive than PAA, the hyaluronic acid solution resulted in a higher AUC mydriasis/time value. Formulations with HA-Na and PAA presented values of surface tension close to that observed in the lacrimal fluid, with the Imax (maximum pupil diameter) being higher than for CMC-Na and AS. Greater than 90% of the mydriatic effect disappeared 4.5 hr after instillation for PAA and AS. Nevertheless, the mydriatic effect remained up to 5.5 hr for HA-Na and CMC-Na. HA-Na solution enhanced the bioavailability oftropicamide, presenting a value of mucoadhesion similar to the reference mucin-mucin.
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Affiliation(s)
- R Herrero-Vanrell
- Departamento de Farmacia y Technología Farmacéutica, Facultad de Farmacia, Universidad Complutense, Madrid, Spain.
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25
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Abstract
1. Despite the accessibility of the front of the eye, efficient delivery of drug to treat various ocular disorders is a challenge to the formulation scientist. The majority of ophthalmic medications are formulated as eye drops. Due to anatomical constraints, the volume that can be administered is limited to approximately 30 microL. This, together with the efficient clearance system that exists in the front of the eye, makes it difficult to maintain an effective pre-ocular drug concentration for a desired length of time. Various formulation strategies have been used to increase pre-ocular retention of eye drops. The most successful of these has been the inclusion of viscosity enhancing polymers, particularly those able to interact with the mucous layer on the eye surface or those that can undergo a transition from a solution to a gel under the conditions of the pre-ocular area. 2. When the target site is intra-ocular, drug must be absorbed from the pre-ocular region into the eye. The main route for absorption is across the cornea. However, absorption of drug across the cornea is inefficient due to its impermeable nature and small surface area. Thus, the intra-ocular bioavailability of topically administered medications is typically less than 10%. 3. Corneal permeability favours moderately lipophilic compounds. These compounds often have a low aqueous solubility. Problems in ocular drug delivery and formulation are compounded for poorly soluble drugs that must be formulated as suspensions. 4. Reformulation of ophthalmic suspensions as solutions has many advantages. This may be achieved by complexation using cyclodextrins. Solubilization using cyclodextrins can overcome many of the formulation problems. However, it is unclear as to their potential for improving ocular bioavailability, which is seemingly drug dependent and may be influenced by both the physicochemical properties of the drug and the complex formed.
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Affiliation(s)
- N M Davies
- Formulation and Drug Delivery Group, School of Pharmacy, University of Otago, Dunedin, New Zealand.
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26
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Paulsson M, Hägerström H, Edsman K. Rheological studies of the gelation of deacetylated gellan gum (Gelrite) in physiological conditions. Eur J Pharm Sci 1999; 9:99-105. [PMID: 10494003 DOI: 10.1016/s0928-0987(99)00051-2] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Gels have been successfully used to increase the mucosal contact time and hence the bioavailability of nasal and ophthalmic formulations. The use of in situ gelling polymers requires a rapid sol-gel transition that produces a strong gel for an optimal contact time. In this study, the rheological behaviour of deacetylated gellan gum (Gelrite) was analysed in order to better understand the reasons for the good performance in humans. Thermal scans were used to study gel formation and other changes in the structure of the samples when the macromolecular and ionic contents were altered. The effect the different ions in tear fluid (Na+, K+, Ca2+) had on the gel strength and the consequences of dilution due to the ocular protective mechanisms were examined. Na+ was found to be the most important gel-promoting ion in vivo. It was also found that gels are formed in tear fluid even when the concentration of Gelrite) is only 0.1%. Samples with concentrations of Gelrite of 0.5-1% do not require more ions than 10-25% of those in tear fluid to form gels. These two findings can partly explain the good performance of Gelrite in vivo. Gels with a high elastic modulus can thus be formed even though dilution of instilled drops takes place.
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Affiliation(s)
- M Paulsson
- Department of Pharmacy, Division of Pharmaceutics, Uppsala University, Uppsala Biomedical Centre, Box 580, SE-751 23, Uppsala, Sweden
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27
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Van Santvliet L, Ludwig A. Influence of the physico-chemical properties of ophthalmic viscolysers on the weight of drops dispensed from a flexible dropper bottle. Eur J Pharm Sci 1999; 7:339-45. [PMID: 9971918 DOI: 10.1016/s0928-0987(98)00036-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The present study investigated the influence of the rheological behaviour, the viscoelasticity and surface tension of various viscolysers on the weight of drops dispensed from a commercially available flexible dropper bottle. Furthermore, the effect of the concentration and molecular weight of some viscolysers and the angle at which the dropper bottle is held, were studied. Up to a value of 25 mPa x s, the viscosity and the rheological behaviour of the solution had no significant influence on the drop weight under conditions simulating patient manipulation. The lower the dynamic surface tension of the solution, however, the lower the weight of drops delivered. The dispensing angle (90 or 45 degrees) of the dropper bottle, on the other hand, had an impact on the weight of drops dispensed.
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Affiliation(s)
- L Van Santvliet
- Department of Pharmaceutical Sciences, Laboratory of Pharmaceutical Technology and Biopharmacy, University of Antwerp (UIA), Universiteitsplein 1, B-2610 Antwerpen (Wilrijk), Belgium
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28
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Abstract
The aim of this review is to give an insight into the many potential applications of chitosan as a pharmaceutical drug carrier. The first part of this review concerns the principal uses of chitosan as an excipient in oral formulations (particularly as a direct tableting agent) and as a vehicle for parenteral drug delivery devices. The use of chitosan to manufacture sustained-release systems deliverable by other routes (nasal, ophthalmic, transdermal, and implantable devices) is discussed in the second part.
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Affiliation(s)
- O Felt
- School of Pharmacy, University of Geneva, Switzerland
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29
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Edsman K, Carlfors J, Petersson R. Rheological evaluation of poloxamer as an in situ gel for ophthalmic use. Eur J Pharm Sci 1998; 6:105-12. [PMID: 9795025 DOI: 10.1016/s0928-0987(97)00075-4] [Citation(s) in RCA: 218] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The contact time of a vehicle on the cornea is of utmost importance for ocular drug delivery. In the present study rheological measurements were performed to study the gel and the sol-gel transition of an in situ gel, Poloxamer 407. The rheological measurements and a small in vivo study of ocular residence times in humans were used to evaluate poloxamer as an ocular vehicle. An increasing concentration of poloxamer resulted in a slightly increasing elasticity of the gels and a decreasing sol-gel transition temperature. The contact time increased with increasing concentration of poloxamer which could be explained and correlated with the rheology of poloxamer solutions/gels mixed with simulated tear fluid. The maximum contact time for the preparations studied was about 1 h. The poloxamer system did not seem to be promising as an ophthalmic in situ gel due to the strong concentration dependence of the sol-gel transition temperature combined with the dilution that occurs in the eye.
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Affiliation(s)
- K Edsman
- Department of Pharmaceutics, Pharmacia Pharmaceuticals, Uppsala, S-751 82 Uppsala, Sweden
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30
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Van Santvliet L, Ludwig A. The influence of penetration enhancers on the volume instilled of eye drops. Eur J Pharm Biopharm 1998; 45:189-98. [PMID: 9704916 DOI: 10.1016/s0939-6411(97)00114-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The influence of the physicochemical properties of various penetration enhancers on the weight of drops dispensed from flexible plastic dropper bottles was examined. Two dropper tips with a different design were compared and the dropper bottle was held in the upright position (90 degrees angle) or at a 45 degrees angle. These two angles were chosen to simulate the manipulation of an eye dropper bottle by the patient. The surface tension of the penetration enhancer solutions was determined using the dynamic drop volume method. The dynamic surface tension values ranged from 65 to 30 mN/m. The lower the surface tension of the solution, the lower the weight of the drop delivered. Both the design of the dropper tip and the manipulation technique of the dropper bottle had a moderate to important influence on the drop weight. The relationship between the surface tension of the penetration enhancer solution instilled and the comfort of the patient was evaluated by an acceptability test based on answering a questionnaire. Penetration enhancers can be used to reduce the drop size of conventional ophthalmic solutions on condition that they do not elicit local irritation.
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Affiliation(s)
- L Van Santvliet
- Department of Pharmaceutical Sciences, University of Antwerp (UIA), Belgium
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31
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Abstract
This paper provides a comprehensive overview of the various approaches currently used in the development of ocular drug delivery systems for the treatment of ocular diseases in animals. It is obvious from the literature that most of the products that are currently available are derived from human medicine without consideration given to the differences which exist between the anatomy and physiology of the eye of various animal species which ultimately affect product design and performance. As a result, many of the products for animal use seem in many circumstances inappropriate for animal care. The article deals with some aspects of eye anatomy and physiology of different animals, and then provides an overview of the most commonly encountered pathologies. The paper then discusses the currently available drug products and finally reviews new delivery concepts. Several hundred references are included in the paper and provide access to further information on the subject.
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32
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Design of ocular/lacrimal and nasal systems through analysis of drug administration and absorption. J Control Release 1997. [DOI: 10.1016/s0168-3659(97)00074-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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von der Ohe N, Stark M, Mayer H, Brewitt H. How can the bioavailability of timolol be enhanced? A pharmacokinetic pilot study of novel hydrogels. Graefes Arch Clin Exp Ophthalmol 1996; 234:452-6. [PMID: 8817289 DOI: 10.1007/bf02539412] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Carbomerbased hydrogels with timolol maleate (T-Gel) were chosen to study the vehicle effect on ocular bioavailability. Pharmacokinetic profiles of T-Gel 0.05% (0.05% timolol), T-Gel 0.025% (0.025% timolol) and commercial timolol ophthalmic solution (TOS 0.1%; 0.1% timolol) were determined and compared. METHODS A single dose was administered to rabbits' eyes. Timolol was determined by HPLC in aqueous humour, blood samples and washings of the ocular surface (as a measure of residence time). Sampling times were 0.5 h, 1 h and 4 h after instillation. RESULTS Concentration versus time curves (AUC) of timolol in aqueous humour demonstrate no significant differences between TOS 0.1% and T-Gel 0.025% (P = 0.19), whereas the difference between T-Gel 0.05% and TOS 0.1% is significant (P = 0.006); the AUC ratio of T-Gel 0.05%:TOS 0.1%:T-Gel 0.025% was 2.14:1:0.87. Timolol blood levels were highest with TOS 0.1% at every time point. Peak levels occurred after 0.5 h with all test products; the ratio of peak levels (Cmax) for T-Gel 0.05%:TOS 0.1%:T-Gel 0.025% was 0.55:1:0.17. Timolol was detected in the washings up to 1 h after instillation of test products; the highest levels were observed after T-Gel 0.05%. CONCLUSION The new vehicle obviously improves the bioavailability of topically applied timolol.
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Affiliation(s)
- N von der Ohe
- Klinik und Poliklinik für Augenheilkunde, Medizinische Hochschule Hannover, Germany
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34
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Lee VH. Ocular epithelial models. PHARMACEUTICAL BIOTECHNOLOGY 1996; 8:425-436. [PMID: 8791823 DOI: 10.1007/978-1-4899-1863-5_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Affiliation(s)
- V H Lee
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles 90033, USA
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35
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36
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Durrani AM, Farr SJ, Kellaway IW. Precorneal clearance of mucoadhesive microspheres from the rabbit eye. J Pharm Pharmacol 1995; 47:581-4. [PMID: 8568625 DOI: 10.1111/j.2042-7158.1995.tb06718.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The ocular disposition of hydrated 111In-labelled microspheres was investigated in the rabbit by gamma scintigraphy. Microspheres of cross-linked poly(acrylic acid) (Carbopol 907) were prepared by a w/o emulsification process. An in-vitro mucoadhesion test of prehydrated microspheres showed that greater adhesion was achieved to a mucus gel at pH 5.0 compared with pH 7.4. Clearance was a biphasic process with a rapid initial phase preceding a slower basal phase. When hydrated in pH 5.0 phosphate buffered saline, clearance during the basal phase was slowed compared with a pH 7.4 buffered preparation. Both prehydrated preparations were retained on the preocular area during the basal phase for longer periods than non-hydrated microspheres. The retention on the ocular surface of approximately 25% of the instilled dose would suggest this technology will have application for controlled ophthalmic drug delivery.
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37
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Durrani A, Farr S, Kellaway I. Influence of molecular weight and formulation pH on the precorneal clearance rate of hyaluronic acid in the rabbit eye. Int J Pharm 1995. [DOI: 10.1016/0378-5173(94)00389-m] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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38
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Tang-Liu DD, Richman JB, Weinkam RJ, Takruri H. Effects of four penetration enhancers on corneal permeability of drugs in vitro. J Pharm Sci 1994; 83:85-90. [PMID: 8138917 DOI: 10.1002/jps.2600830120] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The usefulness of penetration enhancers in promoting drug permeation across the cornea was investigated for drugs varying from hydrophilic to lipophilic. Four purported penetration enhancers [Azone (laurocapram), hexamethylenelauramide, hexamethyleneoctanamide, and decylmethylsulfoxide] were employed. Corneal permeability coefficients of drugs that were either hydrophilic (acetazolamide, cimetidine, guanethidine, and sulfacetamide), moderately lipophilic (bunolol and prednisolone), or lipophilic (flurbiprofen and its amide analogue) were measured in the absence or in the presence of various Azone concentrations. The effects of penetration enhancers on the corneal penetration of cimetidine were also compared. The corneal penetration of hydrophilic compounds was enhanced by at least 20-fold at 0.1% Azone. For prednisolone and bunolol, the maximal enhancement was at 0.025-0.1% Azone and was marginal (two- to 5-fold), whereas Azone inhibited rather than enhanced the corneal penetration of the lipophilic flurbiprofen and its amide analogue. All four enhancers behaved similarly in enhancing corneal penetration of cimetidine and corneal hydration after incubation in vitro. Possible mechanisms of penetration enhancers on corneal drug penetration were discussed. Penetration enhancers may have clinical benefits in improving ocular drug delivery of hydrophilic compounds, however, their utility may depend on the toxicological profiles.
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Affiliation(s)
- D D Tang-Liu
- Department of Drug Metabolism, Allergan, Inc., Irvine, CA 92715
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Bernatchez SF, Tabatabay C, Gurny R. Sodium hyaluronate 0.25% used as a vehicle increases the bioavailability of topically administered gentamicin. Graefes Arch Clin Exp Ophthalmol 1993; 231:157-61. [PMID: 8462888 DOI: 10.1007/bf00920939] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Sodium hyaluronate (SH) solutions have a longer precorneal residence time than isotonic saline solution in rabbits and in humans. The present study investigates the effect of a 0.25% SH vehicle, compared with a phosphate buffer solution (PBS), on the tear concentration after topical administration of gentamicin sulfate (GS) in humans. Eight volunteers received 25 microliters 0.5% GS in PBS in the left eye and 25 microliters 0.5% GS in 0.25% SH in the right eye. Tear samples of 1 microliters were taken from the inferior sulcus using a capillary before instillation and 5, 10, 20, and 40 min after instillation. The tear concentration of GS was determined by radioimmunoassay. There was a statistically significantly higher concentration of GS in the inferior conjunctival sulcus of the SH-instilled eye at 5 min (P < 0.01) and at 10 min (P < 0.05) after instillation (paired t-test, n = 9). At 20 min the concentration of GS in the SH-instilled eye was only slightly higher, and at 40 min GS concentrations in left and right eyes were comparable. SH 0.25% used as a vehicle therefore increases the availability of GS at the ocular surface for at least 10 min. This effect could be due to the prolonged precorneal residence time of SH.
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Affiliation(s)
- S F Bernatchez
- Department of Pharmaceutical Technology, University of Geneva, Switzerland
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40
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Vyas SP, Ramchandraiah S, Jain CP, Jain SK. Polymeric pseudolatices bearing pilocarpine for controlled ocular delivery. J Microencapsul 1992; 9:347-55. [PMID: 1403485 DOI: 10.3109/02652049209021249] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The pseudolatex-based ocular formulations of pilocarpine were prepared using different combinations of Eudragit RS 100 and polyvinyl pyrrolidone for prolonged and controlled release of the drug. The designed system was essentially based on polymeric pseudolatex dispersion. The process variables that effect the latex particle size, drug loading and release profiles of drug were studied. Preparations were evaluated for their in vitro performance with regard to release profile and diffusion co-efficient. The designed system exhibited linear relationship between cumulative drug release (Q) and square root of time (t0.5). The products selected on the basis of in vitro characterization were studied for in vivo performance evaluation. It was observed that the preparations exhibited in vivo prolonged therapeutic efficacy. Thus polymer based pseudolatices hold promise for controlled pilocarpine ocular delivery.
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Affiliation(s)
- S P Vyas
- Pharmaceutics Laboratories, Department of Pharmaceutical Sciences, Sagar, India
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41
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Podder SK, Moy KC, Lee VH. Improving the safety of topically applied timolol in the pigmented rabbit through manipulation of formulation composition. Exp Eye Res 1992; 54:747-57. [PMID: 1623960 DOI: 10.1016/0014-4835(92)90030-v] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The objective of this study was to compare the efficiency of various formulations in maximizing the ratio of ocular to systemic absorption of topically applied timolol in the pigmented rabbit. Formulations of various pHs, tonicities, and concentrations of benzalkonium chloride, EDTA, poly(vinyl alcohol), poly(vinylpyrrolidone), hydroxypropylcellulose, and Na hyaluronate were tested. Ocular absorption was determined by monitoring the timolol concentration in various anterior segment tissues 30 min after instillation of timolol solution, while systemic absorption was determined by monitoring the time course of timolol concentration over 120 min. Timolol was assayed by reversed-phase HPLC. Lowering the solution tonicity to 80 mosmol kg-1 and incorporating polymers into the formulation were the only approaches that promised to improve the safety of topically applied timolol, since they afforded the desired increase in ocular absorption and reduction in systemic absorption. Lowering the solution pH to 6.4 and increasing the tonicity of the solution to 600 mosmol kg-1 reduced systemic absorption but caused either no change or a decrease in ocular absorption. Raising the solution pH to 8.4 and incorporating 0.025% benzalkonium chloride and 0.5% EDTA into the formulation led to an undesirable increase in systemic absorption although ocular absorption was also increased. In the final analysis, the net effect of formulation changes on the ratio of ocular to systemic absorption depended on the interplay of changes in solution drainage; permeability of the cornea, conjunctiva, and nasal mucosa; and fraction of drug in the preferentially absorbed form.
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Affiliation(s)
- S K Podder
- Department of Pharmaceutical Sciences, University of Southern California, School of Medicine, Los Angeles 90033
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43
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Saettone M, Giannaccini B, Chetoni P, Torracca M, Monti D. Evaluation of high- and low-molecular-weight fractions of sodium hyaluronate and an ionic complex as adjuvants for topical ophthalmic vehicles containing pilocarpine. Int J Pharm 1991. [DOI: 10.1016/0378-5173(91)90051-o] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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44
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Kyyrönen K, Urtti A. Effects of epinephrine pretreatment and solution pH on ocular and systemic absorption of ocularly applied timolol in rabbits. J Pharm Sci 1990; 79:688-91. [PMID: 2231330 DOI: 10.1002/jps.2600790808] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The ratio between ocular and systemic drug concentrations describes the relative safety of ophthalmic dosage forms of the same drug in terms of its systemic side effects. In this study, we evaluated the effects of epinephrine pretreatment and solution pH on the aqueous humor:plasma and iris-ciliary body:plasma ratios of peak timolol concentrations after ocular application of timolol. Timolol eyedrops (5 mg/mL, 25 microL) were applied ocularly in pigmented rabbits. Raising pH of the eyedrops from 6.2 to 7.5 did not affect the ratio between ocular and systemic peak drug concentrations, since both ocular and systemic concentrations of timolol were increased. Administration of epinephrine (20 mg/mL, 50 microL) 5 min prior to timolol eyedrop administration reduced the peak timolol concentrations in plasma 65-80%. Epinephrine did not affect the ocular concentrations of timolol. The decreased peak concentrations in plasma were due to the conjunctival and nasal vasoconstricting effects of epinephrine and to the subsequent slower absorption of timolol. Our study demonstrates that compared with currently available eyedrops (pH 6.9), the ocular:systemic concentration ratio of ophthalmic timolol can be improved four- to sixfold in rabbits by combining epinephrine-induced conjunctival and nasal vasoconstriction and improved ocular absorption from pH 7.5 eyedrops.
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Affiliation(s)
- K Kyyrönen
- Department of Pharmaceutical Technology, University of Kuopio, Finland
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45
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Ludwig A, Unlü N, Van Ooteghem M. Evaluation of viscous ophthalmic vehicles containing carbomer by slit-lamp fluorophotometry in humans. Int J Pharm 1990. [DOI: 10.1016/0378-5173(90)90039-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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46
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Ludwig A, Van Ooteghem M. The evaluation of viscous ophthalmic vehicles by slit lamp fluorophotometry in humans. Int J Pharm 1989. [DOI: 10.1016/0378-5173(89)90328-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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47
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Camber O, Edman P. Sodium hyaluronate as an ophthalmic vehicle: some factors governing its effect on the ocular absorption of pilocarpine. Curr Eye Res 1989; 8:563-7. [PMID: 2743795 DOI: 10.3109/02713688908995755] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Sodium hyaluronate, as an additive to aqueous ophthalmic formulations, has been claimed to increase the ocular contact time and, thereby, the drug bioavailability. In the present study, the effect of sodium hyaluronate on corneal residence time and drug absorption in rabbits was investigated. Addition of sodium hyaluronate (0.125%) to a 3H-pilocarpine HCl solution resulted in increased retention of radioactivity in tear fluid and a 2-fold increase in drug concentration in the cornea and aqueous humor. Further, the effects of concentration and molecular weight of sodium hyaluronate on the miosis induced by pilocarpine in rabbits were studied. A significant increase of miotic response was seen at concentrations just less than 0.1% sodium hyaluronate. Pilocarpine solutions prepared from high mol.wt. sodium hyaluronate exhibited a greater miotic response than those prepared from lower mol.wt. samples. This might indicate that other physicochemical properties of sodium hyaluronate influence drug bioavailability.
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Affiliation(s)
- O Camber
- Department of Pharmaceutics, University of Uppsala, Sweden
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48
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Saettone MF, Giannaccini B, Delmonte G, Campigli V, Tota G, La Marca F. Solubilization of tropicamide by poloxamers: physicochemical data and activity data in rabbits and humans. Int J Pharm 1988. [DOI: 10.1016/0378-5173(88)90060-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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50
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Chang SC, Chien DS, Bundgaard H, Lee VH. Relative effectiveness of prodrug and viscous solution approaches in maximizing the ratio of ocular to systemic absorption of topically applied timolol. Exp Eye Res 1988; 46:59-69. [PMID: 3342834 DOI: 10.1016/s0014-4835(88)80093-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The effectiveness of the prodrug approach in maximizing the ratio of ocular to systemic absorption of topically applied timolol was compared with that based on viscous solutions. The pigmented rabbit was the experimental animal. o-Butyryl timolol, a lipophilic ester prodrug of timolol, was found to be twice as effective as hyaluronic acid and poly(vinyl alcohol) solutions in enhancing the ocular absorption of timolol. In addition, it was slightly more effective than retaining the instilled dose in the conjunctival sac for 240 min via nasolacrimal blockade. On the other hand, due to its inability to minimize contact of the instilled dose with the nasal mucosa, o-butyryl timolol was less capable than the viscous solutions in reducing systemic drug absorption. But this could be corrected by reducing the instilled solution volume from 25- to 5 microliter, resulting in a nine-fold reduction in plasma timolol levels while still providing the same amount of drug in the aqueous humor as a five times higher dose of timolol. The net result was a 15-fold improvement in the ratio of ocular to systemic drug absorption, which was also achieved upon retaining the instilled dose in the conjunctival sac for 240 min. It thus appears that the approach based on improved corneal absorption would be as effective as that based on improved retention in the conjunctival sac in maximizing the ratio of ocular to systemic drug absorption, so long as a smaller instilled dose volume of the prodrug is used.
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Affiliation(s)
- S C Chang
- University of Southern California, School of Pharmacy, Los Angeles 90033
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