Formulation of sublingual promethazine hydrochloride tablets for rapid relief of motion sickness

The delivery of antihistaminic agents via the oral route is problematic, especially for elderly patients. This study aimed to develop a sublingual formulation of promethazine hydrochloride by direct compression, and to mask its intensely bitter taste. Promethazine hydrochloride (PMZ) sublingual tablets prepared by direct compression were optimized using Box-Behnken full factorial design. The effect of a taste-masking agent (Eudragit E 100, X1), superdisintegrant (crospovidone; CPV, X2) and lubricant (sodium stearyl fumarate; SSF, X3) on sublingual tablets' attributes (responses, Y) was optimized. The prepared sublingual tablets were characterized for hardness (Y1), disintegration time (Y2), initial dissolution rate (IDR; Y3) and dissolution efficiency after 30 min (Dissolution Efficiency (DE); Y4). The obtained results showed a significant positive effect of the three independent factors on tablet hardness (P < 0.05), and the interactive effect of Eudragit E 100 and CPV on tablet hardness was significant. Disintegration time was mainly affected by Eudragit E 100 and CPV concentrations. Moreover, IDR was employed to assess the taste masking effect, lower values were obtained at higher Eudragit E 100 concentration despite it was statistically insignificant (p > 0.05). Optimized formulation that was suggested by the software was composed of: Eudragit E 100 (X1) = 2.5% w/w, CPV (X2) = 4.13% w/w, and SSF (X3) = 1.0% w/w. The observed values of the optimized formula were found to be close to the predicted optimized values. The Differential Scanning Calorimetric (DSC) studies indicated no interaction between PMZ and tablet excipients.