The objective of this work was to design a diclofenac epolamine (DE) flash tablets (FTs) intended to dissolve in the mouth saliva, thereby improving the DE bioavailability and reducing its first-pass liver metabolism. Design-Expert software was used to build a 31.22 full factorial design (12 runs). FTs were fabricated using lyophilization process. The dissolution response was selected to pick the optimized run. The results indicate that the optimized run (R1) showed the fastest drug dissolution (total dissolution in 12 min). The predicted run (Rp) showed a desirability of about 0.93. Differential scanning calorimetry(DSC) analysis results showed a decrease in the drug melting point of the R1 formulation. Fourier-transform infrared spectroscopy (FTIR) showed the compatibility of the drug with other components of formulation, X-ray powder diffraction (XRPD) analysis showed the evolution of the drug physical state from a crystalline to an amorphous form and scanning electron microscopy(SEM) divugled the disappearance of drug crystals in gelatin strands. The results of the pharmacokinetic study performed in 6 human volunteers evidenced an increase in the maximum DE concentration in plasma and, consequently, an increased bioavailability of the FT formulation as compared with a reference formulation(Fr). Concisely, the developed FTs (R1) showed promising results which could be able to enhance oral bioavailability, reduce the therapeutic dose of the drug, and abate of the complications accompanied with conventional dosage forms. Graphical abstract.
Keywords: Bioavailability; Diclofenac epolamine; Flash tablet; Glycine; Optimization; Sorbitol.