Determination of naloxone and nornaloxone (noroxymorphone) by high-performance liquid chromatography-electrospray ionization- tandem mass spectrometry.
Article Details
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Fang WB, Chang Y, McCance-Katz EF, Moody DE
Determination of naloxone and nornaloxone (noroxymorphone) by high-performance liquid chromatography-electrospray ionization- tandem mass spectrometry.
J Anal Toxicol. 2009 Oct;33(8):409-17. doi: 10.1093/jat/33.8.409.
- PubMed ID
- 19874646 [ View in PubMed]
- Abstract
A highly sensitive method was developed to measure naloxone and its metabolite nornaloxone in human plasma, urine, and human liver microsomes (HLM). Naltrexone-d(3) and oxymorphone-d(3) were used as respective internal standards. Solid-phase extraction, using mixed mode extraction columns and 0.1 M phosphate buffer (pH 5.9), was combined with high-performance liquid chromatography interfaced by electrospray ionization to tandem mass spectrometry. The calibration range in plasma was 0.025 to 2 ng/mL for naloxone and 0.5 to 20 ng/mL for nornaloxone. It was 10 to 2000 ng/mL in urine and 0.5 to 20 ng/mL in HLM for both. Enzymatic hydrolysis of urine was optimized for 4 h at 40 degrees C. Intra- and interrun accuracy was within 15% of target; precision within 13.4% for all matrices. The mean recoveries were 69.2% for naloxone and 32.0% for nornaloxone. Analytes were stable in plasma and urine for up to 24 h at room temperature and in plasma after three freeze-thaw cycles. In human subjects receiving 16 mg buprenorphine and 4 mg naloxone, naloxone was detected for up to 2 h in all three subjects and up to 4 h in one subject. Mean AUC(0-24) was 0.303 +/- 0.145 ng/mL.h; mean C(max) was 0.139 +/- 0.062 ng/mL; and T(max) was 0.5 h. In 24-h urine samples, about 55% of the daily dose was excreted in either conjugated or unconjugated forms of naloxone and nornaloxone in urine. When cDNA-expressed P450s were incubated with 20 ng of naloxone, nornaloxone formation was detected for P450s 2C18, 2C19, and 3A4. Naloxone utilization exceeded nornaloxone formation for 2C19 and 3A4, indicating they may produce products other than nornaloxone. These results demonstrate a new method suitable for both in vivo and in vitro metabolism and pharmacokinetic studies of naloxone.
DrugBank Data that Cites this Article
- Drug Enzymes
Drug Enzyme Kind Organism Pharmacological Action Actions Naloxone Cytochrome P450 2C18 Protein Humans UnknownSubstrateDetails Naloxone Cytochrome P450 2C19 Protein Humans UnknownSubstrateDetails Naloxone Cytochrome P450 3A4 Protein Humans UnknownSubstrateInhibitorDetails