Effect of formulation parameters on the drug release and floating properties of gastric floating two-layer tablets with acetylsalicylic acid

Floating dosage forms of acetylsalicylic acid, used for its antithrombotic effect, were developed to prolong gastric residence time and increase bioavailability. In the two-layer tablet formulation, hydroxypropyl methylcellulose (HPMC) of high viscosity and an effervescent mixture of citric acid and sodium bicarbonate formed the floating layer. The release layer contained the drug, direct tableting agent and different types of matrix-forming polymers such as HPMC of low viscosity, sodium carboxymethylcellulose and chitosan. Tablets were prepared using a direct compression technique. The effect of formulation variables on physicochemical and floating properties and the drug release from tablets were investigated. Floating ability was dependent on the amount of effervescent agent and gel-forming polymer of the floating layer. Drug release was prolonged to 8 hours by changing the type and viscosity of the matrix-forming polymer in the drug-loading layer and all formulations showed a diffusion release mechanisms. U radu su opisane plutajuće tablete acetilsalicilne kiseline za antikoagulacijsku upotrebu s produljenim zadržavanjem u želucu i većom bioraspoloživošću. Plutajući dio tih dvoslojnih tableta sadržavao je hidroksipropil metilcelulozu (HPMC) visoke viskoznosti i efervescentnu smjesu limunske kiseline i natrijevog hidrogenkarbonata. Drugi sloj sadržavao je ljekovitu tvar, sredstvo za izravno tabletiranje i različite vrste matriksnog polimera poput HPMC niske viskoznosti, natrijeve soli karboksimetilceluloze i kitozana. Tablete su pripravljene metodom izravne kompresije. Ispitivan je utjecaj formulacijskih varijabli na fizikokemijska i plutajuća svojstva, te oslobađanje ljekovite tvari. Plutajuća svojstva ovise o količini efervescentnih tvari i gelirajućeg polimera u plutajućem sloju. Promjenom vrste i viskoznosti polimera u matriksnom sloju s lijekom produljeno je oslobađ anje ljekovite tvari na 8 sati. Iz svih formulacija ljekovita tvar oslobađala se difuzijom.