Pharmacokinetics of high-dose extended-infusion meropenem during pulmonary exacerbation in adult cystic fibrosis patients: a case series.

This case series explored the pharmacokinetic/pharmacodynamic (PK/PD) characteristics of meropenem (MEM) in adult cystic fibrosis (CF) patients hospitalized for a pulmonary exacerbation. From January 2015 to June 2016, all adult patients with cystic fibrosis (CF) and chronic pulmonary infection due to meropenem (MEM)-susceptible/intermediate Pseudomonas aeruginosa who received at least 48 h of MEM as an extended 3-hour infusion for treating a pulmonary exacerbation were enrolled. MEM plasma concentrations were determined by high-performance liquid chromatography. Six adult CF patients with a median age of 47 years were included in the study. MEM showed a high Vd (mean 45.98 L, standard deviation [SD] ±34.45). A minimal PK/PD target of 40% T > minimum inhibitory concentration (MIC) with respect to the MEM MIC of P. aeruginosa strains isolated from sputum during exacerbation was achieved in 5/6 patients (83%). MEM failed to achieve this target only in one patient, whose strain showed the highest MEM MIC in our cohort (8 mg/L). In all patients, MEM was well tolerated, and no adverse events were reported. In conclusion, high-dose, extended-infusion MEM during pulmonary exacerbation showed a high Vd in six adult CF patients with high median age, and was well tolerated.

Bromfenac ophthalmic solution 0.09 %: human aqueous humor concentration detected by high-performance liquid chromatography.

The purpose of this study was to evaluate the aqueous humor concentrations of bromfenac ophthalmic solution 0.09 % in patients undergoing phacoemulsification. Patients requiring cataract extraction received one drop (50 µL) of bromfenac 0.09 % solution in the eye to be operated, before bedtime the day before surgery or the morning of the surgery. The last administration was recorded. At the time of paracentesis, an aqueous humor sample was collected with a 30-gauge needle attached to a TB syringe and was later analyzed by high-performance liquid chromatography for drug concentration. 188 treated volunteers and 48 control, untreated, subjects were included in the study. The mean aqueous concentration of bromfenac in the treated group was 37.60 ± 68.86 and 0 nM (nmol/L) in the control group (p < 0.0001). Correlation coefficient in bromfenac group between time elapsed from instillation and drug concentration was -0.16 (p not significant). Bromfenac showed properties of good penetration and stable concentration in aqueous humor up to about 12 h after instillation.

Population pharmacokinetics and probability of target attainment of meropenem in critically ill patients.

PURPOSE: Patients admitted to intensive care unit (ICU) with Klebsiella pneumoniae infections are characterized by high mortality. The aims of the present study were to investigate the population pharmacokinetics parameters and to assess the probability of target attainment of meropenem in critically ill patients to provide information for more effective regimens. METHODS: Twenty-seven consecutive patients were included in the study. Meropenem was administered as 3-h intravenous (i.v.) infusions at doses of 1-2 g every 8 or 12 h. Meropenem plasma concentrations were measured by a high-performance liquid chromatography (HPLC) method, and a population pharmacokinetics analysis was performed using NONMEM software. Meropenem plasma disposition was simulated for extended (3 h; 5 h) or continuous i.v. infusions, and the following parameters were calculated: time during which free drug concentrations were above minimum inhibitory concentration (MIC) (fT > MIC), free minimum plasma concentrations above 4× MIC (fCmin > 4× MIC), probability of target attainment (PTA), and cumulative fraction of response (CFR). RESULTS: Gender and severity of sepsis affected meropenem clearance, whose typical population values ranged from 6.22 up to 12.04 L/h (mean ± standard deviation (SD) value, 9.38 ± 4.47 L/h). Mean C min value was 7.90 ± 7.91 mg/L, suggesting a high interindividual variability. The simulation confirmed that 88 and 97.5 % of patients achieved effective C min > 4× MIC values after 3- and 5-h i.v. infusions of meropenem 2 g × 3/day, respectively. On the contrary, the same total daily doses reached the target C min > 4× MIC values in 100 % of patients when administered as continuous i.v. infusions. CONCLUSIONS: Several factors may influence meropenem pharmacokinetics in ICU patients. Continuous i.v. infusions of meropenem seem to be more effective than standard regimens to achieve optimal therapeutic targets.

In vitro and in vivo antiproliferative activity of metformin on stem-like cells isolated from spontaneous canine mammary carcinomas: translational implications for human tumors.

BACKGROUND: Cancer stem cells (CSCs) are considered the cell subpopulation responsible for breast cancer (BC) initiation, growth, and relapse. CSCs are identified as self-renewing and tumor-initiating cells, conferring resistance to chemo- and radio-therapy to several neoplasias. Nowadays, th (about 10mM)e pharmacological targeting of CSCs is considered an ineludible therapeutic goal. The antidiabetic drug metformin was reported to suppress in vitro and in vivo CSC survival in different tumors and, in particular, in BC preclinical models. However, few studies are available on primary CSC cultures derived from human postsurgical BC samples, likely because of the limited amount of tissue available after surgery. In this context, comparative oncology is acquiring a relevant role in cancer research, allowing the analysis of larger samples from spontaneous pet tumors that represent optimal models for human cancer. METHODS: Isolation of primary canine mammary carcinoma (CMC) cells and enrichment in stem-like cell was carried out from fresh tumor specimens by culturing cells in stem-permissive conditions. Phenotypic and functional characterization of CMC-derived stem cells was performed in vitro, by assessment of self-renewal, long-lasting proliferation, marker expression, and drug sensitivity, and in vivo, by tumorigenicity experiments. Corresponding cultures of differentiated CMC cells were used as internal reference. Metformin efficacy on CMC stem cell viability was analyzed both in vitro and in vivo. RESULTS: We identified a subpopulation of CMC cells showing human breast CSC features, including expression of specific markers (i.e. CD44, CXCR4), growth as mammospheres, and tumor-initiation in mice. These cells show resistance to doxorubicin but were highly sensitive to metformin in vitro. Finally, in vivo metformin administration significantly impaired CMC growth in NOD-SCID mice, associated with a significant depletion of CSCs. CONCLUSIONS: Similarly to the human counterpart, CMCs contain stem-like subpopulations representing, in a comparative oncology context, a valuable translational model for human BC, and, in particular, to predict the efficacy of antitumor drugs. Moreover, metformin represents a potential CSC-selective drug for BC, as effective (neo-)adjuvant therapy to eradicate CSC in mammary carcinomas of humans and animals.

Determination of deferasirox plasma concentrations: do gender, physical and genetic differences affect chelation efficacy?

OBJECTIVES: Bioavailability of deferasirox (DFX) is significantly affected by the timing of administration relative to times and to composition of meals. Its elimination half-life is also highly variable - in some patients as a result of gene polymorphisms. Understanding whether deferasirox plasma levels are related to specific characteristics of patients could help physicians to devise a drug regimen tailored the individual patient. METHODS: We analyzed deferasirox plasma concentrations (CDFX ) in 80 patients with transfusion-dependent anemias, such as thalassemia, by a high performance liquid chromatography (HPLC) assay. We used a multivariate linear regression model to find significant associations between CDFX and clinical/demographical characteristics of patients. All patients were genotyped for UGT1A1. RESULTS: Fifty-six patients were female, 24 were male, the great majority (88%) affected by ß-thalassemia, and 15 were children and adolescents. No statistical correlation was detectable between CDFX and DFX dose (P = 0.6). Age, time from last drug intake to blood sampling, and ferritin levels in the 6 months before study initiation were significantly and inversely associated with CDFX in univariate analysis. In the multivariate analysis, the only two factors independently and inversely associated with CDFX levels were time from last drug intake to blood sampling and ferritin levels (P = 0.006). A significant inverse correlation (P = 0.03) was observed between CDFX and UGT1A1*28 gene polymorphism, but only in patients with levels of lean body mass (LBM) below the median (P for interaction = 0.05). CONCLUSIONS: The results could indicate that a higher plasma DFX concentration could be associated with greater chelation efficacy. As a correlation between dose and CDFX was not demonstrated, it seems useful to monitor the concentrations to optimize and determine the most appropriate dose for each patient. Interesting results emerged from the analysis of genetic and physical characteristics of patients: LBM was a borderline significant effect modifier of the relationship between UGT1A1 polymorphisms and CDFX . Individual patient-tailored dosing of DFX should help to improve iron chelation efficacy and to reduce dose-dependent drug toxicity.

An artificial aqueous humor as a standard matrix to assess drug concentration in the anterior chamber by high performance liquid chromatography methods.

BACKGROUND: The aim of the study was to recreate in-vitro artificial aqueous humor with the same physico-chemical properties of human aqueous humor to be used as a standard matrix in chromatography to assess drug concentration in the anterior and posterior chamber of the human eye. METHODS: The artificial aqueous humor was prepared according to the human aqueous humor chemical compositions reported in the literature. The artificial matrix was then analysed via the HPLC-UV method and compared with aqueous humor from 15 patients who underwent cataract surgery. Known concentrations of widely-used ophthalmological drugs were added to the artificial aqueous humor in order to assess whether it can be used to explore ocular disposition towards topically or systemically administered drugs. RESULTS: No significant differences were found between the two examined aqueous humor types. There were no significant qualitative differences between examined fluids in terms of presence of ophthalmological drugs. CONCLUSIONS: The composition of artificial, in-vitro recreated aqueous humor was similar to that of the human kind. The absence of significant differences in the analysis of tested drugs both in the artificial and in human aqueous humor indicates that artificial aqueous humor may be used to generate a matrix-based standard curve for analytical method validation.

HPLC determination of malondialdehyde as biomarker for oxidative stress: application in patients with alcohol dependence.

BACKGROUND: Chronic and excess ethanol exposure causes an increase in generation of free radicals which attack the polyunsaturated fatty acids in membranes to create lipid peroxides such as malondialdehyde (MDA) which is widely used as an indirect biomarker of oxidative stress. METHODS: In this study a sensitive and reproducible high performance liquid chromatography (HPLC) method for measurement of MDA was applied in a group of alcohol dependent patients who underwent detoxification treatment. RESULTS: Compared to the control group, mean MDA concentrations at baseline were significantly higher in alcohol dependent patients (1.28 +/- 0.58 microM vs. 0.9 +/- 0.21 microM; p < 0.02). However, MDA levels remained almost unchanged after three weeks of detoxification treatment (1.28 +/- 0.58 microM vs. 1.38 +/- 0.61 microM; p > 0.05). Among alcoholic patients, the MDA plasma concentration in smokers was higher than in non smokers both at baseline and after three weeks. CONCLUSIONS: The failure to reduce the levels of MDA after 3 weeks of detoxification treatment suggests that patients with chronic alcohol dependence have difficulty in compensating for alcohol-induced excessive production of free radicals. Furthermore, the possibility of cigarette smoke affecting the MDA plasma concentration cannot be ruled out.

Effect of Aging on Deferasirox Therapy in Transfusion-dependent Patients. A prospective-retrospective, cohort-study.

BACKGROUND: Iron-chelation therapy is life-saving in patients on a chronic transfusion regimen as it reduces organ damage related to iron deposition in the tissues. Deferasirox, an iron-chelator, is characterized by pharmacokinetics variability, and some patients may discontinue the treatment due to toxicities. OBJECTIVE: Understanding whether deferasirox plasma levels are related to patients' specific characteristics could help optimize DFX dosage. METHODS: We analyzed deferasirox plasma concentration in 57 transfusion-dependent anemic patients using the HPLC method in this prospective-retrospective cohort study. All outpatients (3 to 98 years) were treated with deferasirox (film-coated tablet) for at least one year (median dose, 16.5 mg/Kg once a day). Deferasirox plasma concentration was normalized for dose/Kg (C/dose) and corrected with a linear regression model that relates C/dose and the time of blood sampling (Cref/dose). RESULTS: No significant differences in Cref/dose were found between males and females, either between different types of hemoglobinopathies or depending on the presence of the UGT1A1*28 polymorphism. Cref/dose has a positive and significant correlation with age, creatinine, and direct bilirubin. Cref/dose, instead, has a negative and significant correlation with Liver Iron Concentration (LIC), ferritin, and eGFR. Cref/dose was significantly different between three age categories <18yrs, 18-50yrs, and >50yrs, with Cref/dose median values of 1.0, 1.2, and 1.5, respectively. CONCLUSION: The study evidenced that to ensure the efficacy of deferasirox in terms of control over LIC and, at the same time, a lesser influence on renal function, the dose of the drug to be administered to an elderly patient could be reduced.

Exposure to asbestos: correlation between blood levels of mesothelin and frequency of micronuclei in peripheral blood lymphocytes.

Inhalation of asbestos, a mineral extensively used in a variety of applications, is strongly associated with malignant mesothelioma (MM), a fatal cancer of the pleura. Soluble mesothelin-related peptides (SMRP) are a promising biomarker suggested for the screening of MM in healthy asbestos-exposed subjects. In the present study a comparison of micronucleus (Mn) frequencies in peripheral blood lymphocytes (PBL) between 44 asbestos-exposed and 22 control individuals has been performed, and the correlation with serum SMRP has been examined. SMRP levels were found to be significantly higher in subjects exposed to asbestos and in their various subgroups than in controls. Concerning micronucleated lymphocytes, a statistically significant difference from controls was seen in the percentages of both micronucleated mononucleated lymphocytes (MnMNL) and micronucleated binucleated lymphocytes (MnBNL), but the difference was markedly higher for the percentage of micronucleated polynucleated lymphocytes (MnPNL). With respect to the correlation between the frequency of the three types of micronucleated lymphocytes and serum-SMRP values of asbestos-exposed subjects, it was statistically significant for MnMNL, but not for MnBNL and MnPNL.

Assessment of intestinal permeability using sugar probes: influence of urinary volume.

BACKGROUND: As the accuracy of the "Sugar Test" is currently debated, this study was conducted to focus on how urine volumes may impact the test results. METHODS: Fifty-five subjects, 23 healthy and 32 with Irritable Bowel Syndrome (IBS), were enrolled. Lactulose and D-mannitol dissolved in water were administered to all the participating subjects; the urine excreted was collected and the total urine volume was measured. The urine samples were analyzed by High Performance Liquid Chromatography (HPLC). The results were expressed as percentage of urine recovery of lactulose and D-mannitol and lactulose/D-mannitol ratio (LMR). RESULTS: All subjects were divided into two groups: subjects with urine volume < 500 mL and subjects with urine volume > or = 500 mL. Urine analysis showed that the mean LMR was significantly lower in subjects with urine volume > or = 500 mL than in subjects with urine volume < 500 mL (0.02 +/- 0.02 vs 0.04 +/- 0.04; p < 0.05). A significant increase in D-mannitol recovery was found to be associated with greater urine volumes (p < 0.001). CONCLUSIONS: The urine volume may influence urinary excretion of sugar probes. Intake of liquids should therefore be carefully monitored before and during the test and the volume of urine produced over the period of collection should be precisely measured.

Evaluation of Pharmacokinetics and Pharmacodynamics of Deferasirox in Pediatric Patients.

BACKGROUND: Deferasirox (DFX) is commonly used to reduce the chronic iron overload (IO) in pediatric patients. However, the drug is characterized by a large pharmacokinetic variability and approximately 10% of patients may discontinue the treatment due to toxicities. Therefore, the present retrospective study investigated possible correlations between DFX pharmacokinetics and drug-associated toxicities in 39 children (26 males), aged 2-17 years, who underwent an allogeneic hematopoietic stem cell transplantation. METHODS: IO was diagnosed by an abdominal magnetic resonance imaging and DFX was started at a median dose of 500 mg/day. DFX plasma concentrations were measured by a high performance liquid chromatographic method with UV detection and they were analysed by nonlinear mixed-effects modeling. RESULTS: The pharmacometric analysis demonstrated that DFX pharmacokinetics were significantly influenced by lean body mass (bioavailability and absorption constant), body weight (volume of distribution), alanine and aspartate transaminases, direct bilirubin, and serum creatinine (clearance). Predicted DFX minimum plasma concentrations (Ctrough) accounted for 32.4 ± 23.2 mg/L (mean ± SD), and they were significantly correlated with hepatic/renal and hematological toxicities (p-value < 0.0001, T-test and Fisher's exact tests) when Ctrough threshold values of 7.0 and 11.5 mg/L were chosen, respectively. CONCLUSIONS: The population pharmacokinetic model described the interindividual variability and identified Ctrough threshold values that were predictive of hepatic/renal and hematological toxicities associated with DFX.

Safety and pharmacokinetics of medical cannabis preparation in a monocentric series of young patients with drug resistant epilepsy.

OBJECTIVES: To evaluate safety and pharmacokinetic parameters (PK) of medical cannabis in add-on for children and young adults with drug-resistant epilepsy. DESIGN, SETTING: Ten patients (4 females, 6 males, age 2.5-23.2 years) were enrolled in a prospective open trial with a galenic preparation (decoction) of Italian cannabis (FM2, ratio THC:CBD = 3:5, range THC 5.2-7.2 %; CBD 8.2-11.1 %). Patients received the first dose in Hospital, progressively augmented by CBD dose titration (from 1 to 4 mg/kg/day). OUTCOME MEASURES: In order to assess safety, blood parameters, heart rates and electrocardiograms (ECGs) were evaluated before the enrollment and during the follow up. The PK study was performed measuring THC and CBD concentrations by UHPLC-MS/MS in plasma samples collected during the first administration and at each follow-up visit. RESULTS: Two out of ten patients stopped the treatment for adverse events (detected in 6/10: gastroenteric, sleep or behavioral disorders) and difficulties in drug supply. We observed minor ECG alterations in two patients and asymptomatic transient reductions of fibrinogen after 6 months of therapy. The PK study during follow-up revealed statistically significant correlations between THC-CBD blood concentrations and: volumes of decoction, FM2 and THC-CBD daily dosages. CONCLUSIONS: The present study, although with some limitations, shows a good safety profile of medical cannabis in children and young patients with drug-resistant epilepsy and encourages the possibility of further studies with oral cannabis-based drugs. The correlations between THC-CBD plasma concentrations and their administered dosages underline the need of a therapeutic drug monitoring for cannabinoids therapy.

Combined evaluation of genotype and phenotype of thiopurine S-methyltransferase (TPMT) in the clinical management of patients in chronic therapy with azathioprine.

Background The thiopurine S-methyltransferase (TPMT)/azathioprine (AZA) gene-drug pair is one of the most well-known pharmacogenetic markers. Despite this, few studies investigated the implementation of TPMT testing and the combined evaluation of genotype and phenotype in multidisciplinary clinical settings where patients are undergoing chronic therapy with AZA. Methods A total of 356 AZA-treated patients for chronic autoimmune diseases were enrolled. DNA was isolated from whole blood and the samples were analyzed for the c.460G>A and c.719A>G variants by the restriction fragment length polymorphism (RFLP) technique and sequenced for the c.238G>C variant. The TPMT enzyme activity was determined in erythrocytes by a high-performance liquid chromatography (HPLC) assay. Results All the patients enrolled were genotyped while the TPMT enzyme activity was assessed in 41 patients. Clinical information was available on 181 patients. We found no significant difference in the odds of having adverse drug reactions (ADRs) in wild-type patients and variant allele carriers, but the latter had an extra risk of experiencing hematologically adverse events. The enzyme activity was significantly associated to genotype. Conclusions TPMT variant allele carriers have an extra risk of experiencing hematologically adverse events compared to wild-type patients. Interestingly, only two out of 30 (6.6%) patients had discordant results between genotype, phenotype and onset of ADRs.

What is known about deferasirox chelation therapy in pediatric HSCT recipients: two case reports of metabolic acidosis.

To date, in pediatric field, various hematological malignancies are increasingly treated with allogeneic hematopoietic stem cell transplantation (allo-HSCT). Iron overload and systemic siderosis often occur in this particular cohort of patients and are associated with poor prognosis. We describe herein the case of two allo-HSCT patients, on treatment with deferasirox; they showed histopathological elements compatible with venoocclusive disease or vanishing bile duct syndrome in ductopenic evolution before deferasirox started. The first patient developed drug-induced liver damage with metabolic acidosis and the second one a liver impairment with Fanconi syndrome. After withdrawing deferasirox treatment, both patients showed improvement. Measurements of drug plasma concentrations were performed by HPLC assay. The reduction and consequent disappearance of symptoms after the suspension of deferasirox substantiate its role in inducing hepatic damage, probably enabling the diagnosis of drug-induced liver damage. But the difficulties in diagnosing drug-related toxicity must be underlined, especially in compromised subjects. For these reasons, in patients requiring iron-chelating therapy, close and careful drug therapeutic monitoring is strongly recommended.

A UHPLC-MS/MS method for the quantification of Δ9-tetrahydrocannabinol and cannabidiol in decoctions and in plasma samples for therapeutic monitoring of medical cannabis.

Aim: Monitoring of blood levels of Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) is necessary for optimization of administration of medical cannabis. We describe the validation of a ultra-HPLC-MS/MS method for quantifying THC and CBD from plasma and decoctions and its application for therapeutic drug monitoring.Materials & methods: Analyses were performed by using a TSQ Quantiva™ Triple Quadrupole coupled to a Ultimate 3000 UHPLC system with atmospheric pressure chemical ionization after sample preparation with a straightforward method with deuterated internal standards. Results: The method has been validated following EMA guidelines and is linear in plasma from 0.16 to 10 ng/ml for both THC and CBD and in decoctions from 4.7 to 600 ng/ml. Conclusion: Given the unpredictable pharmacokinetic behavior of THC and CBD in patients, monitoring of plasma concentrations is strongly recommended for patients under treatment with medical cannabis.

Development of an Injectable Slow-Release Metformin Formulation and Evaluation of Its Potential Antitumor Effects.

Metformin is an antidiabetic drug which possesses antiproliferative activity in cancer cells when administered at high doses, due to its unfavorable pharmacokinetics. The aim of this work was to develop a pharmacological tool for the release of metformin in proximity of the tumor, allowing high local concentrations, and to demonstrate the in vivo antitumor efficacy after a prolonged metformin exposition. A 1.2% w/w metformin thermoresponsive parenteral formulation based on poloxamers P407 and P124, injectable at room temperature and undergoing a sol-gel transition at body temperature, has been developed and optimized for rheological, thermal and release control properties; the formulation is easily scalable, and proved to be stable during a 1-month storage at 5 °C. Using NOD/SCID mice pseudo-orthotopically grafted with MDA-MB-231/luc+ human breast cancer cells, we report that multiple administrations of 100 mg of the optimized metformin formulation close to the tumor site cause tissue accumulation of the drug at levels significantly higher than those observed in plasma, and enough to exert antiproliferative and pro-apoptotic activities. Our results demonstrate that this formulation is endowed with good stability, tolerability, thermal and rheological properties, representing a novel tool to be pursued in further investigations for adjuvant cancer treatment.

Safety and tolerability of deferasirox in pediatric hematopoietic stem cell transplant recipients: one facility's five years' experience of chelation treatment.

42 pediatric patients with iron overload, who underwent liver biopsy and DFX treatment after hematopoietic stem cell transplantation were included in the study group. The patients were divided into two groups diversified according to deferasirox trough plasma concentrations (DFX Ctrough) with cut-off equal to10 mcg/mL. The average dose of DFX was 25.9 mg/kg in the DFX Ctrough < 10 mcg/mL group versus 19.2 mg/kg in the DFX Ctrough > 10 mcg/mL group (p=0,0003). The mean duration of DFX treatment was 135.7 days in the DFX Ctrough < 10 mcg/mL group versus 41.8 days in the DFX Ctrough > 10 mcg/mL group (p<0.0001). The mean tissue iron concentration in the DFX Ctrough < 10 mcg/mL group was 261.9 µmol/g versus 133.4 µmol/g in the DFX Ctrough > 10 mcg/mL group (p < 0.0001). 21 patients (100%) in the DFX Ctrough > 10 mcg/mL group had ductopenia which was complete in 47.6% of them and severe in 52.4%. All patients with particularly high Ctrough (> 25 mcg/mL) were found to have total ductopenia. 90.5% of all deferasirox-related adverse events and 100% of major adverse events occurred in the DFX Ctrough > 10 mcg/mL group. In the DFX Ctrough < 10 mcg/mL group only one patient interrupted chelation therapy versus 16 (84.2%) patients in the DFX Ctrough > 10 mcg/mL group. We would recommend a close monitoring in pediatric hematopoietic transplant recipients subjected to deferasirox-based therapy because we have observed a high incidence of adverse events and discontinuation of chelation treatment.

Meropenem for treating KPC-producing Klebsiella pneumoniae bloodstream infections: Should we get to the PK/PD root of the paradox?

The objective of this study was to assess the achievement of pharmacokinetic/pharmacodynamic (PK/PD) targets of meropenem (MEM) in critically-ill patients with bloodstream infections (BSI) due to Klebsiella pneumoniae-carbapenemase-producing Klebsiella pneumoniae (KPC-Kp) with MEM minimum inhibitory concentrations (MICs) ≥16 mg/L. Nineteen critically-ill patients with KPC-Kp BSI were given combination therapy including MEM, tigecycline, plus colistin or gentamicin (according to susceptibility testing). MEM was administered as an extended 3-hour infusion of 2 g every 8 hours, or adjusted according to renal function. MEM plasma concentrations were determined by high-performance liquid chromatography. PK/PD targets for MEM were defined as T > 40% 1×MIC and T > 40% 4×MIC. Possible synergisms between MEM and coadministered agents were assessed by time-kill assays based on plasma levels for MEM and on fixed plasma concentrations for the other agents. In none of 19 patients MEM reached any PK/PD target. The actual MEM MICs were 256, 512, and 1024 mg/L in 1, 3, and 15 isolates, respectively. However, theoretically, the PK/PD target of T > 40% 1×MIC could have been achieved in 95%, 68%, 32% and 0% of the isolates for MIC equal to 8, 16, 32, and 64 mg/L, respectively. No synergisms were observed between MEM and coadministered agents. In conclusion, high-dose MEM failed to reach PK/PD targets in 19 patients with BSI due to KPC-Kp with very high MEM MICs. On a theoretical basis, our results suggest a possible usefulness of MEM against resistant blood isolates with MICs up to 32 mg/L.

Measurement of sorafenib plasma concentration by high-performance liquid chromatography in patients with advanced hepatocellular carcinoma: is it useful the application in clinical practice? A pilot study.

Pharmacokinetics and dose-finding studies on sorafenib were conducted on heterogeneous groups of patients with solid tumors. Portal hypertension, gut motility impairment and altered bile enterohepatic circulation may explain different sorafenib toxicological profile in cirrhotic patients. This study evaluated sorafenib plasma concentration in a homogeneous group of cirrhotic patients with hepatocellular carcinoma (HCC). Sorafenib concentrations were determined by liquid chromatography in 12 consecutive patients. Data have been evaluated by the generalized estimating equations method (p value statistical level was set at α = 0.05). (1) There were not significant differences between sorafenib concentrations in patients who tolerate the full dose versus patients with reduced dose due to toxicity; (2) the average sorafenib concentrations measured 3 h after the morning dosing were lower than those measured 12 h after the evening dosing (p = 0.005); (3) sorafenib concentrations decrease overtime (p < 10(-4)); (4) it has been found an association between the development of severe adverse reactions and sorafenib concentrations (p < 10(-5)). The relationship between dose and concentration of sorafenib in HCC patients is poor and not clinically predictable, confirming the variability both in the maximum tolerated dose and in plasma concentrations. Several factors may influence the pharmacokinetics in patients with liver disease. This may explain the inter-patient variability of concentrations and the lack of differences in concentration at different dosages. It could be interesting to extend the series of HCC patients to enhance information on the kinetics of the drug; furthermore, to establish a threshold of plasma sorafenib concentrations to predict severe adverse reactions would be clinically useful.

Uncommon serum creatine phosphokinase and lactic dehydrogenase increase during diosmin therapy: two case reports.

INTRODUCTION: Short-term administration of diosmin is usually considered safe, with only minor side effects (stomach and abdominal pain, diarrhea, dermatological disorders, and headache) occasionally observed. Within a 4-year period, a general practitioner noticed 17 cases of mild, diosmin-induced side effects, two of which showed particular interest. CASES PRESENTATION: Case 1: A 55-year-old Caucasian woman presented with chronic leg venous insufficiency. She was prescribed diosmin 450 mg twice a day. After 5 days of therapy, she developed pain in the legs (myalgia), and diosmin therapy was suspended. She made a spontaneous attempt of drug rechallenge and her leg pain reappeared. Thus, she underwent blood analysis, which showed elevation of creatine phosphokinase levels. Creatine phosphokinase values normalized only after prolonged discontinuation of the therapy. Case 2: A 79-year-old Caucasian man, who was diagnosed with acute hemorrhoidal syndrome. After 21 days of continuous diosmin treatment, increased levels of serum lactic dehydrogenase were detected. In both cases a comprehensive analysis of all possible causes for enzyme elevation was made. CONCLUSIONS: A feasible hypothesis to explain these rare effects could be that exaggerated adrenergic activity occurred on microcirculation, leading to an excessive peripheral vasoconstriction and subsequent ischemic damage. An individual predisposition is strongly suggested. A concurrence of events was probably responsible for the elevation of nonspecific tissue necrosis markers. Physicians and patients must be aware of these rare, but possible, adverse drug reactions.