Conscious and anaesthetised Göttingen mini-pigs as an in-vivo model for buccal absorption - pH-dependent absorption of metoprolol from bioadhesive tablets

Drug Dev Ind Pharm. 2014 May;40(5):604-10. doi: 10.3109/03639045.2014.884119. Epub 2014 Feb 7.

Abstract

The potential of buccal mucosa as a site for systemic absorption has attracted increased attention in recent years creating a need for new predictive in-vivo models. The aim of this study was to evaluate anaesthetised and conscious Göttingen mini-pigs as a model for buccal drug absorption by testing pH-dependent absorption of metoprolol from a solid dosage form. Buccal tablets buffered to pH 6.2 and pH 8.9, oral liquid and intravenous injection were tested in four conscious and anaesthetised Göttingen mini-pigs in a non-randomised cross-over study. Blood samples were collected and processed before analysis by ultra-performance liquid chromatography with tandem mass spectrometry detection. An ex-vivo flow retention model was applied to study release and retention of the bioadhesive buccal tablets. The Tmax obtained from the two buccal conscious groups (55 ± 5 and 35 ± 5 min) were significantly different to the buccal anaesthetised groups (120 ± 0 and 165 ± 15 min) for buccal tablet pH 6.2 and pH 8.9, respectively. Also, the absolute bioavailability from the anaesthetised buccal tablet pH 8.9 (20.7 ± 4.0%) had a significant increase compared to all other buccal tablet groups. In conclusion, this study showed a pH-dependent absolute bioavailability of metoprolol when administrated as bioadhesive buccal tablets to anaesthetised mini-pigs. The anaesthesia was found to delay the time to reach maximal plasma concentration of metoprolol as compared to the conscious pig model when administrated as buccal tablets.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adhesives
  • Anesthesia
  • Animals
  • Biological Availability
  • Chemistry, Pharmaceutical
  • Consciousness
  • Cross-Over Studies
  • Dosage Forms
  • Hydrogen-Ion Concentration
  • Injections, Intravenous
  • Male
  • Metoprolol / administration & dosage*
  • Metoprolol / blood
  • Metoprolol / pharmacokinetics*
  • Models, Animal
  • Oral Mucosal Absorption / physiology*
  • Swine
  • Swine, Miniature / metabolism*
  • Tablets

Substances

  • Adhesives
  • Dosage Forms
  • Tablets
  • Metoprolol