Reference interval determination for anabasine: a biomarker of active tobacco use.

Laboratory detection of nicotine exposure is important for establishing eligibility for organ transplant and elective surgery. Nicotine testing is also used to verify compliance with nicotine replacement therapies (NRT), smoking cessation programs and for life insurance purposes. Nicotine metabolites, such as cotinine and trans-3'-hydroxycotinine, are used as biomarkers of nicotine exposure. For some clinical applications, it is important to distinguish between active use of tobacco products versus NRT. Anabasine is a tobacco alkaloid that has been used as a biomarker of active tobacco use. However, the use of anabasine as an insecticide, and its presence in consumables other than nicotine products, suggests that anabasine may not be specific to tobacco use/exposure. Here, we determine the reference interval for anabasine in the urine of nonsmokers and compare it to the range of anabasine concentrations observed in the presence or absence of nicotine metabolites.

Patterns of free (unconjugated) buprenorphine, norbuprenorphine, and their glucuronides in urine using liquid chromatography-tandem mass spectrometry.

Patterns of buprenorphine and metabolites were examined in 1946 positive urine samples analyzed by liquid chromatography-tandem mass spectrometry for free (unconjugated) buprenorphine and norbuprenorphine (quantitative, 2 to 1000 ng/mL) and buprenorphine-glucuronide (B3G) and norbuprenorphine-glucuronide (N3G) (semi-quantitative, 5 to 1000 ng/mL). Two distribution patterns predominated with 49.1% positive for norbuprenorphine, B3G, and N3G and 41.6% positive for buprenorphine, norbuprenorphine, B3G, and N3G. Buprenorphine, positive in 45.5% of samples, was mostly < 5 ng/mL (median 6.1 ng/mL), but 9.8% were > 1000 ng/mL. Norbuprenorphine, B3G, and N3G had semi-Gaussian distributions with medians of 64.7, 108, and 432 ng/mL, respectively. With buprenorphine < 100 ng/mL (767 samples) or ≥ 100 ng/mL (19 quantifiable samples), the respective median metabolic ratios (free norbuprenorphine/free buprenorphine) were 25.0 and 0.15. In 12 retested "> 1000 ng/mL" buprenorphine samples, free buprenorphine was 4160 to 39,400 ng/mL and free naloxone 2140 to 9560 ng/mL. In 87 subsequent samples with buprenorphine < 20 ng/mL, naloxone concentrations were < 50 ng/mL. Concentrations of buprenorphine > 100 ng/mL (particularly with low metabolite concentrations) are suspect of urine adulteration with medication (4% in the database) that can be checked in most cases by concurrent analysis for naloxone.