Effect of Chronic Hepatitis C on the Activity of the Membrane Transporters P-gp and OATP1B1/BCRP on Patients With Different Stages of Hepatic Fibrosis.

The activity of the membrane transporters organic anion-transporting polypeptide 1B1 (OATP1B1) & breast cancer resistance protein (BCRP) (rosuvastatin) and P-glycoprotein (P-gp) (fexofenadine) was evaluated in patients with chronic hepatitis C virus (HCV) infection (n = 28), genotypes 1 and 3, investigated before the treatment with direct-acting antiviral agents (Phase 1) and up to 30 days after the assessment of the virologic response (Phase 2). Participants allocated in Groups 1 (n = 15; F0/F1 and F2, mild to moderate liver fibrosis) and 2 (n = 13; F3 and F4, advanced course of liver fibrosis/cirrhosis) received in both phases fexofenadine (10 mg) and rosuvastatin (2 mg). OATP1B1 & BCRP activity (rosuvastatin area under the plasma concentration-time curve of rosuvastatin from time zero to infinity (AUC0-∞ )) was reduced in Groups 1 and 2, respectively, by 25% (ratio 0.75 (0.53-0.82), P < 0.01) and 31% (ratio 0.69 (0.46-0.85), P < 0.05) in Phase 1 compared with Phase 2. OATP1B1 & BCRP activity was reduced in Phases 1 and 2, respectively, by 49% (median ratio 1.51 (1.17-2.20), P < 0.05) and 61% (ratio 1.39 (1.16-2.02), P < 0.01) in Group 2 compared with Group 1. P-gp activity (fexofenadine AUC0-∞ ) was also reduced in Phase 1 compared with Phase 2 (ratio Phase2/Phase1 0.79 (0.66-0.96) in Group 1 and 0.81 (0.69-0.96) in Group 2) as well as in Group 2 compared with Group 1 in both Phases (ratio Group2/Group1 1.47 (1.08-2.01) in Phase 1 and 1.51 (1.10-2.07) in Phase 2). Thus, clinicians administering OATP1B1 & BCRP and P-gp substrates with low therapeutic indexes should consider the evolution of the treatment and the stage of HCV infection.

Pharmacokinetics of Carboplatin in Combination with Low-Dose Cyclophosphamide in Female Dogs with Mammary Carcinoma.

This prospective study aimed to evaluate the effect of metronomic cyclophosphamide on carboplatin's tolerability, efficacy, and pharmacokinetics in dogs with mammary carcinoma. Sixteen female dogs with mammary carcinoma were divided into groups: 300 mg/m2 intravenous (i.v.) carboplatin therapy (G1 = 8) or 300 mg/m2 i.v. carboplatin which was associated with 12.5 mg/m2 oral cyclophosphamide in a metronomic regimen (G2 = 8). The investigated animals underwent a clinical evaluation, a mastectomy, a carboplatin chemotherapy, and serial blood sampling for the pharmacokinetic analysis. The adverse events and survival rates were monitored. A non-compartmental analysis was applied to calculate the pharmacokinetic parameters of carboplatin in the 2nd and 4th chemotherapy cycles. Carboplatin PK showed high interindividual variability with a 10-fold variation in the area under the plasma concentration−time curve (AUC) in G1. The systemic plasma exposure to carboplatin was equivalent in both of the treatments considering the AUC and maximum plasma concentration (Cmax) values. Although the red blood cells (p < 0.0001), platelets (p = 0.0005), total leukocytes (p = 0.0002), and segmented neutrophils (p = 0.0007) were reduced in G2, the survival rate increased (p = 0.0044) when it was compared to G1. In conclusion, adding low daily doses of cyclophosphamide to a carboplatin therapy showed promising outcomes in female dogs with mammary tumors.

Sensitive LC-MS/MS Methods for Amphotericin B Analysis in Cerebrospinal Fluid, Plasma, Plasma Ultrafiltrate, and Urine: Application to Clinical Pharmacokinetics.

Neurocryptococcosis, a meningoencephalitis caused by Cryptococcus spp, is treated with amphotericin B (AmB) combined with fluconazole. The integrity of the brain-blood barrier and the composition of the cerebrospinal fluid (CSF) may change due to infectious and/or inflammatory diseases such as neurocryptococcosis allowing for the penetration of AmB into the central nervous system. The present study aimed to develop LC-MS/MS methods capable of quantifying AmB in CSF at any given time of the treatment in addition to plasma, plasma ultrafiltrate, with sensitivity compatible with the low concentrations of AmB reported in the CSF. The methods were successfully validated in the four matrices (25 µl, 5-1,000 ng ml-1 for plasma or urine; 100 µl, 0.625-250 ng ml-1 for plasma ultrafiltrate; 100 µl, 0.1-250 ng ml-1 for CSF) using protein precipitation. The methods were applied to investigate the pharmacokinetics of AmB following infusions of 100 mg every 24 h for 16 days administered as a lipid complex throughout the treatment of a neurocryptococcosis male patient. The methods allowed for a detailed description of the pharmacokinetic parameters in the assessed patient in the beginning (4th day) and end of the treatment with AmB (16th day), with total clearances of 7.21 and 4.25 L h-1, hepatic clearances of 7.15 and 4.22 L h-1, volumes of distribution of 302.94 and 206.89 L, and unbound fractions in plasma ranging from 2.26 to 3.25%. AmB was quantified in two CSF samples collected throughout the treatment with concentrations of 12.26 and 18.45 ng ml-1 on the 8th and 15th days of the treatment, respectively. The total concentration of AmB in plasma was 31 and 20 times higher than in CSF. The unbound concentration in plasma accounted for 77 and 44% of the respective concentrations in CSF. In conclusion, the present study described the most complete and sensitive method for AmB analysis in plasma, plasma ultrafiltrate, urine, and CSF applied to a clinical pharmacokinetic study following the administration of the drug as a lipid complex in one patient with neurocryptococcosis. The method can be applied to investigate the pharmacokinetics of AmB in CSF at any given time of the treatment.

Clinical treatment for hepatitis C reverses CYP2C19 inhibition.

AIMS: Infection by the hepatitis C virus (HCV) generates inflammatory response selectively modulating cytochrome P450 protein (CYP) activities. This study assessed the effect of chronic hepatitis C on CYP2C19 activity in patients with HCV. METHODS: Patients with HCV infection (n = 23) at different fibrosis stages were allocated into groups 1 (F0/F1 and F2, mild to moderate fibrosis) and 2 (F3 and F4, advanced fibrosis stages). Phase 1 was conducted before the treatment with direct-acting antivirals (DAAs) and phase 2 after the sustained virological response. Participants were administered 2 mg of a single oral dose of omeprazole (OME) as probe drug in both phases. Metabolic ratios (MRs) (plasma samples collected at 4 h after OME administration) were calculated by dividing plasma concentrations of 5-hydroxyomeprazole by OME. RESULTS: The MRs for group 1 were 0.45 (0.34-0.60, 90% confidence interval) and 0.69 (0.50-0.96) for phases 1 and 2, respectively, while the MRs for group 2 were 0.25 (0.21-0.31) and 0.41 (0.30-0.56) for phases 1 and 2, respectively. MRs were different (P < .05) between phases 1 and 2 for both groups, as well as between groups 1 and 2 in phase 1, but not in phase 2 (P > .05). CONCLUSIONS: Both groups presented different MRs before and after treatment with DAAs, evidencing that CYP2C19 inhibition during inflammation was at least partially reversed after DAA treatment. Groups 1 and 2 were also found to be different in phase 1 but not phase 2, showing that CYP2C19 metabolic activity does not differ between groups after DAA treatment.

Analysis of daunorubicin and its metabolite daunorubicinol in plasma and urine with application in the evaluation of total, renal and metabolic formation clearances in patients with acute myeloid leukemia.

This report presents improved analysis methods of daunorubicin (DAUN) and its metabolite daunorubicinol (DAUNOL) in small volumes of plasma, as total and unbound concentrations, as well as in urine. This study also presents the pharmacokinetics of DAUN and DAUNOL in patients (n = 12) diagnosed with acute myeloid leukemia treated with intravenous DAUN (60 mg/m2/day, for three days). Serial blood and urine samples were collected up to 144 h after the beginning of the first infusion. The analytical methods presented no significant matrix effect. The linear ranges were 0.1-1000 ng/mL in plasma, 0.05-40 ng/mL in ultrafiltrate and 0.5-3000 ng/ml in urine. The precision and accuracy presented coefficients of variation and standard errors lower than 15 % in the three matrices. The methods allowed for the quantification of samples up to 144 h after the beginning of the first infusion. Unbound fractions for DAUN and DAUNOL were 23.91 % (17.33-32.99) and 29.23 % (25.84-33.07), respectively. The fraction recovered in urine was 4.40 % (3.87-5.03) for DAUN and 7.91 % (6.86-9.19) for DAUNOL. Total 292.96 L/h (261.74-327.90), renal 13.01 L/h (11.44-14.88), and hepatic 280.26 L/h (248.40-317.91) clearances of DAUN, as well as the DAUNOL formation clearance 23.41 L/h (19.09-28.97), were evaluated.

Systemic Lupus Erythematosus Activity Affects the Sinusoidal Uptake Transporter OATP1B1 Evaluated by the Pharmacokinetics of Atorvastatin.

The present study assessed the effect of systemic lupus erythematosus (SLE) activity, a chronic and inflammatory autoimmune disease, on the sinusoidal uptake transporter OATP1B1 using atorvastatin (ATV) as a probe drug. Fifteen healthy subjects, 13 patients with controlled SLE (SLEDAI 0-4), and 12 patients with uncontrolled SLE (SLEDAI from 6 to 15), all women, were investigated. Apparent total clearance of midazolam (MDZ), a marker of CYP3A4 activity, did not vary among the three investigated groups. The controlled and uncontrolled SLE groups showed higher plasma concentrations of MCP-1 and TNF-α, while the uncontrolled SLE group also showed higher plasma concentrations of IL-10. The uncontrolled SLE group showed higher area under the curve (AUC) for ATV (60.47 (43.76-83.56) vs. 30.56 (22.69-41.15) ng⋅hour/mL) and its inactive metabolite ATV-lactone (98.74 (74.31-131.20) vs. 49.21 (34.89-69.42) ng⋅hour/mL), and lower apparent total clearance (330.7 (239.30-457.00) vs. 654.5 (486.00-881.4) L/hour) and apparent volume of distribution (2,609 (1,607-4,234) vs. 7,159 (4,904-10,450) L), when compared to the healthy subjects group (geometric mean and 95% confidence interval). The pharmacokinetics of ATV and its metabolites did not differ between the healthy subject group and the patients with controlled SLE group. In conclusion, uncontrolled SLE increased the systemic exposure to both ATV and ATV-lactone, inferring inhibition of OATP1B1 activity, once in vivo CYP3A4 activity assessed by oral clearance of MDZ was unaltered. The inflammatory state, not the disease itself, was responsible for the changes described in the uncontrolled SLE group as a consequence of inhibition of OATP1B1, because systemic exposure to ATV and its metabolites were not altered in patients with controlled SLE.

Total, renal and hepatic clearances of doxorubicin and formation clearance of doxorubicinol in patients with breast cancer: Estimation of doxorubicin hepatic extraction ratio.

Doxorubicin (DOX) is a cytotoxic drug which has remained as an essential component of chemotherapy regiment for breast cancer. The cardiotoxicity of DOX is related to the accumulation of its main metabolite doxorubicinol (DOXOL) in the cardiac tissue. Although the pharmacokinetics of DOX shows high interindividual variability, there are no significant covariates to improve dose adjustment. The present study reports the pharmacokinetics of both DOX and DOXOL in a homogeneous population of young female patients with breast cancer (n = 12) making use of a standardized drug association, evaluated in the very first chemotherapy cycle, using plasma and urine data that allowed the calculation of the renal clearance of DOX, the formation clearance of DOXOL and the hepatic clearance of DOX. The extensive data availability also made it possible to estimate the hepatic extraction ratio of DOX for the investigated population, as well as to determine DOXOL unbound fraction in plasma for the first time in humans. DOX and DOXOL simultaneous analysis in plasma, plasma ultrafiltrate, and urine were performed by liquid chromatography coupled to mass spectrometry (LC-MS/MS). The pharmacokinetics profile of both DOX and DOXOL showed high variability (geometric coefficient of variation of area under the plasma concentration versus time curve extrapolated to infinity was approximately 215 %). The geometrics means were 0.26 for DOXOL/DOX AUC ratio, 15 % and 17 % for unbound fractions of DOX and DOXOL, respectively, 30.70 L⋅h-1 for total clearance, 0.66 L⋅h-1 for renal clearance, 29.97 L⋅h-1 for hepatic clearance and 0.39 L⋅h-1 for the formation clearance of the metabolite DOXOL. The 95 % confidence interval of the estimated hepatic extraction ratio of DOX ranged from 0.14 to 0.79, which characterizes DOX as a drug of low, intermediate or high hepatic extraction ratio.