Topical gels of lidocaine HCl using cashew gum and Carbopol 940: Preparation and in vitro skin permeation

The present study was attempted to prepare novel topical gels of 4% lidocaine HCl using cashew gum and Carbopol 940. The prepared gels were evaluated for pH, viscosity, and in vitro skin permeation through excised porcine skin. The pH of these topical gels was found within the range of 5.98–6.06; whereas, the viscosity was found 4.58 × 106 to 4.88 × 106 cps. The in vitro skin permeation from these gels showed permeation flux range, 851.34 ± 9.16 to 1568.15 ± 14.03 μg/cm2/h. The highest permeation flux (1568.15 ± 14.03 μg/cm2/h) was observed, when 0.01% menthol was added, which was higher than that of the marketed 4% lidicaine HCl topical gel (1355.41 ± 10.92 μg/cm2/h). These topical gels found best-fit with Korsmeyer–Peppas model and almost the super case-II transport mechanism. The stability study revealed that these gels were physically stable without occurrence of syneresis.