Myrrh Resin (Commiphora myrrha) As Rate Controlling Excipient In Sustained Release Matrix Tablets of Theophylline: Evaluation, Formulation and Optimization Study
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Date
2014-12
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Addis Ababa University
Abstract
Myrrh is an oleo-gum resin, obtained from the stem of various species of Commiphora, Family
Burseraceae. The chief source is Commiphora myrrha. Myrrh is phytotoxically safe raw material
in industries like pharmaceuticals and food industries. The plant based excipients have been
studied for their application in different pharmaceutical dosage forms like matrix sustained
release system.
Theophylline is used as bronchodilator in the management of asthma and chronic obstructive
pulmonary disease. Its narrow therapeutic index (10-20 μg/ml) requires suitable formulation
strategies and sustained-release oral formulations have emerged as the most useful approach.
The aim of this study was to investigate the myrrh resin from Commiphora myrrha as a rate
controlling excipient for sustained release matrix tablets of theophylline.
The moisture content and total ash values of myrrh resin was found to be 4.67±0.577% and
0.24±0.047%, respectively. The sustained release matrix tablets of theophylline were prepared
by wet granulation technique using myrrh resin as rate controlling excipient. The hardness of
different formulations were found to be between 89.8±2.86 and 133.7±3.53N while all tablets
have passed the friability test (<1%). Analysis of dissolution data of the formulations indicated
that the best fitting is with first order kinetics, whereas the mechanism of drug release pattern
follows anomalous or non-fickian diffusion.
The myrrh resin amount (A) and compression force (B) were selected as independent variables
and drug release at 1 h (rel1 h), 12 h (rel12 h) and time to 50% drug release (t50%) were taken as the
response variables. Therefore, the effects of myrrh resin amount (A) and compression force (B)
were further studied and optimized for the desired outputs using central composite design
statistical approach. Design-Expert 8.0.7.1 software was employed to carry out the experimental
design, statistical analysis, numerical and graphical optimization.
By comparing several statistical parameters, linear model was selected for both rel1 h and rel12 h
whereas quadratic model was found to be the best fit model for t50%. The adequacy of the models
was checked by analysis of variance (ANOVA). The ANOVA results revealed that both models
II
have significant values indicating the terms in the models have significant effect (P < 0.05) on
the responses except the interaction effect (AB) of quadratic model which was found to be
insignificant. Model simplification was carried out by eliminating this term (AB) in polynomial
equations in order to improve the model.
Optimization was achieved by simultaneous optimization of rel1 h, rel12 h and t50%. An optimum
region of 24.981%, 91.217% and 2.861 h was obtained by the software for rel1 h, rel12 h and t50% ,
respectively when 17.5% myrrh resin amount (MRA) and 13.9 KN compression force (CF) was
used. The kinetic study showed the optimized formulation followed first order kinetics model
with anomalous release mechanism.
In validation of the optimized formulation, the experimental values were found to be in close
agreement with the predicted values confirming the predictability and validity of the model. This
demonstrated that the optimization technique was successful in designing the theophylline
sustained release matrix tablet formulation by using myrrh resin as rate controlling excipient.
The Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy
(FTIR) analysis confirmed the absence of incompatibility between theophylline and the myrrh
resin. Therefore, the myrrh resin can be used as a potential alternative rate controlling excipient
for sustained release formulation.
Keywords: Myrrh resin, theophylline, sustained release, matrix tablet, optimization, central
composite design
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Keywords
Myrrh resin; theophylline; Sustained release; Matrix tablet; Optimization; Central composite design