Formulation and evaluation of bilayer tablets of diltiazem HCl
Ravi Jalonya*, Pushpendra Soni, Kapil Malviya, Lavakesh Kumar Omray
ONLINE ISSN : 2456-8244ABSTRACT
The present investigation concerns development of bilayer floating tablets of Diltiazem HCl
is class I drug, though its reported bioavailability is only 40 %. It is having very short half life
of 3 to 4 hr. Hence many sustained release formulations were developed for diltiazem HCl.
But they take lag time to start the action. Hence a new approach is tried that gives one
immediate release dose and a sustained release dose in single dosage form call bilayer tablets.
Immediate release layer delivers the initial dose, it contains superdisintegrant which increase
drug release rate whereas sustained release layer float due to gas generating agent and releases
drug at sustained manner for prolonged period. A direct compression method was used to
formulate 9 batches. Superdisintegrants like sodium croscarmellose, crospovidone was used
for immediate release layer and HPMC K4 M, HPMC K 15 M, PVP K30 like polymers were
used in floating layer. A simple visible spectrophotometric method was employed for the
estimation of diltiazem at 236 nm and Beer’s law is obeyed in the concentration range of 5-25
μg/ml. Preformulation studies were carried out to optimize the ratios required for various
grades of polymers. The prepared floating tablets were evaluated for hardness, weight
variation, thickness, friability, drug content uniformity, buoyancy lag time, total floating time,
water uptake (swelling index), and in vitro dissolution studies. Successful formulation was
developed having floating lag time as low as 30 sec and drug release was sustained up to 12
hrs. A biphasic drug release can be obtained by using bilayer tabletting technology which
involved compression of immediate and sustained release layer together. Bilayered floating
tablets with release characteristics offer critical advantages such as, site specificity with
improved absorption and efficacy. This technology can be inculcated to various medicaments
which have stomach as the major site of absorption.
KEYWORDS
Bilayer floating tablets, Diltiazem HCl, Biphasic drug release, HPMC K 15 M
DOI
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