چکیده (انگلیسی):

The objective of this study was to design oral controlled release
matrix tablets of lamivudine using hydroxypropyl
methylcellulose (HPMC) as the retardant polymer and to
study the effect of various formulation factors such as polymer
proportion, polymer viscosity, and compression force
on the in vitro release of drug. In vitro release studies were
performed using US Pharmacopeia type 1 apparatus (basket
method) in 900 mL of pH 6.8 phosphate buffer at 100 rpm.
The release kinetics were analyzed using the zero-order model
equation, Higuchi’s square-root equation, and the Ritger-
Peppas empirical equation. Compatibility of the drug with
various excipients was studied. In vitro release studies revealed
that the release rate decreased with increase in polymer
proportion and viscosity grade. Increase in compression
force was found to decrease the rate of drug release. Matrix
tablets containing 60% HPMC 4000 cps were found to show
good initial release (26% in first hour) and extended the
release up to 16 hours. Matrix tablets containing 80% HPMC
4000 cps and 60% HPMC 15 000 cps showed a first-hour
release of 22% but extended the release up to 20 hours.
Mathematical analysis of the release kinetics indicated that
the nature of drug release from the matrix tablets was dependent
on drug diffusion and polymer relaxation and therefore
followed non-Fickian or anomalous release. No incompatibility
was observed between the drug and excipients used in
the formulation of matrix tablets. The developed controlled
release matrix tablets of lamivudine, with good initial release
(20%-25% in first hour) and extension of release up to 16 to
20 hours, can overcome the disadvantages of conventional
tablets of lamivudine.