Half-life Of Drug Research Articles

1731. Rezafungin Activity against Candida spp. and Aspergillus spp. Isolates Causing Invasive Infections Worldwide in 2021

Abstract Background Rezafungin (RZF) is a once-weekly echinocandin (ECH) with a long half-life and front-loaded drug exposure. RZF is in development to treat candidemia and invasive candidiasis and prevent invasive fungal disease caused by Candida, Aspergillus, and Pneumocystis spp. We evaluated the in vitro activity of RZF, caspofungin (CSF), micafungin (MCF), and anidulafungin (ANF) against a worldwide collection of fungal isolates causing invasive infection. Methods 830 isolates were collected from Europe (EU; 40.2%), North America (NA; 31.6%), Asia-Pacific (APAC; 15.3%), and Latin America (LA; 12.9%), identified by MALDI-TOF and/or sequencing, and tested by CLSI broth microdilution. Isolates included C. albicans (CA; 316 isolates), C. glabrata (CG; 162), C. parapsilosis (CP; 148), C. tropicalis (CT; 83), C. dubliniensis (CD; 21), C. krusei (CK; 19), Cryptococcus neoformans (CN; 10) A. fumigatus (AF; 59), and A. section Flavi (ASF; 12). CLSI criteria was applied, including the recently approved rezafungin provisional breakpoints against Candida spp. Results RFZ inhibited 99.7% of CA, 98.1% of CG, 95.2% of CD, and all CP, CT, and CK (MIC50/90 in Table) at the susceptibility (S) breakpoint (BP). RZF had similar activity to the other ECHs against CA (99.7%S), CG (95.7-96.3%S), CT (100.0%S), CK (100.0%S), and CD (MIC50/90 range, 0.015-0.06/0.03-0.06 mg/L). Although CSF displayed lower MIC50/90 values (0.25/0.25 mg/L) than RZF (MIC50/90, 1/2 mg/L), MCF (MIC50/90, 1/1 mg/L), and ANF (MIC50/90, 2/4 mg/L) against CP, all ECHs but ANF (87.2%S) inhibited 100% of CP isolates at the respective BP. Only 1 CA (EU), 1 CD (EU), and 3 CG (NA) were non-S to RZF, while 1 CA (EU), 6 CG (5 NA, 1 APAC), and 19 CP (8 EU, 5 NA, 4 APAC, 2 LA) were ANF non-S. Limited activity was noted for all ECHs against CN (MIC50, > 4 mg/L). All AF isolates were inhibited by RZF at ≤ 0.06 mg/L, and ANF, MCF, and CSF at ≤ 0.12 mg/L. RZF (MIC range, 0.008-0.06 mg/L) and other ECHs (MIC range, 0.008-0.12 mg/L) were also active against 7 voriconazole non-S AF isolates (4 NA, 3 EU). RZF and other ECHs inhibited all ASF isolates at ≤ 0.06 mg/L. Conclusion RZF was very active against Candida spp., AF, and ASF isolates causing invasive infections worldwide, including voriconazole non-S AF isolates and CP displaying non-S to ANF. Disclosures Cecilia G. Carvalhaes, MD, PhD, AbbVie: Grant/Research Support|Cidara: Grant/Research Support|Melinta: Grant/Research Support|Pfizer: Grant/Research Support Paul Rhomberg, BS, MT(ASCP), Cidara: Grant/Research Support|Pfizer: Grant/Research Support Paul Rhomberg, BS, MT(ASCP), Cidara: Grant/Research Support|Pfizer: Grant/Research Support Greg Strand, MLS (ASCP)CM, Cidara: Grant/Research Support Abby L. Klauer, BS, Cidara: Grant/Research Support Mariana Castanheira, PhD, AbbVie: Grant/Research Support|Cidara: Grant/Research Support|GSK: Grant/Research Support|Melinta: Grant/Research Support|Pfizer: Grant/Research Support|Shionogi: Grant/Research Support.

Adagrasib: A landmark in the KRASG12C-mutated NSCLC.

Adagrasib: A landmark in the KRASG12C-mutated NSCLC.

Pharmacokinetics of Phenprocoumon in Emergency Situations-Results of the Prospective Observational RADOA-Registry (Reversal Agent Use in Patients Treated with Direct Oral Anticoagulants or Vitamin K Antagonists Registry).

Phenprocoumon has been used as an oral anticoagulant in patients with thromboembolic disease for more than 40 years. So far its pharmacokinetics have not been analyzed in emergency situations. Phenprocoumon-treated patients with major bleeding or urgent surgery were included in a prospective, observational registry. Phenprocoumon drug concentrations were analyzed in samples, collected as part of routine care using ultraperformance liquid chromatography tandem mass spectrometry. Moreover, anticoagulant intensity and drug half-life (t1/2) were calculated. 115 patients were included. Phenprocoumon levels declined over time with a half-life of 5.27 and 5.29 days in patients with major bleedings (n = 82) and with urgent surgery (n = 33). Baseline phenprocoumon levels were 2.2 times higher in the bleeding group compared to the surgery group (1.92 vs. 0.87 ng/mL, p < 0.0001). International normalized ratio (INR) values decreased rapidly during the first 24 h. In 27.6% of patients a rebound of INR (recurrent increase > 1.5) was observed which was associated with significantly increased bleeding rates (22% vs. 4.2% in patients with or without INR rebound, p = 0.012). In emergency situations, the long half-life of phenprocoumon may cause INR rebound and associated recurrent bleedings. Optimal management may need to include repeated vitamin K supplementation over days.

Curcumin-laden amphiphilic chitosan microemulsion with enhanced transdermal delivery, skin compatibility and anti-arthritic activity

Transdermal administration can avoid the first-pass effect of liver, improve the bioavailability of drugs and the adaptability of patients. However, there are still many problems, such as low load efficiency, short drug half-life, unfavorable transdermal efficiency, poor skin compatibility, which hinder the development of transdermal administration. In order to solve the above problems, amphiphilic chitosan microemulsion (AC-ME) is developed by using chitosan with hydrophilic carboxyl groups and hydrophobic long alkane chains as surfactant. AC-ME is efficient for drug loading and transdermal delivery, which is demonstrated by extremely high drug loading, improved drug stability and excellent transdermal efficiency. Specifically, the loading amount of curcumin (Cur) can reach up to 3.41 ± 0.13 mg/mL, an increase of approximately 30,000 times compared to its water solution. The light stability of Cur is improved from 43% to 75%. The transdermal process and skin retention of Cur exhibit 1.76-fold and 5.29-fold increase, respectively. Moreover, AC-ME is skin-compatible and does not damage skin structure. Finally, AC-ME can improve the therapeutic effect of Cur and exhibit superb anti-inflammatory effect in the rheumatoid arthritis (RA) model of mice. In a word, AC-ME would be a promising drug carrier for transdermal drug delivery.

CTNI-32. PHASE 2 STUDY OF VAL-083 AND RADIOTHERAPY IN NEWLY DIAGNOSED MGMT-UNMETHYLATED GBM

Abstract VAL-083 is a novel bi-functional DNA targeting agent that induces inter-strand DNA cross-links at N7-guanine, leading to DNA double-strand breaks and cell death. In vitro and in vivo studies have demonstrated VAL-083 circumvents MGMT-mediated chemoresistance and differentiates it from other therapies used in the treatment of GBM, including temozolomide (TMZ). VAL-083 also acts as a radiosensitizer against GBM cancer stem cells in vitro. A Phase 2 study was conducted to evaluate the safety and tolerability of VAL-083 when administered concurrently with radiation therapy (RT) in newly diagnosed MGMT unmethylated GBM. Stage 1 was a dose-escalation phase to confirm the dose of VAL-083 in this setting. Patients received VAL-083 at 20, 30, or 40 mg/m2/day x 3 days every 21 days in combination with standard radiation treatment (RT) (2 Gy/day, 5 days/week for 6 weeks). Stage 2 was an expansion phase to enroll up to 20 additional patients at the 30 mg/m2/day of VAL-083 with RT. A total of 29 patients were enrolled in the study and completed treatment, with 25 patients receiving 30 mg/m2/day VAL-083. The median number of cycles completed by all patients was 9 (range 2-13). Consistent with our prior experience, myelosuppression was the most common adverse event. Pharmacokinetics (Cmax and AUC) of VAL-083 were broadly linear with respect to dose, and drug half-life was 0.8 hrs. In a sub-group of patients, levels of VAL-083 in CSF were found to be at least as high as those in plasma. The median progression free survival (PFS) for all patients enrolled was 9.3 (95%CI: 6.4-12.0) months. Eighteen (18/29; 62.1%) patients have died, and median overall survival for all patients enrolled was 19.6 (95%CI: 14.0-22.4) months. These results support the potential benefit of VAL-083 as a treatment alternative against GBM tumors with MGMT-mediated resistance to TMZ. Clinicaltrials.gov: NCT03050736.

Construction of long circulating and deep tumor penetrating gambogic acid-hydroxyethyl starch nanoparticles

Gambogic acid (GA) has been approved to enter the phase III clinical trial. However, due to its short half-life, low water solubility, poor stability and inflammatory response, GA failed to pass the clinical superiority evaluation. Nano-preparations perform well in prolonging drug half-life, improving drug solubility, and enhancing drug stability etc. Therefore, a self-assembled nanoparticle (GA-HES/NPs) with long circulation and deep tumor penetration ability was designed, in which hydroxyethyl starch (HES) endowed GA-HES/NPs with longer circulation time as well as deep tumor penetration ability, and the simple synthesis method ensured the stability of GA structure. Experimental results showed that GA-HES/NPs owned a certain tumor targeting and deep tumor penetration ability, as well as longer circulation time, which could enhance the therapeutic effect of GA.

A novel formulation of cyclosporine A/phosphatidylserine-containing liposome using remote loading method: Potential product for immunosuppressive effects

In this study, two PEGylated and non-PEGylated liposomal formulations of Cyclosporine A (CsA) were prepared by remote loading procedure to improve the tissue distribution profile of CsA and the therapeutic efficacy thereof. DOPE/DOPS/Chol/α-Tocopherol/mPEG2000 (35/40/19.5/0.5/5) and DOPE/DOPS/Chol/α-Tocopherol (40/40/19.5/0.5) were examined in terms of their physicochemical stability, immunosuppressive efficiency, and pharmacokinetic profiles. Besides, the delayed-type hypersensitivity reaction (DTH) was studied from sheep red blood cells (SRBC) injection to male Wistar rats and skin allograft rejection transplanted from male C57BL into BALB/c mouse. Both liposomes had a size of about 162.2 ± 75 nm with a polydispersity index of <0.14, exhibited a high drug encapsulation efficacy (49.9–61.3%), and showed a long-term (6 months) shelf-life stability. Moreover, the liposomes enhanced the delivery of CsA and the improved immunosuppressive efficiency in vitro compared to non-liposomal CsA. In the animal studies, the liposomes also enhanced the drug half-life in the serum of the rat and improved the tissue distribution of CsA compared to non-liposomal CsA. Besides, the liposomes minimized the DTH and delayed the skin allograft rejection up to 17 days compared to CsA. To sum up, the liposomal formulations of CsA improved both the delivery profile and therapeutic efficacy of CsA. However, further studies need to be done to translate this formulation into the clinics.

Senkyunolide H Affects Cerebral Ischemic Injury through Regulation on Autophagy of Neuronal Cells via P13K/AKT/mTOR Signaling Pathway.

Cerebral ischemia (CI) is associated with high global incidence and risk; therefore, its rapid and reliable therapeutic management is essential for protecting patients' lives and improving health. Senkyunolide H (SH) is remarkably effective against phlebosclerosis, oxidation, and apoptosis. Blood-brain barrier is the main obstacle impeding the delivery of drugs and xenobiotics to brain areas. Drugs' loading in nanoparticles can overcome the blood-brain barrier obstacle and thus directly and completely act on brain tissue, and such a loading can also change the half-life of drugs in vivo and lower the dosage requirement of drugs. In this study, we loaded the SH in lipid nanoparticles to improve its delivery to the brain for the therapy of CI. Thus, this study preliminarily analyzed the mechanism of SH-loaded nanoparticles in CI. The SH-loaded lipid nanoparticles were prepared and characterized with electron microscopy and PS potentiometery. The SH-loaded nanoparticles were intraperitoneally administered to CI-induced rats and brain tissue water content, and neuronal apoptosis and autophagy-associated proteins were determined. Our assays revealed SH-loaded nanoparticle's ability to reduce nerve injury and brain tissue water content in rats with CI and inhibit the apoptosis and autophagy of their neuronal cells (NCs). Additionally, under intervention with SH-loaded nanoparticles, P13K/AKT/mTOR pathway-associated proteins in brain tissue of rats decreased. As the assay results showed, SH-loaded nanoparticles can suppress the autophagy of NCs through medicating P13K/AKT/mTOR pathway and lower apoptosis, thus delivering the effect of treating CI. Results of this study indicate SH-loaded nanoparticles as promising strategy for delivery SH to brain areas for treating CI.

Therapeutic Importance of Biological Half-Life of Antineoplastic Agents- A Review

Lung, prostate, and stomach cancer are the most prevalent cancers among males. Breast, colon, and cervical cancer are the most prevalent cancers among women. The literature also shows that patients suffering from cancer are increasing constantly, and hence the number of different chemotherapy treatments administered is increasing. The main objective of this review article is to summarize the effect of age on the half-life of some antineoplastic drugs belonging to the category of Topoisomerase inhibitors, alkylating agents, anthracyclines, purine analogs, antimetabolites, and N-nitrosoureas along with their pharmacokinetic properties. Literature indicates that highly bound antineoplastic drugs have higher differences in unbound drug concentrations among patients, and in some cases, the amount of concentration is not reflective of the unbound drug level and has an impact on pharmacokinetic parameters, including absorption, the volume of distribution, drug metabolism, and excretion. Protein binding affects the distribution and bioavailability of active drug substances.

Artemisinin resistance and malaria elimination: Where are we now?

The emergence of artemisinin resistance is a major obstacle to the global malaria eradication/elimination programs. Artemisinin is a very fast-acting antimalarial drug and is the most important drug in the treatment of severe and uncomplicated malaria. For the treatment of acute uncomplicated falciparum malaria, artemisinin derivatives are combined with long half-life partner drugs and widely used as artemisinin-based combination therapies (ACTs). Some ACTs have shown decreased efficacy in the Southeast Asian region. Fortunately, artemisinin has an excellent safety profile and resistant infections can still be treated successfully by modifying the ACT. This review describes the pharmacological properties of ACTs, mechanisms of artemisinin resistance and the potential changes needed in the treatment regimens to overcome resistance. The suggested ACT modifications are extension of the duration of the ACT course, alternating use of different ACT regimens, and addition of another antimalarial drug to the standard ACTs (Triple-ACT). Furthermore, a malaria vaccine (e.g., RTS,S vaccine) could be added to mass drug administration (MDA) campaigns to enhance the treatment efficacy and to prevent further artemisinin resistance development. This review concludes that artemisinin remains the most important antimalarial drug, despite the development of drug-resistant falciparum malaria.

Nanocarriers for intracellular co-delivery of proteins and small-molecule drugs for cancer therapy.

In the past few decades, the combination of proteins and small-molecule drugs has made tremendous progress in cancer treatment, but it is still not satisfactory. Because there are great differences in molecular weight, water solubility, stability, pharmacokinetics, biodistribution, and the ways of release and action between macromolecular proteins and small-molecule drugs. To improve the efficacy and safety of tumor treatment, people are committed to developing protein and drug co-delivery systems. Currently, intracellular co-delivery systems have been developed that integrate proteins and small-molecule drugs into one nanocarrier via various loading strategies. These systems significantly improve the blood stability, half-life, and biodistribution of proteins and small-molecule drugs, thus increasing their concentration in tumors. Furthermore, proteins and small-molecule drugs within these systems can be specifically targeted to tumor cells, and are released to perform functions after entering tumor cells simultaneously, resulting in improved effectiveness and safety of tumor treatment. This review summarizes the latest progress in protein and small-molecule drug intracellular co-delivery systems, with emphasis on the composition of nanocarriers, as well as on the loading methods of proteins and small-molecule drugs that play a role in cells into the systems, which have not been summarized by others so far.

Mucoadhesive nanoemulsion enhances brain bioavailability of luteolin after intranasal administration and induces apoptosis to SH-SY5Y neuroblastoma cells

Neuroblastoma is the most frequently diagnosed extracranial solid tumor in children and accounts for 7 % of all childhood malignancies and 15 % cancer mortality in children. Luteolin (LUT) is recognized by its anticancer activity against several types of cancer. The aim of this study was to prepare chitosan-coated nanoemulsion containing luteolin (NECh-LUT), investigate its potential for brain delivery following intranasal administration, and to evaluate its cytotoxicity against neuroblastoma cells. NECh-LUT was developed by cavitation process and characterized for its size, surface charge, encapsulation efficiency, and mucoadhesion. The developed formulation presented size 68 ± 1 nm, zeta potential + 13 ± 1 mV, and encapsulation efficiency of 85.5 ± 0.3 %. The NECh-LUT presented nearly 6-fold higher permeation through the nasal mucosa ex vivo and prolonged LUT release up to 72 h in vitro, following Baker-Lonsdale kinetic model. The pharmacokinetic evaluation of NECh-LUT revealed a 10-fold increase in drug half-life and a 4.4 times enhancement in LUT biodistribution in brain tissue after intranasal administration of single-dose. In addition, NECh-LUT inhibited the growth of neuroblastoma cells after 24, 48 and 72 h in concentrations starting from 2 µM. The NECh-LUT developed for intranasal administration proved to be a promising alternative for brain delivery of LUT, and a viable option for the treatment of neuroblastoma.

LipMetE (Lipophilic Metabolism Efficiency) as a Simple Guide for Half-Life and Dosing Regimen Prediction of Oral Drugs.

The in vivo half-life is a key property of every drug molecule, as it determines dosing regimens, peak-to-trough ratios and often dose. However, half-life optimization can be challenging due to its multifactorial nature, with in vitro metabolic turnover, plasma protein binding and volume of distribution all impacting half-life. We here propose that the medicinal chemistry design parameter Lipophilic Metabolism Efficiency (LipMetE) can greatly simplify half-life optimization of neutral and basic compounds. Using mathematical transformations, examples from preclinical GABAA projects and clinical compounds with human pharmacokinetic data, we show that LipMetE is directly proportional to the logarithm of half-life. As the design parameter LipMetE can be swiftly calculated using the readily available parameters LogD, intrinsic clearance and fraction unbound in human liver microsomes or hepatocytes, this approach enables rational half-life optimization from the early stages of drug discovery projects.

Dapsone-induced Methemoglobinemia Case Report

Abstract Methemoglobinemia is a rare disorder associated with an elevated methemoglobin level that occurs when hemoglobin is in the oxidized ferric ion form rather than reduced ferrous form. In patients with methemoglobinemia, the hemoglobin with oxidized ferric form cannot release oxygen to the tissues which leads to hypoxemia. Methemoglobinemia can be acquired or inherited. The acquired methemoglobinemia happens in patients after they take certain oxidizing drugs. This disorder is mostly treated with 2 mg/kg methylene. This disorder is mostly treated with 2 mg/kg methylene blue. However, administrating ascorbic acid as an antioxidant may also helpful, especially if a patient has taken two doses of methylene blue or if the use of methylene blue is contraindicated. Methemoglobinemia may not cure or may rebound after response to treatment, especially with long half-life drugs such as dapsone. As it states in the leaflet for methylene blue, if methemoglobinemia does not resolve after two doses, one should initiate another alternative. Ascorbic acid is a good alternative because it is an antioxidant to keep tissue from harm of free radicals and also has a role in reducing methemoglobin via co-factor nicotinamide adenine dinucleotide phosphate reeducates needed for glutathione metabolism. We discuss a case of methemoglobinemia treated successfully with oral ascorbic acid after using two doses of methylene blue. Oral ascorbic acid could be beneficial, especially when the patient was taken two doses of methylene blue.

SYST-11 PHASE 2 STUDY OF VAL-083 AND RADIOTHERAPY IN NEWLY DIAGNOSED MGMT-UNMETHYLATED GBM

VAL-083 is a novel bi-functional DNA targeting agent that induces inter-strand DNA cross-links at N7-guanine, leading to DNA double-strand breaks and cell death. In vitro and in vivo studies have demonstrated VAL-083 circumvents MGMT-mediated chemoresistance and differentiates it from other therapies used in the treatment of GBM, including temozolomide (TMZ). VAL-083 also acts as a radiosensitizer against GBM cancer stem cells in vitro. A Phase 2 study was conducted to evaluate the safety and tolerability of VAL-083 when administered concurrently with radiation therapy (RT) in newly diagnosed MGMT unmethylated GBM. Stage 1 was a dose-escalation phase to confirm the dose of VAL-083 in this setting. Patients received VAL-083 at 20, 30, or 40 mg/m2/day x 3 days every 21 days in combination with standard radiation treatment (RT) (2 Gy/day, 5 days/week for 6 weeks). Stage 2 was an expansion phase to enroll up to 20 additional patients at the 30 mg/m2/day of VAL-083 with RT. A total of 29 patients were enrolled in the study and completed treatment, with 25 patients receiving 30 mg/m2/day VAL-083. The median number of cycles completed by all patients was 9 (range 2-13). Consistent with our prior experience, myelosuppression was the most common adverse event. Pharmacokinetics (Cmax and AUC) of VAL-083 were broadly linear with respect to dose, and drug half-life was 0.8 hrs. In a sub-group of patients, levels of VAL-083 in CSF were found to be at least as high as those in plasma. The median progression free survival (PFS) for all patients enrolled was 9.3 (95%CI: 6.4-12.0) months. Eighteen (18/29; 62.1%) patients have died, and median overall survival for all patients enrolled was 19.6 (95%CI: 14.0-22.4) months. These results support the potential benefit of VAL-083 as a treatment alternative against GBM tumors with MGMT-mediated resistance to TMZ. Clinicaltrials.gov: NCT03050736.

The Practical Importance of Half-Life in Psychopharmacology.

The half-life of a drug is most commonly defined as the time taken for the plasma or blood level of the drug to fall by half. Elimination half-life, pharmacologic half-life, and biologic half-life are interchangeably used most commonly to describe the half-life of drugs that follow first-order or linear pharmacokinetics; that is, in single-compartment models, where the fall in blood level is proportionate to the concentration of the drug in blood. In 2 compartment models, where the drug equilibrates between blood and (for example) adipose tissue, during elimination there is a sharp initial fall in blood levels followed by a gradual subsequent fall; when drugs display this biphasic elimination pattern, the half-life corresponding to the second phase is what is clinically relevant, and this half-life is known as the terminal half-life. Half-life is influenced by drug distribution, drug metabolism, and drug excretion, each of which can be influenced by many factors such as age, use of concurrent medications, and presence of liver or renal disease. In order to maintain uniform blood levels and reduce the adverse effect risk, drugs with short half-lives need to be dosed more frequently. Drugs with short half-lives are more likely to be associated with withdrawal or discontinuation syndromes. The duration of action of a drug, time to steady state levels, and time to washout are each influenced by the value of the drug half-life. All these terms and concepts are defined and explained with the help of clinically relevant examples. Mental health care professionals who prescribe to patients need to know the half-lives of the drugs that they prescribe, the half-lives of active metabolites, if any, how these half-lives may differ with individual patient characteristics, and how to use this knowledge to prescribe to best advantage.

Polysaccharide and monosaccharide guided liver delivery of Sorafenib Tosylate – A nano-strategic approach and comparative assessment of hepatospecificity

Hepatospecific delivery by ligand based receptor targeting is an established strategy to augment therapy associated with liver diseases and disorders. Previously, we have investigated the effect of ligand headgroup on cellular uptake mediated by the asialoglycoprotein receptor by in silico and in vitro approach. In this paper, we report the design of agarose based liposomes for delivery to liver cancer cells and provide a proof of concept of the targeting efficiency against galactose liposomes using an in vivo approach. Sorafenib Tosylate loaded targeting liposomes were developed and optimized using factorial design. Comparative evaluation including cell cytotoxicity, pharmacokinetics and biodistribution and hepatospecific uptake was performed for both the liposomal systems. The formulations possessed a particle size of 150 – 180 nm and a zeta potential of 30 - 60 mV depending on the amount of ligand and drug loading, with more than 90% entrapment efficiency. A two-fold increase in cytotoxicity was observed with agarose-based liposomes as compared to galactose based liposomes. In vivo PK evaluation indicated a reduction in half life of drug when loaded in agarose ligand loaded system, probably due to greater uptake in the liver as evidenced in biodistribution study. Intrahepatic disposition revealed a higher PC/NPC uptake ratio with the targeted systems as compared to conventional liposomes, although the agarose-based system resulted in highest uptake ratio. A biocompatible platform for specific delivery of drugs to hepatocytes was established validating a rational approach to design liver targeting systems.

Ocrelizumab quantitation by liquid chromatography-tandem mass spectrometry

IntroductionOcrelizumab is a monoclonal anti-CD20 antibody approved for the treatment of multiple sclerosis (MS). The clinical value of therapeutic drug monitoring (TDM) for this antibody in treatment of MS is unknown, and an adequately specific and precise quantitation method for ocrelizumab in patient serum could facilitate investigation. Liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based quantitation methods have been shown to have higher analytic specificity and precision than enzyme-linked immunosorbent assays. ObjectivesTo establish and validate an LC-MS/MS-based quantitation method for ocrelizumab. MethodsWe present an LC-MS/MS-based quantitation method using immunocapture purification followed by trypsinization and analysis by a triple quadrupole mass analyzer obtaining results within the same day. ResultsWe found that the ocrelizumab peptide GLEWVGAIYPGNGDTSYNQK (Q1/Q3 Quantifier ion: 723.683+/590.77 y112+ Qualifier ion: 723.683+/672.30 y122+) can be used for quantitation and thereby developed a method for quantifying ocrelizumab in human serum with a quantitation range of 1.56 to 200 µg/mL. The method was validated in accordance with EMA requirements in terms of selectivity, carry-over, lower limit of quantitation, calibration curve, accuracy, precision and matrix effect. Ocrelizumab serum concentrations were measured in three MS patients treated with ocrelizumab, immediately before and after ocrelizumab infusion, with additional sampling after 2, 4, 8 and 12 weeks. Measured serum concentrations of ocrelizumab showed expected values for both Cmax and drug half-life over the sampled time period. ConclusionWe have established a reliable quantitation method for serum ocrelizumab that can be applied in clinical studies, facilitating the evaluation of ocrelizumab TDM in MS.

Drug Disposition in Subjects With Obesity: The Research Work of Darrell R. Abernethy.

In 1979, the late Dr. Darrell R. Abernethy and colleagues began a series of clinical studies aimed at understanding the pertinent determinants of drug distribution, elimination, and clearance in obesity, and how those variables are interconnected. The studies confirmed that volume of distribution (Vd ) and clearance are the principal independent biological variables, which conjointly determine elimination of half-life as a dependent variable. For drugs distributed by passive diffusion, their pharmacokinetic Vd - after correcting for plasma protein binding - was increased in obesity, depending in part on the physicochemical lipophilicity of the individual drugs, and the quantitative extent of obesity in overweight individuals. Across all studies, the ratio of mean clearance in obese divided by control groups had an overall median value of 1.21 (range, 0.75-3.11), indicating a small and variable effect of obesity on clearance, without clear directionality. Since drug clearance was not clearly related to lipophilicity or degree of obesity, the prolonged half-life of lipophilic drugs in patients with obesity was largely explained by the increased Vd . Dr. Abernethy further identified delayed attainment of steady state after initiation of multiple-dose treatment, and delayed washout after termination of dosage, as potential clinical consequences of the extended half-life in people with obesity. These consequences for specific drugs have been recently emphasized in contemporary studies of chronic dosage in subjects with obesity. Without data identifying an obesity-related change in clearance for a specific drug, maintenance doses (in milligrams) should be based on ideal weight rather than adjusted upward on the basis of total weight.

Design, Synthesis, and Evaluation of Lung-Retentive Prodrugs for Extending the Lung Tissue Retention of Inhaled Drugs.

A major limitation of pulmonary delivery is that drugs can exhibit suboptimal pharmacokinetic profiles resulting from rapid elimination from the pulmonary tissue. This can lead to systemic side effects and a short duration of action. A series of dibasic dipeptides attached to the poorly lung-retentive muscarinic M3 receptor antagonist piperidin-4-yl 2-hydroxy-2,2-diphenylacetate (1) through a pH-sensitive-linking group have been evaluated. Extensive optimization resulted in 1-(((R)-2-((S)-2,6-diaminohexanamido)-3,3-dimethylbutanoyl)oxy)ethyl 4-(2-hydroxy-2,2-diphenylacetoxy)piperidine-1-carboxylate (23), which combined very good in vitro stability and very high rat lung binding. Compound 23 progressed to pharmacokinetic studies in rats, where, at 24 h post dosing in the rat lung, the total lung concentration of 23 was 31.2 μM. In addition, high levels of liberated drug 1 were still detected locally, demonstrating the benefit of this novel prodrug approach for increasing the apparent pharmacokinetic half-life of drugs in the lungs following pulmonary dosing.