Formulation and Evaluation of Floating Mefenamic Acid Drug Delivery Tablet

2 Abstract: A new floating effervescent controlled-release drug delivery system having a density less than 1 was formulated in an effort to increase the gastric retention time of the dosage form, increase drug absorption and to control drug release. Different formulas were made as tablets by wet granulation technique, using polymers such as; Hydroxypropyl methylcellulose (HPMC) of different viscosity grades (HPMC100SR, HPMC4000SR, HPMC100000CP), carboxymethyl cellulose, methyl cellulose, sodium alginate and eudragit RS. The buoyancy was attributed to air entrapped in the polymer hydroxypropyl methyl cellulose (HPMC). Incorporation of a gas-generating agent together with polymer improved drug release, also the effect of citric acid on drug release and floating properties were studied. The study showed that tablet composition and mechanical strength have a great influence on the floating properties and drug release. It was found that HPMC viscosity had a significant effect on the release and floating properties of the delivery system. Ten formulas were prepared and it was that (F3) containing HPMC K4M mixed with sodium bicarbonate was selected as the best effervescent floating formula that gave sustained mefenamic acid release over 24hrs, with a short lag time (3 seconds) and floating duration 24 hrs. The stability of the prepared tablets F3 was studied at 50, 60 and 70°C for four months and the expected expiration date using Arrhenius plot was 3.1 years at 25°C. On the other hand, the in vivo radiographic studies were performed with Barium sulphate loaded formulation (F3) to justify the increased gastric residence time of the dosage form in the stomach, based on the floating principle was given to 3 male volunteers. X-ray studies showed that the appearance of the tablet in the upper part of the stomach confirms its floating behavior. The change in position of the formulations proves that they does not adhere to the mucous and remained floating for 24 hrs, indicated that gastric retention time was increased by the floating principle.