Incorporating dried blood spot LC-MS/MS analysis for clinical development of a novel oncolytic agent.

AIM: Design and execution of a dried blood spot (DBS-LC-MS/MS) assay for pharmacokinetic analyses in oncology patients. RESULTS & DISCUSSION: The methodology was validated to collect and store DBS samples from multiple clinical sites, and analyze blood with diverse hematocrit ranges (25-55) to match the potential patient population. Bridging data comparing DBS and plasma showed high degree of concordance with DBS:plasma ratios of 0.81, demonstrating no preferential uptake or association with cellular components of the blood. Pharmacokinetic analysis supporting clinical development was performed using 20 µl of blood collected as DBS. Incurred sample reanalysis showed high correlation. CONCLUSION: Successful validation of a DBS method and implementation in the clinic enabled pharmacokinetic analysis during the clinical development of a novel oncolytic agent in oncology patients.

Synthesis of C-14 radiolabeled glucagon receptor antagonist and its use in a human mass balance study.

The synthesis of the radiolabeled glucagon receptor antagonist 1-[14 C] was accomplished based on decarboxylative iodination of acid 2 followed by "reattachment" of 14 C carboxylic function. The method allowed a significant reduction in the number of steps in preparation of the radiolabeled compound. Iodide 4, obtained by the halodecarboxylation, was converted to cyanide 5-[14 C], which was hydrolyzed to provide the radiolabeled acid 2-[14 C]. Coupling with ß-alanine fragment and hydrolysis of ester 6-[14 C] completed the synthesis of the target molecule 1-[14 C]. The resulting compound was utilized in a mass balance and metabolism study where hepatic oxidation followed by a trace amount of sulfate conjugation and elimination was the main clearance pathway for 1 in humans.

Amount of Testosterone on Laundered Clothing After Use of Testosterone Topical 2% Solution by Healthy Male Volunteers.

INTRODUCTION: Testosterone 2% solution (Axiron) applied to armpit(s) is used for replacement therapy in men with a deficiency of endogenous testosterone. AIM: To determine the amount of testosterone on subjects' T-shirts 12 hours after applying testosterone solution, the residual testosterone on subjects' T-shirts after laundering, and the testosterone transferred to unworn textile items during laundering with worn T-shirts. METHODS: Healthy males ≥18 years old applied 2 × 1.5 mL of testosterone 2% solution to both axillae (total testosterone dose: 120 mg) and dressed in cotton long-sleeved T-shirts after a ≥3-minute waiting period. T-shirts were worn 12 hours before being removed and cut into halves, after which a 10 × 10 cm sample of each armpit area was excised for testosterone quantification before or after laundering with samples of unworn textiles. MAIN OUTCOME MEASURES: Testosterone on worn T-shirts before and after laundering, and on unworn textiles laundered with the worn T-shirts. RESULTS: Twelve subjects enrolled and completed, with only minor adverse events. Mean testosterone in unwashed worn T-shirts was 7603 µg, with high between-subject variability (3359 µg to 13,069 µg), representing 13% of the dose to 1 armpit. Mean testosterone in worn, laundered T-shirts was 260 µg (7.55 µg to 1343 µg), representing 3% of the dose to 1 armpit. Mean transferred testosterone to other textiles during laundering ranged from 69 µg on texturized Dacron 56T Double to 10,402 µg on 87/13 nylon/Lycra knit, representing 0.0382% to 5.78% of the dose to 1 armpit. CONCLUSION: Thirteen percent of the testosterone applied to axillae was transferred to T-shirts during wear. Ninety-seven percent of the transferred testosterone was removed from the T-shirts during washing, some of which was then absorbed to various degrees by other textiles. Clinical implications of these findings and biological activity of the remaining/transferred testosterone are unknown.

Effect of deodorant and antiperspirant use and presence or absence of axillary hair on absorption of testosterone 2% solution applied to men's axillae.

INTRODUCTION: Testosterone 2% solution is applied to axillae and is indicated for testosterone replacement therapy in males deficient in endogenous testosterone. AIM: This open-label crossover study evaluated the effect of deodorant/antiperspirant use and presence or absence of axillary hair on absorption of testosterone solution. METHODS: Healthy males (N = 30; ≥50 years of age with baseline testosterone <400 ng/dL) were randomized to one of four treatment sequences involving six treatments. Each treatment consisted of one 1.5-mL dose of testosterone 2% solution (30 mg of testosterone) applied to each axilla. Axillae were unshaved or shaved, and were untreated or pretreated with deodorant/antiperspirant. MAIN OUTCOME MEASURES: Blood samples were taken over 72 hours after each dose for measuring serum testosterone concentrations. RESULTS: Profiles of mean testosterone concentrations were similar across treatments. For all treatments, area under the concentration-time curve through 24 hours (AUC[0-24] ) and 72 hours (AUC[0-72] ), and maximum total testosterone concentration (Cmax ) were similar except for 15% lower Cmax when treatment was applied after deodorant/antiperspirant to shaved vs. unshaved axillae (least squares mean, 531 ng/dL vs. 626 ng/dL, respectively; P = 0.011). This difference is not considered clinically significant. The 95% confidence intervals for AUC(0-24) , AUC(0-72) , and Cmax fell within the traditional bioequivalence limits of 0.8 to 1.25. Incidence of treatment-emergent adverse events (TEAEs) was low (<15%) in each treatment arm, and most TEAEs were mild. CONCLUSIONS: Absorption of testosterone 2% solution was unaffected by use of deodorant/antiperspirant or by the presence or absence of axillary hair. Testosterone solution was generally well tolerated.

Development and validation of a liquid chromatography-tandem mass spectrometric method for the determination of the major metabolites of duloxetine in human plasma.

A sensitive bioanalytical method for the measurement of two major circulating metabolites of duloxetine [4-hydroxy duloxetine glucuronide (LY550408) and 5-hydroxy-6-methoxy duloxetine sulfate (LY581920)] in plasma is reported. This method produced acceptable precision and accuracy over the validation range of 1-1000 ng/mL. Several issues had to be addressed in order to develop an LC/MS/MS assay for these metabolites. First, 4-hydroxy duloxetine glucuronide required chromatographic resolution from the 5-, and 6-hydroxy duloxetine glucuronide isomers. Second, the glucuronide conjugate is readily ionized under positive ESI conditions, while the sulfate conjugate required negative ESI conditions to obtain adequate sensitivity. Finally, the chromatographic conditions needed to separate the glucuronide isomers were not suitable for the analysis of the sulfate conjugate. The present method addressed these challenges, and was successfully applied to multiple human pharmacokinetic studies in which subjects received oral doses of duloxetine hydrochloride.