LC-MS/MS techniques for high-volume screening of drugs of abuse and target drug quantitation in urine/blood matrices.

Liquid chromatography-tandem mass spectrometry, employing electrospray ionization (ESI), has been applied in the analysis of many drugs and drug metabolites. Sample preparation has been an important part of this technique when analyzing biological samples. Here we describe a high-volume urine screening technique for approximately 40 different drugs of abuse as well as methods for quantification of many other drugs in serum, plasma, and whole blood. These techniques can be used in many different settings from clinical and forensic toxicology examinations to pharmacokinetic studies. Sample preparation procedures range from simple "dilute and shoot" methods to more extensive solid-phase extraction techniques.

Opiate screening and quantitation in urine/blood matrices using LC-MS/MS techniques.

Here we describe a high-volume urinary screening technique for opiate drugs as well as other narcotic analgesics. We also describe methods for quantification of the same drug species in serum, plasma, and whole blood. Screening and quantitation of these types of drugs have presented many challenges, among them the potentially low levels in both abuse and therapeutic situations. Liquid chromatography-tandem mass spectrometry (LC-MS/MS), employing electrospray ionization (ESI), has been able to provide the sensitivity needed for the analysis of many drugs and metabolites. These techniques can be used in many different settings from clinical and forensic toxicology examinations to pharmacokinetic studies and, with appropriate considerations, be applied to different sample matrices. Sample preparation procedures range from simple "dilute and shoot" methods to more extensive solid-phase extraction techniques.

Drugs of abuse testing by tandem mass spectrometry: a rapid, simple method to replace immunoassays.

PRIMARY OBJECTIVE: To replace immunoassay screening for drugs of abuse (DOA) with a cost-effective tandem mass spectrometry method. SECONDARY OBJECTIVE: To substantially expand the drugs of abuse assay menu. DESIGN AND METHODS: The requirement was to perform high throughput DOA screening for 200 urine specimens/day for 40 drugs/metabolites. The total analysis time had to be <5 min. We used UPLC chromatography, small particle size LC columns and fast scanning tandem mass spectrometry. Urine samples were hydrolyzed enzymatically, diluted and injected with isotopically labeled internal standards. The data produced was transferred by exporting reports as text files to a LIMS system followed by auto certification of the results. RESULTS: 40 different drugs were separated by UPLC (ultra pressure liquid chromatography) with a run time of 5.2 min. Detection limits were below our cut-off values. Individual drug species instead of drug classes were identified; correlation with GC/MS was excellent. A high throughput, robust assay with acceptable accuracy, precision and specificity was developed. The procedure can also be used as a quantitative method with simple modifications. CONCLUSIONS: An improved, high throughput, cost-effective method for drugs of abuse screening has been implemented. GC/MS confirmations were reduced or eliminated. The new procedure is a viable alternative to our previous immunoassay method. Acceptable turn around times, an expanded menu, simplified sample preparation and analytical reliability makes this method a desirable option in the clinical laboratory setting.

Formate pharmacokinetics during formate administration in folate-deficient young swine.

The objective of the study was to investigate the effect of folate deficiency on formate pharmacokinetics during formate administration in folate-deficient young swine. Methanol is a one of the congeners found in alcoholic beverages. Methanol toxicity is mediated through formic acid and thus plays a significant role in the pathophysiology of alcoholism. Folate is a required cofactor in the metabolism of formate to CO(2) and H(2)O. We investigate the effect of folate deficiency on the pharmacokinetics of formate. Twelve young pigs were pair-matched and randomly placed into 2 groups on acquisition ( approximately 5 weeks). One group was made folate deficient (FFD) by feeding with a folic acid-deficient diet; the other group (FFC) was fed a diet supplemented with folate. Four animals (31-38 kg) from each group were infused (intravenous) with 351 mg/kg of sodium formate. The remaining 2 animals were infused with isotonic sodium chloride solution. Blood samples were collected before and at 10, 20, 30, 45, 60, 90, 120, 180, 240, and 480 minutes post dose and analyzed for formate levels by gas chromatography. Pharmacokinetic parameters were estimated using a noncompartmental approach. Formate (mean +/- SE) accumulation was higher in the FFD group than the FFC group (AUC(0-infinity) of 72.37 +/- 8.29 vs 30.08 +/- 2.58 g min/L, respectively). Elimination was also slower in the FFD group (FFD systemic clearance = 0.12 +/- 0.01 L/min compared with FFC systemic clearance = 0.27 +/- 0.02 L/min). Half-life of elimination was 2.5 times longer in FFD group (113 +/- 1 minute) than in FFC group (45 +/- 6 minutes). Folate deficiency had no influence on the volume of distribution of formate (18.84 +/- 1.05 L in FFD vs 17.21 +/- 1.35 L in FFC). Adequate folate status is important in the elimination of formate. A folate-deficiency state results in a reduction in formate elimination kinetics, which may increase the risk of formate toxicity.