加替沙星聚氰基丙烯酸正丁酯纳米粒小鼠体内分布特征

目的:研究注射用加替沙星聚氰基丙烯酸正丁酯纳米粒(GPN)的体内分布特征。方法:雄性小鼠随机分为3组,分别尾缘静脉给予小鼠加替沙星生理盐水溶液(Ⅰ)、未经修饰的加替沙星GPN(Ⅱ)以及经聚山梨酯-80修饰的GPN(T-GPN,Ⅲ),高效液相法检测血浆、肝、肾、脾及肺脏组织内的浓度,评价GPN的体内分布特征。结果:Ⅰ,Ⅱ,Ⅲ组小鼠肺脏组织中的平均峰浓度分别为17.33,10.13和26.99μg.g-1;平均浓度-时间曲线下面积(AUC0~t)分别为85.99,100.00和242.34 mg.kg-1.h。结论:GNP经聚山梨酯-80修饰后,加替沙星肺脏组织分布量显著增加,具有一定的肺靶向性。     

In vivo microdialysis for PK and PD studies of anticancer drugs

In vivo microdialysis technique has become one of the major tools to sample endogenous and exogenous substances in extracellular spaces. As a well-validated sampling technique, microdialysis has been frequently employed for quantifying drug disposition at the desired target in both preclinical and clinical settings. This review addresses general methodological considerations critical to performing microdialysis in tumors, highlights selected preclinical and clinical studies that characterized drug disposition in tumors by the use of microdialysis, and illustrates the potential application of microdialysis in the assessment of tumor response to cancer treatment.     

Studies on the cyclosporin A loaded stearic acid nanoparticles

Stearic acid nanoparticles were prepared in this study by melt-homogenization to investigate the possibility of them as a new kind of drug carrier system. Some physicochemical properties of stearic acid nanoparticles were studied and morphology examined by transmission electron microscope. Cyclosporin A as a model drug was then encapsulated into stearic acid nanoparticles. Following the establishment of high performance liquid chromatography assay for cyclosporin A analysis in stearic acid nanoparticles or blood samples, the encapsulation ratio of cyclosporin A to stearic acid nanoparticles was estimated and pharmacokinetics as well as bioavailability of cyclosporin A stearic acid nanoparticles after oral administration to Wistar rats were studied, using the Sandimmun Neoral® (an available microemulsion system of cyclosporin A) as a reference. The mean diameter of cyclosporin A stearic acid nanoparticles was 316.1 nm, while the encapsulation ratio of cyclosporin A to stearic acid nanoparticles reached to 88.36%. It was demonstrated by IR spectra and differential scanning calorimetry that there was no chemical reaction occurred between the cyclosporin A and stearic acid. The relative bioavailability of cyclosporin A stearic acid nanoparticles over reference was nearly 80%, and the time to reach maximum concentration (T_max) of cyclosporin A after oral administration of cyclosporin A stearic acid nanoparticles was delayed significantly than the reference, suggesting an obvious sustained release effect. The stearic acid nanoparticles might be a very potential drug carrier.     

Ocular ketoconazole-loaded proniosomal gels: formulation,ex vivo corneal permeation and in vivo studies

Context: Vesicular drug carriers for ocular delivery have gained a real potential. Proniosomal gels as ocular drug carriers have been proven to be an effective way to improve bioavailability and patient compliance.

Objective: Formulation and in vitro/ex vivo/in vivo characterization of ketoconazole (KET)-loaded proniosomal gels for the treatment of ocular keratitis.

Materials and methods: The effect of formulation variables; HLB value, type and concentration of non-ionic surfactants (Tweens, Spans, Brijs and Pluronics) with or without lecithin on the entrapment efficiency (EE%), vesicle size and in vitro KET release was evaluated. An ex vivo corneal permeation study to determine the level of KET in the external eye tissue of albino rabbits and an in vivo assessment of the level of KET in the aqueous humors were performed.

Results and discussion: In vivo evaluation showed an increase in bioavailability up to 20-folds from the optimum KET proniosomal gel formula in the aqueous humor compared to drug suspension (KET-SP). The selected formulae were composed of spans being hydrophobic suggesting the potential use of a more hydrophobic surfactant as Span during the formulation of formulae. Factors that stabilize the vesicle membrane and increase the entrapment efficiency of KET (namely low HLB, long alkyl chain, high phase transition temperature) slowed down the release profile.

Conclusions: Proniosomal gels as drug delivery carriers were proven to be a promising approach to increase corneal contact and permeation as well as retention time in the eye resulting in a sustained action and enhanced bioavailability.     

Formulation and evaluation of Cyclosporin A emulgel for ocular delivery

Abstract

Emulgels have been extensively covered as a promising drug delivery system for the administration of lipophilic drugs. This work was conducted to develop an emulgel formulation for Cyclosporin A (CsA) employing polycarbophil as the gelling agent for ocular delivery. The prepared emulgels were evaluated for their physical appearance, rheological behavior, drug release, stability, precorneal clearance and irritation. Results showed that CsA emulgel formulations prepared with polycarbophil exhibited acceptable physical properties and drug release, which remained consistent after storage for 3 months. A prolonged retention time was also observed on the ocular surface with improved ocular bioavailability and no irritation. Therefore, the polycarbophil-based emulgel could be exploited as a potential hydrophobic drug carrier for topical ocular drug delivery.     

The dose-dependent inhibition of rat renal translation elongation seen after in vivo cyclosporin A is not caused by cyclosporin metabolites

Cyclosporin A (CsA) given to Sprague-Dawley rats in vivo produced a tissue-specific, dose-dependent inhibition of translation elongation in renal microsomes. CsA at an oral dose of 50 mg/kg/day for 6 days reduced renal microsomal translation by 70.5%. Renal cytoplasm from rats treated in vivo with CsA inhibited translation by 55% when added to renal microsomes isolated from tissues of control animals. In contrast, CsA added to renal microsomes in vitro did not inhibit translation. Renal cytoplasm from CsA-treated rats containing translation inhibitory factor was found by HPLC to contain CsA and CsA metabolites M1 and M17. CsA metabolites M1, M17, M18 and M21 were isolated from human bile and tested in vitro for translation elongation inhibitory activity in renal microsomes. CsA, M18 and M21 did not inhibit translation elongation at concentrations of up to 2500 ng/ml. M17 inhibited translation elongation, but only by 8.4% at the highest concentration tested (2500 ng/ml), a level 20-fold higher than that measured in renal cytoplasm (125 ng/ml). Ml produced a concentration-dependent inhibition of translation elongation, beginning at 500 ng/ml, or approximately 2-fold higher than that found in renal cytoplasm (260 ng/ml). M1 at 2500 ng/ml or approximately 10-fold higher than the concentration measured in renal cytoplasm, inhibited translation elongation by 23.8%, only 1/3 that observed upon addition of renal cytoplasm containing translation inhibitory factor. We conclude from these findings that the dose-dependent inhibition of renal translation elongation following in vivo CsA cannot be explained by the renal formation or uptake of known CsA metabolites.     

In vitro and in vivo evaluation of targeting efficiency of Adriamycin hydrochloride magnetic microspheres

The objective of this study was to prepare magnetic microspheres as a targeting drug delivery system and to specifically evaluate its targeting efficiency. The magnetic microspheres were prepared by emulsion cross-linking techniques. Targeting efficiency was specifically investigated by experiments of biodistribution on rats and histological study. Adriamycin hydrochloride (ADR)-loaded magnetic microspheres were successfully prepared with the mean diameter of 3.853 μm (± 1.484 μm), and had its speciality of superparamagnetism. The results of the targeting efficiency study showed that application of the external magnetic field significantly increased the ADR concentration from 40.28 μg/ml to 100.70 μg/ml at 10?min, 36.99 μg/ml to 91.16 μg/ml at 60?min, and 13.71 μg/ml to 28.30 μg/ml at 180?min in liver as the targeting tissue. The relative uptake efficiencies in liver by injection treatment of ADR magnetic microspheres with external magnetic field were 3.87, 5.59, and 3.34 at 10?min, 60?min, and 180?min after administration, respectively. In conclusion, distinguished targeting efficiency was displayed, which indicated that the magnetic microspheres could be applied as a novel targeting drug delivery system.     

In vitro and ex vivo experimental models for evaluation of intranasal systemic drug delivery as well as direct nose-to-brain drug delivery

The intranasal route of administration provides a noninvasive method to deliver drugs into the systemic circulation and/or directly into the brain. Direct nose-to-brain drug delivery offers the possibility to treat central nervous system diseases more effectively, as it can evade the blood–brain barrier. In vitro and ex vivo intranasal models provide a means to investigate physiological and pharmaceutical factors that could play a role in drug delivery across the nasal epithelium as well as to determine the mechanisms involved in drug absorption from the nose. The development and implementation of cost-effective pharmacokinetic models for intranasal drug delivery with good in vitro-in vivo correlation can accelerate pharmaceutical drug product development and improve economic and ecological aspects by reducing the time and costs spent on animal studies. Special considerations should be made with regard to the purpose of the in vitro/ex vivo study, namely, whether it is intended to predict systemic or brain delivery, source and site of tissue or cell sampling, viability window of selected model, and the experimental setup of diffusion chambers. The type of model implemented should suit the relevant needs and requirements of the project, researcher, and interlaboratory. This review aims to provide an overview of in vitro and ex vivo models that have been developed to study intranasal and direct nose-to-brain drug delivery.     

Electrosteric stealth Rivastigmine loaded liposomes for brain targeting: preparation,characterization, ex vivo,bio-distribution and in vivo pharmacokinetic studies

Being one of the highly effective drugs in treatment of Alzheimer’s disease, Rivastigmine brain targeting is highly demandable, therefore liposomal dispersion of Rivastigmine was prepared containing 2?mol% PEG-DSPE added to Lecithin, Didecyldimethyl ammonium bromide (DDAB), Tween 80 in 1:0.02:0.25 molar ratio. A major challenge during the preparation of liposomes is maintaining a stable formulation, therefore the aim of our study was to increase liposomal stability by addition of DDAB to give an electrostatic stability and PEG-DSPE to increase stability by steric hindrance, yielding what we called an electrosteric stealth (ESS) liposomes. A medium nano-sized liposome (478?±?4.94?nm) with a nearly neutral zeta potential (ZP, ?8?±?0.2?mV) and an entrapment efficiency percentage of 48?±?6.22 was prepared. Stability studies showed no major alteration after three months storage period concerning particle size, polydispersity index, ZP, entrapment efficiency and in vitro release study confirming the successful formation of a stable liposomes. No histopathological alteration was recorded for ESS liposomes of the sheep nasal mucosa. While ESS liposomes showed higher % of drug permeating through the sheep nasal mucosa (48.6%) than the drug solution (28.7%). On completing the in vivo pharmacokinetic studies of 36 rabbits showed 424.2% relative bioavailability of the mean plasma levels of the formula ESS compared to that of RHT intranasal solution and 486% relative bioavailability of the mean brain levels.     

环孢素A微乳浓缩液的药代动力学和生物等效性评价

将雄性Ｗｉｓｔａｒ大鼠１６只随机分为两组,分别口服自制和进口环孢素Ａ（ＣｙＡ）微乳浓缩液,采用高效液相色谱法测定血药浓度,对其药代动力学和相对生物利用度进行了研究。试验结果表明两种制剂中ＣｙＡ的药动学过程均符合口服吸收二室模型。自制和进口环孢素Ａ微乳浓缩液的全血药物浓度达峰时间分别为１．５７±０．５５和１．６８±０．４３ｈ;Ｃｍ ａｘ 分别为１７５５．６±２２６．０和１８３２．２±５９８．８ｎｇ／ｍｌ;Ｔ１／２ 分别为１９．９３±６．４４和１９．７９±６．９８ｈ;ＡＵＣ分别为３０６３７．９±７５５２．４和３０３１６．６±６５７８．９ｎｇ·ｈ／ｍ ｌ;自制环孢素Ａ微乳浓缩液的相对生物利用度为１０１．１％ 。经统计分析,两种制剂的药代动力学参数均无显著性差异（Ｐ＞ ０．０５）,两种制剂具有生物等效性。     

In vivo brain electrophoresis – a novel method for chemotherapy of CNS diseases

Objective: The blood–brain barrier (BBB) is a protective mechanism that does its job superbly. So much so, that hitherto, brain chemotherapy has been limited by it. In fact, very few agents are effective against brain disease due to the inherent difficulties of penetrating the BBB. We describe a novel, extremely focused method for delivering drugs to specific diseased areas. This innovative method directly delivers putative substances to the pathological area, bypassing the BBB. Treatment of brain diseases could be improved by targeted, controlled delivery of therapeutic substances to diseased cerebral areas. Our described novel method – in vivo electrophoresis – achieves this.

Methods: This technique was evaluated in beagles after craniotomy was performed and a custom-designed plate with electrodes inserted. The delivery of charged substances to selected areas with predictably guided movement was achieved via a created electrical field. Gadolinium, a compound unable to cross the BBB, was injected intracerebrally whereas an electrical field was created using the implanted electrodes surrounding the injection area. The electrical field-guided Gadolinium movement was evaluated using MRI.

Results: Gadolinium was moved predictably using the created electrical field without complications.

Conclusions: The experiment successfully demonstrated controlled movement of the substance. This technique can significantly change treatment of brain diseases because substances: i) may be moved in a controlled, predictable way – exponentially increasing therapeutic interactions with the target; and ii) no longer need to conform to constraints dictated by the BBB (molecular mass < 500 d; lipophilic), thereby increasing potential number of usable substances.     

In vitro and in vivo evaluation of ranitidine hydrochloride loaded hollow microspheres in rabbits

The objective of this investigation was to develop the hollow microspheres as a new dosage form of floating drug delivery systems with prolonged stomach retention time. Hollow microspheres containing ranitidine hydrochloride (RH) were prepared by a novel solvent diffusion-evaporation method using ethyl cellulose (EC) dissolved in a mixture of ethanol and ether (6:1.0, v/v). The yield and drug loading amount of hollow microspheres were 83.21±0.28% and 20.71±0.32%, respectively. The in vitro release profiles showed that the drug release rate decreased with increasing viscosity of EC and the diameter of hollow microspheres, while increased with the increase of RH/EC weight ratio. Hollow microspheres could prolong drug release time (approximately 24 h) and float over the simulate gastric fluid for more than 24 h. Pharmacokinetic analysis showed that the bioavailability from RH-hollow microspheres alone was about 3.0-times that of common RH gelatin capsules, and it was about 2.8-times that of the solid microspheres. These results demonstrated that RH hollow microspheres were capable of sustained delivery of the drug for longer period with increased bioavailability.     

Colloidal systems for the delivery of cyclosporin A to the anterior segment of the eye

Due to the eye's specific anatomical and physiological conformation, the treatment of eye diseases is a real challenge for pharmaceutical therapy. The presence of efficient protective barriers (i.e., the conjunctival and corneal membranes) and protective mechanisms (i.e., blinking and nasolachrymal drainage) makes this organ particularly impervious to local drug therapy. To overcome these issues, numerous strategies have been envisioned using pharmaceutical technology. Many formulations currently on the market or still under development are emulsions or colloidal systems intended to enhance precorneal residence time and corneal penetration, causing a consequent increase in drug bioavailability after instillation. After a review of some recent developments in the field of cyclosporin A formulations for the eye, a novel micellar formulation of cyclosporine A based on a diblock methoxy-poly(ethylene glycol)-hexysubstituted poly(lactides) (MPEG-hexPLA) is described.     

肽类和蛋白质类药物肺部给药的体内外评价方法

目的介绍肽类和蛋白质类药物肺部给药的体内外评价方法。方法对肽类和蛋白质药物肺部给药研究中的给药方法、药动学评价、药效学评价、肺部沉积、体外评价及安全性评价方法进行综述。结果根据研究的不同阶段选择合适的动物给药模型,采用特异性强、灵敏度高的分析方法是肽类和蛋白质药物肺部给药系统体内评价的关键。肺内沉积是对剂型和给药装置递送效果的综合考察。具有良好体内外相关性的体外评价方法的建立与安全性评价在肺部给药制剂开发中具有十分重要的意义。结论肽类和蛋白质类药物肺部给药的体内外评价方法与其他给药途径有较大区别,在研究和开发中应根据需要选取适当的方法。     

In vivo antidiabetic drug discovery

All of the glucose-lowering agents available today for the treatment of diabetes resulted from the in vivo antidiabetic drug discovery approach. This is not surprising given the limited understanding of the biochemical basis of diabetes. With new developments in the elucidation of the biochemistry and physiology of diabetes, along with the ever-increasing number of drug discovery technologies, screening tests have shifted from in vivo to in vitro and from a cellular to a molecular level. However, there are concerns with this shift because diabetes, especially type 2 diabetes, has multiple and independent molecular defects and most of the molecular targets currently used await clinical validation. One approach (employed by Shaman) has used focused in vivo screening and has been successful in avoiding or minimising the drawbacks of in vivo testing, while maintaining the benefits. It is hoped that the combined use of in vivo and in vitro approaches will generate new breakthroughs in diabetes.     

Pharmacokinetics and efficacy of a ketorolac-loaded ocular coil in New Zealand white rabbits

Eye drops are considered standard practice for the delivery of ocular drugs. However, low patient compliance and low drug levels compromise its effectiveness. Our group developed a ketorolac-loaded ocular coil for sustained drug delivery up to 28 days. The aim of this study was to gain insight into the pharmacokinetics and efficacy of the ocular coil. The pharmacokinetics of the ketorolac-loaded ocular coil versus eye drops were tested in New Zealand White rabbits by repetitive sampling for 28 days. Efficacy of the ocular coil was also tested in New Zealand White rabbits. Ocular inflammation was induced where after the ocular coil was inserted, or eye drops, or no treatment was provided. The total protein concentration and cytokine levels were measured in tears, aqueous humor, and plasma at 4 h, 8 h, 24 h, 4 d, 7 d, 14 d, 21 d, and 28 d. Four h after inserting the ocular coil in the eye, ketorolac levels in aqueous humor and plasma were higher in the ocular coil group than in the eye drop group. Ketorolac released from the ocular coil could be detected up to 28 d in tears, up to 4 d in aqueous humor and up to 24 h in plasma. After inducing inflammation, both the ocular coil and eye drops were able to suppress prostaglandin E₂, TNFα and IL-6 levels in aqueous humor and plasma as compared to the group that received no treatment. To conclude, the ocular coil facilitated a sustained release of the drug and showed similar therapeutic benefit in suppressing post-operative inflammation as eye drops.     

Experimental studies on soft contact lenses for controlled ocular delivery of pirfinedone: in vitro and in vivo

Context: Pirfinedone (PFD) is a novel agent which has the potential to prevent scarring in the eyes. The 0.5% PFD eye drops exhibits poor bioavailability. Whereas, the feasibility of using contact lens as ocular drug delivery device initiated novel possibilities.

Objective: To evaluate the delivery of PFD by soft contact lens (SCL) in vivo, we screened the most suitable lens material for PFD among various commercially available SCL materials in vitro.

Material and methods: Firstly, 11 different SCLs (?1.00 diopter) were respectively soaked in 2?ml of 0.05% PFD-loading solution for 24?h to fully absorb drug, and then placed in fresh phosphate buffered saline (PBS) to release the drug. PFD concentration in PBS was determined by ultraviolet absorbance at 310?nm. Secondly, by immersing in 2?ml of 0.5% PFD eye drops for 24?h, the polymacon lens (0.00 diopter) was then placed on the cornea of New Zealand rabbits. PFD concentrations were detected by high performance liquid chromatography (HPLC) in tears, aqueous humor, conjunctiva, cornea, and sclera at different time points.

Results: PFD showed some affinity for pHEMA-based lenses and the polymacon lens more slowly released more amount of PFD than any other lens in vitro (p < 0.001). Compared with eye drops, drug-loaded SCLs greatly enhanced the retention time and concentrations of PFD in cornea and aqueous humor and consequently improved the bioavailability of PFD.

Conclusion: Polymacon-based SCL is probably a promising vehicle to be an effective ophthalmic delivery system for PFD.     

In vivo toxicity evaluation of gold-dendrimer composite nanodevices with different surface charges

Abstract

Composite nanodevices (CNDs) are multifunctional nanomaterials with potential uses in cancer imaging and therapy. Poly(amidoamine) dendrimer-based composite nanodevices are important members of this group and consist of an organic dendrimer component and an incorporated inorganic component, in this case, gold. This study addresses the short- (14 days) and long-term (78 days) in vivo toxicity of generation-5 (G5; 5 nm) PAMAM dendrimer-based gold-CNDs (Au-CNDs) with varying surface charges (positive, negative and neutral) in C57BL/6J male mice. Detailed toxicological analyses of (1) body weight changes, (2) serum chemistry and (3) histopathological examination of 22 organs showed no evidence of organ injury or organ function compromise. Zeta potential of Au-CNDs showed significant change from their parent dendrimers upon gold incorporation, making the normally lethal positive surface dendrimer biologically safe. Also homeostatic mechanisms in vivo may compensate/repair toxic effects, something not seen with in vitro assays.