Emulgels were prepared by the homogenization technique. During the formulation stage, the goal was to select an optimal polymers ratio and adjust polymer concentration in order to obtain comparable viscosities between designed formulations and control oromucosal gel Anaftin. Briefly, TG in combination with XA (formulation F1) or TG solely (formulation F2) was gradually dispersed in water (in a ratio 6.0/86.3 for F1 and 5.0/87.3 for F2, respectively) and homogenized in an automatic mixing system (1400 rpm for 25 min, Unguator E/S Eprus, Poland). For formulation F3, GG was carefully dispersed in water at temperature 80 °C (polymer to water ratio 0.7/89.6), cooled to 30 °C and homogenized with TG in an automatic homogenizing system (1400 rpm, 25 min). Subsequently, a water solution of preservatives and lecithin in propylene glycol was successively added to gel bases under constant stirring. After that, the ricin oil was emulsified to base. ALA was dispersed in propylene glycol and homogenized with emulgel bases with the final concentration of 5% (w/w). Emulgels composition is shown in Table 2 . All formulations were kept in closed containers at 4 °C. Drug-free emulgel bases B1–B3 were additionally prepared for textural, mucoadhesive and safety studies. The pH of each sample was measured in three repetitions by a glass electrode of pH-meter Orion 3 Star (Thermo Scientific, Waltham, MA, USA).
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