Background: Despite all the technological progresses and conventional medical treatments, pain therapy remains a challenge for both children and adult patients.
Objective: The aim of the study was to identify new transdermal Lidocaine delivery systems that will ensure a controlled release, an improved availability and will finally enhance local pain control.
Materials and methods: The experimental animals were adult Wistar rats weighing between 180-200 g. At the beginning of the experiments, we induced an inflammatory pain by administering λ-carrageenan, using a previously known model. Subsequently, the animals were subjected to a battery of nociception tests: algesimeter, cold plate and hot plate. Once the paw edema was obtained, the tested substance containing Lidocaine or eutectic mixture of local anesthetics (EMLA) cream was applied on the hind paw. Since we wanted to identify if our substance causes any local effect, the samples were collected from the paw, from the area where it was administered.
Results: At algesimetric testing, it has been showed that the tested substance enters into its action slowly, up to 15 minutes after administration and reaches it maximum effect within 15-30 minutes, then the effect diminishes but does not disappear even at two hours. When compared to EMLA, the analgesic cream that exists in the markets, our substance has superior analgesic properties at 15 and respectively 30 minutes after administration. The effect of the tested substance is still present after two hours, lower than in the maximum range (15-30 minutes), but higher than EMLA's effect. The histopathological exam revealed an inflammatory reaction in all groups.
Conclusions: The tested substance proved analgesic properties longer and higher than EMLA but did not influenced the inflammatory reaction.