title: Development of Bilayer Tablets with Modified Release of Selected Incompatible Drugs.
abstract: BACKGROUND
  The oral route is considered to be the most convenient and commonly-employed route for drug delivery. When two incompatible drugs need to be administered at the same time and in a single formulation, bilayer tablets are the most appropriate dosage form to administer such incompatible drugs in a single dose.
  
  
  OBJECTIVE
  The aim of the present investigation was to develop bilayered tablets of two incompatible drugs; telmisartan and simvastatin.
  
  
  METHODS
  The bilayer tablets were prepared containing telmisartan in a conventional release layer using croscarmellose sodium as a super disintegrant and simvastatin in a slow-release layer using HPMC K15M, Carbopol 934P and PVP K 30 as matrix forming polymers. The tablets were evaluated for various physical properties, drug-excipient interactions using FTIR spectroscopy and in vitro drug release using 0.1M HCl (pH 1.2) for the first hour and phosphate buffer (pH 6.8) for the remaining period of time. The release kinetics of simvastatin from the slow release layer were evaluated using the zero order, first order, Higuchi equation and Peppas equation.
  
  
  RESULTS
  All the physical parameters (such as hardness, thickness, disintegration, friability and layer separation tests) were found to be satisfactory. The FTIR studies indicated the absence of interactions between the components within the individual layers, suggesting drug-excipient compatibility in all the formulations. No drug release from the slow-release layer was observed during the first hour of the dissolution study in 0.1M HCl. The release-controlling polymers had a significant effect on the release of simvastatin from the slow-release layer. Thus, the formulated bilayer tablets avoided incompatibility issues and proved the conventional release of telmisartan (85% in 45 min) and slow release of simvastatin (80% in 8 h).
  
  
  CONCLUSIONS
  Stable and compatible bilayer tablets containing telmisartan and simvastatin were developed with better patient compliance as an alternative to existing conventional dosage forms.
authors.affiliation: Department of Pharmaceutics, Laureate Institute of Pharmacy, Kathog, Tehsil-Dehra, Distt-Kangra, Himachal Pradesh, India.
authors.forename: Neha
authors.initials: N
authors.lastname: Dhiman
authors.affiliation: Department of Pharmaceutics, Laureate Institute of Pharmacy, Kathog, Tehsil-Dehra, Distt-Kangra, Himachal Pradesh, India.
authors.forename: Rajendra
authors.initials: R
authors.lastname: Awasthi
authors.affiliation: Department of Pharmaceutics, Laureate Institute of Pharmacy, Kathog, Tehsil-Dehra, Distt-Kangra, Himachal Pradesh, India.
authors.forename: Shammy
authors.initials: S
authors.lastname: Jindal
authors.affiliation: Ram-Eesh Institute of Vocational and Technical Education, Greater Noida, Uttar Pradesh, India.
authors.forename: Smriti
authors.initials: S
authors.lastname: Khatri
authors.affiliation: School of Pharmaceutical Sciences, Shoolini University, Solan, Himachal Pradesh, India.|School of Pharmacy and Biomedical Sciences, University of Newcastle, Newcastle, Callaghan NSW, Australia.
authors.forename: Kamal
authors.initials: K
authors.lastname: Dua
mesh_terms: D001562:Benzimidazoles / Q000008:administration & dosage* / Q000493:pharmacokinetics; D001565:Benzoates / Q000008:administration & dosage* / Q000493:pharmacokinetics; D002266:Carboxymethylcellulose Sodium; D004338:Drug Combinations; D004344:Drug Incompatibility; D065546:Drug Liberation; D065347:Hypromellose Derivatives; D007700:Kinetics; D019821:Simvastatin / Q000008:administration & dosage* / Q000493:pharmacokinetics; D013607:Tablets / Q000138:chemical synthesis*; D000077333:Telmisartan
chemical_list: D001562:Benzimidazoles; D001565:Benzoates; D004338:Drug Combinations; D013607:Tablets; D065347:Hypromellose Derivatives; D019821:Simvastatin; D002266:Carboxymethylcellulose Sodium; D000077333:Telmisartan; C584697:hypromellose 2208 (15000 MPA.S)
keywords: bilayer tablet; conventional release; incompatible; release kinetics; sustained release