Stability studies on orthosiphon stamineus (benth) tablet formulations
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Date
2006
Authors
Mohammad Alduais, Mohammad All
Journal Title
Journal ISSN
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Abstract
The chemical stability of Orthosiphon stamineus was evaluated based on the
marker compounds of sinensetin, eupatorin and 3'-hydroxy-5,6,7,4'tetramethoxyflavone
(TMF) by accelerating stability testing according to the
ICH guidelines for stability testing of new drug substance and drug products.
Orthosiphon stamineus Benth (Lamiaceae) is one of the popular traditional
herbal medicines extensively used for many centuries in Southeast Asia like
Indonesia and Malaysia. Evaluation of the chemical stability of herbal drugs is
an important part of quality control of herbal drug preparation. Both
0. stamineus leaf powder and extract were prepared by wet granulation method
using carboxymethyl cellulose (CMC) as binder. Half of the tablets were coated
with hydroxypropylmethyl cellulose and polyethylene glycol as plasticizer. The
dried extract and leaf powder of 0. stamineus were considered as drug
substance while tablet and coated tablet as drug product. Samples were
exposed for a 6- month period, under four different temperature conditions and
relative humidity (30°C/ 65% RH, 40°C/ 75% RH, 50°C/ 85% RH, and 60°C/
85% RH). Samples were analysed monthly for six months using
chromatographic methods such as HPLC and HPTLC and spectroscopic
methods such as FT-IR and UV-Visible spectrophotometry. The experimental
data were used to evaluate rate constants, half-lives, and activation energies for
the decomposition of marker compounds in 0. stamineus. The quantitative
analysis for the determination of shelf life was carried out using HPLC method
based on the quantification of major chemical markers, sinensetin, TMF and
eupatorin.
A prediction of the shelf life of the product was made by accelerating the
decomposition process and extrapolating the results to normal storage
conditions. Due to this reason stability tests were performed under exaggerated
conditions (e.g. elevated temperatures) in order to accelerate degradation
process for fast stability prediction. Arrhenius equation was applied to predict
the shelf life (tgo) of marker compounds at room temperature. The chemical
fingerprinting using HPTLC, UV-Vis and FTIR with Chemometrics showed that
the active constituents in 0. stamineus stored at 30°C/ 65% RH remain stable
during the period of study. Based on the shelf life of t90 (90% of active
component of the drug still available) the shelf life at 25°C were as follows: leaf
product 13.3 months, leaf tablet 14.2 months, leaf coated tablet 17.2 months,
extract 12.9 months, extract tablet 16.2 months and extract coated tablet 23.2
months. Coated tablet gave higher degree of stability as compared to noncoated
tablets and crude drug (leaf powder or extract) because the coating
material reduces the effect of oxygen and moisture on the stability of the
compound. Tablets also gave better shelf life as compared to crude drug (leaf
powder or extract). This is may be due to the presence of excipients and
binding agents which gives some degree of protection to the active compounds.
Description
Keywords
Orthosiphon stamineus (benth) , Tablet formulations