Detection of bumetanide in an over-the-counter dietary supplement.

Bumetanide is a loop diuretic used clinically to treat heart failure, acute renal failure, high blood pressure, and edema. However, diuretics may also be used by athletes as masking agents and to decrease weight. Taken as masking agents, diuretics increase urine production and decrease urinary concentrations of banned performance-enhancing agents, such as anabolic steroids. StarCaps is an over-the-counter dietary supplement marketed as a diet aid. The manufacturer claims that the product contains only natural cleansing agents and emphasizes that it is free from traditional appetite suppressants such as sympathomimetic amines. However, no such disclaimer is made concerning diuretic agents. A single StarCaps capsule was administered to two male and two female volunteers, and their urine specimens were collected at discrete intervals (2, 4, 8, and 12 h) post administration. The specimens were analyzed by a high-performance liquid chromatography-mass spectrometry quadrupole (HPLC-MS) method, and bumetanide was detected in all specimens (4.6 to 351.3 ng/mL). Adjusting the bumetanide concentrations for creatinine content did little to normalize the excretion profiles. Bumetanide was also detected in the StarCaps capsules at concentrations approaching therapeutic doses. HPLC-quadrupole-time-of-flight mass spectrometry was used to confirm the presence of bumetanide in the urine samples and StarCaps capsules. The results showed that unregulated dietary supplements may put consumers at risk for unwitting consumption of prescription medications, and that it is possible for athletes to inadvertently test positive for bumetanide and face disciplinary actions.

Analysis of the nutritional supplement 1AD, its metabolites, and related endogenous hormones in biological matrices using liquid chromatography-tandem mass spectrometry.

1,5alpha-Androsten-3beta,17beta-diol and/or 1,5alpha-androsten-3,17-dione (1AD) is an over-the-counter pro-hormone nutritional supplement designed to enhance strength and performance in athletes. 1AD purportedly mimics the pharmacological activity of testosterone through activation of the pro-hormones to their active form 1,5alpha-androsten-17beta-ol-3-one or Delta(1)-testosterone. This testosterone analogue ostensibly possesses strong androgenic potency without the adverse effects associated with aromatization of testosterone to estrogens. We have developed a highly sensitive and selective liquid chromatography-tandem mass spectrometry assay for the simultaneous determination of 1AD, its analogues, and several structurally related endogenous hormones in plasma and urine. The limits of quantitation for the analytes ranged from 0.25 to 0.5 ng/mL. The accuracy of the assay was 92-113% with a precision of 2-12% relative standard deviation (RSD) for all analytes at 1.0, 5.0, and 15.0 ng/mL, respectively. The interassay precision was 6-16% RSD, and the accuracy was 90-105%. We have used this assay to determine the unconjugated and total (conjugated and unconjugated) concentrations of 1AD, its analogues, androstenediol, androstenedione, testosterone, dihydrotestosterone, and estradiol, in plasma and urine, as well as to investigate the metabolic fate of the three 1AD analogues (diol, dione, and active forms) when incubated with rat liver microsomes or rat testicular homogenates. Concentrations of both unconjugated and total testosterone in plasma were approximately 1.5 ng/mL and ranged from undetectable to 4.1 ng/mL in urine. 1AD and its analogues were not detected in plasma or urine. In vitro metabolism experiments using rat liver microsomes and testicular homogenates provided evidence for the interconversion of the three 1AD analogues, biosynthesis, and decomposition of several endogenous hormones, as well as evidence for 1AD analogue-induced changes in the typical profiles of testosterone and androstenedione in testicular tissue.

Metabolism of capsaicin by cytochrome P450 produces novel dehydrogenated metabolites and decreases cytotoxicity to lung and liver cells.

Capsaicin is a common dietary constituent and a popular homeopathic treatment for chronic pain. Exposure to capsaicin has been shown to cause various dose-dependent acute physiological responses including the sensation of burning and pain, respiratory depression, and death. In this study, the P450-dependent metabolism of capsaicin by recombinant P450 enzymes and hepatic and lung microsomes from various species, including humans, was determined. A combination of LC/MS, LC/MS/MS, and LC/NMR was used to identify several metabolites of capsaicin that were generated by aromatic (M5 and M7) and alkyl hydroxylation (M2 and M3), O-demethylation (M6), N- (M9) and alkyl dehydrogenation (M1 and M4), and an additional ring oxygenation of M9 (M8). Dehydrogenation of capsaicin was a novel metabolic pathway and produced unique macrocyclic, diene, and imide metabolites. Metabolism of capsaicin by microsomes was inhibited by the nonselective P450 inhibitor 1-aminobenzotriazole (1-ABT). Metabolism was catalyzed by CYP1A1, 1A2, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4. Addition of GSH (2 mM) to microsomal incubations stimulated the metabolism of capsaicin and trapped several reactive electrophilic intermediates as their GSH adducts. These results suggested that reactive intermediates, which inactivated certain P450 enzymes, were produced during catalytic turnover. Comparison of the rate and types of metabolites produced from capsaicin and its analogue, nonivamide, demonstrated similar pathways in the P450-dependent metabolism of these two capsaicinoids. However, production of the dehydrogenated (M4), macrocyclic (M1), and omega-1-hydroxylated (M3) metabolites was not observed for nonivamide. These differences may be reflective of the mechanism of formation of these metabolites of capsaicin. The role of metabolism in the cytotoxicity of capsaicin and nonivamide was also assessed in cultured lung and liver cells. Lung cells were markedly more sensitive to cytotoxicity by capsaicin and nonivamide. Cytotoxicity was enhanced 5 and 40% for both compounds by 1-ABT in BEAS-2B and HepG2, respectively. These data suggested that metabolism of capsaicinoids by P450 in cells represented a detoxification mechanism (in contrast to bioactivation).