Acta Pharm. 58 (2008) 151-162
Original research paper
Effect of various surfactants and their
concentration on controlled release of captopril from polymeric matrices
ALI NOKHODCHI, DAVOUD
HASSAN-ZADEH, FARNAZ MONAJJEM-ZADEH and NITA TAGHI-ZADEH
a.nokhodchi@kent.ac.uk
Medway School of Pharmacy, The University of Kent
and Greenwich, Central Ave., Chatham Maritime ME4 4TB, Kent, UK
Drug Applied
Accepted February 14, 2008
Various methods are available to
formulate water soluble drugs into sustained release dosage forms by retarding
the dissolution rate. One of the methods used to control drug release and thereby
prolong therapeutic activity is to use hydrophilic and lipophilic polymers. In
this study, the effects of various polymers such as hydroxypropyl
methylcellulose (HPMC), ethylcellulose (EC) and sodium carboxymethylcellulose
(CMC) and surfactants (sodium lauryl sulphate, cetyltrimethylammonium bromide
and Arlacel 60) on the release rate of captopril were investigated. The results
showed that an increase in the amount of HPMC K15M resulted in reduction of the
release rate of captopril from these matrices. When HPMC was partly replaced by
NaCMC (the ratio of HPMC/NaCMC was 5:1), the release rate of the drug
significantly decreased. However, there was no significant difference in
release rate of captopril from matrices produced with ratios of 5:1 and 2:1 of
HPMC/NaCMC. The presence of lactose in matrices containing HPMC and NaCMC
increased the release rate of captopril. It was interesting to note that
although partial replacement of HPMC by EC reduced the release rate of the drug
(ratio of HPMC/EC 2:1), the release rate was increased when the ratio of
HPMC/EC was reduced to 1:1. The effects of various surfactants on the release
rate of captopril from HPMC/EC 1:1 matrices were also investigated. The results
showed that the surfactants did not significantly change the release rate of
the drug. Release data were examined kinetically and the ideal kinetic models
were estimated for the drug release. The kinetic analysis of drug release data
from various formulations showed that incorporation of surfactants in HPMC/EC
matrices did not produce a zero-order release pattern.
Keywords: captopril, polymers, controlled
release, surfactant, release kinetic