The Impact of Dose and Solubility of Additives on the Release from HPMC Matrix Tablets—Identifying Critical Conditions

Purpose  The dissolution of HPMC matrix tablets containing different amounts of highly soluble (mannitol) or poorly soluble (dicalcium phosphate, DCP) was studied to deduce the parameters critical to release robustness. Methods  The release of HPMC and additives was studied using a modified USP II method at two paddle stirring rates, 50 and 125 rpm, at HPMC content varying from 15% to 100%. Results  At HPMC contents between 30% and 35% a critical point was identified and found crucial to the release from the HPMC/mannitol tablets. Below this point the matrix rapidly disintegrated in a non robust manner. At higher HPMC contents the mannitol release became increasingly diffusion controlled with maintained matrix integrity. The release robustness was lower for HPMC/DCP than HPMC/mannitol tablets at high HPMC contents, however, lacking critical points. The critical point was interpreted as the percolation threshold for HPMC and differences explained in terms of water transport into the matrix. Conclusion  The release robustness was lower for formulations with additives of low solubility having an erosion controlled release than for additives with higher solubility and a diffusion controlled release. However, for additives creating a steep osmotic pressure gradient, an HPMC content above the percolation threshold becomes vital for maintaining the release robustness.     

乙肝清HPMC K4M/PVP K30骨架缓释片的研制与体外评价

目的进行乙肝清HPMC K4M/PVP K30骨架缓释片的研制与体外评价。方法以中药赶黄草和贯叶连翘的提取物为原料药,以HPMC K4M和PVP K30两种粘度不同,水合行为差异较大的亲水高分子材料联合使用作为骨架材料,制备缓释12 h的"乙肝清骨架缓释片"。以"HPMC+PVP K30"总量在处方中的百分量和HPMC在"HPMC+PVP K30"总量中的百分量为考察因素,通过处方单因素考察和星点设计—效应面法进行优化,得到最佳的制剂处方。并通过均一性实验和体外释药行为研究进行体外评价。结果本片剂优化处方中最低HPMC K4M与PVP K30用量不得低于20%。最佳制剂处方为骨架材料HPMC+PVP K30总量占片剂质量的27.03%,HPMC占HPMC+PVP K30总量的49.04%。本处方具有良好的重现性与稳定性;片剂药物释放符合一级释放模型。结论制备了载药量40%的乙肝清提取物缓释片,并优化得到了其最佳的制剂处方。     

Levcromakalim- and Isoprenaline-induced Relaxation of Human Isolated Airways—Role of the Epithelium and of K+ Channel Activation

Summary: In this study we have investigated the mechanism of action of levcromakalim and isoprenaline in human isolated airways with respect to the K⁺ channels they activate and the possibility that these smooth muscle relaxants activate K⁺ channels on the airway epithelium. Mechanical removal of the epithelial layer (mean percentage of epithelium present 20±3%, n=20 tissues) did not affect the relaxation responses to levcromakalim or isoprenaline, either in terms of maximal relaxation or sensitivity. Whilst having no effect on isoprenaline-induced relaxation, studied from basal tone, the ATP-sensitive K⁺ channel blocker BRL 31660 (10, 30 and 50 μM) reduced relaxation responses induced (from basal tone) by levcromakalim from 74±6% (of the maximal response to isoprenaline) to 48±12% (n=7), 9±9% (n=4) and 0 (n=4), respectively. Charybdotoxin, a blocker of high conductance Ca²⁺-activated K⁺ channels, at concentrations of 30 and 100 nM, had no effect on either levcromakalim- or isoprenaline-induced relaxation responses and yet charybdotoxin was active at K_Ca channels in outside-out patches of hippocampal granule cells. Moreover, tetraethylammonium (10 mM) inhibited neither isoprenaline- nor levcromakalim-induced relaxation. This study has demonstrated that the relaxation responses elicited in human bronchus to isoprenaline and levcromakalim are likely to be the result of direct effects on the smooth muscle with no contribution from epithelial receptors or K⁺ channels. The actions of levcromakalim appear to be mediated only via activation of K_ATP channels. Further, we have made the important observation that, under the experimental conditions of our study, isoprenaline does not activate the K_Ca channel to produce relaxation in human bronchus.     

Drug release from HPMC matrices in milk and fat‐rich emulsions

“Biorelevant” media for the fed stomach, including fat emulsions, are routinely used during in vitro testing of solid dosage forms. However, their complexity undoubtedly creates difficulties in identifying factors which affect drug release. Here, we show fats can directly influence drug release from hydroxypropyl methylcellulose (HPMC; Methocel K4M) matrices which are often subjected to biorelevant testing. Model fat systems included milk (0.1%–3.5% fat) and the parenteral emulsion Intralipid® (20%–30% fat). The matrix showed good extended‐release properties for at least 12 h in these media (USP‐1/USP‐4), but at the highest fat concentration, release was retarded and shifted towards zero‐order release. Confocal imaging studies using a water‐soluble (fluorescein) and fat‐soluble (Nile red) fluorophore provided evidence of phase separation of Intralipid® at the surface of the emerging gel. Combined magnetic resonance imaging–USP‐4 drug release testing provided further evidence for deposition of fat on the tablets. We propose that the aqueous portion of the emulsion is removed by the hydrating matrix, causing coalescence and deposition of a fat layer at the surface, and these deposits cause slower drug release by reducing the matrix surface area available for release. Therefore, there is a risk of a direct interaction between fat emulsions and HPMC tablets, with resultant effects on drug release in vitro. © 2011 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 100:4823–4835, 2011     

In vitro and in vivo evaluation of novel immediate release carbamazepine tablets: complexation with hydroxypropyl-β-cyclodextrin in the presence of HPMC

Carbamazepine (CBZ)-hydroxypropyl-β-cyclodextrin (HP-β-CD) complex in the presence of HPMC was prepared and characterized by differential scanning calorimetry (DSC) and X-ray diffractometer intended for improving the dissolution rate of CBZ. The phase-solubility method was used to investigate the effect of HP-β-CD and HPMC on the solubility of CBZ. Tablets of the resulting complex were prepared using direct compression method and the bioavailability was evaluated in beagle dogs using a UPLC/MS/MS method. The results showed solubility of CBZ was increased up to 95 times by complexation with HP-β-CD in the presence of 0.1% HPMC. The results of DSC and X-ray diffraction proved a formation of complex between CBZ and HP-β-CD. Dissolution rate of CBZ was notably improved from complex tablets with more than 97.39% released within 10 min; whereas for the commercial tablets, around 60% was released within 30 min. Using commercial tablets as the reference formulation, the bioavailability of complex tablets was considerably increased by 1.5-fold (P<0.05) and T(max) was reduced to 0.88 h compared with 1.25 h for commercial tablets. Furthermore, a lower inter-subject variability (49.9%) was observed compared with that of the commercial tablets (39.7%). It is evident from the results herein that complexation with HP-β-CD in the presence of HPMC is a feasible way to prepare a rapidly acting and better absorbed CBZ oral product.     

Penetration‐Enhancing Effect of Ethanol–Water Solvent System and Ethanolic Solution of Carvone on Transdermal Permeability of Nimodipine from HPMC Gel Across Rat Abdominal Skin

The aim of this investigation was to find the effect of the ethanol–water solvent system and the ethanolic solution of carvone on the permeation of nimodipine across rat abdominal skin in order to select a suitable solvent system and optimal concentration of carvone for the development of membrane‐moderated transdermal therapeutic system of nimodipine. The solubility of nimodipine in water, ethanol, and ethanol–water cosolvent systems, or the selected concentration of carvone [2% (w/w) to 12% (w/w)] in 60:40 (v/v) ethanol–water were determined. The effect of these solvents or cosolvent systems on the transdermal permeation of nimodipine was also studied using in vitro permeability studies across the rat abdominal skin. The cosolvent system containing 60:40 (v/v) of ethanol–water showed highest permeability across the rat abdominal skin. Further, the effect of ethanolic solution [60% (v/v) ethanol–water] of carvone [2% (w/w) to 12% (w/w)] on the in vitro permeation of nimodipine across the rat abdominal skin from 2% (w/w) hydroxypropyl methylcellulose (HPMC) gel was also investigated. The transdermal permeability of nimodipine across rat abdominal skin was enhanced further by the addition of carvone to HPMC gel prepared with 60% (v/v) of ethanol. There was a steady effect on the flux of nimodipine (161.02 ± 4.14 µg/cm²/hr) with an enhancement ratio of 4.56 when carvone was incorporated at a concentration of 10% (w/w) in HPMC gels prepared with 60% (v/v) ethanol. The Fourier transform infrared data indicated that ethanolic solution of carvone increased the transdermal permeability of nimodipine across the rat abdominal skin by partial extraction of lipids in the stratum corneum. The results suggest that 10% (w/w) of carvone in 60% (v/v) ethanol–water, along with HPMC as antinucleating agent may be useful for enhancing the skin permeability of nimodipine from the membrane‐moderated transdermal therapeutic system.     

用HPMC直接压制骨架片

HPMC(羟丙基甲基纤维素)是一种具有多方面用途的药用辅料。作为薄膜包衣材料、成膜剂和助悬剂等,国内多有报导和应用。HPMC另一重要用途,作为直接压制骨架型(或蚀解型)控释片剂的基质,具有广阔的发展前途。因为它生产工艺简单,释药速率容易调节,成品质量稳定。国外已有许多成功的实例,如用HPMC压制的控释水杨酸钠片、苯佐卡因片、硫酸奎尼丁片、氯喹维林片、氯化钾片、氨茶碱片、心得安片、和异丙嗪片等。我们试制的葡萄糖酸锌片,在体外溶出试验中也显示了满意的结     

PI3Kγ integrates cAMP and Akt signalling of the μ-opioid receptor

BACKGROUND AND PURPOSE

The μ-opioid receptor has been characterized as the main mediator of opioid signalling in neuronal cells. Opioid-induced pain suppression was originally proposed to be mediated by μ-opioid receptor-induced inhibitory effects on cAMP, which is known to mediate inflammatory hypernociception. Recent investigations revealed PI3Kγ and Akt (PKB) as additional elements of μ-opioid receptor signalling. Hence, we investigated the interaction between pronociceptive cAMP and antinociceptive PI3K/Akt signalling pathways.

EXPERIMENTAL APPROACH

The human neuroblastoma cell line SK-N-LO and primary dorsal root ganglia (DRG) cells from mice were used to elucidate mediators of μ-opioid receptor signalling. In both cellular systems cAMP was manipulated by stimulation of adenylate cyclase and consequent effects on PI3K/Akt signalling were analysed.

KEY RESULTS

Morphine stimulated Akt phosphorylation on Ser⁴⁷³ and Thr³⁰⁸ in a dose- and time-dependent manner indicating a functional μ-opioid receptor/Akt signalling pathway in μ-SK-N-LO cells. This effect of morphine was suppressed by the μ-opioid receptor inhibitor, naloxone, Pertussis toxin, an inhibitor of G_i heterotrimeric G-proteins, and the pan PI3K inhibitor wortmannin. cAMP-elevating agents also suppressed μ-opioid receptor-dependent stimulation of PI3Kγ lipid kinase and Akt activities in SK-N-LO cells and DRG.

CONCLUSIONS AND IMPLICATIONS

The data unveil a hitherto unknown interaction of pronociceptive cAMP and antinociceptive PI3K/Akt signalling pathways in neuronal cells. PI3Kγ was identified as a mediator of the inhibitory action of cAMP on Akt in SK-N-LO cells and DRG. The data indicate that PI3Kγ has a critical role in cAMP-mediated inflammatory hypernociception and analgesic signalling via μ-opioid receptors and PI3K/Akt in neuronal cells.     

Discovery and in Vivo Evaluation of Dual PI3Kβ/δ Inhibitors

Structure-based rational design led to the synthesis of a novel series of potent PI3K inhibitors. The optimized pyrrolopyridine analogue 63 was a potent and selective PI3Kβ/δ dual inhibitor that displayed suitable physicochemical properties and pharmacokinetic profile for animal studies. Analogue 63 was found to be efficacious in animal models of inflammation including a keyhole limpet hemocyanin (KLH) study and a collagen-induced arthritis (CIA) disease model of rheumatoid arthritis. These studies highlight the potential therapeutic value of inhibiting both the PI3Kβ and δ isoforms in the treatment of a number of inflammatory diseases.     

烟酸HPMC缓释骨架片的实验研究

目的实验研制烟酸HPMC缓释骨架片.方法用亲水性骨架材料HPMC与烟酸混合,湿法制粒,压制成缓释骨架片.并通过正交试验优化烟酸骨架片的处方.结果处方中HPMC的用量、粘合剂均对该缓释骨架片的释药速率有显著影响,而HPMC的粘度则影响不大.结论按最佳处方制备的缓释骨架片体外药物释放接近Higuchi模型,能维持药物在12h缓慢释放.     

Discovery and optimization of new benzimidazole- and benzoxazole-pyrimidone selective PI3Kβ inhibitors for the treatment of phosphatase and TENsin homologue (PTEN)-deficient cancers

Most of the phosphoinositide-3 kinase (PI3K) kinase inhibitors currently in clinical trials for cancer treatment exhibit pan PI3K isoform profiles. Single PI3K isoforms differentially control tumorigenesis, and PI3Kβ has emerged as the isoform involved in the tumorigenicity of PTEN-deficient tumors. Herein we describe the discovery and optimization of a new series of benzimidazole- and benzoxazole-pyrimidones as small molecular mass PI3Kβ-selective inhibitors. Starting with compound 5 obtained from a one-pot reaction via a novel intermediate 1, medicinal chemistry optimization led to the discovery of compound 8, which showed a significant activity and selectivity for PI3Kβ and adequate in vitro pharmacokinetic properties. The X-ray costructure of compound 8 in PI3Kδ showed key interactions and structural features supporting the observed PI3Kβ isoform selectivity. Compound 8 achieved sustained target modulation and tumor growth delay at well tolerated doses when administered orally to SCID mice implanted with PTEN-deficient human tumor xenografts.     

Expression and clinical significance of HER-2,TOPO-Ⅱα and PI3K in ovarian epithelial cancer

目的 探讨原癌基因人类表皮生长因子受体2(HER-2)、拓扑异构酶Ⅱ(Topo-Ⅱα)和磷脂酰肌醇3激酶(PI3K)在卵巢上皮癌组织中的表达、相互关系及临床意义.方法 采用免疫组化SP方法检测58例卵巢上皮癌(卵巢癌组)、20例卵巢良性上皮性肿瘤(良性组)及10例卵巢正常组织标本(对照组)中HER-2、TOPO-Ⅱα及PI3K的表达情况.结果 HER-2在对照组、良性组中的阳性表达率分别为10.0%、15.0%,显著低于卵巢癌组的46.6%;卵巢癌组中TOPO-Ⅱα的阳性表达率(53.4%)显著高于对照组(10.0%)和良性组(15.0%)(P<0.05);PI3K在卵巢癌组的阳性表达率(69.0%)明显高于对照组(0.0%)和良性组(20.0%) (P<0.05);而良性组和对照组间比较差异无统计学意义(P＞0.05).HER-2、TOPO-Ⅱα及PI3K的表达与卵巢上皮癌临床分期、细胞组织学分化有显著相关性(P＜0.05),而与年龄、组织学类型无显著相关性(P＞0.05);卵巢上皮癌中HER-2分别与TOPO-Ⅱα、PI3K 的表达之间均呈正相关(P＜0.05),TOPO-Ⅱα与PI3K的表达呈正相关(P＜0.05).结论 HER-2、TOPO-Ⅱα和PI3K的表达均与卵巢上皮癌的发生、发展及侵袭、转移有关,并对卵巢上皮癌的发展起协同作用,对临床治疗及预后判断具有重要的指导意义.     

Downregulation of Kυ4.2 and Kυ4.3 channel gene expression in right ventricular hypertrophy induced by monocrotaline in rat

INTRODUCTION The calcium-independent transient outward potas-sium current (Ito) is activated by depolarization and playsa key role in controlling the amplitudes and cardiac ac-tion potential duration (APD). Ito contributesto the phase1 repolarization of action potential in myocytes, theprolongation of APD is the result of decrease in Ito den-sity[1]. Ito which is encoded by genes of Kv1.4, Kv4.2,and Kv4.3[2], based on differences in kinetics, as wellas recovery from inactivation…     

烟酸HPMC缓释骨架片的实验研究

目的 实验研制烟酸HPMC缓释骨架片。方法 用亲水性骨架材料HPMC与烟酸混合,湿法制粒,压制成缓释骨架片。并通过正交试验优化烟酸骨架片的处方。结果 处方中HPMC的用量、粘合剂均对该缓释骨架片的释药速率有显著影响,而HPMC的粘度则影响不大。结论 按最佳处方制备的缓释骨架片体外药物释放接近Higuchi模型,能维持药物在12h缓慢释放。     

布洛芬HPMC骨架片药物释放因素研究

目的 考察影响布洛芬亲水性骨架片体外释药的各种因素。方法 以羟丙基甲基纤维素（HPMC）为骨架材料，用湿法制粒和粉末直接压片法制备缓释骨架片，并考察HPMC用量，粒度，制备方法，片子大小及其它辅料对布洛芬HPMC骨架片的体外释药的影响。结果 布洛芬HPMC骨架片的体外释药均符合Higuchi方程。HPMC的用量，粒度和制法，片子大小对布洛芬的释放速率均有显著影响。湿法制片的释药速率比干法慢。布洛共姝释药速率随HPMC粒度的减小和片子的增大而减慢。淀粉，PVP、MCC、EC的加入（每片HPMC的含量不变）均减慢布洛芬释药速率。结论 HPMC用量、粒度、制备方法、片子大小及其它辅料为布洛芬骨架片释放速率的主要因素。     

含心得安及十二烷基硫酸钠的HPMC骨架片

羟丙基甲基纤维素(HPMC)是制缓释骨架片的合适基质。这类药片的药物释放速率约与时间的平方根成比例。文献报道药物释放速率与药物及HPMC在骨架中的比例,片子形状及其它辅料的存在有关,而与压片压力、药物粒度,HPMC的粘度级别(对水溶性药物)无关。本文研究心得安骨架片每片含心得安160 mg,HPMC K_(15)M70mg,硬脂酸镁2.3     

人工神经网络预测氟比洛芬HPMC缓释片的药物释放

以难溶性药物氟比洛芬为模型药物，制备17个处方并进行释放度检查。HPMC用量和转速作为自变量，取其中14个处方为训练处方，其余3个处方为验证处方，将上述自变量作为人工神经网络的输入，药物在各个取样时间点的释放为输出，采用剔除一点交叉验证法建立人工神经网络模型。通过线性回归和相似因子法比较人工神经网络和基于二元二项式的响应面法的预测能力。结果表明，用人工神经网络得到的预测值与实测值更接近。