DEVELOPMENT OF GASTRORETENTIVE FLOATING TABLETS OF
DILTIAZEM HYDROCHLORIDE AND ITS STATISTICAL OPTIMIZATION
VENKATA SRIKANTH MEKA*, KOHILA VANI A/P J GUDY, RAVI SHESHALA
School of Pharmacy, International Medical University, Kuala Lumpur-57000, Malaysia
*corresponding author: venkatasrikanthmeka@gmail.com
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Abstract:
This study aimed to develop gastroretentive floating tablets of diltiazem hydrochloride, using a release retarding polymer and
to apply statistical approach of response surface methodology for further formulation optimization. Response surface
methodology using the central composite design was used to study the effect of formulation variables on the floating lag
time (FLT), time taken for 90% of drug to be released (t90%) and total floating time (TFT), and to optimize the formulations.
The floating tablets were prepared using direct compression method using Polyethylene Oxide (PEO WSR) coagulant as the
release retarding polymer and sodium bicarbonate as the gas generating agent. A 32 factorial design was applied to optimize
the drug release profile. The quantity of PEO WSR coagulant and concentration of sodium bicarbonate were selected as the
independent variables. The floating lag time (FLT) and total floating time (TFT) of conventional formulations (BC1 - BC4)
were varied from 10 - 40 sec and 6-8 hrs respectively. The FLT of statistical formulations (BS1 - BS9) were in the range of 5
- 53 sec and the TFT for the same formulations were in the range of 0.12 - 10 hrs. The statistically optimized formula
suggested by the central composite design was 34.45 mg of PEO WSR coagulant and 30 mg of sodium bicarbonate. The
statistically optimized formulation passed all the physicochemical tests. From the in vitro buoyancy studies, the FLT of the
statistical optimized formulation (Bso) was found to be at 19 sec. The experimental t90% and TFT were 6.4 hours and 8.5
hours respectively. The calculated relative errors of all variables were within 5%, concluding that the statistically optimized
formulation is valid. The applied FTIR and DSC studies on the statistically optimized formulation led to the conclusion that
there were no interactions between drug and polymer.

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