title: Formulation and In-vitro Characterization of Sustained Release Matrix Type Ocular Timolol Maleate Mini-Tablet.
abstract: The purpose of this study was preparation and evaluation of sustained release matrix type ocular mini-tablets of timolol maleate, as a potential formulation for the treatment of glaucoma. Following the initial studies on timolol maleate powder, it was formulated into ocular mini-tablets. The polymers investigated in this study included cellulose derivatives (HEC, CMC, EC) and Carbopol 971P. Mannitol was used as the solubilizing agent and magnesium stearate as the lubricant. Mini-tablets were prepared by through mixing of the ingredients, followed by direct compression. All the prepared formulations were evaluated in terms of physicochemical tests, including uniformity of weight, thickness, crushing strength, friability and in-vitro drug release. Four groups of formulations were prepared. The presence of different amounts of cellulose derivatives or Carbopol 971P, alone, was studied in group A formulations. In group B formulations, the effect of adding Carbopol 971P alongside different cellulose derivatives was investigated. Group C formulations were made by including mannitol as the solubilizing agent, alongside Carbopol 971P and a cellulose derivative. In group D formulations, mini-tablets were made using Carbopol 971P, alongside two different cellulose derivative. The selected formulation (C1) contained ethyl cellulose, Carbopol 971P, mannitol and magnesium stearate, which showed almost 100% drug release over 5 h. Based on kinetic studies, this formulation was found to best fit the zero-order model of drug release. However, the Higuchi and Hixson -Crowell models also showed a good fit. Hence, overall, formulation C1 was chosen as the best formulation.
authors.affiliation: Department of Pharmaceutics, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Seyed Alireza
authors.initials: SA
authors.lastname: Mortazavi
authors.affiliation: Department of Pharmaceutics, Pharmaceutical Sciences Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Jafariazar
authors.affiliation: Department of Pharmaceutics, Pharmaceutical Sciences Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Yasaman
authors.initials: Y
authors.lastname: Ghadjahani
authors.affiliation: Department of Pharmaceutics, Pharmaceutical Sciences Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Hoda
authors.initials: H
authors.lastname: Mahmoodi
authors.affiliation: Department of Pharmaceutics, Pharmaceutical Sciences Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Farzaneh
authors.initials: F
authors.lastname: Mehtarpour
keywords: Carbopol 971P; Cellulose derivative; Kinetics models; Mini-tablet; Ocular drug delivery; Sustained release; Timolol maleate
references.citation: AAPS PharmSciTech. 2007 Dec 28;8(4):E118
references.pmid: 18181539
references.citation: Iran J Pharm Res. 2013 Winter;12(Suppl):21-30
references.pmid: 24250668
references.citation: J Ocul Pharmacol Ther. 1996 Fall;12(3):245-52
references.pmid: 8875330
references.citation: Iran J Pharm Res. 2010 Spring;9(2):107-14
references.pmid: 24363715
references.citation: Iran J Pharm Res. 2013 Winter;12(Suppl):3-10
references.pmid: 24250666
references.citation: J Pharm Bioallied Sci. 2011 Apr;3(2):280-5
references.pmid: 21687359
references.citation: J Ocul Pharmacol Ther. 2012 Aug;28(4):350-8
references.pmid: 22320419
references.citation: J Pharm Sci. 1963 Dec;52:1145-9
references.pmid: 14088963