Ignacio Ortega

Effect of P-glycoprotein inhibition on methadone analgesia and brain distribution in the rat.

Methadone is an opiate drug that has been identified as an in‐vitro substrate of the efflux pump P‐glycoprotein (P‐gp), active in the intestinal epithelium and in the blood–brain barrier (BBB), among other sites. The objective of this study was to test in vivo, in the rat model, the role of P‐gp modulation on the analgesic effect and brain uptake of methadone, as well as identify the most relevant site via dual oral and intravenous (i.v.) experiments. The P‐gp specific inhibitor (valspodar or PSC833) was preadministered (10 mg kg−1 i.v.) to test groups. Analgesia was measured using the tailflick test. The ED50 for oral methadone (2, 3, 6 and 8 mg kg−1) decreased three‐fold in valspodar groups compared with controls (2.23 + 0.002 mg kg−1 and 6.07 + 0.07 mg kg−1; P < 0.0001). The overall analgesic effect (% antinociception) was elevated 3.1 times in pretreated compared with control rats (90.65% + 0.22 vs 29.23% + 14.0; P < 0.01) after 6 mg kg−1 oral methadone and 2.8 times after i.v. (0.35 mg kg−1) administration (91.75% + 4.27 vs 32.45% + 9.0; P < 0.01). The brain:plasma distribution ratio was higher in pretreated animals and AUCbrain (overall brain concentration) was 6 times higher after oral methadone and 4 times higher after i.v. compared with controls, disproportionally increased relative to plasma, implying an active process at the BBB. P‐gp, and hence substrate comedication, plays a critical role in the evolution of the methadone analgesic effect and in its brain uptake, independent of the administration route.

Sex specificity in methadone analgesia in the rat: a population pharmacokinetic and pharmacodynamic approach.

AbstractPurpose. To quantify the extent to which a sex-specific dichotomy in the temporal evolution of the analgesic effect, after intravenous (i.v.) methadone injection in the rat, relates to the pharmacokinetics (PK) and pharmacodynamics (PD) that mediate the dose-to-effect pathway. Methods. Tail-flick analgesia was measured after i.v. methadone injection (0.35 mg/kg) in female (n = 16) and male (n = 16) Sprague-Dawley rats. The PK were evaluated in separate female (n = 56) and male (n = 56) rats after they had received the same dose of methadone i.v. (0.35 mg/kg). A bicompartmental model described the kinetics and a sigmoid Emax model-related drug effect vs. simulated concentrations (pharmacodynamics) at the times of effect measurement. All model parameters as well as interanimal and assay variabilities were estimated with a mixed-effects population method using the program NONMEM. Results. The area under the effect-time curve (AUCE0-120) was (mean ± interanimal SD) 1859 ± 346 min in the females, which was significantly lower than the 4871 ± 393 min in the males (P < 0.0001). On the contrary, the profiles of concentration vs. time were higher in females and, therefore, corresponded inversely to the effect vs. time-relative magnitudes. The central volume of distribution, V1, was 1.94 ± 0.37 l/kg for female rats and 3.01 ± 0.33 l/kg for male rats. Also, the central clearance was 0.077 ± 0.006 l/min/kg and 0.102 ± 0.005 l/min/kg, respectively, for female and male rats. Both parameters differed significantly between sexes (P < 0.0001). The pharmacodynamic maximum observed effect parameter (Emax) was 37% ± 29% in female rats and 85% ± 16% in male rats, and these values were significantly different (P < 0.0001). The parameter for the concentration eliciting half of Emax (EC50) was 24.1 ± 7.5 μg/l in female rats and 20.3 ± 2.9 μg/l in male rats, and the Hill-related exponent, γ, was 6.3 ± 3.9 in female rats and 5.5 ± 4.1 in male rats. These parameters did not differ significantly (at the P < 0.05 level). Conclusions. A sex-specific dichotomy in the methadone antinociceptive effect, in the rat, was not proportionally related to plasma concentrations. Each sex corresponded to a distinct subpopulation of the PK parameters and one of the pharmacodynamic parameters (Emax). When the course of a drug involves PK or PD subpopulations, PK/PD modeling can afford the safest prediction of the effect-time evolution for a particular dose.

In vitro pharmacodynamic modelling of anidulafungin against Candida spp.

The aim of this study was to fit anidulafungin in vitro static time-kill data from nine strains of Candida with a pharmacodynamic (PD) model in order to describe the antifungal activity of this drug against Candida spp. Time-kill data from strains of Candida albicans, Candida glabrata and Candida parapsilosis clades were best fit using an adapted sigmoidal Emax model and resulted in a set of PD parameters (Emax, EC50 and Hill factor) for each fungal strain. The data were analysed with NONMEM 7. Anidulafungin was effective in a species- and concentration-dependent manner against the strains of C. glabrata and C. parapsilosis clades as observed with the EC50 estimates. Maximum killing rate constant (Emax) values were higher against C. glabrata and C. parapsilosis complex strains. In conclusion, we demonstrated that the activity of anidulafungin against Candida can be accurately described using an adapted sigmoidal Emax model.

Simulation of sirolimus exposures and population variability immediately post renal transplantation: importance of the patient's CYP3A5 genotype in tailoring treatment.

The rapid achievement of efficacious exposure to sirolimus (SRL) after renal transplantation is crucial. However, there is high unpredictability in the dose to exposure relationship. Part of the variation is related to patients originating from subpopulations of fast or slow metabolizers via the CYP3A5*1/*3 genotype. The probability of achieving therapeutic SRL blood concentrations for each subpopulation under two equal‐intensity increasing‐frequency protocols after the start of treatment was explored with Monte Carlo simulation. The population pharmacokinetic model and inter‐patient variability distributions of Djebli et al. (DRH2006) were sampled. They developed a base and final model with a genotype covariate for CL/F in patients receiving calcineurin inhibitor (CNI)‐free therapy with SRL, mycophenolate mofetil and corticosteroids. Fast metabolizers (expressers) had a CL/F of 28.3 l/h whilst slow metabolizers (non‐expressers) had a CL/F of 14.1 l/h. Here, in simulation, a standard 10 mg QD SRL was contrasted with a higher frequency of 5 mg BID SRL as related to the proportion of next dosed patients being within the 15–30 ng/ml trough levels on day 7 after transplantation. Near 0% of expressers on either regimen reached or exceeded the 30 ng/ml trough on day 7. Expressers showed protocol dependence for the chance of being within the 15–30 ng/ml range with the 5 mg BID protocol doubling those chances. Non‐expressers appeared less protocol dependent for the probability of being above or below the 15–30 ng/ml range. The ability to determine the genotype early on may help to rationalize the initial titration of individual patients receiving CNI‐free renal transplantation treatment with SRL. Copyright

An ex vivo native environment precision medicine test shows high clinical correlation with responses to first line acute myeloid leukemia treatment

P Preventive and Personalized Medicine (PPPM) as the healthcare model of the near future and its tool, i.e., Translational Medicine (TraMed), represent an innovative model of healthcare services to consolidate advanced healthcare and robust platform for relevant branches of predictive diagnostics, personalized therapeutics and preventive drugs. To achieve the implementation of PPPM concept into practice, it is necessary to create a new strategy based upon the sub-clinical recognition of biomarkers long before the disease clinically manifests itself. This strategy would secure preventive measures whose personalization could have a significant influence on demographics! Meanwhile, penetration of new technologies into the market would demand the reforms not only in the area of healthcare but in medical education as well. Therefore, the problem of the preparation of specialists of the newest generation to secure priority in growing up medical doctors as creative artists is becoming particularly urgent and would require significant revision of training programs and curricula of the higher education as applicable to the medical schools. Modernization and integration of widely accepted medical and teaching standards require consolidation of both the life sciences and medicine that may become the conceptual basis for the medical curricula. The main goal of this training is not to achieve advanced training and expansion of technological skills but to provide development of novel multifaceted approaches to build academic schools of the newest generations and to outline curricula and courses to suit markets of the newest medical platforms. PPPM consists of a wide variety of tests and tools including so much complicated areas as networking, mathematic modeling, nanotools and nanotechnologies, cloudy and mobile technologies to suit the requests and standards of the new healthcare model. Coordinated measures to optimize the progress should be well-focused on solving the accumulating problems in healthcare and the concomitant economic burden that societies across the globe are facing more and more. Taking into consideration the current trends and personal experience, we have made first steps towards direct involvement in the modernization of the healthcare model. Guided by the above-mentioned facts, a non-canonical approach has become setting up under the aegis of EPMA (Brussels, EU), PMC (Washington, DC, USA) and ISPM (Tokyo, Japan) a unique team of medical students, young researchers, entrepreneurs in drug designing, clinicians and administrators of the future to come. Used as an educational-methodical kernel is a three-level basic education system (undergraduate, graduate, and postgraduate) to suit the continuing education. Group and individual vectors as part of the basic inventory are represented by translational medicine, bioinformatics, drug design, translational tools, regulatory courses, etc. The model for accelerated development of continuous vocational education (CVE) in PPPM and TraMed is based on the combinatorial approaches (competence, moduletype approach, personal activity, program-design and problem-oriented) to the elucidation of innovative processes of modernization of the existing educational model. The application of the model for development of CVE has required a new type of the infrastructure of the curricula. PPPM whilst secured by the upgraded educational system would offer great and real promise for the future. And the next generations will speak about the XXI century as a time, when healthcare services became predictive and preventive and its outcomes secured and guaranteed!RESULTS Background: We have overcome the limitations of 40 years of ex vivo testing. The aim of this study is to determine the ability of Vivias novel test (based on studying the ex-vivo sensitivity to drugs) to predict the complete remission (CR) rates after induction chemotherapy with cytarabine (Ara-C) and idarubicin (Ida) in 1st line AML.. Material and Methods: This has been an observational clinical trial where bone marrow samples from adult patients diagnosed with de novo AML in Spanish centers from the PETHEMA group were included. Whole marrow samples maintaining their Native Environment were incubated for 48h in well plates containing Ara-C, Ida, or their combination. Pharmacological responses are calculated using population models. Induction response was assessed according to the Cheson criteria (2003). Patients attaining a CR/CRi were classified as responders and the remaining as resistant. Results: 390 patient samples were used to calculate the dose response (DR) curves for Ara-C alone, Ida alone, and their synergism. For clinical correlation we used 142 patients with median 56 years. The strongest clinical predictors were the Area Under the Curve (AUC) of the DR of Ara-C (P=1.34E-05), and the AUC of IDA (P=3.9E-05). The GAM models revealed a significant relationship (RSquare=0.452 and deviance explained=45%) between these predictors and higher probabilities of post-induction resistance. Fig 1A shows a table illustrating the correlation between clinical outcome (columns) and the test predictions (lines). Using the cut off determined by the GAM models. The test obtain a high Specificity and Positive Protective Value (95% and 80,77%) and a lower sensitivity (50%) with a general prediction of a 81,69%. Interestingly, the 5 cases that the test identify as resistant but were clinically sensitive have high level of minimal residual disease. On the other hand, the test does not properly identify 21/142 that are clinically resistant and the test predicts as sensitive (bottom left quadrant right panel). This mismatched subgroup mimics the problems from molecular markers where a resistant clone present in a minority of leukemic cells cannot be detected yet drives the patient response. Consistent with this analysis, adding the cytogenetic risk factor to the ex vivo results, identifying the high risk population by molecular markers that might be present in a minority of the cells, significantly improves the correlation; Fig. 1B shows the 90% overall correlation achieved in 117 patient samples adding the cytogenetic risk factor, with a major improvement in the sensitivity from 50% to 72%. Both approaches lead to substantial improvements in estimated overall survival. ABSTRACT© 2019 The Egyptian Journal of Internal Medicine | Publ Background/purpose of the study Chronic hepatitis C virus (HCV) infection is considered one of the major healthproblems.About170millionpatientswere infectedwithHCVworldwide.Till few years, Egypt was considered the highest HCV prevalent country worldwide, with predominant genotype number 4. The host immunity plays a major role in HCV infection with evolving data confirming the role of T-helper 17 cells in the formation of chronic HCV infection. The aim of our work was to determine the role of interleukins 17A (IL17A), 17F (IL17F) in the formation of chronic hepatitis C infection. Patients and methods We classify the patients into two groups: the first group included 51 chronic HCV patients who did not take antiviral therapy (the study group) and the second group included 51 healthy blood donors (as a control group). The levels of IL17A and IL17F in the serum of both groups were measured using the sandwich enzymelinked immunosorbent assay method. Results The serum values of IL17A were higher in patients with chronic HCV than the other group with the mean values being 52.9±32.6 pg/ml in the patient group and 17.1 ±10.4 pg/ml in the control group. IL17F was slightly higher in the HCV patient group than the control group, but it was statistically insignificant. Moreover, there were significant positive correlations between IL17A and alanine aminotransferase, viral load, and degree of liver fibrosis. Conclusion Patients with chronic HCV infections had a higher serum level of IL17A than the normal persons and it is positively correlated with alanine aminotransferase, viral load, and degree of liver fibrosis. This suggests its pivotal role in the formation of chronic HCV infection; so, it can be used as a new marker for disease progression due to its positive correlation with the severity of liver injury.