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Iontophoretic delivery of transdermal patches containing lignocaine with clonidine and epinephrine in healthy volunteers: Effect of concentration of epinephrine and clonidine on local anesthesia

The ultimate aim of the initiating the study was find out effect of admixture of Clonidine and/or Epinephrine on Lignocaine. After co- administering clonidine (150 μg, n=20) or Epinephrine (200 μg, n=20) to Lignocaine, end points like sensory or motor blockade, depth of anesthesia, cool and hot sensation, plasma level of Lignocaine was studied. Total 60 subjects received the combination aforesaid formulation via iontophoretic patch. The prepared patches matched with standard measures required for transdermal delivery. The subjects in different groups shows resemblance in terms of age, height, body weight etc. Sedation score of motor or sensory blockade showed indifferent results. Only few subjects (n=2) showed complete freedom from any type of pain (3.34%) on administration of Epinephrine. VAS score in range of 0-7 was observed with that of clonidine (range 1-8). In subjects with clonidien plasma level concentration of Lignocaine found to be higher (3.2 μmol/L.) when compared to epinephrine (2.6 μmol/L) due to lack of vasoconstriction effect in epinephrine. This increase availability of Lignocaine reduces margin of safety with clonidine. Mild type of irritation persisting only for 2-5 min was observed in few patients entering the trial. No patient involved report swelling, itching, edema.

Author(s): Li Xiao, Tianzuo Li