The study of the analgesic and anti-edematous activity of purified naphthalan oil on the model of psoriasis

Aim. To study the analgesic and anti-edematous activity of test samples of soft dosage forms containing purified naphthalan oil (PNO) on the model of psoriasis-like skin lesions and with additional inflammation induced by carrageenan. Materials and methods. Psoriasis-like skin lesions were modeled by applying imiquimod to mice on a shaved area of the back skin. Additional inflammation was induced by injecting carrageenan under the plantar aponeurosis of the hind limb. The analgesic and anti-edematous effects of test samples of soft dosage forms containing PNO were studied, namely, an ointment with 10 % purified naphthalan oil and 3 % salicylic acid (PNO-SA), a cream with 10 % purified naphthalan oil and 0.064 % betamethasone dipropionate (PNO-BD), a cream with 10 % purified naphthalan oil and 10 % urea (PNO-U), and a cream with 10 % purified naphthalan oil, 0.064 % betamethasone dipropionate, and 10 % urea (PNO-BD-U). The analgesic effect of the test samples was assessed using the “tail flick” test to determine the pain threshold. The anti-edematous effect was evaluated by measuring the paw volume (standard units) using the plethysmometric method with the subsequent calculation of anti-edematous activity (AEA). Results. It was found that in mice with psoriasis-like skin lesions, test samples containing PNO did not exhibit algogenic effects or increase the pain sensitivity. The PNO-SA ointment demonstrated a statistically significant higher pain threshold or a tendency toward a higher pain threshold on Day 14 of the treatment. In conditions of additional pain induction by carrageenan, all groups receiving PNO test samples showed an increased pain threshold 4 hours after phlogogen administration. The PNO-SA, PNO-U, and PNO-BD-U test samples also exhibited higher pain threshold values compared to the pathology control group. These findings suggest the analgesic effect of soft dosage forms containing PNO. It was found that the highest anti-edematous effect was observed in the PNO-SA group 2 hours after carrageenan administration (AEA 78.6 %) and in the PNO-U group 4 hours after administration (AEA 91.7 %). At the same time, in the PNO-SA group, unlike the other groups, there was no statistically significant increase in the paw volume during the experiment. Conclusions. Among the test samples studied, PNO-SA is of the greatest interest taking into account the analgesic and anti-edematous activity. It is advisable to conduct further studies to assess the effectiveness and safety of this dosage form in models of psoriasis-like skin lesions in vitro and in vivo in order to develop a medicinal product for psoriasis treatment.