Pharmacokinetics of heated intraperitoneal oxaliplatin.

OBJECTIVE: To evaluate the pharmacokinetic inter-patient variability of 30-min hyperthermic intraperitoneal oxaliplatin chemotherapy. PATIENTS AND METHODS: Data were obtained from 24 patients who were treated according to two procedures of heated intra-operative intraperitoneal oxaliplatin. For the first procedure (12 patients), the solution instilled within the peritoneal cavity contained oxaliplatin, and a delay of 8-10 min was necessary to reach a temperature of 42-43 degrees C. For the second procedure (12 patients), the cavity was initially filled only with the dextrose solution, and oxaliplatin was added to the peritoneal instillate when temperature reached 42-43 degrees C. Plasma and peritoneal fluid oxaliplatin concentrations were analyzed according to a population pharmacokinetic approach using NONMEM. RESULTS: Peritoneal and total plasma data were simultaneously analyzed according to a three-compartment pharmacokinetic model. The peritoneal half-life ranged between 18 and 42 min. The mean peritoneal clearance was 5.47 L/h (+/-21%), and the mean plasma clearance was 3.71 L/h (+/-47%). The heated intra-operative procedure did not have any impact on oxaliplatin pharmacokinetics. CONCLUSION: The inter-individual variability was larger for plasma pharmacokinetic parameters than that for peritoneal parameters. However, the percentage of oxaliplatin dose absorbed during a 30-min hyperthermic intraperitoneal chemotherapy may vary from 40 to 68%. The present pharmacokinetic model will be useful to implement pharmacokinetic evaluation of further clinical trials of hyperthermic intraperitoneal chemotherapy based on platinum compounds' administration.

Development and validation of an UHPLC-MS/MS method for simultaneous quantification of ibrutinib and its dihydrodiol-metabolite in human cerebrospinal fluid.

Ibrutinib is an orally administered first-in-class irreversible Bruton's tyrosine kinase (BTK) covalent inhibitor for the treatment of patients with B-cell malignancies. Several isolated clinical observations reported its efficacy in central nervous system dissemination. Herein, we described the development and validation of an ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) procedure for the quantification of ibrutinib and its active metabolite PCI-45227 in cerebrospinal fluid (CSF). This is the first complete validated method for quantification of ibrutinib and PCI-45227 in CSF. The compounds were eluted on a Waters BEH C18 column (50.0 × 2.1 mm; 1.7 µm) using a gradient elution with a mobile phase composed of ammonium formate buffer 5 mM pH 3.2 and acetonitrile +0.1% formic acid with a flow rate of 400 µL·min-1. Two deuterated internal standards were used to obtain the most accurate quantification. The CSF samples were prepared by a simple and rapid dilution. The method was validated by testing the selectivity, response function, intra-day and inter-day precisions, trueness, limits of detection (LOD) and lower limits of quantification (LLOQ). The validation results proved that the methods were suitable to quantify ibrutinib and PCI-45227 in real biological CSF samples from 0.50 (ibrutinib) or 1.00 (PCI-45227) to 30.00 ng·mL-1. Furthermore, the developed method was adapted to allow the quantification of both compounds in plasma and the results were compared to those reported in literature. The plasmatic samples were treated by protein precipitation and the method was validated to quantify ibrutinib and PCI-45227 in real biological plasmatic samples from 5.00 to 491 ng·mL-1. Lastly, for both matrices, accuracy profiles were plotted from the trueness and precision results using a 20% α-risk (ß = 80%) and the tolerance intervals were comprised within the acceptance limits fixed at ±25% for the LLOQ and ±15% for the other concentrations. Finally, these methods were successfully applied to quantify ibrutinib and PCI-45227 in real human CSF and plasma samples.

Dexamethasone as a probe for CYP3A4 metabolism: evidence of gender effect.

BACKGROUND: A study was conducted to evaluate prospectively the correlation between docetaxel clearance and pharmacokinetics of dexamethasone previously obtained in 21 patients. PATIENTS AND METHODS: Dexamethasone pharmacokinetics were performed in 17 patients 24 h before docetaxel treatment as monochemotherapy. Dexamethasone and docetaxel plasma concentrations were determined by HPLC methods. Determination of docetaxel unbound fraction in plasma was performed using microequilibrium dialysis. RESULTS: Significant correlation was observed between observed plasma docetaxel clearances (CL(docetaxel)) and values predicted from dexamethasone plasma clearance (CL(dexa)), unbound plasma docetaxel fraction estimated from serum alpha1-acid glycoprotein level (fu(alpha1-AAG)), and hepatic metastasis status. However, after splitting of the prospective data set according to gender, no correlation was observed for males (R(2) = 0.08, NS, n = 10), then strong correlation was observed for females (R(2) = 0.78, P < 0.01, n = 7). Multivariate analysis was performed from data obtained in the women included in the first study and those of this prospective study (n = 18). Docetaxel CL was significantly correlated with CL(dexa) (P = 0.001) and fu(alpha1-AAG) (P = 0.01) according to the relationship (with +/-95% confidence intervals): CL(docetaxel) (l/h) = 1.92 (+/-0.94) x CL(dexa) (l/h) + 2.68 (+/-1.95) x fu(alpha1-AAG) (%) (R(2) = 0.68). CONCLUSION: Dexamethasone may be used to predict docetaxel clearances in females, but not in males.

Coupling strength assumption in statistical energy analysis.

This paper is a discussion of the hypothesis of weak coupling in statistical energy analysis (SEA). The examples of coupled oscillators and statistical ensembles of coupled plates excited by broadband random forces are discussed. In each case, a reference calculation is compared with the SEA calculation. First, it is shown that the main SEA relation, the coupling power proportionality, is always valid for two oscillators irrespective of the coupling strength. But the case of three subsystems, consisting of oscillators or ensembles of plates, indicates that the coupling power proportionality fails when the coupling is strong. Strong coupling leads to non-zero indirect coupling loss factors and, sometimes, even to a reversal of the energy flow direction from low to high vibrational temperature.

Dose and time dependencies of 5-fluorouracil pharmacokinetics.

OBJECTIVES: The purpose of this study was to examine the interpatient and intrapatient variability of the Michaelis-Menten plasma parameters of 5-fluorouracil administered according to a schedule combining a bolus of 400 mg/m2 followed by 22-hour infusion of 600 mg/m2 for 2 consecutive days. PATIENTS: A pharmacokinetic population approach was used to analyze the data from 21 patients with colorectal cancer. RESULTS: The 5-fluorouracil plasma concentrations versus time were best described by a two-compartment model with nonlinear elimination from the central compartment. The relationships between the pharmacokinetic parameters and patient characteristics were tested. On day 1 the mean values (with interindividual variability as expressed by the coefficient of variation) were 1390 mg x h(-1) (20%), and 5.57 mg x L(-1) (22%) for the maximum rate of elimination, and the half-saturating plasma concentration. The maximum rate of elimination was positively correlated to the body surface area and the percentage of liver involvement by metastatic disease determined by tomodensitometric examination. The model was successfully tested with independent data sets corresponding to other schedules. The analysis of this intrapatient variability showed that the half-saturating plasma concentration increased from day 1 to day 2, especially in the patients with low lymphocyte cell dihydropyrimidine dehydrogenase activity. CONCLUSION: The pharmacokinetic parameters obtained in this study would be useful to predict the 5-fluorouracil plasma concentrations following other schedules of administration of 5-fluorouracil and to study the possible pharmacokinetic interactions between 5-fluorouracil and other drugs.

[Tetanus in adults: mortality. Study in 130 cases]. / Tétanos del adulto: mortalidad. Estudio en 130 casos.

Out of the 557 cases of tetanus in adult patients seen in our institution over 61 years, we have selected for analysis the 130 patients who where admitted to our service since its creation in 1968. We have found a trend toward older patient age in recent years. The age distribution showed a bimodal curve which was maintained in the different periods and was due, in the last one to the population of parenteral drug abusers. In the last 20 years there has been an increase in severe forms (p less than 0.001). The mortality was statistically associated with clinical severity (p less than 0.001) and with the surgical portal of entry (p less than 0.05). The development of intensive care reduced the mortality rate from 58.3% in the period before ICU to 24.6% in the 130 patients cared for since the service was created (p less than 0.001). In the last 10 years, the mortality rate of 41 patients was 9.7%. The most common cause of death was cardiac arrest (68.7%). Superinfection was the second cause (25%). The use of beta-blockers in patients with severe tetanus, with significant autonomic abnormalities, reduced the mortality from 72.7% to 14.8% (p less than 0.001). The mortality of superinfection has been maintained, without statistically significant changes.