title: Adhesive properties: a critical issue in transdermal patch development.
abstract: BACKGROUND
  Transdermal patches and medicated plasters (patch) represent well-established prolonged release dosage forms. Even if satisfactory adhesion to the skin is strictly linked to the efficacy and safety of the therapeutic treatment, nowadays numerous reports of in vivo 'adhesion lacking' are still addressed to regulatory agencies. The adhesive properties of a patch should be characterized considering i) the ability to form a bond with the surface of another material on brief contact and under light pressure (tack); ii) the resistance of the adhesive to flow (shear adhesion); and iii) the force required to peel away a patch from a surface (peel adhesion).
  
  
  METHODS
  In this manuscript, the most widely used methods to measure adhesive properties during development studies are described, along with the quality control of patches. The influence of formulative variables on patch adhesive properties, and their possible relationship with the in vivo adhesion performances, is also discussed.
  
  
  CONCLUSIONS
  The Pharmacopoeias should consider the opportunity of introducing compendial testing to assay the quality of adhesive patch properties, and regulatory agencies should issue proper guidelines to evaluate these features during development.
authors.affiliation: Università degli Studi di Milano, Department of Pharmaceutical Science, Via G. Colombo, 71-20131, Milano, Italy. francesco.cilurzo@unimi.it
authors.forename: Francesco
authors.initials: F
authors.lastname: Cilurzo
authors.forename: Chiara G M
authors.initials: CG
authors.lastname: Gennari
authors.forename: Paola
authors.initials: P
authors.lastname: Minghetti
mesh_terms: D000268:Adhesiveness; D000279:Administration, Cutaneous; D000818:Animals; D002626:Chemistry, Pharmaceutical; D016503:Drug Delivery Systems / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D004364:Pharmaceutical Preparations / Q000008:administration & dosage*; D012212:Rheology; D012869:Skin Absorption; D014014:Tissue Adhesives / Q000737:chemistry; D057968:Transdermal Patch
chemical_list: D004364:Pharmaceutical Preparations; D014014:Tissue Adhesives