P44: Detection and determination of methadone in oral fluid from patients admitted to a drug-maintenance program

Abstract

Introduction Oral fluid (OF) is a combination of gingival crevicular fluid (composition similar to serum) and fluid released from salivary glands (parotid, submandibular and sublingual). It is an alternative matrix that may have advantages over blood and urine for drug analysis among patients in treatment programs. OF can be collected painlessly, rapidly, non-invasively and the risk of adulteration is considered to be much lower. The aim of the present study is to investigate if OF can be used as alternative to urine and blood samples to monitor drug abuse in opioid-dependent patients in methadone (MTD) maintenance therapy. Methods Gas chromatography-mass spectrometry has been applied for screening of MTD presence in OF. The liquid chromatography with conventional UV detection has been used for quantitative determination of MTD. The results are compared to those obtained from urine sample (GC-MS screening) and blood samples (HPLC quantitation) taken at the same time. The quantitative determination of MTD in OF is performed by based liquidliquid extraction (ethyl acetate) and that in blood – by solidphase extraction on mixed mode sorbent. Resultats There is a good correlation in identified drugs by the screening performed as well as MTD presence. MTD in OF was measured in concentration range from 0.08 to 3,10 μg/mL following daily 150 mg/day intake depending on time of sampling. The result is not directly related to MTD blood concentration (c.a. 0,20 μg/mL), as the kinetic is different in both samples. Conclusion OF can be considered as a suitable non-invasive sample for screening of MTD in opioid-dependent patients subjective on substitutive therapy. Depending on time of sampling the concentration of MTD is highly variable while that in blood seems to be more stable in time.