In-vitro and In-vivo Relationship of Gabapentin from Floating and Immediate Release Tablets

Gabapentiniseffectiveagainst post-traumaticspinalinjury-inducedneuropathicpain.Itrequireshighdosageand frequency inthemanagementofneuropathicpain.Thepresentresearchworkwasanattempttoformulate andevaluategabapentingastro-retentivetabletstoprolonggastricresidenceandincreasedrug absorptionand furtherincreasebioavailability.Thefloatingtabletsofgabapentinwerepreparedintwodoses(300and600mg) byusingtwopolymers(hydroxylpropylmethylcelluloseandhydroxylpropylcellulose).Immediaterelease tabletsofgabapentincontaining thesamedoseswerepreparedandusedasreferenceformulations.The physicochemicalcharacteristicsofthepreparedtabletsweredetermined(drug content,weightvariation,friability, hardness,thicknessand diameter). Drugreleasefromthepreparedtabletswasfollowed and foundthatby increasingdrug concentrationinthetabletsreleaserateincreases.Floatingtabletsshowedprolongeddrugrelease (over96%)tomorethan15hrs.Immediatereleasetabletsshowedover97%drugreleasewithin48min.In-vivoresultsshowedthatplasmaexposuretogabapentininanimalsreceivingthedrug doesnotdose proportionalandtherefore maynotreachtherapeuticallyusefullevels.AUC0-24andCmaxincaseof300mgtabletsaremorethanthoseincaseof 600 mgtablets.Thein-vivo releaseofgabapentin doesnot correlatewiththein-vitroreleaseofthedrug.