combining a drug such as fentanyl with an effervescent agent used as penetration enhancer to influence the permeability of the medicament in the oral cavity; compressing to form tabletUS2007003685315 Sep 200615 Feb 2007Cima Labs Inc.Generally linear effervescent oral fentanyl dosage form and methods of administeringEP0197504A23 Abr 198615 Oct 1986Merck & Co., Inc.pH-mediated drug delivery syst