Parul Nigam
Assistant Professor, Rama University, Kanpur
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Author: Parul Nigam
Journal: Pexacy International Journal of Pharmaceutical Science
Volume/Issue: Volume 2, Issue 5
Page Range: 12-23
Publication Date: 12/05/2023
Contact: parulnigamm@gmail.com
Abstract- The limited solubility of Rebamipide, a therapeutic agent used for treating gastrointestinal disorders such as peptic ulcers, often restricts its bioavailability. This study focuses on enhancing the solubility of Rebamipide through the development of solid dispersions using polyethylene glycol 4000 (PEG-4000) and polyvinylpyrrolidone K-30 (PVP K-30) as hydrophilic carriers. Various formulation techniques, including solvent evaporation, co-precipitation, and melt extrusion, were employed to prepare these solid dispersions. Comprehensive physicochemical characterization was performed to assess the properties of the formulated dispersions. The study found a marked increase in the solubility and dissolution rate of Rebamipide in the solid dispersions compared to its pure form. The optimized solid dispersion formulation, particularly with PEG-4000 and PVP K-30, exhibited enhanced bioavailability in pharmacokinetic evaluations. These findings suggest that the use of PEG-4000 and PVP K-30 in the formulation of solid dispersions for Rebamipide can significantly improve its solubility, thereby offering a promising avenue for more effective treatment of gastrointestinal disorders.
Keywords- Rebamipide, Solid Dispersion, PEG-4000, PVP K-30, Solubility Enhancement, Bioavailability, Gastrointestinal Disorders, Solvent Evaporation, Co-precipitation, Melt Extrusion.
Article can be accessed online on: PEXACY International Journal of Pharmaceutical Science
*Corresponding Author- parulnigamm@gmail.com
Update: Received on 04/05/2023; Accepted; 09/05/2023, Published on; 12/05/2023
Introduction
In present scenario, tablet is considered as one of the best solid dosage forms due to its easy preparation method and administration1. From all the types of tablet, the oral disintegration form is the most acceptable and suitable for all the age-group of patients. With the help of saliva in the mouth these can easily be disintegrate and dissolved2. This class is also useful for sustained action treatments, for example in case of dysphagia. If the solubility of such class of drug has been increased, it will be more useful and acts more rapidly3. To increase the disintegration and pharmacokinetics of this class of drugs, solid dispersion technique has been used. By performing this technique, not only the dissolution rate of drug increases but also the chances of toxicity will get reduced4.
Solid dispersion has been defined as “Dispersion of one or more active substances in a hydrophilic transport or substrate generated by fusion, solvent, or melting solvent technique in a solid state.” Solid dispersion increases porosity of the drug and hence, solubility also increases. It is also responsible for transforming insoluble drugs into an amorphous state, which allows for greater solubility5. Enhancing the wetting properties of the substances surface, as well as particle size reduction and improving the interfacial area accessible for drug dissolution, can help increase drug dissolution rates from a solid dispersion6.
Materials and Methods
Rebamipide was purchased from Global Scholar Scientific Solutions, (Lucknow); Polyvinyl Pyrrolidone K-30 from Yarren Chem Products, (Mumbai); Poly-ethylene glycol 4000 from S.D. Fine-Chem, Ltd, (Mumbai); Potassium dihydrogen phosphate from Merck Ltd., (Mumbai); Ethanol from Changshu Hongsheng Fine Chemical co. Ltd.; Sodium hydroxide pellets and Hydrochloric acid from Thermo Fisher Scientific Pvt. Ltd. (Mumbai).
Methodology
The methodology comprises of following steps-
- Preparation of Calibration Curve-
- Preparation of std. curve in phosphate buffer
- Preparation of std. curve in 0.1N Hcl
- Preparation of Solid dispersion by solvent evaporation method
Preparation of Calibration curve
The preparation of calibration curve of pure drug was performed with the help of UV spectroscopy.
- Preparation of standard curve in phosphate buffer (pH 6.8)
10 mg of drug Rebamipide was accurately weighed and placed in a100 ml volumetric flask containing some amount of solvent then made the volume up to 100ml with phosphate buffer. The standard stock solution thus obtained was then serially diluted with phosphate buffer to get 2,4,6,8,10μg/ml.The absorbance of the solution was determined using phosphate buffer as blank,at 226nm.The absorbance value was plotted against concentration to obtain the calibration curve.
- Preparation of standard curve in 0.1 N HCl
10 mg of drug Rebamipide was accurately weighed and placed in a100 ml volumetric flask containing some amount of solvent then madethe volume up to 100ml.The standard stock solution thus obtained was then serially diluted with 0.1 N HCl to get 2,4,6,8,10μg/ml.The absorbance of the solution was determined using 0.1N HCl as blank,at 224nm.The absorbance value was plotted against concentration to obtain the calibration curve.
Preparation of solid dispersion by solvent evaporation method
Rebamipide solid dispersion were prepared by solvent evaporation method. Different carriers(PVP K-30, PEG-4000) used in different ratio as shown in table (1). The drug and carrier were taken separately in different ratio(1:1, 1:2, 1:3) wt:wt and transferred into motar pestle and triturate to form a mixture. Add 25 ml of ethanol and mix properly. The content transfer into a beaker and heat for 5-10min at 30-40˚C.The solvent was removed by leaving it for 24 hr .The dried solidifing mass were scraped,crushed and grinded in mortar and pestle and pass through sieve no 60 and store in closed container.
Formulation table:
| Formulation code | Drug(Rebamipide) | PEG-4000 | PVP K-30 |
| F1 | 200mg | – | 200mg |
| F2 | 200mg | – | 400mg |
| F3 | 200mg | – | 600mg |
| F4 | 200mg | 200mg | – |
| F5 | 200mg | 400mg | – |
| F6 | 200mg | 600mg | – |
Characterization of solid dispersion
(a) Partical size determination
The particle sizewas determined using optical microscopy. A tleast 100 particles of solid dispersion were counted for precise size distribution.
(b) Determination of production yield
The production yield of solid dispersion of various batches were calculated using the weight of final product with respect to the initial total weight of the drug and polymer used and percent production yield were calculated as per the formula mentioned below-
Percentage yield = Practical yield/ Theoretical yield*100
(c) Determination of drug content
A sample of dried 10 mg of solid dispersion was taken in a 10 ml volumetric flask containing some amount of phosphate buffer pH6.8 and made up volume up to 10 ml with phosphate buffer.Filter it through the whatman filter paper.Drug content was determined by UV spectrophotometer at 226nm.
(d) Solubility studies
An excess amount of pure drug and prepared solid dispersion were placed in contact with 10 ml of 0.1 N HCl and phosphate buffer in a closed container. The suspension were sonicated for 15 min and kept at constant temperature (37±0.5˚C) in a water bath. After 72hr. the suspension were filtered and diluted appropriately and quantified by UV spectroscopy at 226nm.
Spectrophotometric study
Standard solution of Rebamipide was prepared by dissolving 10 mg of drug in 100ml of 0.1 N HCl .The final concentration after dilution was 10μg/ml.The λ-max of Rebamipide was to be found 224nm.
Figure 1- UV analysis of Rebamipide
Calibration curve of Rebamipide in 0.1N HCl
STOCK SOLUTION (1) – 10 mg of Rebamipide dissolve in 100 ml of 0.1 N HCl to get the solution of 100μg/ml.
STOCK SOLUTION (2) – From stock solution (1),we take 10 ml and dilute up to 100ml with 0.1 N HCl to get the solution 10 μg/ml. From stock (2) we take 2,4,6,8,10ml and transfer to the 10 ml volumetric flask and final volume made with same solvent, then we get drug concentration 2,4,6,8,10μg/ml. The absorbance value of respective concentration at the wave length 224nm and plot the calibration curve.
| Conc.(μg/ml) | Abs. |
| 2 | 0.062 |
| 4 | 0.084 |
| 6 | 0.10 |
| 8 | 0.11 |
| 10 | 0.119 |
Calibration curve of Rebamipide in Phosphate buffer pH6.8
STOCK SOLUTION (1) – 10 mg of Rebamipide dissolve in 100 ml of phosphate buffer to get the solution of 100μg/ml.
STOCK SOLUTION (2) – From stock solution (1),we take 10 ml and dilute up to 100ml with phosphate buffer to get the solution 10 μg/ml. From stock (2) we take 2,4,6,8,10ml and transfer to the 10 ml volumetric flask and final volume made with same solvent,then we get drug concentration 2,4,6,8,10μg/ml.The absorbance value of respective concentration at the wave leanth 224nm and plot the calibration curve.
| Conc.(μg/ml) | Abs. |
| 2 | 0.026 |
| 4 | 0.035 |
| 6 | 0.059 |
| 8 | 0.064 |
| 10 | 0.080 |
Figure 2- Standard plot of Rebamipide in phosphate buffer
Particle size analysis
Particle size was determined using optical microscope. At least100 particles of solid dispersion were counted for precise size distributation. The particle size distribution of solid dispersion of F1 to F6 was found to be 70μm, 65μm, 45μm, 67μm, 63μm, 37μm respectively.
Production yield
Production yield of solid dispersion determined for all formulation F1 to F6 70.1% to 85%.It was indicated that the formulation F4 has higher production yield.(shown in below table)
| F1 | 0.30 gm | 75% |
| F2 | 0.421gm | 70.1% |
| F3 | 0.612gm | 76.5% |
| F4 | 0,340gm | 85% |
| F5 | 0.49gm | 81.6% |
| F6 | 0.584gm | 73% |
Drug content studies
The drug content studies was determined in phosphate buffer through UV-spectometer at λ-max 224 nm. The percentage drug content shown in below table:
| Formulation | Absorbance | Concentration | %drug content |
| F1 | 0.044 | 4.68 mg | 93.6 |
| F2 | 0.036 | 3.52 mg | 105.6 |
| F3 | 0.027 | 2.21 mg | 88.4 |
| F4 | 0.039 | 3.95 mg | 79 |
| F5 | 0.038 | 3.81 mg | 110 |
| F6 | 0.031 | 2.79 mg | 101 |
Solubility studies
The solubility studies of Rebamipide and all the formulation was studied in both solvent (i.e. 0.1 N HCl and Phosphate buffer pH 6.8).
In 0.1 N HCl the formulation F3 shown good solubility while in solvent phosphate buffer the formulation F5 show good solubility.
Solubility data in 0.1N HCl :
| Formulation | Abs. | Conc./ml |
| Rebamipide | 0.069 | 250μg |
| F1 | 0.208 | 1987μg |
| F2 | 0.493 | 5550μg |
| F3 | 0.817 | 9600μg |
| F4 | 0.229 | 2250μg |
| F5 | 0.101 | 650μg |
| F6 | 0.079 | 375μg |
Solubility data in Phosphate buffer (pH 6.8):
| Formulation | Abs. | Conc./ml |
| Rebamipide | 0.325 | 4540μg |
| F1 | 0.393 | 5526 μg |
| F2 | 0.382 | 5366 μg |
| F3 | 0.389 | 5468 μg |
| F4 | 0.252 | 3482 μg |
| F5 | 0.551 | 7815 μg |
| F6 | 0.435 | 6134 μg |
IR Spectroscopy
IR spectra are important record which gives sufficient information about the structure of a compound. FTIR spectra of solid dispersion (Rebamipide and poly ethylene glycol 4000) were obtain using FTIR spectrometer.
FTIR Spectral data of solid dispersion
| Frequency(cm-1) | Functional group |
| 3269 | O-H stretching carboxylic acid |
| 2881 | N-H stretching amine |
| 1725 | C=O stretching aldehyde |
| 1643 | C=C stretching alkene |
| 1540 | N-O stretching nitro compound |
| 1466 | C-H bending alkane |
| 1422 | O-H bending carboxylic acid |
| 1279 | C-O stretching aromatic ester |
| 757 | C-Cl stretching |
Scanning electron microscopy (SEM)
SEM pictures of selected formulation (F5) was presented in below figure. It showed irregular shaped glassy appearance in addition to size reduction. The smaller particle size lead to great the wetted area, and hence the better solubility.
Conclusion
The drug (Rebamipide) have potent anti-ulcer property but fails to show the desired action due to less oral bioavailability.
The physiochemical evaluation of drug concludes that it belong to BCS-IV system i.e. low solubility low permeability and among the present conventional drug delivery system the solid dispersion was found as one of the best carrier system for the delivery of drug through oral route.
As per the data obtain from the evaluation study it was found that among the prepared set of formulations F1, F2 ,F3, F4, F5, F6 the formulation F5 possess best result in reference to estimation of drug content, formulation F3 possess good solubility in .1N HCL, Formulation f 5 showed better solubility in PBS (6.8) as compare to pure drug.
The above experiment conclude that the incorporation of drug within the system enhances the solubility of drug molecule.
References
- Ramesh V, Meenakshi S, Jyothirmayee N, Bullebbai M, Noorjahan SK, Rajeswari G, Nagesh Babu G, Madhavi D (2016) Enhancement of solubility, dissolution rate and bioavailability of BCS Class II Drugs. Int J Pharma Chem Res 2(2):80–95
- BhaskarR MO, Ravindra MG (2018) Review: solid dispersion techniques for enhancement of solubility of poorly soluble drug. Ind. J. Pharma Bio Res 6(2):43–52
- Hussain MD, Saxena V, Brausch JF, Talukder RM. Ibuprofen–phospholipid solid dispersions: Improved dissolution and gastric tolerance. Int J Pharm . 2012;422(1–2):29
- Kim HK, Kim JI, Kim JK, Han JY, Park SH, Choi KY, Chung IS Dig Dis Sci. 2007 Aug; 52(8):1776-82. Preventive effects of rebamipide on NSAID-induced gastric mucosal injury and reduction of gastric mucosal bloRebamipide, a mucoprotective drug, inhibits NSAIDs-induced gastric mucosal injury: possible involvement of the downregulation of 15-hydroxyprostaglandin dehydrogenase.
- 8. Tanigawa T, Watanabe T, Ohkawa F, Nadatani Y, Otani K, Machida H, Okazaki H, Yamagami H, Watanabe K, Tominaga K, Fujiwara Y, Takeuchi K, Arakawa T J Clin Biochem Nutr. 2011 Mar; 48(2):149-53. od flow in healthy volunteers.
- 9.Review article: rebamipide and the digestive epithelial barrier. Matysiak-Budnik T, Heyman M, Mégraud F Aliment Pharmacol Ther. 2003 Jul; 18 Suppl 1():55-62
- 10.A randomized controlled trial of rebamipide plus rabeprazole for the healing of artificial ulcers after endoscopic submucosal dissection. Fujiwara S, Morita Y, Toyonaga T, Kawakami F, Itoh T, Yoshida M, Kutsumi H, Azuma T J Gastroenterol. 2011 May; 46(5):595-602.
- 21. Konno H, Handa T, Alonzo DE, Taylor LS. Effect of polymer type on the dissolution profile of amorphous solid dispersions containing felodipine. Eur J Pharm Biopharm . 2008;70(2):493–9. 22. Lust A, Laidmäe I, Palo M, Meos A, Aaltonen J, Veski P. et al. Solid-state dependent dissolution and oral bioavailability of piroxicam in rats. Eur J Pharm Sci . 2013;48(1–2):47–54.
- 23. Nepal PR, Han H-K, Choi HK. Enhancement of solubility and dissolution of Coenzyme Q10 using solid dispersion formulation. Int J Pharm . 2010;383(1–2):147–53.
- 24. Vo CL, Park C, Lee BJ. Current trends and future perspectives of solid dispersions containing poorly water-soluble drugs. Eur J Pharm Biopharm . 2013;85(3 Pt B):799–813.
- 25. Adibkia K, Barzegar-Jalali M, Maheri-Esfanjani H, Ghanbarzadeh S, Shokri J, Sabzevari A. et al. Physicochemical characterization of naproxen solid dispersions prepared via spray drying technology. Powder Technol . 2013;246:448–55.
- Sakurai K, Sasabe H, Koga T, Konishi T. Mechanism of hydroxyl radical scavenging by rebamipide: Identification of mono-hydroxylated rebamipide as a major reaction product. Free Radic Res. 2004;38: 487–94.
- Sun, M., Deng, Z., Shi, F., Zhou, Z., Jiang, C., Xu, Z. … & Zhang, W. (2020). Rebamipide-loaded chitosan nanoparticles accelerate prostatic wound healing by inhibiting M1 macrophage-mediated inflammation via the NF-κB signaling pathway. Biomaterials Science.
- Nguyen, T. T., Hwang, K. M., Kim, S. H., & Park, E. S. (2020). Development of novel bilayer gastro retentive tablets based on hydrophobic polymers. International journal of pharmaceutics, 574, 118865.
- Narala, A., Guda, S., & Veerabrahma, K. (2019). Lipid Nanoemulsions of Rebamipide: Formulation, Characterization, and In Vivo Evaluation of Pharmacokinetic and Pharmacodynamic Effects. AAPS PharmSciTech, 20(1), 26.
- Kudur, M. H., & Hulmani, M. (2013). Rebamipide: A novel agent in the treatment of recurrent aphthous ulcer and Behcet’s syndrome. Indian journal of dermatology, 58(5), 352
- Chauhan, B., Shimpi, S., Paradkar, A. Preparation and evaluation of glibenclamide – polyglycolized glycerides solid dispersions with silicon dioxide by spray drying techniques. Eur. J. Pharm. Sci. 2005, 26 (2): 219-230.
- Chaumeil, J. C. Micronization: A method of improving the bioavailability of poorly soluble drugs. Methods and findings in Exp. Cli. Pharmac.. 1998, 20 (3): 211-215.
- Chiou, W.L., Riegelman, S. Pharmaceutical applications of solid dispersion systems. J. Pharm. Sci. 1971, 60 (9): 281–1285.
- Charman, S. A., Charman, W. N., Rogge, M. C., Wilson, T. D., Dutko, F. J., Pouton, C. W., Self-emulsifying drug delivery system: Formulation and biopharmaceutical evaluation of an investigational lipophilic compound. Pharm. Res. 1992, 9 (1): 87-93.