Thomas P. Moyer

Warfarin Genotyping Reduces Hospitalization Rates Results From the MM-WES (Medco-Mayo Warfarin Effectiveness Study)

OBJECTIVES This study was designed to determine whether genotype testing for patients initiating warfarin treatment will reduce the incidence of hospitalizations, including those due to bleeding or thromboembolism. BACKGROUND Genotypic variations in CYP2C9 and VKORC1 have been shown to predict warfarin dosing, but no large-scale studies have prospectively evaluated the clinical effectiveness of genotyping in naturalistic settings across the U.S. METHODS This national, prospective, comparative effectiveness study compared the 6-month incidence of hospitalization in patients receiving warfarin genotyping (n = 896) versus a matched historical control group (n = 2,688). To evaluate for temporal changes in the outcomes of warfarin treatment, a secondary analysis compared outcomes for 2 external control groups drawn from the same 2 time periods. RESULTS Compared with the historical control group, the genotyped cohort had 31% fewer hospitalizations overall (adjusted hazard ratio [HR]: 0.69, 95% confidence interval [CI]: 0.58 to 0.82, p < 0.001) and 28% fewer hospitalizations for bleeding or thromboembolism (HR: 0.72, 95% CI: 0.53 to 0.97, p = 0.029) during the 6-month follow-up period. Findings from a per-protocol analysis were even stronger: 33% lower risk of all-cause hospitalization (HR: 0.67, 95% CI: 0.55 to 0.81, p < 0.001) and 43% lower risk of hospitalization for bleeding or thromboembolism (HR: 0.57, 95% CI: 0.39 to 0.83, p = 0.003) in patients who were genotyped. During the same period, there was no difference in outcomes between the 2 external control groups. CONCLUSIONS Warfarin genotyping reduced the risk of hospitalization in outpatients initiating warfarin. (The Clinical and Economic Impact of Pharmacogenomic Testing of Warfarin Therapy in Typical Community Practice Settings [MHSMayoWarf1]; NCT00830570).

Optimized isocratic conditions for analysis of catecholamines by high-performance reversed-phase paired-ion chromatography with amperometric detection

We studied high-performance liquid chromatographic separation of the catecholamines epinephrine, norepinephrine, 3,4-dihydroxybenzylamine and dopamine utilizing an isocratic aqueous mobile phase flowing over a bonded octadecylsilane (μBondapak C18) solid phase, with amperometric detection of the eluate. Separation was not dependent upon ionic strength of the mobile phase, while a definite dependence upon solvent pH was observed. Detector response showed a marked dependence upon both ionic strength and pH of the liquid phase, with optimum conditions for signal response occurring at pH 5.8 in an aqueous medium of 0.07-mole/l salt concentration. To achieve a baseline separation of the four catecholamines, inclusion of an aliphatic sulfonate as a paired ion was necessary. Heptanesulfonate was found to be the paired ion of choice. In the presence of the paired ion, a sensitivity was achieved which gave a peak more than ten times baseline noise when 100 fmoles of norepinephrine were injected on the column.

The Clinical Spectrum of the Eosinophilia-Myalgia Syndrome Associated with L-Tryptophan Ingestion: Clinical Features in 20 Patients and Aspects of Pathophysiology

We describe the clinical spectrum of the L-tryptophan-associated eosinophilia-myalgia syndrome in 20 patients. In all but one case, patients met the Centers for Disease Control (CDC) case definition for the syndrome: peripheral blood eosinophilia (eosinophil count greater than 1.0 x 10(9)/L) and generalized, disabling myalgias without other recognized causes. Three patients with eosinophilia and myalgia developed eosinophilic fasciitis, and 4 other patients developed, respectively, pneumonitis and myocarditis, neuropathy culminating in respiratory failure, encephalopathy, and fibrosis about the common bile duct. No relation was apparent between dose or duration of L-tryptophan exposure and the eosinophilia-myalgia syndrome. No organic contaminants were identified in L-tryptophan preparations taken by patients or asymptomatic users when these preparations were examined by chromatography or mass spectroscopy. Biopsy specimens in 12 patients showed a mononuclear exudate with a variable admixture of eosinophils in affected tissues, including skin, fascia, muscle, and some viscera. Eosinophil toxic granule proteins, major basic protein, and eosinophil-derived neurotoxin were elevated in the serum and urine of patients compared with normal control subjects (P less than 0.01 and P less than 0.02, respectively). Immunofluorescence showed major basic protein deposited outside of eosinophils in affected tissues, indicating that toxic granule proteins are released in diseased organs. Treatment included withdrawal of L-tryptophan in all cases. Corticosteroids were prescribed for 16 patients and diuretics alone for 1 patient; no drugs were prescribed for 3 patients. Four patients have recovered fully, others are stable or slowly recovering, and 1 is gravely ill despite prolonged treatment.

Warfarin Sensitivity Genotyping: A Review of the Literature and Summary of Patient Experience

The antithrombotic benefits of warfarin are countered by a narrow therapeutic index that contributes to excessive bleeding or cerebrovascular clotting and stroke in some patients. This article reviews the current literature describing warfarin sensitivity genotyping and compares the results of that review to the findings of our study in 189 patients at Mayo Clinic conducted between June 2001 and April 2003. For the review of the literature, we identified relevant peer-reviewed articles by searching the Web of Knowledge using key word warfarin-related adverse event. For the 189 Mayo Clinic patients initiating warfarin therapy to achieve a target international normalized ratio (INR) in the range of 2.0 to 3.5, we analyzed the CYP2C9 (cytochrome P450 2C9) and VKORC1 (vitamin K epoxide reductase complex, subunit 1) genetic loci to study the relationship among the initial warfarin dose, steady-state dose, time to achieve steady-state dose, variations in INR, and allelic variance. Results were compared with those previously reported in the literature for 637 patients. The relationships between allelic variants and warfarin sensitivity found in our study of Mayo Clinic patients are fundamentally the same as in those reported by others. The Mayo Clinic population is predominantly white and shows considerable allelic variability in CYP2C9 and VKORC1. Certain of these alleles are associated with increased sensitivity to warfarin. Polymorphisms in CYP2C9 and VKORC1 have a considerable effect on warfarin dose in white people. A correlation between steady-state warfarin dose and allelic variants of CYP2C9 and VKORC1 has been demonstrated by many previous reports and is reconfirmed in this report. The allelic variants found to most affect warfarin sensitivity are CYP2C9*1*1-VKORC1BB (less warfarin sensitivity than typical); CYP2C9*1*1-VKORC1AA (considerable variance in INR throughout initiation); CYP2C9*1*2-VKORC1AB (more sensitivity to warfarin than typical); CYP2C9*1*3-VKORC1AB (much more sensitivity to warfarin than typical); CYP2C9*1*2-VKORC1AB (much more sensitivity to warfarin than typical); CYP2C9*1*3-VKORC1AA (much more sensitivity to warfarin than typical); and CYP2C9*2*2-VKORC1AB (much more sensitivity to warfarin than typical). Although we were unable to show an association between allelic variants and initial warfarin dose or dose escalation, an association was seen between allelic variant and steady-state warfarin dose. White people show considerable variance in CYP2C9 allele types, whereas people of Asian or African descent infrequently carry CYP2C9 allelic variants. The VKORC1AA allele associated with high warfarin sensitivity predominates in those of Asian descent, whereas white people and those of African descent show diversity, carrying either the VKORC1BB, an allele associated with low warfarin sensitivity, or VKORC1AB or VKORC1AA, alleles associated with moderate and high warfarin sensitivity, respectively.

Fluoride excess and periostitis in transplant patients receiving long-term voriconazole therapy.

BACKGROUND We describe a heart transplant patient with painful periostitis and exostoses who was receiving long-term therapy with voriconazole, which is a fluoride-containing medication. Elevated plasma and bone fluoride levels were identified. Discontinuation of voriconazole therapy led to improvement in pain and reduced fluoride and alkaline phosphatase levels. METHODS To determine whether voriconazole is a cause of fluoride excess, we measured plasma fluoride levels in 10 adult post-transplant patients who had received voriconazole for at least 6 months and 10 post-transplant patients who did not receive voriconazole. To assess the effect of renal insufficiency on fluoride levels in subjects receiving voriconazole, half were recruited on the basis of a serum creatinine level of ≥1.4 mg/dL on their most recent measurement, whereas the other 5 subjects receiving voriconazole had serum creatinine levels <1.4 mg/dL. All control subjects had serum creatinine levels of ≥1.4 mg/dL. Patients were excluded from the study if they received a fluorinated pharmaceutical other than voriconazole. RESULTS All subjects who received voriconazole had elevated plasma fluoride levels, and no subjects in the control group had elevated levels (14.32 μmol/L ± 6.41 vs 2.54 ± 0.67 μmol/L; P<.001). Renal function was not predictive of fluoride levels. Plasma fluoride levels remained significantly higher in the voriconazole group after adjusting for calcineurin inhibitor levels and doses. Half of the voriconazole group subjects had evidence of periostitis, including exostoses in 2 patients. Discontinuation of voriconazole therapy in patients with periostitis resulted in improvement of pain and a reduction in alkaline phosphatase and fluoride levels. CONCLUSIONS Voriconazole is associated with painful periostitis, exostoses, and fluoride excess in post-transplant patients with long-term voriconazole use.

Routine clinical determination of lead, arsenic, cadmium, and thallium in urine and whole blood by inductively coupled plasma mass spectrometry

Abstract For the measurement of As, Cd, Pb, and Tl in urine or whole blood, judicious choices of internal standard elements for matrix correction and the development of a refined isobaric arsenic correction are necessary to produce accurate ICP-MS results. Ga and Rh are chosen as internal standards for As and Cd respectively. Bi is better for the correction of Pb and Tl than Re. An empirically derived equation relating the measurement of 16 O 35 Cl to the 40 Ar 35 Cl contribution to the arsenic signal at mass 75 is refined by measuring the responses at mass 51 and 75 for urines with added hydrochloric acid. Overall, ICP-MS results for blood and urine are within 6% of Zeeman GFAAS results for patient samples. For surveys, the overall average of ICP-MS results is within 3% of target.

Cerebral effects of high-dose midazolam and subsequent reversal with Ro 15-1788 in dogs.

The effects of a continuous high-dose infusion of midazolam on cerebral function, metabolism, and hemodynamics were studied in nine dogs receiving a spinal anesthetic and breathing 65% nitrogen/35% oxygen. In five dogs, the effects of 65% nitrous oxide (N2O) inspired and the benzodiazepine antagonist Ro 15-1788 were also examined. Midazolam was infused at a rate of 0.66 mg.kg-1.min-1 for 60 min for a total dose of 40 mg.kg-1. Cerebral metabolic rate for oxygen (CMRO2) and cerebral blood flow (CBF) (measured by venous outflow technique) both decreased until a plateau level was reached at approximately 75% of control values (4.0 +/- 0.2 ml.min-1.100 g-1 and 49 +/- 3 ml.min-1.100 g-1, respectively, mean +/- SEM). This occurred after 6-10 mg.kg-1 of midazolam, corresponding to serum midazolam levels between 18.4 +/- 3.8 and 31.2 +/- 3.3 micrograms.ml-1. Serum midazolam levels increased throughout the midazolam infusion, reaching a mean value of 53 +/- 5.5 micrograms.ml-1 by the end of the midazolam infusion. A similar plateau was seen for changes in the electroencephalogram (EEG), which never developed burst suppression. Five dogs inspired 65% nitrous oxide/35% oxygen during minutes 30-45 of the midazolam infusion, rather than 65% nitrogen/35% oxygen. Nitrous oxide had no effect upon CMRO2, but significantly increased CBF when compared to dogs receiving nitrogen. Ro 15-1788, 1.0 mg.kg-1 caused a return of CMRO2 and EEG activity to control levels. CBF and intracranial pressure (ICP) increased markedly, to greater than control levels immediately following Ro 15-1788.(ABSTRACT TRUNCATED AT 250 WORDS)

The determination of mercury in whole blood and urine by inductively coupled plasma mass spectrometry

Abstract An inductively coupled mass spectrometric (ICP-MS) method for the determination of mercury in whole blood and urine was developed. Gold and dichromate in hydrochloric acid were evaluated as agents to reduce mercury spray chamber memory. Dichromate with hydrochloric acid was found to be superior to gold. We evaluated the rapid introduction of sample to promote equilibrium and the rapid introduction of wash solutions after the sample analyses to minimize mercury memory. This ‘fast pump’ mode (2.5 ml/min) was used for 20 s at the beginning and end of each sample-wash cycle. The mercury detection limit is 0.15 μg/l in the original sample before dilution. Regressions and correlation coefficients for ICP-MS vs. target concentrations for interlaboratory comparison samples from the Centre de Toxicologie du Quebec were: whole blood: y=1.0x−0.6; r=0.9801; n=27 and urine: y=0.84x+8; r=0.9915; n=42. Patient samples were analyzed by ICP-MS and cold vapor atomic absorption spectrometry (CVAAS). Regressions and correlations for patient samples were: urines: y=0.93x+1; r=0.8763; n=456 and whole blood: y=1.1x+0.2; r=0.9357; n=251. ICP-MS correlation with CVAAS for 29 urine samples containing 15–150 μg Hg/specimen was: y=0.94x+4; r=0.9864.

Temporal effects of nicotine nasal spray and gum on nicotine withdrawal symptoms

Abstract Nicotine nasal spray and nicotine gum have been found to be effective in relieving nicotine withdrawal symptoms. In this randomized single-blind study, 91 cigarette smokers were randomly assigned to a single 1 mg dose of active nicotine nasal spray (n = 29), active 4 mg nicotine gum (n = 31), saline placebo nasal spray (n = 16) or placebo gum (n = 15). Following overnight abstinence, subjects repeatedly completed visual analog scales for assessing nicotine withdrawal symptoms over 30 min preceding (time -30 min to time 0) and 120 min following a single dose of study medication. This sequence was performed 3 times during the day. Nicotine withdrawal symptoms were assessed on a 41-point visual analog scale (1 = no withdrawal, 41 = extreme withdrawal). At the initial session only, blood samples for serum nicotine levels were taken at baseline, then at 5, 10, 30 and 120 min following study drug administration. The mean (± SD) age of the subjects was 38.6 (±10.1) years, 48% were females, smoking rate was 24.5 (±7.8) cigarettes per day, and years of smoking was 19.9 (±10.0). A single 1 mg dose of nicotine nasal spray provided more immediate relief for craving for a cigarette compared to a single 4 mg dose of nicotine gum. Serum venous nicotine levels for the active nicotine nasal spray and nicotine gum were comparable at 5 and 10 min while the levels were higher for nicotine gum at 30 and 120 min. Changes in withdrawal symptoms were not found to be related to serum venous nicotine levels. Our findings provide a rationale for the as needed use of nicotine nasal spray to control withdrawal symptoms, possibly in combination with other medications with longer acting effects.

Liver Biopsy Diagnosis of Homozygous Hemochromatosis: A Diagnostic Algorithm

The diagnosis of homozygous hemochromatosis (HH) should be based on appropriate findings on liver biopsy specimens. In cases with equivocal morphologic features, quantitative tissue iron determination and calculation of the hepatic iron index generally enable one to distinguish HH from other types of hepatic iron overload. In this article, we describe a diagnostic algorithm that is designed to avoid diagnostic errors because of histologic misinterpretation or erroneous, usually false-negative, chemical iron studies. The algorithm also delineates a cost-effective method of using quantitative tissue iron analysis. Diagnostic biopsy features of uncomplicated HH include (1) hemosiderosis that involves primarily hepatocytes, with or without inactive cirrhosis, and (2) a tissue iron index of 1.9 or higher. Findings such as prominent fatty changes or lymphocytic piecemeal necrosis indicate the presence of HH in conjunction with another complicating condition or secondary iron overload in the absence of HH.