Utilization of an Amorphous Form of a Water-Soluble GPIIb/IIIa Antagonist for Controlled Release from Biodegradable Microspheres

Purpose. We prepared injectable microspheres for controlled release of TAK-029, a water-soluble GPIIb/IIIa antagonist and discussed the characteristics of controlled release from microspheres. Methods. Copoly(dl-lactic/glycolic)acid (PLGA) microspheres were used for controlled release of TAK-029 [4-(4-amidinobenzoylglycyl)-3-methoxycarbonyl-2-oxopiperazine-l-acetic acid]. They were prepared with a solid-in-oil-in-water (S/O/W) emulsion solvent evaporation technique using either a crystalline form or an amorphous form of the drug. Results. An amorphous form of TAK-029 gave more homogeneous S/O dispersion and higher viscosity than its crystalline form when added to dichloromethane solution of PLGA, resulting in a high drug entrapment into microspheres and a well-controlled release of the drug. Additions of sodium chloride into an external aqueous phase and L-arginine into an oil phase also increased entrapment of the drug, and reduced initial burst of the drug from the microspheres. The micro-spheres demonstrated a desirable plasma level profile in therapeutic range (20–100 ng/ml) for 3 weeks in rats after single subcutaneous injection. Conclusions. A well-controlled release of TAK-029, a water-soluble neutral drug, with small initial burst was achieved by utilizing its amorphous form as a result of possible interaction with PLGA and L-arginine.     

Lipid-lowering effects of TAK-475, a squalene synthase inhibitor,in animal models of familial hypercholesterolemia

The lipid-lowering effects of 1-[2-[(3R,5S)-1-(3-acetoxy-2,2-dimethylpropyl)-7-chloro-1,2,3,5-tetrahydro-2-oxo-5-(2,3-dimethoxyphenyl)-4,1-benzoxazepine-3-yl] acetyl] piperidin-4-acetic acid (TAK-475), a novel squalene synthase inhibitor, were examined in two models of familial hypercholesterolemia, low-density lipoprotein (LDL) receptor knockout mice and Watanabe heritable hyperlipidemic (WHHL) rabbits. Two weeks of treatment with TAK-475 in a diet admixture (0.02% and 0.07%; approximately 30 and 110 mg/kg/day, respectively) significantly lowered plasma non-high-density lipoprotein (HDL) cholesterol levels by 19% and 41%, respectively, in homozygous LDL receptor knockout mice. The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, simvastatin and atorvastatin (in 0.02% and 0.07% admixtures), also reduced plasma levels of non-HDL cholesterol. In homozygous WHHL rabbits, 4 weeks of treatment with TAK-475 (0.27%; approximately 100 mg/kg/day) lowered plasma total cholesterol, triglyceride and phospholipid levels by 17%, 52% and 26%, respectively. In Triton WR-1339-treated rabbits, TAK-475 inhibited to the same extent the rate of secretion from the liver of the cholesterol, triglyceride and phospholipid components of very-low-density lipoprotein (VLDL). These results suggest that the lipid-lowering effects of TAK-475 in WHHL rabbits are based partially on the inhibition of secretion of VLDL from the liver. TAK-475 had no effect on plasma aspartate aminotransferase and alanine aminotransferase activities. Thus, the squalene synthase inhibitor TAK-475 revealed lipid-lowering effects in both LDL receptor knockout mice and WHHL rabbits.     

Effects of long-term treatment with nonselective endothelin receptor antagonist, TAK-044, on remodeling of cardiovascular system with sustained volume overload

To assess the role of endothelin-1 (ET-1) on cardiovascular remodeling, nonselective endothelin-receptor antagonist TAK-044 was administered for the long term to rabbits with or without arteriovenous (A-V) shunt formation. Six weeks after sham operation (n = 12) or carotid-jugular shunt formation (n = 21), TAK-044 (30 mg/day) or saline was infused subcutaneously using osmotic mini pumps for another 6 weeks. Twelve weeks after operation, left ventricular (LV) diameter was enlarged with the presence of an A-V shunt; however, the levels of LV diameter and arterial pressure or the postmortem weight of LVs of shunt rabbits were similar between saline and TAK-044 groups. A linear relation of the luminal diameter and the medial cross-sectional area of the left and right carotid arteries was similar between shunt + saline and shunt + TAK-044 groups. In saline groups, myocardial ET-1 levels were higher in shunt than in sham rabbits (217+/-22 vs. 136+/-19 pg/g tissue; p < 0.01 between rabbit groups) without changes in plasma ET-1 concentrations during saline infusion for 6 weeks. Differences in plasma ET-1 levels before and 6 weeks after the administration of TAK-044 were 0.32+/-0.78 and 0.16+/-0.28 pg/ml (NS between periods) in shunt and sham groups, respectively. In TAK-044 groups, myocardial ET-I levels 12 weeks after operation were similarly lower in both sham (105+/-7.4 pg/g tissue) and shunt rabbits (126+/-9.2 pg/g tissue) than in those with saline administration; however, the plasma ET-1 concentrations were increased significantly 6 weeks after TAK-044 administration by 5.0+/-0.6-fold and 3.5 +/-0.3-fold (p < 0.01) of the levels 6 weeks after operation in shunt and sham groups (NS between groups), respectively. Accordingly, myocardial but not plasma ET-1 levels were increased by a long-term burden of volume overload and were attenuated by a long-term administration of TAK-044 without altering drastically the hemodynamics or vascular remodeling. These results suggest that endogenous ET-1 does not play a major role in the compensatory stage of cardiovascular remodeling in the present volume-overload model.     

NSAID Drugs Release from Injectable Microspheres Produced by Supercritical Fluid Emulsion Extraction

Supercritical fluid emulsion extraction is an innovative technology that uses supercritical carbon dioxide (SC‐CO₂) to extract the dispersed oily phase of an emulsion. This technology was used to produce poly‐lactic‐co‐glycolic acid (PLGA) microspheres charged with two common NSAIDs: piroxicam (PX) and diclophenac sodium (DF). Single (O/W) and double (W/O/W) emulsions were tested and a comparative study between the characteristics of the microspheres obtained by SC‐CO₂ extraction and the ones produced by conventional solvent evaporation (SE) is proposed. Varying the droplet dimensions, microspheres with mean diameters (MDs) of 1, 2, and 3 µm were obtained; however, the microspheres produced by SC‐CO₂ gave always a better reproduction of the MD of original droplets because aggregation phenomena often modify the mean size and distribution of the microparticles produced by SE. Moreover, very efficient drug loadings (88% w/w of DF in PLGA using W/O/W emulsion and 97% of PX w/w in PLGA starting from O/W emulsion) were measured in the products obtained by SC‐CO₂, respectively; whereas, the SE produced a drug loading of 30% in the case of double emulsion and of 70% for single emulsion. Solvent residue of 10 ppm was also measured by SC‐CO₂ technology against the 600 ppm of the SE products. The release profiles of the entrapped drugs were also monitored to check the structure of the microspheres produced by this new technology. © 2009 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 1484–1499, 2010     

Sustained-release microcapsules of a bone formation stimulant, TAK-778, for local injection into a fracture site.

The benzothiepin derivative (2R,4S)-(-)-N-(4-diethoxyphosphorylmethylphenyl)-1,2,4,5-tetrahydro-4-methyl-7,8-methylenedioxy-5-oxo-3-benzothiepin-2-carboxamide (TAK-778) is a potent bone formation stimulant. A sustained release formulation was prepared by encapsulating the drug into biodegradable microcapsules for local application to fracture repair in rats. The microcapsules consisted of TAK-778 (10% w/w) and a biodegradable polymer, copoly (d,l-lactic/glycolic acid), with a copolymer ratio of 85:15 (mol/mol) and an average molecular weight of 15 k. The TAK-778 amount at the injection site progressively diminished for 4 weeks after administration, and the serum level of TAK-778 was sustained over the same period. The local concentration of TAK-778 after administration of the microcapsules was simulated by a two-compartment open model. In the model, a first-order release rate constant and a transfer rate constant were obtained from the release profile of the microcapsules and the serum level of TAK-778 after administration of the TAK-778 solution, respectively. Localization at the injection site was examined by radiography using microcapsules in which iodoform was encapsulated as a contrast agent. The microcapsules formed a clot at the injection site, and their spread was narrowly restricted. The local concentration was calculated to be maintained within the range 10(-3)-10(-6) M over 4 weeks on the assumption that the dose and spread volume were 5 mg of TAK-778/site and 3 mL, respectively.     

Effect of its demethylated metabolite on the pharmacokinetics of unchanged TAK-603, a new antirheumatic agent, in rats.

A factor in the dose-dependent pharmacokinetics of ethyl 4-(3, 4-dimethoxyphenyl)-6,7-dimethoxy-2-(1,2, 4-triazol-1-yl-methyl)quinoline-3-carboxylate (TAK-603) in rats was shown to be due to the inhibition of metabolic clearance of unchanged TAK-603 by its major metabolite, M-I, in other words, product inhibition. The effect of M-I on the metabolic clearance of TAK-603 was studied using rats continuously infused i.v. with this metabolite at rates of 5.3 and 16.0 mg/h/kg. The total body clearance of TAK-603 was decreased remarkably in M-I-infused rats, and the decline of total body clearance depended on the steady-state plasma concentrations of M-I. The effect of M-I generated from the dosed parent drug on the plasma concentration-time profile of TAK-603 was investigated using bile-cannulated rats after i.v. injection of 14C-labeled TAK-603 at doses of 1 and 15 mg/kg. Elimination rates of TAK-603 from rat plasma increased in the bile-cannulated rats in which systemic M-I levels were reduced by interrupting its enterohepatic circulation. To express, simultaneously, the relationships between TAK-603 and M-I in plasma concentration-time profiles, a kinetic model based on the product inhibition was developed for the bile-cannulated rats. A good agreement between calculated curves and the observed concentrations of both TAK-603 and M-I was found at 1 and 15 mg/kg, and the calculated curves were drawn using constant parameters for the two dosages. These results show that the product inhibition by M-I is one factor responsible for the dose-dependent pharmacokinetics of TAK-603 in rats.     

Disposition of TAK-044, a new endothelin antagonist,in rats and dogs

The disposition of TAK-044 (cyclo[D-alpha-aspartyl-3-[(4-phenylpiperazin-1-yl)carbonyl]-L-alanyl-L- alpha-aspartyl-D-2-(2-thienyl) glycyl-L-leucyl-D-tryptophyl] disodium, CAS 157380-72-8), a new endothelin antagonist, was studied in rats and dogs by using 14C-labeled drug ([14C]TAK-044). After a single intravenous administration of [14C]TAK-044 at 3 mg/kg to rats and dogs, the concentrations of TAK-044 in plasma declined biphasically; t1/2 alpha and t1/2 beta were 0.03 and 1.10 h in rats, and 0.06 and 0.57 h in dogs, respectively. Plasma clearance and the volume of distribution at steady-state for TAK-044 were 1.66 l/h/kg and 2.09 l/kg in rats, 2.37 l/h/kg and 0.50 l/kg in dogs, respectively. In rats, TAK-044 was distributed widely into tissues, but the 14C concentrations in tissues except for the liver, kidney, and intestine were lower than that in plasma. The in vitro protein binding amounted to 91 to 92% in rat plasma and 88 to 90% in dog plasma. TAK-044 was hardly distributed into the erythrocytes of either species. TAK-044 was hardly metabolized, the radioactivity in plasma and excreta being mostly unchanged compound. Elimination of the radioactivity from the body was almost completed within 48 h in either species. The dosed radioactivity was excreted mostly in the feces via the hepatobiliary route. The rate of excretion of TAK-044 in the bile was dose-dependently prolonged.     

Alendronate PLGA microspheres with high loading efficiency for dental applications

Purpose: Alendronate sodium, used systemically as a bone protective agent, proved to also be effective locally in various dental bone applications. Development of alendronate-loaded microspheres with high loading efficiency for such applications would be greatly challenged by the hydrophilicity and low MW of the drug. The aim of this study was to incorporate alendronate sodium, into poly (lactide-co-glycolide) (PLGA) microspheres (MS) with high loading efficiency.

Methods: Three multiple emulsion methods: water-in-oil-in-water (W/O/W), water-in-oil-in-oil (W/O₁/O₂) and solid-in-oil-in-oil (S/O₁/O₂) were tested. In addition to entrapment efficiency, MS were characterized for surface morphology, particle size, in vitro drug release and in vitro degradation of the polymer matrix. Alendronate microspheres with maximum drug loading and good overall in vitro performance were obtained using the W/O₁/O₂ emulsion technique.

Results: Drug release from the microspheres exhibited a triphasic release pattern over a period of 13 days, the last fast release phase being associated with more rapid degradation of the PLGA matrix.

Conclusions: Biocompatible, biodegradable PLGA microspheres incorporating alendronate sodium with high loading efficiency obtained in this study may offer promise as a delivery system for bisphosphonates in dental and probably other clinical applications.     

Microencapsulation of a hydrophilic drug into a hydrophobic matrix using a salting-out procedure. I: Development and optimization of the process using factorial design

The congealable disperse phase method for preparing sustained release microspheres involves an emulsification process using water as the external phase and molten hydrophobic wax as the disperse phase into which the drug is loaded. Attempts to entrap highly water-soluble drugs using this process have often resulted in low loading efficiency as the drugs partition into the external water phase during emulsification and are lost. A novel method employing salts and wetting agents was developed to improve the loading efficiency of the highly water-soluble drug, guaifenesin, using this method. The drug/wax ratio (D/W) and the presence of salts and wetting agents greatly influenced microsphere properties. To optimize the process for drug loading efficiency and release rate, three different D/Ws, salts and wetting agents were chosen and a full 3³ factorial design experiment was performed. Any significant differences among the levels of the variables and their individual and joint effects on entrapment efficiency and T₅₀ (time for 50% drug release) were determined. Entrapment efficiencies in the range 35.1-86.3% were obtained for the various factor-level combinations of the variables. Particle size was in the range 140-385 µm and T₅₀ was 0.59-2.72 h for the microspheres obtained. The D/W and type of salt used significantly affected drug entrapment and T₅₀, while the nature of wetting agent was not significant at p &lt; 0.05. The microspheres prepared using 1:4 D/W showed the highest entrapment efficiency and slowest drug release.     

Formulation and evaluation of controlled-release of telmisartan microspheres: In vitro/in vivo study

The aim of this work was to design a controlled-release drug-delivery system for the angiotensin-II receptor antagonist drug telmisartan. Telmisartan was encapsulated with different EUDRAGIT polymers by an emulsion solvent evaporation technique and the physicochemical properties of the formulations were characterized. Using a solvent evaporation method, white spherical microspheres with particle sizes of 629.9–792.1 μm were produced. The in vitro drug release was studied in three different pH media (pH 1.2 for 2 hours, pH 6.8 for 4 hours, and pH 7.4 for 18 hours). The formulations were then evaluated for their pharmacokinetic parameters. The entrapment efficiency of these microspheres was between 58.6% and 90.56%. The obtained microspheres showed good flow properties, which were evaluated in terms of angle of repose (15.29–26.32), bulk and tapped densities (0.37–0.53 and 0.43–0.64, respectively), Carr indices and Hausner ratio (12.94–19.14% and 1.14–1.23, respectively). No drug release was observed in the simulated gastric medium up to 2 hours; however, a change in pH from 1.2 to 6.8 increased the drug release. At pH 7.4, formulations with EUDRAGIT RS 100 showed a steady drug release. The microsphere formulation TMRS-3 (i.e., microspheres containing 2-mg telmisartan) gave the highest C_max value (6.8641 μg/mL) at 6 hours, which was three times higher than C_max for telmisartan oral suspension (TOS). Correspondingly, the area under the curve for TMRS-3 was 8.5 times higher than TOS. Particle size and drug release depended on the nature and content of polymer used. The drug release mechanism of the TMRS-3 formulation can be explained using the Higuchi model. The controlled release of drug from TMRS-3 also provides for higher plasma drug content and improved bioavailability.     

Effect of oral administration of zanapezil (TAK-147) for 21 days on acetylcholine and monoamines levels in the ventral hippocampus of freely moving rats

Zanapezil (TAK-147 (3-[1benzylpiperdin-4-yl]-1-(2,3,4,5-tetrahydro-1 H-1-benzazepin-8-yl) propan-1-one fumarate)) is a selective acetylcholine (ACh) esterase inhibitor under investigation as a drug for Alzheimer's disease (AD) treatment. In this study, the effects of TAK-147 at 2 mg kg(-1) p.o. for 21 days, compared to donepezil (E2020), on the levels of ACh, catecolamines and indoleamines were investigated in the ventral hippocampus (VH) of freely moving rats by microdialysis-high-performance liquid chromatography. The results revealed that the VH contains 92.05+/-21.97 fmol 20 microl(-1) ACh and the following monoamines levels (pg 30 microl(-1)), norepinephrine (NE) 1.92+/-0.39, epinephrine (Epi) 1.91+/-0.183, 3-methoxy-4-hydroxyphenylglycol (MHPG) 11.53+/-3.22, normetanephrine 3.26+/-0.61, dopamine (DA) 0.77+/-0.23, 3,4-dihydroxyphenylacetic acid (DOPAC) 3.37+/-1.01, homovanillic acid (4-hydroxy-3-methoxyphenylacetic acid; HVA) 4.04+/-0.93, 3-methoxytyramine 0.64+/-0.13, serotonin (5-HT) 0.73+/-0.16 and 5-hydroxyindoleacetic acid (5-HIAA) 313.15+/-18.42. On the 21st day and prior to the last dose, TAK-147 increased ACh, Epi, DA and 5-HT, whereas E2020 increased MHPG, Epi and DA. Following the last dose, TAK-147 increased NE, whereas E2020 increased NE, ACh and 5-HT in addition to their effects prior to the last dose. TAK-147 decreased HVA : DA ratio, but only marginally decreased DOPAC : DA and 5-HIAA : 5-HT ratios. On the other hand, E2020 decreased ratios of HVA : DA, DOPAC : DA (prior to the last dose), and 5-HIAA : 5-HT (90-180 min after the last dose). Both drugs decreased MHPG : NE only at 180 min after the last dose. The results also showed that TAK-147 increased Epi : NE ratio prior to and for 120 min following the last dose, whereas E2020 increased the ratio only before the last dose. The present results show that TAK-147 at a subthreshold dose could differentially increase ACh and 5-HT, compared to MHPG increased by E2020. The last dose of each drug could extend their effects to other monoamines. The increase of the monoamines levels, in addition to that on the ACh, and decrease of their oxidation could be of value in the treatment of the AD, other dementic diseases and the cohort neurological disorders depending on the type of the monoamine underlying the disorder.     

TAK-242通过调控JAK2/STAT3通路抑制小鼠心肌缺血再灌注损伤炎症反应

目的：探讨Toll样受体4拮抗剂TAK-242抑制小鼠心肌缺血/再灌注损伤（ischemia/reperfusion,I/R）炎症反应的分子机制。方法：选用48只雄性C57BL/6小鼠随机分为4组：假手术组（sham）、模型组（I_30min /R_24h）、给药组[I/R+TAK-242（3 mg·kg^-1）]、干预组[I/R+TAK-242+AG490（15 mg·kg^-1）]。再灌注24 h后心脏超声检测小鼠心功能,氯化三苯基四氮唑（TTC）染色法测定心肌梗死面积,HE染色观察心肌病理改变,WB检测心肌JAK2/STAT3磷酸化水平,ELISA检测血清IL-6、TNF-α、IL-10和高迁移率族蛋白B1（HMGB1）浓度。结果：与sham组比较,I/R组小鼠左心室收缩期直径（LVIDs）延长（P<0.01）,左心室射血分数（LVEF）和左心室短轴缩短分数（LVFS）显著降低（P<0.001或P<0.01）,心梗面积明显增加并出现心肌炎性浸润,心肌p-JAK2/p-STAT3表达明显升高（P<0.01或P<0.05）,血清IL-6、IL-10、TNF-α和HMGB1水平显著升高（P<0.001或P<0.01）。与I/R组比较,TAK-242给药组小鼠LVIDs缩短（P<0.05）,LVEF和LVFS显著升高（P<0.01或P<0.05）,心梗面积缩小（P<0.01）,心肌炎症浸润减轻,心肌p-JAK2/p-STAT3表达降低（P<0.01或P<0.05）,血清IL-6和TNF-α水平明显下降（P<0.001或P<0.01）,而IL-10和HMGB1浓度进一步升高（P<0.01）。与TAK-242给药组比较,AG490干预可显著加强TAK-242治疗作用,包括心肌收缩功能增强,心梗面积缩小及炎性浸润程度减轻,心肌p-JAK2/p-STAT3表达降低（P<0.05）,血清IL-6、TNF-α浓度下降而IL-10、HMGB1浓度升高（P<0.01或P<0.05）。结论： Toll样受体4拮抗剂TAK-242抑制小鼠I/R炎症反应与JAK2/STAT3信号通路失活有关。     

Lipid-lowering properties of TAK-475, a squalene synthase inhibitor,in vivo and in vitro

1. Squalene synthase is the enzyme that converts farnesyl pyrophosphate to squalene in the cholesterol biosynthesis pathway. We examined the lipid-lowering properties of 1-[[(3R,5S)-1-(3-acetoxy-2,2-dimethylpropyl)-7-chloro-5-(2,3-dimethoxyphenyl)-2-oxo-1,2,3,5-tetrahydro-4,1-benzoxazepin-3-yl]acetyl]piperidine-4-acetic acid (TAK-475), a novel squalene synthase inhibitor. 2. TAK-475 inhibited hepatic cholesterol biosynthesis in rats (ED(50), 2.9 mg kg(-1)) and showed lipid-lowering effects in beagle dogs, marmosets, cynomolgus monkeys and Wistar fatty rats. 3. In marmosets, TAK-475 (30, 100 mg kg(-1), p.o., for 4 days) lowered both plasma non-high-density lipoprotein (HDL) cholesterol and triglyceride, but did not affect plasma HDL cholesterol. On the other hand, atorvastatin (10, 30 mg kg(-1), p.o., for 4 days) lowered the levels of all these lipids. A correlation between decrease in triglyceride and increase in HDL cholesterol was observed, and TAK-475 increased HDL cholesterol with a smaller decrease in triglyceride than did atorvastatin. 4. TAK-475 (60 mg kg(-1), p.o., for 15 days) suppressed the rate of triglyceride secretion from the liver in hypertriglyceridemic Wistar fatty rats, which show an enhanced triglyceride secretion rate from the liver compared with their lean littermates. 5. In HepG2 cells, TAK-475 and its pharmacologically active metabolite, T-91485, increased the binding of (125)I-low-density lipoprotein (LDL) to LDL receptors. 6. These results suggest that TAK-475 has clear hypolipidemic effects in animals via inhibition of hepatic triglyceride secretion and upregulation of LDL receptors, and that TAK-475 might increase HDL cholesterol by decreasing triglyceride. Thus, TAK-475 is expected to be useful for the treatment of dyslipidemia.     

Pharmacokinetics,safety, and tolerability of sodium phenylacetate and sodium benzoate in healthy Japanese volunteers: A phase I,single-center,open-label study

TAK-123, a combination of sodium phenylacetate (NaPA) and sodium benzoate (NaBZ), is an intravenously administered drug developed for the treatment of acute hyperammonemia in infants, children, and adults with urea cycle enzyme deficiencies. The aim of the current study was to evaluate the pharmacokinetics, safety, and tolerability after intravenous infusion of TAK-123 in Japanese healthy adult volunteers. Ten volunteers received a 3.75 g/m² loading dose of TAK-123 over a period of 1.5 h followed by a maintenance infusion of the same dose over 24 h. Phenylacetate (PA) and benzoate (BZ) and their respective metabolites, phenylacetylglutamine (PAG) and hippurate (HIP) were measured over a 24-h period using a high-performance liquid chromatography/tandem mass spectrometry method. Non-compartmental analysis was performed using WinNonlin® Professional. During the loading dose, plasma levels of both PA and BZ peaked at 1.5 h. Plasma PA levels plateaued and were maintained up to 6.5 h, whereas plasma BZ levels declined rapidly after switching to maintenance infusion. Urinary excretion ratios of PAG and HIP at 48 h after the administration were 99.3% and 104%, respectively, suggesting that almost all NaPA and NaBZ were metabolized and excreted into urine. Overall, TAK-123 was well-tolerated in healthy Japanese adults.     

Systemic, pulmonary, and renal hemodynamic effects of endothelin ET(A/B)-receptor blockade in patients with maintained left ventricular function

Endothelin-1 (ET-1) regulates vascular tone in congestive heart failure and modulates renal function. Its role in patients with normal left ventricular (LV) function and its renal effects are unclear. Cardiac and renal hemodynamics were studied in 24 patients with normal LV function and coronary arteries after single-dose, double-blind, randomized administration of TAK-044 (25, 50, or 100 mg, i.v.), an ET(A/B)-receptor antagonist, or placebo. Hemodynamics were monitored using Swan-Ganz and arterial catheters, and ET levels were measured. Renal function was assessed by clearance techniques. In the absence of a dose-response relation, TAK-044 patients were analyzed as a single group. Most hemodynamic effects occurred during the first 4 h. TAK-044 reduced mean arterial (-9.3 mm Hg, p < 0.001), pulmonary (-1.8 mm Hg, p = 0.01), and pulmonary capillary wedge pressure (-1.6 mm Hg, p < 0.001) between 30 min and 4 h. Mean reduction in systemic vascular resistance was 279 dyne/s/cm2 (p < 0.001), whereas heart rate increased 6.1 beats/min (p < 0.001) and cardiac index by 0.37 L/m2 (p = 0.01). Stroke volume index, right atrial pressure, and pulmonary vascular resistance did not change. TAK-044 increased renal plasma flow in proportion to the increase in cardiac output (+119 ml/min, 4 h after TAK-044; p < 0.05) and ET-1 levels (2.5-fold; p < 0.05). No serious side effects were noted. In patients with normal cardiac function, ET-receptor blockade causes vasodilation and reduces systemic but not pulmonary vascular resistance and increases cardiac index and renal plasma flow.     

In vitro and in vivo release of poly(DL-lactic acid) microspheres containing neurotensin analogue prepared by novel oil-in-water solvent evaporation method.

Poly(DL-lactic acid) (PLA) microspheres containing a neurotensin analogue [NA; H(CH3)-Arg-Lys-Pro-Trp-tert-Leu-Leu-OEt.3HCl] were prepared by a novel oil-in-water (o/w) solvent evaporation method, and the release behaviors were evaluated in vitro. About 20% of the loaded NA was released initially, and the subsequent release lasted for a month from microspheres prepared with PLA of molecular weight 2000 (PLA 2000). A smaller initial release from PLA 4000 and PLA 6000 microspheres was found, but a lag time of 2-3 weeks during which the drug was not released was observed with PLA 4000 and PLA 6000 microspheres. The addition of relatively hydrophilic monoglycerides decreased the lag time, and a fairly constant release of NA was achieved. The pharmacokinetic behavior of NA from PLA 2000 microspheres was studied in rats. The release of the drug after a subcutaneous injection exhibited pseudo-zero-order kinetics for 1 month. The initial release of the drug from the microspheres was reflected in a sharp increase of the plasma levels of the de-ester form of NA [H(CH3)-Arg-Lys-Pro-Trp-tert-Leu-Leu-OH], and the subsequent steady-state levels agreed well with the predicted levels obtained from analysis of constant-infusion kinetics.     

Pharmacokinetic and pharmacodynamic modeling of the metastin/kisspeptin analog,TAK-448, for its anti-tumor efficacy in a rat xenograft model

TAK-448 is the investigational metastin/kisspeptin analog, which is known to have an anti-tumor effect through suppression of androgen hormones (luteinizing hormone and testosterone) levels. This study developed pharmacokinetic-pharmacodynamic (PK/PD) models of TAK-448 and leuprorelin acetate (TAP-144) in a rat vertebral-cancer of the prostate (VCaP) androgen-sensitive prostate cancer xenograft model to quantitatively assess and compare the anti-tumor effects of both drugs. A potential contribution of the hormone-independent direct effects of TAK-448 to the tumor growth inhibition was also investigated in the in vivo rat xenograft model, because our in vitro experiments revealed that TAK-448 may also directly suppress VCaP cellular proliferation. The PK/PD model successfully described the time course of tumor growth inhibition after drug treatment as well as the development of resistance to the inhibition of androgen hormones, following drug treatment or castration. The EC₅₀ of the hormone-dependent inhibitory effect of TAK-448 was much lower than that of TAP-144, and TAK-448 also has a faster onset of anti-tumor effect than TAP-144, demonstrating that TAK-448 has a stronger overall anti-tumor effect than TAP-144. In addition, model inference, by incorporating a hormone-independent inhibition pathway of TAK-448 into the PK-PD model, suggested that such a direct inhibition pathway for TAK-448 cannot be excluded, as also indicated by in vitro studies, but its EC₅₀ would be approximately three orders of magnitude higher than that of the hormone-dependent pathway. This study helps to understand the potential and mechanism of TAK-448 as a prostate cancer treatment.     

Development of composite PLGA microspheres containing exenatide-encapsulated lecithin nanoparticles for sustained drug release

This study aimed to prepare poly (D, L-lactic-co-glycolic acid) microspheres (PLGA-Ms) by a modified solid-in-oil-in-water (S/O/W) multi-emulsion technique in order to achieve sustained release with reduced initial burst and maintain efficient drug concentration for a prolonged period of time. Composite PLGA microspheres containing exenatide-encapsulated lecithin nanoparticles (Ex-NPs-PLGA-Ms) were obtained by initial fabrication of exenatide-loaded lecithin nanoparticles (Ex-NPs) via the alcohol injection method, followed by encapsulation of Ex-NPs into PLGA microspheres. Compared to Ms prepared by the conventional water-in-oil-in-water (W/O/W) technique (Ex-PLGA-Ms), Ex-NPs-PLGA-Ms showed a more uniform particle size distribution, reduced initial burst release, and sustained release for over 60 d in vitro. Cytotoxicity studies showed that Ms prepared by both techniques had superior biocompatibility without causing any detectable cytotoxicity. In pharmacokinetic studies, the effective drug concentration was maintained for over 30 d following a single subcutaneous injection of two types of Ms formulation in rats, potentially prolonging the therapeutic action of Ex. In addition, administration of Ex-NPs-PLGA-Ms resulted in a more smooth plasma concentration-time profile with a higher area under the curve (AUC) compared to that of Ex-PLGA-Ms. Overall, Ex-NPs-PLGA-Ms prepared by the novel S/O/W method could be a promising sustained drug release system with reduced initial burst release and prolonged therapeutic efficacy.     

Protein loaded biodegradable microspheres based on PLGA-protein bioconjugates.

Biodegradable poly(D,L-lactic-co-glycolic acid) (PLGA) was chemically conjugated to lysozyme, a model protein drug, by coupling a terminal carboxylic acid in PLGA with primary amine groups present in lysozyme. The conjugation was carried out in dimethylsulphoxide (DMSO) by using carbodiimide as a coupling agent. The PLGA-lysozyme conjugate, dissolved in a co-solvent system of DMSO and methylene chloride, was directly formulated into microspheres by an oil-in-water (O/W) single emulsion solvent evaporation technique. Morphological characteristics of the resultant microspheres, loading efficiencies, and protein release behaviours with protein instability problems were investigated in comparison with those of the microspheres prepared by water-in-oil-water (W/O/W) double emulsion and O/W single emulsion techniques which employed PLGA with unconjugated lysozyme for the formulation.     

Preparation of biodegradable microspheres containing water-soluble drug, β-lactam antibiotic

Poly (l-lactic acid) (PLLA) microspheres loaded with ampicillin sodium (AMP-Na), β-lactam antibiotic, were prepared by a w/o/w multiple emulsion-solvent evaporation method. The amounts of each component in three phases (inner water phase, organic phase, and outer water phase) were carefully examined in the preparation of PLLA microspheres. The stirring rate, another preparation parameter, was also investigated for study on the effect of mechanical stress on the drug loading and morphology of PLLA microspheres. Most of the preparation parameters had a great influence on the drug loading, surface morphology and size distribution of PLLA microspheres. PLLA microspheres with 15.89 w/w% drug loading were subjected to thein vitro release experiment. The release of ampicillin sodium was constant at a rate of 1.68 μg/ml/day per 1 mg of microspheres for 18 days after a 4 days initial burst effect.