Lignocaine Plasma Levels following Topical Gel Application in Laparoscopic and Hysteroscopic Procedures

Abstract

The study aim was to determine plasma lignocaine concentrations resulting from topical application of a newly formulated, sterile two-pack lignocaine gel in laparoscopic and hysteroscopic procedures. This was an open label single-centre study in which six female patients underwent laparoscopy and six underwent hysteroscopy. One venous blood sample was extracted pre-gel application, followed by 10 samples over a 24 hour period following application. Samples were centrifuged, stored at -20°C and subsequently analysed for lignocaine and its metabolite, monoethyl-glycinexylidide. Application of gel in doses between 2.7 and 5.8 mg/kg of lignocaine resulted in a maximum plasma concentration in any patient of 1520 ng/ml lignocaine and 240 ng/ml monoethyl-glycinexylidide. These maximum concentrations were recorded in a patient undergoing a laparoscopic procedure and patients undergoing hysteroscopic procedures all recorded lower maximum concentrations compared with patients undergoing laparoscopy; the maximum observed concentrations in a patient having a hysteroscopy were 420 ng/ml lignocaine and 56 ng/ml of monoethyl-glycinexylidide.A new sterile two-pack topical lignocaine gel, applied at the end of laparoscopic and hysteroscopic procedures in doses up to 5.84 mg/kg, resulted in plasma lignocaine levels below those known to have the potential to cause central nervous system toxicity.