Terminal Plasma Half-life Research Articles

ApoA-IMilano phospholipid complex (ETC-216) infusion in human volunteers. Insights into the phenotypic characteristics of ApoA-IMilano carriers

Epidemiological studies support an inverse correlation between HDL-C and cardiovascular disease. However, low HDL-C levels do not always segregate with premature disease. These include, LCAT deficiency and the apolipoproteinA-IMilano (AIM) variant. AIM has a cysteine for arginine at position 173 in the otherwise cysteine free protein permitting AIM homodimerization and apoA-II heterodimerization. We relate the biochemical characteristics of low HDL-C phenotype AIM carriers to lipoprotein changes in humans administered recombinant dimeric AIM/palmitoyl-oleoyl phosphatidyl choline (ETC-216). Pharmacokinetic analysis of infused ETC-216 suggest a slow distribution of AIM into peripheral tissue and an extremely long terminal half-life in plasma. Following ETC-216 administration to normal human volunteers, an initial dose-dependent HDL-C elevation was observed. Thereafter, subjects transiently acquired a lipoprotein profile similar to that of AIM carriers, including reduced HDL-C and mild hypertriglyceridemia. The time-dependent changes in plasma lipids/lipoproteins may support an increased tissue cholesterol removing capacity of ETC-216. These findings provide mechanistic insight into the rapid removal of atheromatous plaques observed in humans, possibly linked to enhanced cholesterol removal capacity of ETC-216.

Safety, tolerability, pharmacokinetics and pharmacodynamics of VTP-43742, a RORγt inhibitor, in normal healthy volunteers

Abstract VTP-43742 is an orally active RORγt inhibitor being developed for the treatment of autoimmune disorders, including psoriasis, through inhibition of IL-17A production and down regulation of the IL-23 receptor. Safety, tolerability, pharmacokinetic (PK) and pharmacodynamic (PD) profiles of VTP-43742 were assessed in two, randomized, double-blind, placebo-controlled studies in which VTP-43742 was administered to normal healthy volunteers. The first study was a single ascending dose (SAD) study (N = 53) in which participants were randomized to a one-time administration of VTP-43742 (7 dose levels, 30–2000 mg) or placebo. The second study (NCT02555709) was a multiple ascending dose (MAD) study in which participants (N = 40) received VTP-43742 (5 dose levels, 100–1400 mg/d) or placebo once daily for 10 days. VTP-43742 was shown to be safe and generally well tolerated at all dose levels in both studies. No serious adverse events were reported, and all study subjects completed dosing. No clinically significant clinical chemistry, hematologic or ECG abnormalities were observed, and dose proportionality was demonstrated across all dose levels. In the SAD study, VTP-43742 had a terminal plasma half-life of ~30 hours. In an ex vivo whole blood assay (WBA) of IL-17A secretion, VTP-43742 suppressed RORγt dependent secretion of IL-17A in a dose-responsive manner; >90% inhibition was observed at the higher doses which was mostly maintained over 24 hours. In the MAD study, those receiving VTP-43742 showed >90% inhibition of RORγt dependent IL-17A secretion in the WBA for a full 24hrs in all but the lowest dose cohort. These data support the further development of VTP-43742 for the treatment of autoimmune disorders.

Targeted erythropoietin selectively stimulates red blood cell expansion in vivo

The design of cell-targeted protein therapeutics can be informed by natural protein-protein interactions that use cooperative physical contacts to achieve cell type specificity. Here we applied this approach in vivo to the anemia drug erythropoietin (EPO), to direct its activity to EPO receptors (EPO-Rs) on red blood cell (RBC) precursors and prevent interaction with EPO-Rs on nonerythroid cells, such as platelets. Our engineered EPO molecule was mutated to weaken its affinity for EPO-R, but its avidity for RBC precursors was rescued via tethering to an antibody fragment that specifically binds the human RBC marker glycophorin A (huGYPA). We systematically tested the impact of these engineering steps on in vivo markers of efficacy, side effects, and pharmacokinetics. huGYPA transgenic mice dosed with targeted EPO exhibited elevated RBC levels, with only minimal platelet effects. This in vivo selectivity depended on the weakening EPO mutation, fusion to the RBC-specific antibody, and expression of huGYPA. The terminal plasma half-life of targeted EPO was ∼28.3 h in transgenic mice vs. ∼15.5 h in nontransgenic mice, indicating that huGYPA on mature RBCs acted as a significant drug sink but did not inhibit efficacy. In a therapeutic context, our targeting approach may allow higher restorative doses of EPO without platelet-mediated side effects, and also may improve drug pharmacokinetics. These results demonstrate how rational drug design can improve in vivo specificity, with potential application to diverse protein therapeutics.

Pharmacokinetics of long-acting cefovecin in copper rockfish (Sebastes caurinus).

To assess the pharmacokinetic properties of cefovecin in a cold-water teleost species. 10 healthy adult copper rockfish (Sebastes caurinus), sex unknown. Cefovecin (16 mg/kg) was administered SC to the rockfish. Blood samples were collected at predetermined points for measurement of plasma cefovecin concentrations (3 samples/fish). Plasma cefovecin concentrations were measured via liquid chromatography with mass spectrometry. Pharmacokinetic analysis was performed by means of naïve pooled analysis and compartmental modeling. Plasma protein binding of cefovecin was determined by ultrafiltration. Cefovecin administration appeared to be well tolerated by the rockfish. Pharmacokinetic analysis resulted in a maximum plasma concentration of 104.8 μg/mL at 2.07 hours after administration. Plasma terminal half-life was 32.5 hours, and area under the curve was 5,132 h·g/mL. Plasma protein binding was low (< 10%) for plasma concentrations of 10 and 100 μg of cefovecin/mL when assessed at 7.8° and 20°C. Plasma concentrations > 1 μg/mL persisted for the full 7-day follow-up period. SC administration of cefovecin to copper rockfish at a dose of 16 mg/kg yielded plasma concentrations > 1 μg/mL that persisted to 7 days, but some interindividual variability was observed. The low degree of plasma protein binding but high circulating concentration of free drug may allow an extended administration interval in rockfish. Studies are needed to assess the efficacy and safety of this dose in rockfish.

Antibacterial efficacy and pharmacokinetic evaluation of sanguinarine in common carp (Cyprinus carpio) following a single intraperitoneal administration

Sanguinarine (SA), with antimicrobial and antiparasitic activities against fish pathogens, exhibits great potential commercial use in aquaculture. However, little information on pharmacokinetics of SA restricts further application in aquaculture. In this study, pharmacokinetics of SA in common carp (Cyprinus carpio) following a single intraperitoneal administration [10mgkg(-1) BW (body weight)] was evaluated by high-performance liquid chromatography (HPLC). The peak concentration (Cmax ) of SA in kidney was 11.8μgg(-1) , which was higher than in other tissues and plasma. The terminal half-life in fish tissue and plasma was as follows: 42.3h (kidney)>37.2h (liver)>20.1h (gill)>18.8h (muscle)>10.9h (spleen)>10.0h (plasma). Additionally, we determined the bacterial loads in tissues of common carp infected with Aeromonas hydrophila after i.p. administration of SA at 0, 5, 10 and 20mgkg(-1) BW. The results showed that i.p. administration of SA at 10mgkg(-1) BW significantly enhanced antibacterial efficacy against A.hydrophila, where the antibacterial ratio in the gill, kidney, spleen and liver on day 5 was 95.13%, 93.33%, 90.09% and92.82%, respectively. Overall, these results suggested the potential of SA to treat A.hydrophila infection in common carp farming industry.

Biodistribution and Pharmacokinetics Study of siRNA-loaded Anti-NTSR1-mAb-functionalized Novel Hybrid Nanoparticles in a Metastatic Orthotopic Murine Lung Cancer Model.

Small interfering RNA (siRNA) is effective in silencing critical molecular pathways in cancer. The use of this tool as a treatment modality is limited by lack of an intelligent carrier system to enhance the preferential delivery of this molecule to specific targets in vivo. In the present study, the in vivo behavior of novel anti-NTSR1-mAb-functionalized antimutant K-ras siRNA-loaded hybrid nanoparticles, delivered by i.p. injection to non-small-cell lung cancer in mice models, was investigated and compared to that of a naked siRNA formulation. The siRNA in anti-NTSR1-mAb-functionalized hybrid nanoparticles was preferentially accumulated in tumor-bearing lungs and metastasized tumor for at least 48 hours while the naked siRNA formulation showed lack of preferential accumulation in all of the organs monitored. The plasma terminal half-life of nanoparticle-delivered siRNA was 11 times higher (17–1.5 hours) than that of the naked siRNA formulation. The mean residence time and AUClast were 3.4 and 33 times higher than the corresponding naked siRNA formulation, respectively. High-performance liquid chromatography analysis showed that the hybrid nanoparticle carrier system protected the encapsulated siRNA against degradation in vivo. Our novel anti-NTSR1-mAb-functionalized hybrid nanoparticles provide a useful platform for in vivo targeting of siRNA for both experimental and clinical purposes.

Pharmacokinetics of the Experimental Non‐Nucleosidic DNA Methyl Transferase Inhibitor N‐Phthalyl‐l‐Tryptophan (RG 108) in Rats

DNA methyl transferase (DNMT) inhibitors can re-establish the expression of tumour suppressor genes in malignant diseases, but might also be useful in other diseases. Inhibitors in clinical use are nucleosidic cytotoxic agents that need to be integrated into the DNA of dividing cells. Here, we assessed the in vivo kinetics of a non-nucleosidic inhibitor that is potentially free of cytotoxic effects and does not require cell division. The non-specific DNMT inhibitor N-phthalyl-L-tryptophan (RG 108) was injected subcutaneously in rats. Blood was drawn 0, 0.5, 1, 2, 4, 6, 8 and 24 hr after injection and RG 108 in plasma was measured by high-performance liquid chromatography coupled to mass spectrometry. Trough levels and area under the curve (AUC) were significantly higher with multiple-dose administration and cytochrome inhibition. In this group, time to maximal plasma concentration (tmax , mean ± S.D.) was 37.5 ± 15 min., terminal plasma half-life was approximately 3.7 h (60% CI: 2.1-15.6 h), maximal plasma concentration (Cmax) was 61.3 ± 7.6 μM, and AUC was 200 ± 54 μmol·h/l. RG 108 peak levels were not influenced by cytochrome inhibition or multiple-dose administration regimens. Maximal tissue levels (Cmax in μmol/kg) were 6.9 ± 6.7, 1.6 ± 0.4 and 3.4 ± 1.1 in liver, skeletal and heart muscle, respectively. We conclude that despite its high lipophilicity, RG 108 can be used for in vivo experiments, appears safe and yields plasma and tissue levels in the range of the described 50% inhibitory concentration of around 1 to 5 μM. RG 108 can therefore be a useful tool for in vivo DNMT inhibition.

A Phase I Study Investigating the Safety, Tolerability, Pharmacokinetics and Pharmacodynamic Activity of the Hepcidin Antagonist PRS-080#022. Results from a Randomized, Placebo Controlled, Double-Blind Study Following Single Administration to Healthy Subjectsa

▪PRS-080#022 is a 20kD AnticalinTM protein linked to 30kD linear poly-ethylene-glycol that specifically binds to human hepcidin 25, thereby inhibiting its activity. PRS-080#022 is developed for the treatment of functional iron deficient anemia associated with chronic kidney disease or cancer. Elevated levels of hepcidin restrict iron availability and contribute to functional iron deficiency and anemia. Thus, antagonizing hepcidin with PRS-080#022 has the potential to improve iron availability and erythropoiesis, thereby avoiding overload with exogenous iron and reducing the administered levels of Erythropoiesis-Stimulating Agents.48 healthy male subjects were treated in this placebo controlled, double-blind Phase I study with ascending doses of PRS-080#022 in 6 cohorts at 0.08, 0.4, 1.2, 4.0, 8.0, and 16.0 mg/kg. 6 subjects per cohort received PRS-080#022 and 2 subjects received placebo (NCT02340572). Placebo or active treatments were administered by intravenous infusion over 2 hours. Safety, tolerability, the pharmacokinetics of total and free PRS-080#022, serum hepcidin concentrations as well as parameters of iron metabolism (ferritin, serum iron, transferrin saturation, reticulocytes and hemoglobin) were investigated.PRS-080#022 was well tolerated. 39 adverse events (AE) were reported during or after treatment in 22 subjects. All such AEs were mild or moderate and no serious AE was observed. Headache was the most frequently observed AE (10 subjects). Otherwise, no association of AEs to specific organs and no apparent dose dependency or difference between placebo and active treatment were observed. Notably, no hypersensitivity or infusion reactions were noted and vital signs, body temperature and ECG were unchanged.Pharmocokinetics of total PRS-080#022 followed a two-compartment model and was consistent between dose cohorts and within subjects of each cohort (Figure 1). Maximal concentration (Cmax) and area under the time curve (AUC) increased proportionally with dose (Table 1). Cmax was reached about 1 h after the 2 h infusion period (Table 1). The terminal plasma half life (T1/2) of PRS-080#022 ranged from 71 to 81 hours among dose cohorts (Table 1). The volume of distribution was small with 49 to 65 ml/kg, consistent with a distribution mainly to the blood volume.Administration of PRS-080#022 resulted in a decrease of free hepcidin which was observed already 1 h after start of infusion. PRS-080#022 administration induced a transient increase in serum iron concentration and transferrin saturation (TSAT), with both responses exhibiting a comparable time course and at doses of 0.4 mg/kg and higher. TSAT increased to > 90% in individual subjects. Serum iron concentrations reached about 50 µmol/l in individual subjects and did not further increase with dose. Importantly, the time period at which elevated serum iron concentrations and TSAT were observed increased with dose from about 18 h at 0.4 mg/kg to about 120 h at 16 mg/kg PRS-080#022. This is reflected by an increase of the AUC of the serum iron response relative to baseline and placebo (Table 1). In contrast, ferritin levels were largely unaffected by treatment.The excellent safety profile and the confirmed activity of PRS-080#022 on iron metabolism observed in healthy subjects warrants further investigations in anemic patients. A study investigating safety, pharmacokinetics and activity on erythropoiesis in anemic end-stage chronic kidney disease patients is in preparation.aFunded by the European Community FP7 health program grant GA-No. 278408 and supported by the EUROCALIN consortium (www.eurocalin-fp7.eu)TableSummary of pharmacokinetic and pharmacodynamic parametersPRS-080#022 dose[mg/kg]Pharmacokinetic Parameters (group means ± SD)Pharmacodynamic Parameter(group means ± SD)Cmax[µg/ml]AUC0-inf[h*µg/ml]Tmax[h]T1/2[h]Vss[ml/kg]Serum Iron AUC0-240# [h*µmol/l]0.082.1±0.3162 ± 172.8 ± 0.481.2 ± 8.756.2 ± 8.039 ± 28070.410.6 ± 1.6761 ± 1633.3 ± 1.670.5 ± 27.754.2 ± 9.81174 ± 11501.233.9 ± 4.42264 ±1672.7 ± 0.880.0 ± 10.351.3 ± 4.1958 ± 11784.0120.4 ± 19.67491 ± 7303.7 ± 3.173.1 ± 8.947.8 ± 5.61579 ± 22228.0246.3 ± 56.815066 ± 24964.3 ± 2.879.6 ± 9.753.3 ± 9.31134 ± 220716.0366.2 ± 40.925572 ± 40753.0 ± 0.680.2 ± 11.664.6 ± 14.63480 ± 2123#Response as Area Under the Curve 0-240h over baseline, placebo subtracted [Display omitted] DisclosuresMoebius:Pieris Pharmaceuticals Inc.: Employment. Feuerer:Pieris Pharmaceuticals Inc.: Other: contracted clinical research. Fenzl:Pieris Pharmaceuticals Inc.: Other: contracted clinical research. van Swelm:PIERIS: Other: member of the EU FP7 Eurocalin consortium. Swinkels:PIERIS: Other: member of EU FP7 Eurocalin consortium. Hohlbaum:Pieris Pharmaceuticals Inc.: Employment.

Abstract 19606: PZ-128: First in Human Pepducin Inhibitor of PAR-1 Pharmacokinetics, Pharmacodynamics, Safety, and Tolerability

Background: PZ-128 is a first-in-class cell penetrating lipopeptide pepducin that inhibits PAR-1-G protein signaling by forming a structure highly similar to the corresponding off-state juxtamembrane region of the GPCR. PZ-128 inhibited PAR-1 and thrombosis in non-human primates. Its effects in humans are unknown. Methods and Results: PZ-128 was administered by continuous intravenous infusion (0.01 mg/kg to 2 mg/kg) to patients with multiple cardiovascular risk factors (n=31). Safety, tolerability, and pharmacokinetic (PK) effects were assessed. Platelet receptor function was assessed by conventional aggregation at baseline and 0.5, 1, 2, 6, 24 h and 8-11 d post-dosing. There were no effects on ECG, hematologic or clinical chemistry parameters. At 0.5 mg/kg given over 2 h there was 40 % and 50 % inhibition (8 μM SFLLRN) at 0.5 and 2 h, respectively. At 1-2 mg/kg, there was 25% and 75% inhibition at 0.5 h and 95-100% inhibition at 1-2 h (p&lt;0.05 for 1 mg dose). Maximal platelet aggregation (8 μM SFLLRN) was 66-100% recovered by 24 h at 0.5-2 mg/kg. There was no significant inhibition of PAR-4, ADP, or collagen receptors at any time point. PZ-128 plasma levels were linear with dose (R=0.99) and reached Cmax levels of 2 μM, 2.5 μM, 5 μM, and 12 μM at 0.3, 0.5, 1 and 2 mg/kg doses, respectively. The terminal elimination plasma half-life was 49 ± 6 min. Conclusion: PZ-128 is a promising parenteral antiplatelet agent that provided rapid, specific, dose-dependent, and reversible inhibition of platelet PAR-1 through a novel mechanism.

Variation in absorption and half-life of hydrocortisone: a need to consider plasma terminal half-life in dosing schedules

METHODS Congenital adrenal hyperplasia (CAH) due to a deficiency in the enzyme 21-hydroxylase (P450c21) is the commonest form of CAH. The conventional treatment of the condition uses hydrocortisone as a replacement glucocorticoid along with 9 alpha-Fludrocortisone as the mineralocorticoid replacement. Hydrocortisone is usually given in a three times per day regimen although in infancy and in puberty a four times per day regimen is more common. The concentration of cortisol resulting from the administration of hydrocortisone is dependent on the absorption of hydrocortisone from the gastrointestinal tract, balanced against the clearance of cortisol from the circulation. Although there are other components operative, such as the enterohepatic circulation, cortisol concentrations in the circulation can be conceived as a balance between the two parameters absorption and clearance. Clearance of cortisol from the circulation can be measured by an intravenous bolus administration of hydrocortisone, whereas absorption can be determined from a series of pharmacological parameters, such as the maximum concentration attained (Cmax) and the time to peak concentration (tmax). The conventional replacement dosing when using hydrocortisone is calculated on a body size basis. Other than this very little attention has been paid to individualise the dosing schedule using measures of absorption and clearance.

ATNT-26PHASE I/II STUDY OF DIANHYDROGALACTITOL IN PATIENTS WITH RECURRENT MALIGNANT GLIOMA

ATNT-26. PHASE I/II STUDY OF DIANHYDROGALACTITOL IN PATIENTS WITH RECURRENT MALIGNANT GLIOMA Kent Shih1,2, Mahish Patel1,3, Nicholas Butowski4, Jeffrey Bacha5, Dennis Brown5, Anne Steino5, Richard Schwartz5, Sarath Kanekal5, Lorena Lopez5, and Howard Burris1,2; Sarah Cannon Research Institute, Nashville, TN, USA; Tennessee Oncology, Nashville, TN, USA; Florida Cancer Specialists & Research Institute, Florida, USA; University of California San Francisco Division of NeuroOncology, San Francisco, CA, USA; DelMar Pharmaceuticals, Vancouver, BC, Canada Glioblastoma multiforme (GBM) is the most common brain cancer. Front-line systemic therapy with temozolomide is often ineffective due to O-methylguanine-DNA-methyltransferase (MGMT)-mediated resistance. Dianhydrogalactitol (VAL-083) is a bi-functional DNA N cross-linking agent that crosses the blood-brain barrier and demonstrated cytotoxic activity independent of MGMT in vitro. The main goal of this clinical trial was to determine an appropriate dose for Phase II/III trials in refractory GBM. METHODS: Open-label, single-arm Phase I/II dose-escalation study in patients with histologically-confirmed GBM, previously treated with radiation and must have failed both temozolomide and bevacizumab, unless contraindicated. The study utilized 3 + 3 dose-escalation design. Patients received VAL-083 on days 1, 2, 3 of a 21-day cycle. RESULTS: 30 GBM patients were enrolled across 8 dose cohorts ranging from 1.5 to 50mg/m/d. No drug-related severe adverse events were reported, and myelosuppression was mild at doses ≤40mg/m/d. Dose limiting toxicities (DLT) consisting of thrombocytopenia were observed at 50mg/m/d. Platelet nadir occurred around day 20, and DLT-related symptoms resolved rapidlyand spontaneously without concomitant treatment. Pharmacokinetic analyses show dosedependent linear systemic exposure with a short 1-2h plasma terminal halflife; Cmax ranged 739-1130ng/mL (5.1-7.7 mM) at 40mg/m/d resulting in calculated CNS concentrations within the IC50 range observed for multiple GBM cell-lines in vitro. Preliminary analysis shows increasing dose-dependent median survival with median OS 1⁄4 9.0 months at doses ≥30mg/m/d vs. 4.4 months at doses ,10mg/m/d. An expansion cohort of up to 14 patients has been initiatedat40mg/m/d.Asmall cohort (n 1⁄4 3) atan interim 45mg/m/d dose will also be studied, and the expansion cohort may be continued at this higher dose if safety data warrant. CONCLUSIONS: VAL-083 dosing appears limited by myelosuppression; however, 40mg/m/d dose exhibited favorable safety profile, with a trend toward improved survival vs. lower doses. Updated safety and efficacy data from the expansion cohort will be presented. ClinicalTrials.gov Identifier NCT01478178. Neuro-Oncology 17:v10–v17, 2015. doi:10.1093/neuonc/nov205.26 Published by Oxford University Press on behalf of the Society for Neuro-Oncology 2015.

Bisphenol A glucuronide deconjugation is a determining factor of fetal exposure to bisphenol A

Previous studies in experimental animals have shown that maternal exposure to bisphenol A (BPA) during late pregnancy leads to high plasma concentrations of BPA glucuronide (BPAG) in fetus compared to mother due to the inability of BPAG to cross the placental barrier. A recent in vitro study has reported that BPAG can exert adipogenic effect underlining the need for characterization of the fetal disposition of BPAG.Experiments were conducted in chronically catheterized fetal sheep to determine the contribution of BPAG hydrolysis to BPA to the elimination of BPAG from the fetal compartment and its resulting effect on the overall fetal exposure to free BPA. Serial sampling of fetal arterial blood, amniotic fluid, maternal venous blood and urine was performed following separate single doses of BPA and BPAG administered intravenously to eight fetal/maternal pairs after cesarean section, and repeated BPAG doses given to two fetal sheep. On average 67% of the BPA entering the fetal circulation was rapidly eliminated through fetal to maternal clearance, with a very short half-life (20min), while the remaining fraction (24%) was glucuronoconjugated. BPA conjugation–deconjugation cycling was responsible for a 43% increase of the overall fetal exposure to free BPA. A very specific pattern of fetal exposure to free BPA was observed due to its highly increased persistence with a hydrolysis-dependent plasma terminal free BPA half-life of several tens of hours. These findings suggest that although the high fetal to maternal clearance of free BPA protects the fetus from transient increases in free BPA plasma concentrations associated with maternal BPA intake, low but sustained basal free BPA concentrations are maintained in the fetus through BPA conjugation–deconjugation cycling. The potential health implications of these low but sustained basal concentrations of free BPA in fetal plasma should be addressed especially when considering time-dependent effects.

Pharmacokinetic Properties of a Novel D-Peptide Developed to be Therapeutically Active Against Toxic β-Amyloid Oligomers.

It has been shown that amyloidβ (Aβ) oligomers play an important role in the pathology of Alzheimer's disease (AD). D3, a peptide consisting solely of D-enantiomeric amino acid residues, was developed to specifically eliminate Aβ oligomers and is therapeutically active in transgenic AD mice. D-peptides have several advantages over L-peptides, but little is known about their pharmacokinetic potential in vivo. Here, we analysed the pharmacokinetic properties of RD2, a rationally designed and potent D3 derivative. The pharmacokinetic analysis was performed using (3)H-RD2 after administration via several routes in mice. The time dependent amount of radiolabelled RD2 was measured in plasma and several organ homogenates by liquid scintillation counting. Furthermore, binding to plasma proteins was estimated. RD2 penetrates into the brain, where it is thought to implement its therapeutic function. All administration routes result in a maximal brain concentration per dose (Cmax/D) of 0.06 (μg/g)/(mg/kg) with brain/plasma ratios ranging between 0.7 and 1.0. RD2 shows a small elimination constant and a long terminal half-life in plasma of more than 2days. It also exhibits high bioavailability after i.p., s.c. or p.o. administration. These excellent pharmacokinetic properties confirm that RD2 is a very promising drug candidate for AD.

Therapy and pharmacological properties of hydroxychloroquine and chloroquine in treatment of systemic lupus erythematosus, rheumatoid arthritis and related diseases.

This review examines the pharmacokinetics, modes of action and therapeutic properties of the anti-malarial drugs, hydroxychloroquine (HCQ) and chloroquine (CQ), in the treatment of systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and related conditions, as well as osteoarthritis (OA). Both HCQ and CQ have historically been employed successfully for the treatment of SLE and RA for over 70 years. HCQ has been used extensively for SLE where it has a good reputation for controlling the dermatological complications in SLE. It has also been reported to effectively control the symptoms of Sjøgren's syndrome, as well as preventing thrombosis in phospholipid antibody (aPL) syndrome. In RA and SLE, HCQ is preferred because of the lower incidence of gastrointestinal adverse reactions compared with CQ and it might have a lower risk of ocular adverse reactions. There is increasing evidence that HCQ may reduce atherosclerosis and risks of cardiovascular disease in rheumatic patients. Both HCQ and CQ have been shown to improve glycaemia and reduce the risks of type II diabetes mellitus. Although both HCQ and CQ are effective in low-moderate RA, HCQ is now preferred as part of combination therapy for more severe disease. The advantages of combination therapy are that the doses of the individual drugs may be lowered so reducing adverse reactions. Both HCQ and CQ are diastereoisomers, have basic properties and are given as the sulphate and phosphate salts. While being relatively well absorbed orally and with good bioavailability, they have long and variable plasma terminal elimination half-lives (approximately 40-60 days). This reflects their high volume of distribution, V D (HCQ 44,000L; CQ 65,000L) which extends into aqueous compartments, long mean residence time (HCQ 1300 h; CQ 900 h) and with about half the drugs (metabolites) undergoing renal clearance. The strong binding to melanin reflects the ocular injury and dermatological properties of these drugs. The consensus is that the occurrence of ocular adverse reactions can be minimised by close attention to the dose (which should be set on a body weight basis) with regular (e.g. quarterly) retinal examination. Although HCQ and CQ can pass through the placenta, the use of these drugs during pregnancy does not appear to risk harm to the baby and might be beneficial to the mother with SLE and her child by controlling the SLE disease activity, which is known to be an important factor affecting pregnancy outcome. The modes of action of HCQ and CQ in these arthritides represent somewhat of an enigma. Undoubtedly, these drugs have multiple actions related, in part, their ability to accumulate in lysosomes and autophagosomes of phagocytic cells as well as affecting MHC Class II expression and antigen presentation; actions of the production of pro-inflammatory cytokines [e.g. interleukin-1 (IL-1) tumour necrosis factor-α (TNFα)]; control of toll-like receptor-9 activation; and leucocyte generation of reactive oxygen species (ROS); i.e. antioxidant activity. The actions of these drugs on T and B cells are less clear but may depend on these leucocyte-mediated actions. Anti-malarials also protect against cytokine-mediated cartilage resorption. This and other actions may underlie the potential benefits in treating OA. The exact relationships of these various actions, mostly determined in vitro, have not been specifically defined in vivo or ex vivo in relation to clinical efficacy. HCQ and CQ have a good reputation for being effective and relatively safe treatments in SLE, mild-moderate RA and Sjøgren's syndrome. There is need for (a) more information on their mode of action in relation to the control of these diseases, (b) scope for developing formulations that have improved pharmacokinetic and therapeutic properties and safety, and (c) further exploring their use in drug combinations not only with other disease modifying agents but also with biologics.

Population pharmacokinetic modeling of plasma and intracellular ribavirin concentrations in patients with chronic hepatitis C virus infection.

Ribavirin, a guanosine analog, is a broad-spectrum antiviral agent. Ribavirin has been a fundamental component of the treatment of hepatitis C virus (HCV) infection for decades, but there is a very limited understanding of the clinical pharmacology of this drug. Furthermore, it is associated with a major dose-limiting toxicity, hemolytic anemia. Ribavirin undergoes intracellular phosphorylation by host enzymes to ribavirin monophosphate (RMP), ribavirin diphosphate (RDP), and ribavirin triphosphate (RTP). The intracellular forms have been associated with antiviral and toxic effects in vitro, but the kinetics of these phosphorylated moieties have not been fully elucidated in vivo. We developed a model to characterize the plasma pharmacokinetics of ribavirin and the difference between intracellular phosphorylation kinetics in red cells (nonnucleated) and in peripheral blood mononuclear cells (nucleated). A time-independent two-compartment model with first-order absorption described the plasma data well. The cellular phosphorylation kinetics was described by a one-compartment model for RMP, with the formation rate driven by plasma concentrations and the first-order degradation rate. RDP and RTP rapidly reached equilibrium with RMP. Concomitant telaprevir use, inosine triphosphatase genetics, creatinine clearance, weight, and sex were significant covariates. The terminal ribavirin half-life in plasma and phosphorylated anabolites in cells was approximately 224 h. We found no evidence of time-dependent kinetics. These data provide a foundation for uncovering concentration-effect associations for ribavirin and determining the optimal dose and duration of this drug for use in combination with newer direct-acting HCV agents. (This study has been registered at ClinicalTrials.gov under registration no. NCT01097395.).

Clinical and preclinical pharmacokinetics and pharmacodynamics of mipomersen (kynamro(®)): a second-generation antisense oligonucleotide inhibitor of apolipoprotein B.

Mipomersen (Kynamro®), a second-generation 2′-O-methoxyethyl chimeric antisense oligonucleotide (ASO), inhibits the synthesis of apolipoprotein B (apoB) and is indicated in the US as an adjunct therapy for homozygous familial hypercholesterolemia (HoFH) at a dose of 200 mg subcutaneously (SC) once weekly. The pharmacokinetic (PK) properties of mipomersen are generally consistent across all species studied, including mouse, rat, monkey, and humans. After SC administration, mipomersen is rapidly and extensively absorbed. It has an apparent plasma and tissue terminal elimination half-life of approximately 30 days. Mipomersen achieves steady-state tissue concentrations within approximately 4–6 months of once-weekly dosing. It does not exhibit PK-based drug–drug interactions with other concomitant medications, either involving competition for plasma protein binding or alterations in disposition of any evaluated drugs. Furthermore, mipomersen does not prolong the corrected QT (QTc) interval. There have been no ethnic- or gender-related differences in PK observed. In clinical trials, both as a single agent and in the presence of maximal lipid-lowering therapy, mipomersen has demonstrated significant dose-dependent reductions in all measured apoB-containing atherogenic lipoproteins. Overall, mipomersen has well-characterized PK and pharmacodynamic properties in both animals and humans, and is an efficacious adjunct treatment for patients with HoFH.

Phase 1 Study Results of a Novel Controlled-Release Formulation of Anagrelide (GALE-401) for the Treatment of Thrombocytosis

Introduction: Despite recent advances in the diagnosis and management of myeloproliferative neoplasms (MPNs), treatment of essential thrombocythemia (ET) has remained largely unchanged since the introduction of anagrelide in the US during 1997. Anagrelide is indicated for the treatment of thrombocythemia, to reduce the elevated platelet count and risk of thrombosis, and to ameliorate symptoms including thrombohemorrhagic events. The primary pharmacological effect of anagrelide is inhibition of megakaryocyte hypermaturation leading to reduced platelet production. Anagrelide also inhibits cyclic AMP phosphodiesterase III (PDE3), and common drug related adverse events (AEs; e.g., headache, palpitations, fluid retention, nausea and diarrhea) are believed to be due to this mechanism. Although initiating treatment at low doses and slowly increasing the dose to reach a target decreased platelet count may mitigate AEs, over 20% of patients still withdraw from treatment due to poor tolerability. As the currently marketed anagrelide product is an immediate release (IR) formulation with peak plasma concentrations (Cmax) that may exceed that needed for platelet reduction and cause unwanted PDE3 inhibition and AEs, an alternate formulation that modifies this pharmacokinetic (PK) profile may improve patient tolerability, adherence and treatment outcomes. This has led to the development and study of a controlled-release (CR) formulation of anagrelide (GALE-401).Methods: 98 healthy adult subjects were enrolled among 5 Phase 1 clinical trials of anagrelide CR, including 12 placebo-control subjects and 86 subjects who received single or multiple doses ranging from 0.2 to 0.6 mg twice daily (b.i.d.) for up to 41 days. The trials included an open-label, single dose developmental study; two placebo-controlled multiple dose ranging studies; a food effect study; and a comparative crossover PK study vs. IR reference product. Safety parameters included routine laboratory, ECG, and clinical evaluations. PK was assessed by measurements of plasma anagrelide and its active metabolite using a validated HPLC-MS/MS method. Pharmacodynamic activity was assessed by daily platelet count determinations in the multiple dosing studies.Results: Single doses of anagrelide CR were well tolerated, and the only drug-related AE reported in 2 or more subjects was headache. In the b.i.d. dose-ranging studies, the frequency and severity of AEs were similar between anagrelide CR and placebo groups, with the exception of decreased platelet counts in subjects receiving anagrelide CR. All AEs were transient, mild or moderate in severity, and no severe or serious AEs were reported.Anagrelide CR demonstrated dose proportional PK characteristics. Following a single 0.5 mg dose in the fasted state, the mean time to maximum plasma concentration (Tmax) and terminal elimination half-life (t1/2) were 2.0±1.5 hrs and 10.4±9.3 hrs (mean ± SD), respectively; in contrast, Tmax and t1/2 following IR was 1.0±0.9 hrs and 1.4±0.2 hrs, respectively. Cmax and total plasma exposure (AUC0-inf) with anagrelide CR were reduced to 26% and 59% of IR, respectively. However, steady-state PK following 6 daily 0.5 mg b.i.d. doses of anagrelide CR or IR showed similar AUC0-inf values, while Cmax with anagrelide CR remained nearly unchanged (29%). Plasma exposure was higher when anagrelide CR was administered in the fed state, as demonstrated by the ratio of least-squares mean values for Cmax and AUC0-t, which were increased by 100% and 60%, respectively.The platelet lowering effect of anagrelide CR was evident in the 2 multiple dose ranging studies. In a placebo-controlled study of 0.2 to 0.6 mg b.i.d. dosing for up to 21 days, a dose-related decrease in platelet counts was observed, and the 0.6 mg cohort was halted early due to excessive platelet reductions. Anagrelide CR did not have a relevant impact on platelet function as assessed by template bleeding time. [Display omitted] Conclusion: Anagrelide CR is a promising, novel formulation of anagrelide that exhibited the desired PK profile of a significantly reduced Cmax, while maintaining plasma exposure to induce platelet count reductions. The product was well tolerated with an AE profile that was not distinguishable from placebo. These data support the importance of an ongoing Phase 2 study in patients with MPN-related thrombocytosis, including ET. DisclosuresLaliberte:Galena Biopharma, Inc.: Employment, Equity Ownership. Glidden:Galena Biopharma, Inc.: Consultancy, Equity Ownership, Patents & Royalties. Hamilton:Galena Biopharma, Inc.: Employment, Equity Ownership.

Phase 1 dose-escalation study of S-222611, an oral reversible dual tyrosine kinase inhibitor of EGFR and HER2, in patients with solid tumours

BackgroundS-222611 is a reversible inhibitor of EGFR, HER2 and HER4 with preclinical activity in models expressing these proteins. We have performed a Phase 1 study to determine safety, maximum tolerated dose (MTD), pharmacokinetic profile (PK) and efficacy in patients with solid tumours expressing EGFR or HER2. Patients and methodsSubjects had advanced tumours not suitable for standard treatment, expressing EGFR or HER2, and/or with amplified HER2. Daily oral doses of S-222611 were escalated from 100mg to 1600mg. Full plasma concentration profiles for drug and metabolites were obtained. Results33 patients received S-222611. It was well tolerated, and the most common toxicities, almost all mild (grade 1 or 2), were diarrhoea, fatigue, rash and nausea. Only two dose-limiting toxicities occurred (diarrhoea and rash), which resolved on interruption. MTD was not reached. Plasma exposure increased with dose up to 800mg, exceeding levels eliciting pre-clinical responses. The plasma terminal half-life was more than 24h, supporting once daily dosing. Responses were seen over a wide range of doses in oesophageal, breast and renal tumours, including a complete clinical response in a patient with HER2-positive breast carcinoma previously treated with lapatinib and trastuzumab. Four patients have remained on treatment for more than 12months. Downregulation of pHER3 was seen in paired tumour biopsies from a responding patient. ConclusionsContinuous daily oral S-222611 is well tolerated, modulates oncogenic signalling, and has significant antitumour activity. The recommended Phase 2 dose, based on PK and efficacy, is 800mg/day.

Plasma concentration-dependent suppression of endogenous hydrocortisone in the horse after intramuscular administration of dexamethasone-21-isonicotinate.

Detection times and screening limits (SL) are methods used to ensure that the performance of horses in equestrian sports is not altered by drugs. Drug concentration-response relationship and knowledge of concentration-time profiles in both plasma and urine are required. In this study, dexamethasone plasma and urine concentration-time profiles were investigated. Endogenous hydrocortisone plasma concentrations and their relationship to dexamethasone plasma concentrations were also explored. A single dose of dexamethasone-21-isonicotinate suspension (0.03 mg/kg) was administered intramuscularly to six horses. Plasma was analysed for dexamethasone and hydrocortisone and urine for dexamethasone, using UPLC-MS/MS. Dexamethasone was quantifiable in plasma for 8.3 ± 2.9 days (LLOQ: 0.025 μg/L) and in urine for 9.8 ± 3.1 days (LLOQ: 0.15 μg/L). Maximum observed dexamethasone concentration in plasma was 0.61 ± 0.12 μg/L and in urine 4.2 ± 0.9 μg/L. Terminal plasma half-life was 38.7 ± 19 h. Hydrocortisone was significantly suppressed for 140 h. The plasma half-life of hydrocortisone was 2.7 ± 1.3 h. Dexamethasone potency, efficacy and sigmoidicity factor for hydrocortisone suppression were 0.06 ± 0.04 μg/L, 0.95 ± 0.04 and 6.2 ± 4.6, respectively. Hydrocortisone suppression relates to the plasma concentration of dexamethasone. Thus, determination of irrelevant plasma concentrations and SL is possible. Future research will determine whether hydrocortisone suppression can be used as a biomarker of the clinical effect of dexamethasone.

Abstract 4632: Plasma and tumor pharmacokinetics of IV LMP400, a novel indenoisoquinoline topoisomerase I inhibitor, in a canine phase I study

Abstract Introduction: LMP400 is one of 3 indenoisoquinolines that are being evaluated in pet dogs with lymphoma to define their safety, pharmacokinetics, and pharmacodynamic modulation (COTC007b). LMP400 forms stable DNA-topoisomerase I (Top1) cleavable complexes and induces unique DNA cleavage sites relative to approved Top1 poisons; LMP400 is not a substrate for ABC transporters and does not have the stability issues that most camptothecin analogs do. Here we report the plasma and uncoupled tumor pharmacokinetics of LMP400 administered IV daily x 5 to patient dogs. Methods: Eligibility included: dogs &amp;gt;15 kg with histologically confirmed non-Hodgkin's lymphoma with nodal presentation (stage 2 or greater) and minimal nodes size for biopsy of 3 cm in the longest dimension, performance status of Grade 0 or 1 and informed owner consent. Dose levels (DL) explored were 8, 16, 24, and 40 mg/m2/day through a 3+3 dose escalation study design. LMP400 was administered over 1 h IV daily x 5, Q28D. LMP400 was quantitated with a validated LC-MS/MS assay (PMID: 20236781), and plasma pharmacokinetic parameters determined non-compartmentally with PK Solutions and plasma and tumor parameters compartmentally with ADAPT5 through iterated two stage (ITS) and maximum likelihood solution with the expectation maximization algorithm (MLEM). Results: All fifteen dogs had useable pharmacokinetic data. Non-compartmental analysis suggested linear relationships between plasma Cmax and AUC vs. dose and tumor C2h vs. dose. Plasma terminal half-life was 11.9 ± 5.0 h and the CL was 26.7 L/h/m2. In line with the t1/2, slight plasma accumulation was observed on this daily times 5 schedule. Compartmental modeling with a 2 compartment linear model resulted in a good fit to the data. The parameters and %CVs respectively for Ke, Vc, Kcp, Kpc, Kct and Ktc were 0.181 h-1 (42.6%), 108 L/m2 (32.7%), 0.250 h-1 (30.1%), 0.0602 h-1 (67%), 0.0632 h-1 (3.65%), and 0.649 h-1 (42.2%). Plasma compartmental CL and half-life were 19.5 L/h/m2 and 29.7 h. Conclusion: The plasma pharmacokinetics of LMP400 in dogs display biphasic behavior, a relatively high total body clearance at 19.5 L/h/m2, and a terminal half-life of 29.7 h. LMP400 distributed to the tumors and mean tumor concentrations were at least 10-fold higher than plasma concentrations at equivalent time points of 2, 6 and 120 h. This favorable biodistribution to tumor (lymph node) may be a valuable distinction to consider in the translation of this novel indenoisoquinoline to the clinic. Support: N01-CM-2011-00015, N01-CM-42202 and P30-CA-47904 Citation Format: Julie L. Eiseman, Julianne Holleran, David L. McCormick, Miguel Muzzio, Joseph M. Covey, Chand Khanna, Christina Mazcko, Yves Pommier, Melissa Paoloni, James D. Doroshow, Joseph E. Tomaszewski, Jan H. Beumer. Plasma and tumor pharmacokinetics of IV LMP400, a novel indenoisoquinoline topoisomerase I inhibitor, in a canine phase I study. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4632. doi:10.1158/1538-7445.AM2014-4632