HPMC K15M and chitosan mixed matrices can be used to modify release rates in hydrophilic matrix tablets prepared by direct
compression. Incorporating the highly porous low-density copolymer (approximately 12%) in the matrix tablets provides densities
that were lower than that of the release medium. These tablets floated almost immediately upon contact with the release medium,
showing no lag times (unlike conventional floating systems) in floating behavior because low density is provided from the
beginning (t = 3 s). Extended floating times are achieved because of the air entrapped within the low-density copolymer particles, which
is only slowly removed from the system upon contact with the release medium. As expected, tablets without low density copolymer
(e.g., consisting of 40 mg polymer and 40 mg famotidine) sank to the bottom of the vessel showing no floating behavior. Faster
release of the drug from the hydrophilic matrix was probably a result of faster dissolution of the highly water-soluble drug
from the core and its diffusion out of the matrix forming the pores for entry of solvent molecules. Therefore, one can formulate
floating dosage forms that can show excellent floating lag times using low-density copolymer and achieve desired release profile.
James R. Benson (chairman, CEO, president), Nai-Hong Li (research director), and Finny Bhathena (representative in India)
of Polygenetics are acknowledged for their kind support of the research work.
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J.A. Raval, PhD,* is an assistant professor in the department of pharmaceutics and pharmaceutical technology at Shree S.K.
Patel College of Pharmaceutical Education and Research, Ganpat Universiy, Kherva-382711, Gujarat, India, tel. and fax 91 2762
. M.M. Patel is a principal at Kalol Institute of Pharmacy (Kalol, Gujarat, India). Nai-Hong Li is a research director at
Polygenetics (Los Gatos, CA). J.K. Patel is a principal at Nootan Pharmacy College (Visnagar, Gujarat, India).
*To whom all correspondence should be addressed.
Submitted: Dec. 15, 2008. Accepted: Feb. 19, 2009.