title: Formulation development of gastroretentive tablets of lamivudine using the floating-bioadhesive potential of optimized polymer blends.
abstract: OBJECTIVE
  The current studies entail successful formulation of optimized gastroretentive tablets of lamivudine using the floating-bioadhesive potential of carbomers and cellulosic polymers, and their subsequent in-vitro and in-vivo evaluation in animals and humans.
  
  
  METHODS
  Effervescent floating-bioadhesive hydrophilic matrices were prepared and evaluated for in-vitro drug release, floatation and ex-vivo bioadhesive strength. The optimal composition of polymer blends was systematically chosen using central composite design and overlay plots. Pharmacokinetic studies were carried out in rabbits, and various levels of in-vitro/in-vivo correlation (IVIVC) were established. In-vivo gamma scintigraphic studies were performed in human volunteers using (99m) Tc to evaluate formulation retention in the gastric milieu.
  
  
  RESULTS
  The optimized formulation exhibited excellent bioadhesive and floatational characteristics besides possessing adequate drug-release control and pharmacokinetic extension of plasma levels. The successful establishment of various levels of IVIVC substantiated the judicious choice of in-vitro dissolution media for simulating the in-vivo conditions. In-vivo gamma scintigraphic studies ratified the gastroretentive characteristics of the optimized formulation with a retention time of 5 h or more.
  
  
  CONCLUSIONS
  Besides unravelling the polymer synergism, the study helped in developing an optimal once-a-day gastroretentive drug delivery system with improved bioavailability potential exhibiting excellent swelling, floating and bioadhesive characteristics.
authors.affiliation: University Institute of Pharmaceutical Sciences (UGC Centre of Advanced Studies), Panjab University, Chandigarh 160 014, India. bsbhoop@yahoo.com
authors.forename: Bhupinder
authors.initials: B
authors.lastname: Singh
authors.forename: Babita
authors.initials: B
authors.lastname: Garg
authors.forename: Subhash Chand
authors.initials: SC
authors.lastname: Chaturvedi
authors.forename: Sharry
authors.initials: S
authors.lastname: Arora
authors.forename: Rachana
authors.initials: R
authors.lastname: Mandsaurwale
authors.forename: Rishi
authors.initials: R
authors.lastname: Kapil
authors.forename: Baljinder
authors.initials: B
authors.lastname: Singh
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000269:Adhesives / Q000737:chemistry*; D000328:Adult; D002482:Cellulose / Q000737:chemistry*; D002626:Chemistry, Pharmaceutical; D003692:Delayed-Action Preparations; D016503:Drug Delivery Systems; D005260:Female; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D019259:Lamivudine / Q000008:administration & dosage* / Q000097:blood; D008297:Male; D012995:Solubility; D013270:Stomach; D055815:Young Adult
chemical_list: D000180:Acrylic Resins; D000269:Adhesives; D003692:Delayed-Action Preparations; C479038:carbomer; D019259:Lamivudine; D002482:Cellulose