title: Noninvasive delivery systems for peptides and proteins in osteoporosis therapy: a retroperspective.
abstract: OBJECTIVE
  The aim of this review is to provide the reader general and inspiring prospects in various attempts to make noninvasive delivery systems of calcitonin and teriparatide feasible and as convenient as possible.
  
  
  BACKGROUND
  Calcitonin and teriparatide play an important role in both calcium homeostasis and bone remodelling. Currently calcitonin is available as a subcutaneous injection and as a nasal spray whereas teriparatide is administered subcutaneously. In the past few years, an increasing number of articles about drug delivery systems for calcitonin and teriparatide have been published. These delivery systems have been developed to overcome the inherent barriers for the uptake across the diverse membranes on the various routes for protein and peptide delivery.
  
  
  RESULTS
  Co-administration of permeation enhancers, mucoadhesive agents, viscosity modifying agents, multifunctional polymers, protease inhibitors as well as encapsulation and chemical modification are utilized in order to improve calcitonin and teriparatide absorption after oral, nasal, pulmonal, or buccal administration.
  
  
  CONCLUSIONS
  The majority of research groups have been working on the development of formulations based on the encapsulation of molecules in biodegradable and biocompatible polymeric nanoparticles. However these observations are based on data obtained under different experimental conditions. Hence, it is difficult to compare the obtained results in order to draw general conclusions about the most promising characteristics required for oral and nasal formulations for these peptides.
authors.affiliation: Department of Pharmaceutical Technology, Institute of Pharmacy, Leopold-Franzens-University Innsbruck, Innsbruck, Austria.
authors.forename: Herbert
authors.initials: H
authors.lastname: Hoyer
authors.forename: Glen
authors.initials: G
authors.lastname: Perera
authors.forename: Andreas
authors.initials: A
authors.lastname: Bernkop-Schnürch
mesh_terms: D000818:Animals; D050071:Bone Density Conservation Agents / Q000008:administration & dosage / Q000627:therapeutic use; D016723:Bone Remodeling / Q000187:drug effects; D002116:Calcitonin / Q000008:administration & dosage* / Q000627:therapeutic use; D002118:Calcium / Q000378:metabolism; D016503:Drug Delivery Systems; D005079:Excipients / Q000737:chemistry; D006801:Humans; D010024:Osteoporosis / Q000188:drug therapy*; D010455:Peptides / Q000008:administration & dosage / Q000627:therapeutic use; D011506:Proteins / Q000008:administration & dosage / Q000627:therapeutic use; D019379:Teriparatide / Q000008:administration & dosage* / Q000627:therapeutic use
chemical_list: D050071:Bone Density Conservation Agents; D005079:Excipients; D010455:Peptides; D011506:Proteins; D019379:Teriparatide; D002116:Calcitonin; D002118:Calcium