Plasma Drug Levels Research Articles

A novel pellets/thermosensitive hydrogel depot with low burst release for long-term continuous drug release: Preparation, characterization, in vitro and in vivo studies

The purpose of this study was to develop a pellets/thermosensitive gel hybrid depot (Pellets-Gel), designed to provide a novel implant delivery system for long-term steady controlled release of poor soluble drug with less burst release. Pellets made from PLGA and PEG loaded with curcumin (CUR-Pellets)were fabricated via combination of solvent evaporation and extrusion spheronization technique and were characterized by the appearance, drug loading (DL), structure, thermal behavior and morphology. The sol-gel conversion properties, polymers degradation characteristics, drug release kinetics in vitro of final optimized CUR loaded Pellets-Gel (CUR-Pellets-Gel) were evaluated, in vivo pharmacokinetics study were also performed on Sprague-Dawley rats. The results demonstrated that pellets with a diameter about 1.0 mm has a high loading capacity of CUR (30% (w/w)) can be simply produced. In in vitro study, CUR-Pellets-Gel showed a low burst release (2.67%) and release completeness up to 91.83%. In the pharmacokinetics study, the in vivo burst release of CUR-Pellets-Gel was significantly decreased reflected by the AUC (0-1d)/AUC (0-td) value. CUR-Pellets-Gel showed a smoother plasma drug level with a longer drug release profile for 78 days. These results demonstrated that this hybrid depot of pellets/thermosensitive gel could be more potential application in enhanced therapeutic effects of poor soluble drugs by continuously delivering for long periods of time without burst release.

Pharmacogenomic Research in Direct Oral Anticoagulants

Oral anticoagulants play an important role in the prevention and treatment of thromboembolic diseases.Warfarin,a traditional oral anticoagulant,is limited in clinical use due to its limitations such as narrow therapeutic window and requirements on frequent monitoring and dose adjustment.Direct oral anticoagulants(DOACs)such as dabigatran,rivaroxaban,apixaban,and edoxaban are increasingly used to prevent and treat venous thrombosis or thrombus formation.However,recent studies have documented inter-individual variability in plasma drug levels of DOACs.This article summarizes the recent advances in the pharmacogenomics of DOACs.

Interfacial tension effects on the properties of PLGA microparticles

Many types of long-acting injectables, including in situ forming implants, preformed implants, and polymeric microparticles, have been developed and ultimately benefited numerous patients. The advantages of using long-acting injectables include greater patient compliance and more steady state drug plasma levels for weeks and months. However, the development of long-acting polymeric microparticles has been hampered by the lack of understanding of the microparticle formation process, and thus, control of the process. Of the many parameters critical to the reproducible preparation of microparticles, the interfacial tension (IFT) effect is an important factor throughout the process. It may influence the droplet formation, solvent extraction, and drug distribution in the polymer matrix, and ultimately drug release kinetics from the microparticles. This mini-review is focused on the IFT effects on drug-loaded poly(lactic-co-glycolic acid) (PLGA) microparticles.

Safe administration of high-dose methotrexate with minimal drug level monitoring: Experience from a center in north India.

High-dose methotrexate (HDMTX) is recommended to be administered with serial monitoring of methotrexate (MTX) levels, which may not be universally feasible in resource-limited settings. In this study, we evaluated the overall experience of administration of HDMTX at our center by monitoring a single drug level at 54h from the start of MTX infusion. This retrospective study was performed at a tertiary level hospital in north India, over a 5-year period (2011-2015). All patients <18years of age with newly diagnosed acute lymphoblastic leukemia (ALL) and T-non-Hodgkin lymphoma (T-NHL) were enrolled in the study. Details of HDMTX and all significant toxicities requiring prolonged or repeat hospitalization were retrieved from the medical records. All eligible patients received HDMTX as per the recommendations followed by at least three doses of leucovorin rescue, before drug levels were sent at 54h. Subsequent leucovorin doses were adjusted accordingly. The records of 598 cycles of HDMTX in 184 patients were reviewed. A total of 531 of 598 cycles (88.7%) were managed with monitoring only a single plasma drug level at 54h from the beginning of infusion. Delayed MTX clearance was seen in 260 of 598 cycles (43.5%). Only three episodes (0.5%) were associated with significant toxicity. There were no deaths. The strategy of monitoring MTX concentration at 54h was safe in our cohort. Although recommended, dynamic monitoring of plasma drug levels may not always predict toxicity.

The Effect of Omeprazole on the Pharmacokinetics of Piroxicam Profiles with High Performance Liquid Chromatography (HPLC) Method

Piroxicam is an anti-inflammatory drug of the NSAID class that is commonly used as an analgesic and anthireumatic drug. Its use is often combined with gastric drugs, one of which is omeprazole, considering the side effects of piroxicam which can irritate the stomach. Piroxicam and omeprazole work on the same enzyme, CYP-450 so that it can affect the pharmacokinetic profile especially in the metabolic and excretion phases of piroxicam. This research is an experimental study using 3 male rabbits. Measurement of plasma levels of piroxicam drug is carried out using a High Performance’s Liquid Chromatography (HPLC) tool. The validation method is used to determine LOD and LOQ values, accuracy, and precision tests. The results of data analysis using t-tables. The results showed the value of pharmacokinetic parameters in the absorption phase increased or there were differences but did not show any significant effect on each group. While the pharmacokinetic parameter values ​​in the metabolic and excretion phases decreased and showed no differences between groups. The administration of omeprazole and piroxicam together and the administration of piroxicam which was given an hour earlier by omeprazole can inhibit the enzyme that stimulates the metabolism of piroxicam so that it affects the pharmacokinetic parameters in the absorption phase and also excretion but is not significant.

Analysis of Drug Metabolizing Gene Panel in Osteosarcoma Patients Identifies Association Between Variants in SULT1E1, CYP2B6 and CYP4F8 and Methotrexate Levels and Toxicities.

High-dose methotrexate is a cornerstone agent in the chemotherapeutic treatment of patients with osteosarcoma. However, patients often develop methotrexate-induced toxicities. We aim to identify determinants of methotrexate-induced toxicities in osteosarcoma patients by investigating the relation between drug plasma levels, methotrexate-induced toxicities, and germline variants in genes related to drug absorption, distribution, metabolism, and elimination. A cohort of 114 osteosarcoma patients was genotyped for 1,931 variants in 231 genes using the Drug Metabolism Enzymes and Transporters Plus array. Methotrexate plasma levels and laboratory measurements during and after high-dose methotrexate treatment concerning renal function, liver damage, and myelopoiesis to reflect toxicity outcomes were obtained. One hundred and thirteen patients and a subset of 545 variants in 176 genes passed quality control checks. Methotrexate plasma levels showed associations with creatinine, alanine aminotransferase, and hemoglobin. Genetic variant rs3736599 in the 5’-untranslated region of SULT1E1 was associated with lower 48 hour methotrexate plasma levels [coef -0.313 (95% CI -0.459 – -0.167); p = 2.60 × 10-5]. Association with methotrexate-induced decreased thrombocyte counts was found for two intronic variants in CYP2B6 {rs4803418 [coef -0.187 (95% CI -0.275 – -0.099); p = 3.04 × 10-5] and rs4803419 [coef -0.186 (95% CI -0.278 – -0.093); p = 8.80 × 10-5]}. An association with increased thrombocyte counts was identified for the intronic variant rs4808326 in CYP4F8 [coef 0.193 (95% CI 0.099 – 0.287); p = 6.02 × 10-5]. Moreover, a secondary analysis with a binary approach using CTCAE toxicity criteria resulted in a nominal significant associations (p < 0.05) for two out of three variants (rs4803418 and rs4808326). This is the first study to identify genetic variants in SULT1E1, CYP2B6, and CYP4F8 to be associated with methotrexate pharmacokinetics and toxicities. Validation of these variants in an independent cohort and further functional investigation of variants in the identified genes is needed to determine if and how they affect methotrexate plasma levels and the development of methotrexate-induced toxicities.

Withdrawal Notice: Lipid Carriers Mediated Targeted Delivery of Neurotherapeuticals: Challenges, Role of Blood Brain Barrier and Promises of Nanotechnology Based Approaches in Neuronal Disorders

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Analysis of Potential Interaction between Antiretrovirals and Comorbid Medications of HIV Patients at a Top Referral Hospital in Indonesia

Background: HIV/AIDS usually present with comorbid diseases such as tuberculosis, pneumonia, toxoplasmosis, fungal infections, etc., that need multiple medications. Potential interaction between ARV and comorbid drugs is unavoidable. Objective: This study aimed to investigate the potential interaction between ARV drugs and medications used to treat comorbid diseases among HIV patients at the Dr. Cipto Mangunkusumo Hospital, Jakarta. Methods: This was an observational study using medical record data of 121 HIV/AIDS patients treated at the CM Hospital between January 2016 and July 2017. Potential interaction was classified as “major” if it could lead to increase or decrease of plasma drug levels which potentially result in either drug toxicity or treatment failure, or clinically significant harm to the patient; “moderate” if the interaction is not major, but with the recommendation of close monitoring. National, European, Australian, and Liverpool iChart guidelines were used for the classification of drug interactions. Results: Major interactions were noted in 17 (14.05%)patients. Fourteen of them received rifampicin, which potentially decreases plasma level of nevirapine (9 patients), rilpivirine (1 patient), and lopinavir/ritonavir (4 patients). Potential increase of ARV level was found in 3 patients involving interaction between voriconazole-efavirenz (2) and omeprazole-rilpivirine (1). Moderate interaction with the potential decrease of ARV level occurred in 46 patients (38.01%); consisting of a combination of rifampicin with efavirenz (38 pts), rifampicin with zidovudine (6 pts), and phenytoin with efavirenz or nevirapine (2 patients). Conclusion: Potential major interaction occurred in 17 (14.05%), which mostly attributed to rifampicin use; while moderate interaction occurred in 46 (38.01%) of patients. Although no serious adverse event was observed in this study, special care should be taken when the drugs with potential major interaction are to be administered

Handling and performance characteristics of a new small caliber radiopaque embolic microsphere.

The in vitro and in vivo handling and performance characteristics of a small caliber radiopaque embolic microsphere, 40–90 μm DC Bead LUMI™ (LUMI40‐90), were studied. Microsphere drug loading and elution and effects on size, suspension, and microcatheter delivery were evaluated using established in vitro methodologies. In vivo evaluations of vascular penetration (rabbit renal artery embolization), long‐term biocompatibility and X‐ray imaging properties, pharmacokinetics and local tissue effects of both doxorubicin (Dox) and irinotecan (Iri) loaded microspheres (swine hepatic artery embolization) were conducted. Compared to 70–150 μm DC Bead LUMI (LUMI70‐150), LUMI40‐90 averaged 70 μm versus 100 μm, which was unchanged upon drug loading. Handling, suspension, and microsphere delivery studies were successfully performed. Dox loading was faster (20 min) and Iri equivalent (<10 min) while drug elution rates were similar. Contrast suspension times were longer with no delivery complications. Vascular penetration was statistically greater (rabbit) with no unexpected adverse safety findings (swine). Microspheres ± drug were visible under X‐ray imaging (CT) at 90 days. Peak plasma drug levels and area under the curve were greater for LUMI40‐90 compared to LUMI70‐150 but comparable to 70–150 μm DC BeadM1™ (DC70‐150). Local tissue effects showed extensive hepatic necrosis for Dox, whereas Iri displayed lower toxicity with more pronounced lobar fibrosis. LUMI40‐90 remains suspended for longer and have greater vessel penetration compared to the other DC Bead LUMI sizes and are similarly highly biocompatible with long‐term visibility under X‐ray imaging. Drug loading is equivalent or faster with pharmacokinetics similar to DC70‐150 for both Dox and Iri.

Late Pulmonary Embolism after COVID-19 Pneumonia despite Adequate Rivaroxaban Treatment.

IntroductionSARS-CoV-2 infection may predispose patients to thrombotic disease. Patients with COVID-19 pneumonia who are receiving non-vitamin K antagonists or direct oral anticoagulants for chronic disease are usually switched to heparin treatment during hospitalization. However, information about the most appropriate antithrombotic therapy after the acute infection phase is lacking.Case DescriptionWe report the case of a patient with chronic atrial fibrillation who was recently hospitalized for severe COVID-19 pneumonia. Four weeks after discharge he experienced an episode of an acute pulmonary embolism while on rivaroxaban therapy with adequate drug plasma levels, and in the absence of strong predisposing risk factors.ConclusionThis case highlights the risk of thrombotic complications after COVID-19 infection, raises some concern about their underlying mechanisms, and supports the use of effective anti-thrombotic therapy.LEARNING POINTSCOVID-19 infection is associated with frequent thrombotic events.A pro-coagulative status could be triggered by the persistent inflammatory phase of the infection despite anticoagulation.Adequate antithrombotic therapy is necessary for the prevention of acute and later thrombotic complications and needs close monitoring.

Consideration of Pannexin 1 channels in COVID-19 pathology and treatment.

Pannexin1 (PANX1) is a ubiquitously expressed, channel-forming protein found in a number of tissues thoughout the body (e.g. lung, vasculature, liver, central nervous system, immune system) that is important in many key physiological and immune responses. PANX1 channels passively flux ATP (predominantly), multiple metabolites, and likely other small anions. PANX1 channels regulate inflammation and host responses to several pathogens, including viruses. While there is currently no evidence suggesting novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and PANX1 directly interact, there is an urgent need for therapeutic strategies, especially those targeting the hyper-inflammation and cytokine storm that occurs in severe cases of COVID-19. Here we argue that PANX1, and drugs known to target PANX1 (including the FDA-approved drug probenecid), should be the focus of further investigation in the context of SARS-CoV-2 infection and its associated pathology in COVID-19 patients.

Development and validation of an HPLC-MS/MS method for the determination of filgotinib, a selective Janus kinase 1 inhibitor: Application to a metabolic stability study

Filgotinibis aselective Janus kinase 1 inhibitor drug which is currently under investigation for the treatment of rheumatoid arthritis and Crohn s disease. The aim of the present study was to develop an accurate, simple and sensitive LC-MS/MS method for the determination of filgotinib (FLG) in human liver microsomes (HLMs) and its application to a metabolic stability study. Chromatographic separation was carried on using of a reversed phase C18 column. The mobile phase was mixture of acetonitrile and ammonium formate (10 mM, pH 3.8) (30:70, v/v), under isocratic elution at a flow rate of 0.3 mL/min. Veliparib was used as internal standard. FLG was extracted from HLMs by precipitation. An electrospray ionization source was used to assay of FLG. The assay of FLG at m/z 426 → 358 and 426 → 291 for FLG and IS at 245 → 145 and 245 → 84 was attained through MRM. The linearity of the investigated method was observed from 5 to 500 ng/mL (correlation coefficient r2 = 0.999). The LOD was 1.43 ng/mL, while the LOQ was 4.46 ng/mL. The investigated method exhibited good recovery (98.42–108.6%) and precision (ranged from 0.88% to 4.7%). The investigated method was successfully employed for a metabolic stability study of FLG in the HLMs matrix. The metabolic stability of FLG was evaluated by measuring two parameters, in vitro t1/2 (48.47 min) and intrinsic clearance (14.29μL/min/mg). The results of the metabolic study confirm that FLG is execrated from the human body at a slower rate compared to related tyrosine kinase inhibitors. Therefore, drug plasma levels and kidney function should be monitored due to potential bioaccumulation.

Determination of piperaquine concentration in human plasma and the correlation of capillary versus venous plasma concentrations.

A considerable challenge in quantification of the antimalarial piperaquine in plasma is carryover of analyte signal between assays. Current intensive pharmacokinetic studies often rely on the merging of venous and capillary sampling. Drug levels in capillary plasma may be different from those in venous plasma, Thus, correlation between capillary and venous drug levels needs to be established. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was used to develop the method. Piperaquine was measured in 205 pairs of capillary and venous plasma samples collected simultaneously at ≥24hr post dose in children, pregnant women and non-pregnant women receiving dihydroartemisinin-piperaquine as malaria chemoprevention. Standard three-dose regimen over three days applied to all participants with three 40mg dihydroartemisinin/320mg PQ tablets per dose for adults and weight-based dose for children. Correlation analysis was performed using the program Stata® SE12.1. Linear regression models were built using concentrations or logarithm transformed concentrations and the final models were selected based on maximal coefficient of determination (R2) and visual check. An LC-MS/MS method was developed and validated, utilizing methanol as a protein precipitation agent, a Gemini C18 column (50x2.0mm, 5μm) eluted with basic mobile phase solvents (ammonium hydroxide as the additive), and ESI+ as the ion source. This method had a calibration range of 10-1000 ng/mL and carryover was negligible. Correlation analysis revealed a linear relationship: Ccap = 1.04×Cven+4.20 (R2 = 0.832) without transformation of data, and lnCcap = 1.01×lnCven+0.0125, (R2 = 0.945) with natural logarithm transformation. The mean ratio (±SD) of Ccap/Cven was 1.13±0.42, and median (IQR) was 1.08 (0.917, 1.33). Capillary and venous plasma PQ measures are nearly identical overall, but not readily exchangeable due to large variation. Further correlation study accounting for disposition phases may be necessary.

Variability in the efficacy of a standardized antenatal steroid treatment was independent of maternal or fetal plasma drug levels: evidence from a sheep model of pregnancy

Administration of antenatal steroids is standard of care for women assessed to be at imminent risk of preterm delivery. There is a marked variation in antenatal steroid dosing strategy, selection for treatment criteria, and agent choice worldwide. This, combined with very limited optimization of antenatal steroid use per se, means that treatment efficacy is highly variable, and the rate of respiratory distress syndrome is decreased to perhaps as low as 40%. In some cases, antenatal steroid use is associated with limited benefit and potential harm. We hypothesized that individual differences in maternofetal steroid exposure would contribute to observed variability in antenatal steroid treatment efficacy. Using a chronically catheterized sheep model of pregnancy, we aimed to explore the relationship between maternofetal steroid exposure and antenatal steroid treatment efficacy as determined by functional lung maturation in preterm lambs undergoing ventilation. Ewes carrying a single fetus underwent surgery to catheterize a fetal and maternal jugular vein at 119 days' gestation. Animals recovered for 24 hours before being randomized to either (1) a single maternal intramuscular injection of 2 mL saline (negative control group, n=10) or (2) a single maternal intramuscular injection of 0.25 mg/kg betamethasone phosphate plus acetate (antenatal steroid group, n=20). Serial maternal and fetal plasma samples were collected from each animal after 48 hours before fetuses were delivered and ventilated for 30 minutes. Total and free plasma betamethasone concentration was measured by mass spectrometry. Fetal lung tissue was collected for analysis using quantitative polymerase chain reaction. One animal from the control group and one animal from the antenatal steroid group did not complete their treatment protocol and were removed from analyses. Animals in the antenatal steroid group were divided into a responder subgroup (n=12/19) and a nonresponder subgroup (n=7/19) using a cutoff of partial pressure of arterial CO2 at 30-minute ventilation within 2 standard deviations of the mean value from saline-treated negative control group animals. Although antenatal steroid improved fetal lung maturation in the undivided antenatal steroid group and in the responder subgroup both physiologically (blood gas- and ventilation-related data) and biochemically (messenger ribonucleic acid expression related to fetal lung maturation), these values did not improve relative to saline-treated control group animals in the antenatal steroid nonresponder subgroup. No differences in betamethasone distribution, clearance, or protein binding were identified between the antenatal steroid responder and nonresponder subgroups. This study correlated individual maternofetal steroid exposures with preterm lung maturation as determined by pulmonary ventilation. Herein, approximately 40% of preterm lambs exposed to antenatal steroids had lung maturation that was not significantly different to saline-treated control group animals. These nonresponsive animals received maternal and fetal betamethasone exposures identical to animals that had a significant improvement in functional lung maturation. These data suggest that the efficacy of antenatal steroid therapy is not solely determined by maternofetal drug levels and that individual fetal or maternal factors may play a role in determining treatment outcomes in response to glucocorticoid signaling.

An Elvitegravir Nanoformulation Crosses the Blood-Brain Barrier and Suppresses HIV-1 Replication in Microglia.

Even with an efficient combination of antiretroviral therapy (ART), which significantly decreases viral load in human immunodeficiency virus type 1 (HIV-1)-positive individuals, the occurrence of HIV-1-associated neurocognitive disorders (HAND) still exists. Microglia have been shown to have a significant role in HIV-1 replication in the brain and in subsequent HAND pathogenesis. However, due to the limited ability of ART drugs to cross the blood–brain barrier (BBB) after systemic administration, in addition to efflux transporter expression on microglia, the efficacy of ART drugs for viral suppression in microglia is suboptimal. Previously, we developed novel poly (lactic-co-glycolic acid) (PLGA)-based elvitegravir nanoparticles (PLGA-EVG NPs), which showed improved BBB penetration in vitro and improved viral suppression in HIV-1-infected primary macrophages, after crossing an in vitro BBB model. Our objective in the current study was to evaluate the efficacy of our PLGA-EVG NPs in an important central nervous system (CNS) HIV-1 reservoir, i.e., microglia. In this study, we evaluated the cyto-compatibility of the PLGA-EVG NPs in microglia, using an XTT (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) assay and cellular morphology observation. We also studied the endocytosis pathway and the subcellular localization of PLGA NPs in microglia, using various endocytosis inhibitors and subcellular localization markers. We determined the ability of PLGA-EVG NPs to suppress HIV-1 replication in microglia, after crossing an in vitro BBB model. We also studied the drug levels in mouse plasma and brain tissue, using immunodeficient NOD scid gamma (NSG) mice, and performed a pilot study, to evaluate the efficacy of PLGA-EVG NPs on viral suppression in the CNS, using an HIV-1 encephalitic (HIVE) mouse model. From our results, the PLGA-EVG NPs showed ~100% biocompatibility with microglia, as compared to control cells. The internalization of PLGA NPs in microglia occurred through caveolae-/clathrin-mediated endocytosis. PLGA NPs can also escape from endo-lysosomal compartments and deliver the therapeutics to cells efficiently. More importantly, the PLGA-EVG NPs were able to show ~25% more viral suppression in HIV-1-infected human-monocyte-derived microglia-like cells after crossing the in vitro BBB compared to the EVG native drug, without altering BBB integrity. PLGA-EVG NPs also showed a ~two-fold higher level in mouse brain and a trend of decreasing CNS HIV-1 viral load in HIV-1-infected mice. Overall, these results help us to create a safe and efficient drug delivery method to target HIV-1 reservoirs in the CNS, for potential clinical use.

Validated LC-MS/MS Panel for Quantifying 11 Drug-Resistant TB Medications in Small Hair Samples

Drug resistant-tuberculosis (DR-TB) is a growing public health threat, and assessment of therapeutic drug levels may have important clinical benefits. Plasma drug levels are the current gold standard assessment, but require phlebotomy and a cold chain, and capture only very recent adherence. Our method uses hair, a matrix that is easily collected and reflective of long-term adherence, to test for 11 anti-TB medications. Previous work by our group shows that antiretroviral drug levels in hair are associated with HIV outcomes. Our method for DR-TB drugs uses 2 mg of hair (3 cm proximal to the root), which is pulverized and extracted in methanol. Samples are analyzed with a single LC-MS/MS method, quantifying 11 drugs in a 16 min run. Lower limits of quantification (LLOQs) for the 11 drugs range from 0.01 ng/mg to 1 ng/mg. Drug presence is confirmed by comparing ratios of two mass spectrometry transitions. Samples are quantified using the area ratio of the drug to the deuterated, 15N-, or 13C-labeled drug isotopologue. We used a calibration curve ranging from 0.001-100 ng/mg. Application of the method to a convenience sample of hair samples collected from DR-TB patients on directly observed therapy (DOT) indicated drug levels in hair within the linear dynamic range of nine of the eleven drugs (isoniazid, pyrazinamide, ethambutol, linezolid, levofloxacin, moxifloxacin, clofazimine, bedaquiline, pretomanid). No patient was on prothionamide, and the measured levels for ethionamide were close to its LLOQ (with further work instead examining the suitability of ethionamide's metabolite for monitoring exposure). In summary, we describe the development of a multi-analyte panel for DR-TB drugs in hair as a technique for therapeutic drug monitoring during drug-resistant TB treatment.

M204. ULTRA-RESISTANT SCHIZOPHRENIA IS ASSOCIATED WITH A DELAY TO INITIATE CLOZAPINE AND WITH LESS ABDOMINAL OBESITY. SEX DIFFERENCES IN INSULINEMIA AND LEPTIN LEVELS ARE OBSERVED BETWEEN RESPONDERS AND NOT RESPONDERS

Background30% patients suffering from schizophrenia fail to obtain therapeutic benefit even after two appropriate antipsychotic trials and are considered resistant. The recommended treatment in these cases is clozapine (CLZ), but only 40% of patients with resistant schizophrenia show clinical response, a condition called ultra-resistance (UR) and defined as the lack of antipsychotic response after 8 to 12 weeks of treatment with at least 400 mg/day of clozapine or plasma levels ≥ 350 ng/ml. The objective of the present study is to identify factors associated with UR in in a group of patients from Argentina.MethodsA paired case-control study was conducted, being cases those patients with UR schizophrenia and controls those who responded to CLZ; both groups were matched by age and sex. The response to CLZ was measured using the PANSS (UR was defined with a total score ≥ 80). The following parameters were compared between groups: months of untreated psychosis, months until the introduction of clozapine, body mass index (BMI), waist circumference, fasting blood glucose, insulinemia, triglyceridemia, HDL cholesterol, ultrasensitive C-reactive protein (CRP) and plasma leptin levels. Clozapine and nor-clozapine plasma trough levels were measured by HPLC-MS/MS.Results9 men (M) and 7 women (W) with the diagnosis of UR schizophrenia were matched with the same number of responders (R) to clozapine. Total PANSS scores (mean ± SD) for each group were as follows: W-R 48.9 ± 11; W-UR 88.4 ± 6 (p < 0.0001); M-R 60.5 ± 7; M-UR 112.8 ± 23 (p < 0.0001). CLZ dose was significantly higher both in W-UR and in M-UR than in paired controls (p < 0.05). Nonsignificant differences were observed for nor-CLZ plasma concentration among groups. Clozapinemia was not different among men but it was significantly higher in W-UR in comparison with W-R (p < 0.05).Significant differences were detected in the amount of months that passed before initiation of CLZ both for women (W-R 140.9 ± 124, W-UR 255.6 ± 153, p < 0.005) and men (M-R 104.0 ± 51. 6 versus M-UR 174.6± 65; p < 0.05). Body mass index (kg/m2) was significantly lower in UR patients: W-R 35.3 ± 6 versus W-UR 26.9 ± 3 (p < 0.05) and M-R 30.6 ± 5 versus M-UR 22.7 ± 4 (p <.005). Waist circumference (cm) was also significantly lower in UR independently of sex: W-R 110.6 ± 12 versus W-UR 98.5 ± 8 (p < 0.05); M-R 113.9 ± 15 versus M-UR 87.4 ± 9 (p <0 .005). Insulinemia (UI/ml) was significantly lower in M-UR than in M-R (16.1± 8 versus 9.4 ± 7, p<0.005) but not in women. Also significant differences were found in leptin levels (pg/ml) in men but not in women (M-R 1824.0 ± 1139 versus M-UR 477.6 ± 692; p < 0.05). No differences were observed in the number of antipsychotics received before CLZ, months of untreated psychosis, fasting glycemia, trygliceridemia, HDL cholesterol, CRP, HbA1c and diastolic or systolic arterial blood pressure.DiscussionTime to CLZ initiation could be a critical factor predisposing to UR. The absence of clozapine-induced abdominal obesity and changes in BMI are also to be associated with poor clinical response, independently of plasma drug levels. Differences between ultra-resistant men and women concerning insulin and leptin plasma levels should be further investigated. As far as we know, this is the first paired case-control study aimed to investigate factors associated with CLZ resistance in schizophrenia.

In Brain and in Vein Detection of Antibiotics Using Electrochemical-DNA Biosensors

Current approaches towards drug dosing rely on venous draws measurements performed on test patients which are laboratory-analyzed and returned the following days. This practice forces physicians to administer potentially toxic or ineffective concentrations of drugs to patients since dosages are determined based on weight and age of this test group even though pharmacokinetics may differ in each individuals. Having a technology that would in contrast allow, direct, continuous, real-time monitoring of drugs in the living body would revolutionize healthcare and allow personalized drug dosage and adjustment while enabling the development of artificial organs responsible of adjusting these levels.Motivated by this goal, we have developed a class of electrochemical aptamer-based (E-AB) sensors[1]. These sensors are comprised of a redox-reporter-modified DNA “probe” that is attached by one terminus to a self-assembled monolayer deposited on an interrogating gold electrode. The binding of an analyte to this probe alters the kinetics with which electrons exchange to/from the redox reporter via binding-induced conformational changes producing an easily measured change in current when the sensor is interrogated using square-wave voltammetry (see Figure) [2]. E-AB sensors are capable of detecting with high specificity their molecular targets in flowing whole blood and directly in the living body. I will present during this presentation some of these sensors deployed in the vein [3] and in the brain of sedated rats to monitor the pharmacokinetics of the antibiotic, vancomycin. The ability of acquiring high frequency measurements of drug plasma levels using these biosensors has also allowed us to develop a technology that improves our ability to deliver them [3]. Due to their small size, these sensors can also be deployed directly in the brain of freely moving animals to monitor molecules with unmatched temporal resolution [4]. All these advancement in developing E-AB sensors are aimed towards developing new analytical tools for personalized medicine while improving our understanding of drug metabolism.[1]: Dauphin Ducharme, P. and Plaxco, K. W. Anal. Chem. 2016 88: 11654–11662.[2]: Li, H., Dauphin Ducharme, P., Ortega, G., Plaxco, K. W. J Am. Chem. Soc. 2017, 139, 11207-11213.[3]: Dauphin-Ducharme, P., Yang, K., Arroyo-Currás, N., Ploense, L. K., Zhang, Y., Gerson, J., Kurnik, M., Kippin, T. E., Stojanovic, M., Plaxco, K. W. ACS Sensors 2019, 4, 2832-2837.[4]: Ploense, K. L., Dauphin-Ducharme, P., Arroyo-Currás, N., Curtis, S. D., Williams, S., Schwarz, N., Kippin, T. E., Plaxco, K. W. 2019 In preparation. Figure 1

Contemporaneous management of ampicillin infusions in the outpatient setting through the use of therapeutic drug monitoring

The use of ampicillin in the outpatient setting has traditionally been avoided because of the short half-life and instability in solution of this drug. However, recent in vitro data and two case series support the safe and effective administration of ampicillin by continuous infusion in the community. Therapeutic drug monitoring (TDM) of beta-lactam antibiotics can be used to optimise antibiotic exposure and ensure adequate clinical responses. A case series is presented of patients receiving ampicillin via prolonged infusion in the outpatient setting, with TDM to ensure adequate plasma antibiotic levels were achieved.Three patients who received ampicillin by continuous infusion under the Outpatient Parenteral Antimicrobial Therapy (OPAT) program are described, including details of antibiotic dose and steady-state plasma drug concentration as measured by high-performance liquid chromatography. All three patients had an infection with ampicillin-susceptible Enterococcus faecalis; one patient had post-partum endometritis, one had urosepsis and one had a complex polymicrobial bone and joint infection.Adequate plasma drug levels were achieved in all patients. Management of the antibiotic temperature and infusion times, and appropriate timing of drug levels in the community were required. Two patients achieved clinical cure, while the third required further surgical debridement and antibiotic therapy.TDM in this setting enabled the contemporaneous management and dose alteration of ampicillin. Ampicillin may be a safe and effective drug when administered by continuous infusion with appropriate TDM in the community setting.

Erythrodermic psoriasis in a dialyzed patient successfully treated with Secukinumab.

Erythrodermic psoriasis is a severe, life-threatening condition with additional complications, when occurring in hemodialyzed patients, as the majority of treatments are contraindicated. A 44-years-old man, of Philippine origins, with a 15-years-history of psoriasis treated with cyclosporine developed progressive hypertension and renal insufficiency. Despite drug dismission, renal function worsen to end-stage, and hemodialysis was necessary three times a week. Phototherapy was not able to control the skin condition, progressing to erythroderma, and after nephrology consultation, the patient consent to the off-label secukinumab treatment, at the standard regimen (300 mg subcutaneously once weekly at weeks 0-4 followed by 300 mg every 4 weeks). Seven days after the first injection, a rapid improvement was noted, with the psoriasis area severity index (PASI) score passing from 31.5 to 17.6. At the 52-week-follow-up visit, the patient was completely clarified, without any side effects. The case supports secukinumab effectiveness and safety in difficult patients, including erythrodermic psoriasis with end-stage renal failure, as drug plasma levels seem not to be affected by hemodialysis. Results are rapidly achieved, and long term maintained, with the additional advantage of a very comfortable monthly administration.