Preparation and characterization of bear bile-loaded pH sensitive in-situ gel eye drops for ocular drug delivery

Document Type: Original Article

Authors

1 School of Pharmaceutical Sciences, Sun Yat-sen University, University Town, Guangzhou 510006, PR China

2 Yunnan Dai Medicine Co., Ltd., Yunnan 678699, PR China

Abstract

Objective(s): In this study, a stable bear bile-loaded pH sensitive in-situ eye drop gel was prepared for sustain delivery and enhanced therapeutic application.
Materials and Methods: Bear bile-loaded in-situ ocular gels with different Carbopol/Hydroxypropyl methylcellulose (HPMC)  ratios were prepared and their stability was tested in PBS at a series of pH at 40 °C. The morphology was observed by SEM examination and rheology was observed by Rheometer equipped with a 60-mm cone-plate at apex angle of 1°. Gel erosion and release kinetics of Tauroursodeoxycholic acid (TUDCA) was determined by HPLC. While, the in vivo dwelling time was obtained after administering the fluorescent-loaded gel in ocular disease-free New Zealand rabbits. Finally, biocompatibility and toxicity was observed by irritation test and H&E staining of eye-ball tissues, respectively.
Results: The bear bile-loaded in-situ ocular gel showed excellent stability at different pH (pH 5.0, 5.5, 6.0, 6.5, 7.0 and 8.0) up to 5 days, and bear bile extract significantly attenuated the gelling ability of the in-situ gel. The viscosity of in-situ gels formulation was decreased with increase in shear rate (0.01 to 100 s-1), and morphological examination of freeze-dried preparation showed three-dimensional reticular structure at physiological pH. The in-situ ocular gel exhibited promising sustained drug release up to 160 min in vitro, and showed prolonged retention time up to 3-folds in vivo. Finally, the biocompability data confirmed that the formulation did not induce any toxic effects and was completely compatible with eye tissues.
Conclusion: pH sensitive in-situ ocular gel provides new research opportunities to efficiently treat eye diseases.

Keywords


1. Järvinen K, Järvinen T, Urtti A. Ocular absorption following topical delivery. Adv Drug Deliv Rev 1995;16:3-19.
2. Janagam DR, Wu L, Lowe TL. Nanoparticles for drug delivery to the anterior segment of the eye. Adv Drug Deliv Rev 2017; 122:31-64.
3. Weng Y, Liu J, Jin S, Guo W, Liang X, Hu Z. Nanotechnology-based strategies for treatment of ocular disease. Acta Pharm Sin B 2017; 7:281-291.
4. Huang M, Song J, Lu B, Huang H, Chen Y, Yin W, et al. Synthesis of taurine–fluorescein conjugate and evaluation of its retina-targeted efficiency in vitro. Acta Pharm Sin B 2014; 4:447-453.
5. He Zx, Wang Zh, Zhang Hh, Pan X, Su Wr, Liang D. Doxycycline and hydroxypropyl-β cyclodextrin complex in poloxamer thermal sensitive hydrogel for ophthalmic delivery. Acta Pharm Sin B 2011; 1:254-260    
6. Yu S, Wang Q-M, Wang X, Liu D, Zhang W, Ye T, et al. Liposome incorporated ion sensitive in situ gels for opthalmic delivery of timolol maleate. Int J Pharm 2015; 480:128-136.
7. Jaiswal M, Kumar M, Pathak K. Zero order delivery of itraconazole via polymeric micelles incorporated in situ ocular gel for the management of fungal keratitis. Colloids Surf B Biointerfaces 2015; 130:23-30.
8. He W, Guo X, Feng M, Mao N. In vitro and in vivo studies on ocular vitamin A palmitate cationic liposomal in situ gels. Int J Pharm 2013; 458:305-314.
9. Agrawal AK, Das M, Jain S. In situ gel systems as ‘smart’carriers for sustained ocular drug delivery. Expert Opin Drug Deliv 2012; 9:383-402.
10. Kotreka UK, Davis VL, Adeyeye MC. Development of topical ophthalmic in situ gel-forming estradiol delivery system intended for the prevention of age-related cataracts. PloS One 2017; 12:e0172306.
11. Gupta H, Aqil M, Khar R, Ali A, Bhatnagar A, Mittal G. An alternative in situ gel-formulation of levofloxacin eye drops for prolong ocular retention. J Pharm Bioallied Sci 2015; 7:9-14.
12. Duan Y, Cai X, Du H, Zhai G. Novel in situ gel systems based on P123/TPGS mixed micelles and gellan gum for ophthalmic delivery of curcumin. Colloid Surf B Biointerfaces 2015; 128:322-330.
13. Appiah S, Revitt M, Jones H, Vu M, Simmonds M, Bell C. Anti-inflammatory and hepatoprotective medicinal herbs as potential substitutes for bear bile.  Int Rev Neurobiology 2017; 135:149-180.
14. Chen Hw, Shen Al, Liu Ly, Peng J, Chu Jf. Bear bile powder inhibits growth of hepatocellular carcinoma via suppressing STAT3 signaling pathway in mice. Chin J Integr Med 2020;26:370-374.
15. Boatright JH, Nickerson JM, Moring AG, Pardue MT. Bile acids in treatment of ocular disease. J Ocul Biol Dis Infor 2009; 2:149-159.
16. Vang S, Longley K, Steer CJ, Low WC. The unexpected uses of urso- and tauroursodeoxycholic acid in the treatment of non-liver diseases. Glob Adv Health Med 2014; 3:58-69.
17. Li Y, Zhang X, Wang J, Sellers JT, Boyd AP, Nickerson JM, et al. Effect of systemic treatment with Tauroursodeoxycholic Acid (TUDCA) on retinal ganglion cell death following optic nerve crush. BioRxiv 2019; 733568.
18. Mandal S, Thimmasetty MK, Prabhushankar G, Geetha M. Formulation and evaluation of an in situ gel-forming ophthalmic formulation of moxifloxacin hydrochloride. Int J Pharm Investigat 2012; 2:78-82.
19. Draize JH, Woodard G, Calvery HO. Methods for the study of irritation and toxicity of substances applied topically to the skin and mucous membranes. J Pharmacol Exp Ther.1944; 82:377-390.
20. Luo Q, Chen Q, Wu Y, Jiang M, Chen Z, Zhang X, et al. [Chemical constituents of bear bile]. Zhongguo Zhong Yao Za Zhi 2010; 35:2416-2419.
21. Pal R, Rhodes E. Viscosity/concentration relationships for emulsions. J Rheol 1989; 33:1021-1045.
22. Silva JP, Dhall S, Garcia M, Chan A, Costa C, Gama M, et al. Improved burn wound healing by the antimicrobial peptide LLKKK18 released from conjugates with dextrin embedded in a carbopol gel. Acta Biomater 2015; 26:249-262.
23. Pal K, Banthia A, Majumdar D. Preparation of novel pH-sensitive hydrogels of carboxymethyl cellulose acrylates: A comparative study. Mater Manuf Process 2006; 21:877-882.
24. Zhang Y, Chu CC. Biodegradable dextran–polylactide hydrogel networks: Their swelling, morphology and the controlled release of indomethacin. J Biomed Mater Res 2002; 59:318-328.
25. Chauhan S, Nainwal N, Bisht T, Saharan V. An investigation of in-vitro release of rabeprazole sodium from pulsatile release tablet containing HPMC-EC blend as time lagged press coating. Int J Pharm Sci Res 2018; 9:2825-2831.
26. Mantopoulos D, Murakami Y, Comander J, Thanos A, Roh M, Miller JW, et al. Tauroursodeoxycholic acid (TUDCA) protects photoreceptors from cell death after experimental retinal detachment. PloS One 2011; 6:e24245.
27 Feng Y, Siu K, Wang N, Ng K-M, Tsao S-W, Nagamatsu T, et al. Bear bile: dilemma of traditional medicinal use and animal protection. J Ethnobiol Ethnomed 2009; 5:2.
28. Charoo NA, Kohli K, Ali A. Preparation of in situ‐forming ophthalmic gels of ciprofloxacin hydrochloride for the treatment of bacterial conjunctivitis: In vitro and in vivo studies. J Pharm Sci 2003; 92:407-413.
29. Varela-Garcia A, Concheiro A, Alvarez-Lorenzo C. Soluplus micelles for acyclovir ocular delivery: Formulation and cornea and sclera permeability. Int J Pharm 2018; 552:39-47.
30. Qin Y, Chang R, Ge S, Xiong L, Sun Q. Synergistic effect of glycerol and ionic strength on the rheological behavior of cellulose nanocrystals suspension system. Int J Biol Macromol 2017; 102:1073-1082.
31. Li C, Wang J, Wang Y, Gao H, Wei G, Huang Y, et al. Recent progress in drug delivery. Acta Pharm Sin B 2019;6:1145-1162.
32. Esposito S. “Traditional” sol-gel chemistry as a powerful tool for the preparation of supported metal and metal oxide catalysts. Materials 2019; 12:668.
33. Mohammad IS, Teng C, Chaurasiya B, Yin L, Wu C, He W. Drug-delivering-drug approach-based codelivery of paclitaxel and disulfiram for treating multidrug-resistant cancer. Int J Pharm. 2019; 557:304-313.