A sensitive and reproducible method for the determination of morphine and the metabolites morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) was developed. The method was validated for perfusion fluid used in microdialysis as well as for sheep and human plasma. A C18 guard column was used to desalt the samples before analytical separation on a ZIC HILIC (hydrophilic interaction chromatography) column and detection with tandem mass spectrometry (MS/MS). The mobile phases were 0.05% trifluoroacetic acid (TFA) for desalting and acetonitrile/5 mM ammonium acetate (70:30) for separation. Microdialysis samples (5 microL) were directly injected onto the system. The lower limits of quantification (LLOQ) for morphine, M3G and M6G were 0.50, 0.22 and 0.55 ng/mL, respectively, and the method was linear from LLOQ to 200 ng/mL. For plasma, a volume of 100 microL was precipitated with acetonitrile containing internal standards (deuterated morphine and metabolites). The supernatant was evaporated and reconstituted in 0.05% TFA before the desalting process. The LLOQs for sheep plasma were 2.0 and 3.1 ng/mL and the ranges were 2.0-2000 and 3.1-3100 ng/mL for morphine and M3G, respectively. For human plasma, the LLOQs were 0.78, 1.49 and 0.53 ng/mL and the ranges were 0.78-500, 1.49-1000 and 0.53-500 ng/mL for morphine, M3G and M6G, respectively.

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Background and purpose:The effect of age on the distribution of morphine and morphine-3-glucuronide (M3G) across the blood-brain barrier (BBB) was studied in a sheep model utilizing intracerebral microdialysis. The effect of neonatal asphyxia on brain drug distribution was also studied. Experimental approach: Microdialysis probes were inserted into the cortex, striatum and blood of 11 lambs (127 gestation days) and six ewes. Morphine, 1 mg·kg, was intravenously administered as a 10 min constant infusion. Microdialysis and blood samples were collected for up to 360 min and analysed using liquid chromatography-tandem mass spectrometry. The half-life, clearance, volume of distribution, unbound drug brain : blood distribution ratio (Kp,uu) and unbound drug volume of distribution in brain (Vu,brain) were estimated. Key results: Morphine Kp,uu was 1.19 and 1.89 for the sheep and premature lambs, respectively, indicating that active influx into the brain decreases with age. Induced asphyxia did not affect transport of morphine or M3G across the BBB. Morphine Vu,brain measurements were higher in sheep than in premature lambs. The M3G Kp,uu values were 0.27 and 0.17 in sheep and premature lambs, indicating a net efflux from the brain in both groups. Conclusions and implications:The morphine Kp,uu was above unity, indicating active transport into the brain; influx was significantly higher in premature lambs than in adult sheep. These results in sheep differ from those in humans, rats, mice and pigs where a net efflux of morphine from the brain is observed.

Introduction There is considerable uncertainty about the reproducibility of the various instruments used to measure dyspnea, their ability to reflect changes in symptoms, whether they accurately reflect the patient's experience and if its evolution is similar between acute heart failure syndrome patients and nonacute heart failure syndrome patients. URGENT was a prospective multicenter trial designed to address these issues. Methods Patients were interviewed within 1 hour of first physician evaluation, in the emergency department or acute care setting, with dyspnea assessed by the patient using both a five-point Likert scale and a 10-point visual analog scale (VAS) in the sitting (60º) and then supine (20º) position if dyspnea had not been considered severe or very severe by the sitting versus decubitus dyspnea measurement. Results Very good agreements were found between the five-point Likert and VAS at baseline (0.891, P <0.0001) and between changes (from baseline to hour 6) in the five-point Likert and in VAS (0.800, P <0.0001) in acute heart failure (AHF) patients. Lower agreements were found when changes from baseline to H6 measured by Likert or VAS were compared with the seven-point comparative Likert (0.512 and 0.500 respectively) in AHF patients. The worse the dyspnea at admission, the greater the amplitude of improvement in the first 6 hours; this relationship is stronger when dyspnea is measured with VAS (Spearman's rho coefficient = 0.672) than with the five-point Likert (0.272) (both P <0.0001) in AHF patients. By the five-point Likert, only nine patients (3% (1% to 5%)) reported an improvement in their dyspnea, 177 (51% (46% to 57%)) had no change, and 159 (46% (41% to 52%)) reported worse dyspnea supine compared with sitting up in AHF patients. The PDA test with VAS was markedly different between AHF and non-AHF patients. Conclusions Both clinical tools five-point Likert and VAS showed very good agreement at baseline and between changes from baseline to tests performed 6 hours later in AHF patients. The PDA test with VAS was markedly different between AHF and non-AHF patients. Dyspnea is improved within 6 hours in more than threequarters of the patients regardless of the tool used to measure the change in dyspnea. The greater the dyspnea at admission, the greater the amplitude of improvement in the first 6 hours.