This is a very interesting article from Australia regarding the bioavailability of cocaine following atomised application prior to endoscopic sinus surgery. The well-established practice of preparing the nasal mucosa for sinus surgery involves the placement of a usually modified Moffett’s solution into the nose via a variety of methods. It is important to establish the availability of cocaine in the body after surgery, particularly as this is normally practised as a day-case procedure. The author’s formula is 2mls of 5% cocaine with 1ml of 1:1000 adrenaline made up to 10mls with normal saline, giving a total of 100mg of cocaine. This is then placed into the nose using an atomiser in a head-down position for five minutes. Twelve adult patients with a mean age of 50 were enrolled; average BMI was 28. No patients had renal or liver disease. Exclusion criteria included those that used cocaine recreationally, had severe ischaemic heart disease or large volume nasal disease which may interfere with mucosal application. An IV cannula was placed at induction and all blood samples were taken from here. An initial sample was taken at 10 minutes prior to Moffett’s administration which occurred at time zero and further samples were obtained at 10, 20, 30, 60 minutes and at two, four, six and 12 hours. Samples were frozen and tested by a forensic science laboratory for cocaine and its principal degradation product benzoylecgonine. The samples were analysed using liquid chromatography mass spectrometry. Each run included a blank and quality control sample, all results were analysed twice and the mean reported. Six patients demonstrated a peak cocaine concentration at two hours post-administration (13-30ug/L), five patients peaked earlier at 60 minutes (14-31ug/L) and one patient at four hours (42ug/L). The mean weak concentration was 22.6ug/L.
The level of cocaine decreased steadily after the peak but was still detectable at six hours, however undetectable at 12 hours. The degradation product benzoylecgonine was first detected at 60 minutes in 11 patients, it was detected at 30 minutes in one patient. Peak levels were found two-to-six hours after administration, mean 81ug/L and was detected in all 12 patients at 12 hours, mean 51.7ug/L.
So, peak absorption of cocaine appears to occur at 60-120 minutes, cocaine may be detected at six hours post administration. The metabolite may still be detected at 12 hours. In the UK, the legal cut-offs for driving are 10ug/L for cocaine and 50ug/L for benzoylecgonine. It is therefore possible that a patient administered Moffett’s for endoscopic sinus surgery could fail this test at 12 hours post-administration, when discharged.