The present research was designed to evaluate different matrix, drug-in-adhesive and reservoir formulations of fentanyl transdermal patches. The target was to design drug-in-adhesive patches (DIAPs); a full factorial design was used. Different types and amounts of liquid, pressure-sensitive adhesives (PSAs) were used and evaluated with respect to drug release and adhesive properties. A very simple but precise method, the simplified peel 180° test, was developed to measure and compare adhesive properties of transdermal patches. The results showed that release kinetics obeyed the square root of time or Higuchi model, indicating the diffusion controlled release mechanism. It was found that the amount of fentanyl needed for each 10 cm2 three-days DIAP should be 3.3 mg. The respective amounts for reservoir and matrix patches were 2.5 and 5 mg. It was concluded that acrylic PSAs showed the best adhesion and release properties.U radu su evaluirani različiti matriksni, adhezivni i spremišni ljekoviti oblici za transdermalnu primjenu fentanila. U dizajniranju adhezivnih flastera (DIAPs) uspotrebljene su različite vrste i količine tekućih adheziva osjetljivih na tlak (PSAs). Evaluirano je oslobađanje ljekovite tvari i adhezivna svojstva. Za mjerenje i usporedbu adhezivnih svojstava transdermalnih flastera razvijena je vrlo jednostavna, ali precizna "metoda ljuštenja". Rezultati su pokazali da kinetika oslobađanja slijedi kvadratni korijen vremena (Higuchijev model), ukazujući da se ljekovita tvar oslobađa difuzijom. Pokazalo se da je za svakih 10 cm2 DIAP-a za trodnevnu uporabu potrebno 3,3 mg fentanila. Ta količina je za spremišne i matriksne flastere iznosila 2,5, odnosno 5 mg. Najbolja adhezivna svojstva i oslobađanje fentanila bilo je iz akrilatnih pripravaka
