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Tropical Journal of Pharmaceutical Research
Pharmacotherapy Group, Faculty of Pharmacy, University of Benin, Benin City, Nigeria
ISSN: 1596-5996 EISSN: 1596-5996
Vol. 14, No. 10, 2015, pp. 1737-1748
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Bioline Code: pr15227
Full paper language: English
Document type: Research Article
Document available free of charge
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Tropical Journal of Pharmaceutical Research, Vol. 14, No. 10, 2015, pp. 1737-1748
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Formulation Optimization and In-vitro Evaluation of Oral Floating Captopril Matrix Tablets using Factorial Design
Ahsan, Muhammad; Abbas, Nasir; Hussain, Amjad; Saeed, Hamid; Shah, Pervaiz Akhtar; Mohammad, Sohail & Arshad, Muhammad Sohail
Abstract
Purpose: To develop a zero-order sustained release floating formulation of captopril, and optimize its
drug release for enhanced oral bioavailability.
Methods: A relatively new approach, 32 full factorial design, was used to formulate floating captopril
matrix tablets and to systematically optimize its drug release using varying levels of xanthan gum and
hydroxypropyl methylcellulose (HPMC) K100M polymers. Calcium carbonate was used as gasgenerating
agent. After setting the levels by preliminary trials, nine tablet formulations (F1 - F9) were
prepared by wet granulation method using Design Expert Software® - suggested combinations of
polymers. The concentrations of HPMC K100M (X1) and xanthan gum (X2) were chosen as control
variables. Conversely, the response variables selected were timed to release 50 % of the drug (t50%) at
6 h (Q6) and 12 h (Q12). Fourier transform infrared (FTIR) spectroscopy and differential scanning
calorimetry (DSC) were used to assess compatibility between the drug and the excipients. The validity
of the developed mathematical equations was assessed by designing three extra check-points.
Results: The response surface plots drawn demonstrated the suitability of the hydrophilic matrixforming
agents for formulating controlled release floating tablets of captopril. FTIR and DSC spectra
showed no noticeable incompatibility between drug and polymers in both physical mixtures and in
formulations. Floating time lag remained < 5.5 min with floating duration > 12 h. Considerable
agreement was observed between predicted and actual release parameters. Fitting the data into
different kinetic models showed that non-Fickian behavior for diffusion exponent (n) differed from 0.588
and 0.811.
Conclusion: Optimum formulation (F4) showed satisfactory release profile. Moreover, the study
successfully demonstrated influence of polymer blends in controlling release variables.
Keywords
Captopril; Xanthan gum; Hydroxy propyl methyl cellulose; Factorial design; Bioavailability
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