Evaluation of interleukin-6 and its soluble receptor components sIL-6R and sgp130 as markers of inflammation in inflammatory bowel diseases.

PURPOSE: Interleukin-6 (IL-6) production and signalling are increased in the inflamed mucosa in inflammatory bowel diseases (IBD). As published serum levels of IL-6 and its soluble receptors sIL-6R and sgp130 in IBD are from small cohorts and partly contradictory, we systematically evaluated IL-6, sIL-6R and sgp130 levels as markers of disease activity in Crohn's disease (CD) and ulcerative colitis (UC). METHODS: Consecutive adult outpatients with confirmed CD or UC were included, and their disease activity and medication were monitored. Serum from 212 CD patients (815 measurements) and 166 UC patients (514 measurements) was analysed, and 100 age-matched healthy blood donors were used as controls. RESULTS: IL-6 serum levels were significantly elevated in active versus inactive CD and UC, also compared with healthy controls. However, only a fraction of IBD patients showed increased serum IL-6. IL-6 levels ranged up to 32.7 ng/mL in active CD (> 5000-fold higher than in controls), but also up to 6.9 ng/mL in inactive CD. Increases in active UC (up to 195 pg/mL) and inactive UC (up to 27 pg/mL) were less pronounced. Associations between IL-6 serum levels and C-reactive protein concentrations as well as leukocyte and thrombocyte counts were observed. Median sIL-6R and sgp130 levels were only increased by up to 15%, which was considered of no diagnostic significance. CONCLUSIONS: Only a minority of IBD patients shows elevated IL-6 serum levels. However, in these patients, IL-6 is strongly associated with disease activity. Its soluble receptors sIL-6R and sgp130 do not appear useful as biomarkers in IBD.

Quantitative determination of peptide drug in human plasma samples at low pg/ml levels using coupled column liquid chromatography-tandem mass spectrometry.

Plasma concentrations after administration of peptide drugs are often low due to the high potency often seen with this class of compounds. In this work a bioanalytical method based on coupled column liquid chromatography-tandem mass spectrometry (LC-MS/MS) is presented for quantification of a peptide drug, FE 202158, under clinical development. A volume of 0.5 ml human plasma is solid phase extracted on a weak cationic exchanger. After evaporation of the solvent to dryness, the reconstituted sample is injected into a coupled column liquid chromatography system. A heart-cut from the initial column, a cyano column, is trapped on a C(4) column and thereafter injected into a microbore C(18) column. For the detection a triple quadrupole mass spectrometer, equipped with a TurboIonSpray interface working in positive ion mode, is used. The design of the system is described and the gain in sensitivity and selectivity, compared to a conventional system, is discussed. Data from validation of the bioanalytical method are presented. For human plasma samples a lower limit of quantification (LLOQ) of 5.00 pg/ml (=4.77 pmol/l) was achieved. The inter-assay precision was less than 11% and bias was within +/-4% over the whole validated range of 5.00-860 pg/ml.

Pharmacokinetics and renal excretion of desmopressin after intravenous administration to healthy subjects and renally impaired patients.

OBJECTIVE: To evaluate the influence of renal impairment on the pharmacokinetics of desmopressin. METHODS: Twenty-four subjects were enrolled in the study, 18 with varying degrees of renal impairment and six healthy volunteers. Each subject received a single intravenous dose of 2 microg desmopressin. Blood and urine samples were collected for 24 h and assayed for desmopressin by radioimmunoassay. Plasma concentrations and the amounts of desmopressin excreted in the urine were analysed simultaneously by use of mixed effects modelling. RESULTS: Only mild adverse events were observed. Both the renal and the nonrenal clearance of desmopressin were found to vary with the creatinine clearance (CrCL). A decrease of 1.67% in the CrCL (corresponding to 1 ml min(-1) from 60 ml min(-1)) was found to cause a 1.74% decrease in the renal clearance and a 0.93% decrease in the nonrenal clearance. The fall in renal clearance caused the amount of desmopressin excreted in urine to decrease from 47% in healthy subjects to 21% in the patients with severe renal impairment. The mean systemic clearance of desmopressin was 10 litres h(-1) in healthy subjects and 2.9 litres h(-1) in patients with severe renal impairment (difference -7.5 litres h(-1), 95% CI [-11; -4.3] litres h(-1)). Correspondingly, the mean terminal half-life, was 3.7 h in healthy subjects and 10 h in patients with severe renal impairment (difference 6.7 h, 95% CI [4.0; 9.4] h). CONCLUSION: Although desmopressin appears to be safe and well-tolerated by patients with impaired renal function, great caution should be exercised when titrating towards an efficient dosage regimen if patients with moderately or severely impaired renal function are to be treated with desmopressin at all.