Increased plasma neurotensin concentrations in patients with Parkinson's disease.

Plasma neurotensin (NT) was measured by radioimmunoassay in propanol extracted and unextracted plasma from 16 parkinsonian patients (four before treatment) and 16 age and sex matched controls. Mean plasma NT concentrations were consistently higher in parkinsonian patients than in controls and higher in the four untreated patients than in levodopa treated patients suggesting that plasma NT measurement may represent an easy detectable additional index in diagnosing parkinsonism and provides a novel approach to research in this field.

Is diclofenac a valuable CYP2C9 probe in humans?

INTRODUCTION: Besides the low therapeutic index drug tolbutamide, there is no validated in vivo probe to assess the genetically determined CYP2C9 activity in humans. The in vitro CYP2C9-specific substrate diclofenac might be a valuable, well-tolerated probe candidate. In order to validate diclofenac as an in vivo CYP2C9 probe, we planned to show that urinary 4'-hydroxydiclofenac/diclofenac metabolic ratio (MR) would correlate to the apparent partial metabolic clearance of diclofenac into 4'-hydroxydiclofenac (Clmet). PATIENTS AND METHODS: Eighteen healthy volunteers received a single oral dose of 50 mg diclofenac in its enteric-coated form. Blood and urinary pharmacokinetics of diclofenac were studied over 48 h. Identification of the CYP2C9 alleles (CYP2C9*1, CYP2C9*2, and CYP2C9*3) was performed with genomic DNA sequencing. RESULTS: We observed a dramatic inter-individual variability in the delay of diclofenac intestinal absorption since its first detectable blood concentration ranged from 0.5 h to more than 12 h after drug intake. The Clmet of diclofenac could not be determined in two subjects who started to absorb the drug after 12 h. No correlation could be observed between Clmet of diclofenac and the different MRs calculated at 0-4 h, 0-8 h, 0-12 h, 0-24 h and 0-48 h urinary collections. The Clmet of diclofenac in heterozygous subjects tended to be lower than among wild-type homozygous subjects, but this difference did not reach statistical significance due to an insufficient number of subjects studied. CONCLUSION: Diclofenac, in its enteric-coated form, is not a useful in vivo CYP2C9 probe probably because of its highly variable intestinal absorption rate. However, since we found a lower metabolic clearance of diclofenac in heterozygous CYP2C9 subjects, as observed with other CYP2C9 substrates, diclofenac, in another galenic form, might be a potential probe to quantify CYP2C9 activity in humans.

Adenoviral transduction of human 'clinical grade' immature dendritic cells enhances costimulatory molecule expression and T-cell stimulatory capacity.

The therapeutic use of dendritic cells (DC) in antigen-specific anti-tumor vaccines, requires sufficient numbers of functional DC, the preparation of which should comply with the code of Good Manufacturing Practice. In addition, the expression of tumor specific antigen should be possible in these DC. As a preclinical step, the method reported here was developed in healthy volunteers. Monocytes (Mo) were isolated by leukapheresis from 12 donors, purified by elutriation and then cultured for 6 days in sealed bags in AIM-V serum free medium with granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-13 (IL-13). Between 6x10(8) and 1x10(9) immature DC (iDC) could be differentiated from one leukapheresis. Cells displayed a characteristic iDC phenotype (CD1a(+), CD14(-), CD80(+), CD86(+), HLA DR(+), CD83(-)), and had potent allogeneic and antigen dependent autologous T cell-stimulatory capacity. Moreover, iDC could be further differentiated into mature DC by CD40 ligation as assessed by CD83 expression and the upregulation of HLA-DR and costimulatory molecules. After infection with a recombinant adenovirus encoding for beta-galactosidase (betaGal), 50% to 80% of iDC expressed betaGal without toxicity. Adenovirus infection increased the expression of both costimulatory molecules and CD83, and also increased allogeneic stimulatory capacity. Thus, the method developed here allows us to use large numbers of functional iDC as will be required for therapeutic uses in man. These DC can express a transgenic protein.

Effect of a single oral dose of moxifloxacin (400 mg and 800 mg) on ventricular repolarization in healthy subjects.

BACKGROUND: Moxifloxacin is a new fluoroquinolone. In vitro studies have suggested that it could prolong ventricular repolarization. The main objective of this study was to measure the actual effect of single oral doses of moxifloxacin on QT interval duration in healthy volunteers. METHODS: Nine men and 9 women participated in a double-blind, randomized, placebo-controlled, crossover study. Each participant received single oral doses (400 mg and 800 mg) of moxifloxacin or placebo. At the time of expected moxifloxacin maximum concentration, several electrocardiographic recordings were obtained at rest and during the course of a submaximal exercise test. QT interval and the corresponding RR interval value were measured within a wide range of RR intervals in each subject. RESULTS: ANOVA showed that both moxifloxacin doses increased mean QT intervals compared with placebo. The mean QT interval duration at RR = 1000 ms was 379 +/- 24 ms during placebo, 394 +/- 33 ms during moxifloxacin 400 mg (P < .05), and 396 +/- 28 ms during moxifloxacin 800 mg (P < .05). Moxifloxacin-induced QT interval prolongation remained significant at all tested heart rates. The increase in QT interval duration relative to placebo remained between 2.3% +/- 2.8% and 4.5% + 3.8% across the range of RR intervals tested. CONCLUSION: Moxifloxacin prolongs QT interval duration. The amplitude of this effect is small, and the risk of moxifloxacin-induced torsades de pointes is expected to be minimal when the drug is administered at the recommended dose of 400 mg/d. However, moxifloxacin should not be used in patients with predisposing factors of torsades de pointes such as electrolyte disturbances and bradycardia or during coadministration of proarrhythmic drugs.

Assessment of CYP2D6 and CYP2C19 activity in vivo in humans: a cocktail study with dextromethorphan and chloroguanide alone and in combination.

OBJECTIVES: Dextromethorphan and chloroguanide (INN, proguanil) are used as prototypic phenotyping substrates of polymorphically expressed CYP2D6 and CYP2C19 in humans. We determined whether the dextromethorphan/dextrorphan and chloroguanide/cycloguanil metabolic ratios, obtained after administration of the parent drugs either alone or in combination, are equivalent. METHODS: Thirty-six healthy male volunteers received single oral doses of 80 mg dextromethorphan and 200 mg chloroguanide during a three-period, randomized crossover study. Plasma and urine were collected to calculate metabolic ratios and analyze the disposition kinetics of the probe drugs. RESULTS: All subjects were extensive metabolizers for both CYP2D6 and CYP2C19. Chloroguanide kinetics and urinary metabolic ratio were not altered after dextromethorphan administration. Dextromethorphan urinary metabolic ratio increased from -2.52 +/- 0.67 to -2.03 +/- 0.58 (P < .001) in the presence of chloroguanide. This was caused by an increase of dextromethorphan without a significant change of dextrorphan in both urine and plasma. Inhibition of CYP3A-dependent biotransformation of dextromethorphan to methoxymorphinan did not appear to be responsible for this change because the log(dextromethorphan/methoxymorphinan) urinary ratio, an index of CYP3A activity, did not significantly change during chloroguanide coadministration. The chloroguanide and dextromethorphan metabolic ratio determined from urine collection correlated with the corresponding metabolic ratio determined from plasma obtained 3 hours after oral administration. CONCLUSION: When CYP2D6 and CYP2C19 activity are assessed, dextromethorphan and chloroguanide cannot be associated in a cocktail because chloroguanide increases the dextromethorphan metabolic ratio. CYP2D6 and CYP2C19 activity can be determined from a blood sample drawn 3 hours after oral administration of dextromethorphan and chloroguanide, respectively.

A study of the relative bioavailability of cysteamine hydrochloride, cysteamine bitartrate and phosphocysteamine in healthy adult male volunteers.

AIMS: Cysteamine, the only drug available for the treatment of cystinosis in paediatric patients, is available as the hydrochloride, the bitartrate and as sodium phosphocysteamine salts. It has been suggested that cysteamine bitartrate and phosphocysteamine are better tolerated and may have a better bioavailability than cysteamine hydrochloride. This has, however, never been demonstrated. METHODS: We compared the pharmacokinetics and tolerance of these three formulations of cysteamine in 18 healthy adult male volunteers in a double-blind, latin-square, three-period, single oral dose cross-over relative bioavailability study. RESULTS: No statistical difference was found between relative bioavailabilities, AUC (0, infinity) (geometric mean and s.d. in micromol l(-1) h: 169+/-51, 158+/-46, 173+/-49 with cysteamine hydrochloride, phosphocysteamine and cysteamine bitartrate respectively), Cmax (geometric mean and s.d. in micromol l(-1); 66+/-25.5, 59+/-12, 63+/-20) and tmax (median and range in h: 0.88 (0.25-2), 1.25 (0.25-2), 0.88 (0.25-2)) with each of the three forms of cysteamine tested. Bioequivalence statistics (90% confidence intervals) showed non equivalence of Cmax of cysteamine base as the only non equivalence of pharmacokinetics between the three formulations: 90% CI for Cmax relative ratios to cysteamine hydrochloride were [75.6-105.81 for phosphocysteamine and [74.2-124.2] for cysteamine bitartrate. The only significant adverse event was vomiting whose frequency was inversely correlated with body weight (Spearman's r=-0.76, P<0.001). The nature of the salt tested did not influence vomiting. CONCLUSIONS: While none of the three forms of cysteamine tested has a clear advantage over the others in terms of pharmacokinetics and tolerance profile, this should now however be addressed in patients treated for cystinosis during repeat administrations.