Studies on the effect of pilocarpine incorporation into a submicron emulsion on the stability of the drug and the vehicle.

In order to obtain a novel ocular formulation with a potential for prolonging pilocarpine activity, the drug (2.0%) was incorporated into a submicron emulsion containing soya-bean oil and lecithin as emulgator. The effect of drug incorporation into the emulsion on its physical stability and on the other hand, the potential of the vehicle to reduce drug degradation at pH higher than 5.0 was studied. The pH was adjusted to 6.5 or 5.0 and the physicochemical stability of the formulations was observed. The mean diameter of oily particles in the resulting emulsions measured by a laser diffractometer was 0.6-0.7 micron and this was larger than in a drug-free emulsion where a 0.33 micron value was measured. The formulations were physically stable for 6 months at 4 degrees C, but progressing chemical degradation of pilocarpine was noted at pH 6.5. At that pH nearly 8% of pilocarpine was degraded to isopilocarpine and pilocarpic acid, both in the emulsion and in the solution. Thus, it may be concluded that pilocarpine in submicron emulsion is not protected against degradation. The presence of pilocarpine changes the physical stability of the vehicle since the formulation was easily destabilized during autoclaving or at room temperature. In the presence of higher concentration of lecithin (2.4%) or co-emulgators (poloxamer 2.0% or Tween 80 0.5%) the mean droplet size in the emulsions was the same as in a drug-free system. However the emulsions containing poloxamer were not stable during storage. Viscosity of pilocarpine emulsions can be increased by addition of methylcellulose or sodium carmellose (1.0%), but an intensive creaming occurs in these systems. Pilocarpine base is less suitable for emulsion preparation than hydrochloride salt, and emulsions prepared at pH 5.0 show the most satisfying stability.     

Increased partitioning of pilocarpine to the oily phase of submicron emulsion does not result in improved ocular bioavailability

Submicron emulsions containing pilocarpine as ion-pair with mono-dodecylphosphoric acid were prepared. Physical stability of these preparations was confirmed during 4 months of storage at 4 degrees C. Approximately 50% of the drug was found in the aqueous phase of emulsion separated using an ultrafiltration technique, while the rest was present in the oily phase and interphase. The miotic effect observed in rabbits after application of the ion-pair in aqueous solution or in submicron emulsion was the same; indicating that the drug distribution into the oily phase of the colloidal vehicle does not improve ocular bioavailability.     

Gadolinium incorporated reconstituted chylomicron emulsion for potential application in tumor neutron capture therapy.

Gadolinium (Gd) neutron capture therapy (NCT) is currently under development as a potential approach for tumor therapy. Nanoparticles have been suggested as a potential delivery system to carry or target Gd to tumors for thermal or epithermal neutron irradiation. The reconstituted chylomicron emulsion is an artificial chylomicron remnant prepared using commercially available natural and biocompatible lipids. We proposed to use this nanometer-scale emulsion to deliver Gd to solid tumors by modifying the surface of the emulsion. A lipophilic Gd compound, gadolinium acetylacetonate (GdAcAc), was incorporated into the emulsion, resulting in a final pure Gd concentration of more than 1 mg/mL. The apparent solubility of GdAcAc was enhanced by about 6000-fold by this incorporation. The emulsion particles were shown to be stable in a two-week short-term stability study when stored at 4 degrees C. In addition, no extensive particle aggregation was observed when the emulsion particles were incubated in simulated biological media such as serum. Also, GdAcAc does not significantly 'leak' out from the emulsion particles. Only approximately 5% was released in 20 h in a SDS (0.5% w/v) in phosphate buffered saline (pH 7.4, 10 mM) medium. Finally, the emulsion particles were coated with polyethylene glycol (PEG), and injected into Balb/C mice via the tail vein. A significant proportion (71.6 +/- 18.4%) of the PEG-coated, GdAcAc-incorporated emulsion remained circulating in the blood 5 h after the injection, while the PEG-free emulsion was mainly accumulated inside the liver. This chylomicron emulsion may be used to deliver Gd into solid tumors for NCT.     

A novel stable supersaturated submicron lipid emulsion of tirilazad.

This paper describes a novel supersaturated submicron lipid emulsion for parenteral drug delivery. Tirilazad was used as an amphiphilic model drug for the preparation and characterization of the supersaturated emulsions with concentrations more than two times higher than the drug solubility in the emulsion. Analysis of particle size distribution using photon correlation spectroscopy indicated that the mean particle diameters of the supersaturated 10 and 20% lipid emulsions of tirilazad were approximately 210 and 240 nm, respectively, and that the mean particle size and size distribution of the supersaturated tirilazad emulsions were not different from those of the non-supersaturated tirilazad emulsions. The apparent viscosity of the supersaturated tirilazad emulsions, as measured by continuous rheometry, was similar to that of the non-supersaturated tirilazad emulsions. However, the zeta potential of the supersaturated tirilazad emulsions, as determined by the electrophoretic light-scattering technique, was found to be dependent on drug load and was lower than that of the non-supersaturated tirilazad emulsion. Fractionation by ultracentrifugation showed that at low drug loads, the amount of drug associated with the emulsion particles and the infranatant fraction appeared to increase linearly with increasing concentration of the drug. By contrast, the amount of drug associated with the emulsion particles increased rapidly, whereas the amount of drug associated with the infranatant fraction remained constant for emulsions with a high drug load. These results suggest that the excess drug in the supersaturated emulsions is largely associated with the lipid phase. Accelerated stability studies under stress conditions (i.e., autoclaving and shaking) and long-term storage stability tests demonstrated that the supersaturated tirilazad emulsions had excellent physical stability over the study period of 16 months.     

茴拉西坦亚微乳处方及制备工艺考察

目的制备茴拉西坦亚微乳,并进行质量评价。方法采用组织捣碎-高压均质工艺制备茴拉西坦亚微乳,正交试验优化处方,单因素考察制备工艺,并测定所制乳剂zeta电位、粒径、pH值及药物含量。结果茴拉西坦亚微乳最佳处方和工艺为注射用中链油125 g.L-1、大豆磷脂和pluronicF68总量为30 g.L-1、大豆磷脂和pluronic F68的质量比为1∶4,56 MPa均质5次;所得乳剂zeta电位为-30.8 mV,粒径为(149±21)nm,pH值为6.0,茴拉西坦含量为1.5 g.L-1。结论所得乳剂理化性质良好,符合静脉注射要求。     

静脉注射多西他赛亚微乳在大鼠的组织分布及排泄研究

目的研究比较多西他赛(docetaxel,DTX)亚微乳注射剂及普通注射剂在大鼠体内的组织分布及原型药物的排泄情况。方法以DTX注射剂(商品名:泰索帝)为参比,48只SD大鼠随机分成2组,分别经尾静脉注射DTX亚微乳注射剂(75 mg.m-2)和DTX注射剂(75 mg.m-2),在给药后5、30、60、300 min各处死6只大鼠,于相应部位取各组织适量。另取大鼠10只,随机分为2组,分别静脉注射亚微乳注射剂或普通注射剂(75 mg.m-2),收集给药前及给药后0~4、4~10、10~18、18~24、24~36 h的尿液、粪便。组织及排泄物中的DTX浓度以HPLC-UV法测定。结果 DTX亚微乳注射剂及普通注射剂在体内分布广泛而迅速。DTX亚微乳在心和肺中的浓度显著低于注射剂(P<0.05),但在脾脏中的浓度高于注射剂(P<0.05)。肾脏中的分布在早期较注射剂明显增加,后期较注射剂明显降低(P<0.05),其他组织器官的分布无显著性差异(P>0.05)。两者经粪便和尿液排泄的原型药物无显著性差异(P>0.05),36 h尿排累积百分率均<2%,粪排累积百分率均<6%。结论与普通注射剂相比,亚微乳不影响DTX在大鼠体内的原型药物排泄。在安全性及药效学评价中,应特别关注剂型改变后心、肺、肾及脾脏的毒性及药效变化。     

葛根素亚微乳的制备及表征

为降低葛根素的溶血副反应，制备葛根素亚微乳，进行处方及工艺优化，并考察其理化特征。结合磷脂复合物技术，采用相转变-超声乳化法制备葛根素亚微乳，以平均粒径、跨距、包封率和总评“归一值”为评价指标，采用中心优化设计考察乳化时间、搅拌转速、超声时间的影响，对结果进行多元线性和二项式拟合，利用效应面法优化最佳工艺条件。各指标二项式拟合方程均优于多元线性回归方程，确定最佳工艺条件: 乳化时间为15 min，搅拌转速为2 000 r·min^-1，超声时间为30 min，制备的葛根素静注亚微乳的平均粒径为228.23 nm，跨距0.628 4，包封率为84.32%，含量为9.98 mg·mL^-1，zeta电位为-29.03 mV。结果表明，相转变-超声乳化法制备的葛根素亚微乳粒径小，分布均匀，包封率高，稳定性好，理化指标稳定。     

The study to reduce the hemolysis side effect of puerarin by a submicron emulsion delivery system

A safe and effective delivery system with a submicron emulsion for puerarin was studied. Puerarin submicron emulsion was prepared by a novel complex-phase inversion-high press homogenization technology. The mechanism to reduce the hemolysis side effect of puerarin was studied by blood cell counts in rabbits. The average diameter, zeta potential and entrapment efficiency of the emulsion prepared was 198.14+/-8.61 nm, -29.45+/-1.47 mV, 87.32+/-0.34%, respectively. Compared with control group, the red blood cell values, packed cell volume, plasma hemoglobin level, haptoglobin level and osmotic fragility of puerarin i.v. group was significantly different (p<0.05) at 42, 43 d, respectively. The blood cell parameter values of puerarin submicron emulsion group were not significantly different (p>0.05) in contrast to control group. Such observations indicated that the intravascular hemolysis occurred at 42, 43 d in puerarin i.v. group rabbits, the hemolysis did not occur for puerarin emulsion group rabbits. As an explanation for these results, it was proposed that the puerarin was either incorporated into the lipophilic core or intercalated between the phospholipid molecules at the interface. It could be concluded that puerarin submicron emulsions prepared markedly reduced the hemolysis effect of puerarin.     

硝酸咪康唑乳浊液和环包物的药效及刺激性比较

目的:比较硝酸咪康唑乳浊液和环包物的药效和刺激性.方法:运用试管稀释法进行体外抗真菌试验,阴道内接种白色念珠菌进行体内抗真菌试验; 制备宫颈炎模型,观察硝酸咪康唑乳浊液和环包物对黏膜的刺激性.结果:体外抗真菌试验的结果显示乳浊液的抑菌浓度小于环包物;体内抗真菌试验显示用药组白色念珠菌数与对照组相比均明显减少,但环包物组的抑菌效果略差于乳浊液组(P> 0.05 );刺激性试验显示环包物组显著小于乳浊液组.结论:硝酸咪康唑乳浊液的抑菌作用较强,而环包物的刺激性较小.     

In vivo evaluation of submicron emulsions with pilocarpine: the effect of pH and chemical form of the drug

Submicron emulsions containing 2.0% w/v pilocarpine as pilocarpine HCl, soybean oil (10% w/v) and egg lecithin (1.2% w/v) were formulated. Emulsions at pH 5.0, 6.5 and 8.5 were applied to the rabbit's eye, and the reduction in pupil diameter was measured for 6 h. The miotic effect was compared with that obtained with aqueous solutions at the same pH. A prolonged miotic effect was observed when the submicron emulsion was used as a vehicle. After application of emulsions at pH 5.0, 6.5 or 8.5, the time when 20% reduction of pupil diameter was still observed was 3.9 +/- 1.1 h, 4.3 +/- 1.3 h and 5.3 +/- 0.8 h, respectively, while, after application of a solution, this parameter was shorter by 30-40%. AUC(0-6h) values were larger after application of the submicron emulsions in comparison to aqueous solutions; however, statistically significant differences were only observed for emulsions at pH 6.5. Although the bioavailability of the drug is pH dependent, emulsions at higher pH cannot be considered for clinical use because of pilocarpine degradation which occurs with a similar rate as in aqueous solutions. Introduction of pilocarpine into the oily phase in the form of pilocarpine base or its oleate did not improve either the physicochemical or the pharmacological properties of the formulations. Irrespective of the pH and chemical form of pilocarpine used for emulsion preparation, practically all drug was found in the aqueous phase of the emulsion; thus, partitioning to the oily phase was negligible.     

硫酸氢氯吡格雷亚微乳注射液的制备及其性质考察

目的:制备硫酸氢氯吡格雷亚微乳注射液,并对其性质进行考察。方法:以注射用大豆油和注射用中链脂肪酸三酰甘油为混合油相,以蛋黄卵磷脂、泊洛沙姆188和聚山梨酯-80为复合乳化剂,采用高压均质法制备硫酸氢氯吡格雷亚微乳注射液,通过粒度和粒度分布、Zeta电位、pH值、渗透压和含量测定以及稳定性考察等对其性质进行研究。结果:制备的乳剂外观为乳白色,略带蓝色乳光。3批样品的粒径分别为(158±22)、(160±22)和(161±33)nm,平均Zeta电位为(-37.70±0.79)mV,平均pH值为(7.51±0.03),平均渗透压为(279.33±0.58)mmol.kg-1,平均含量为(99.19±1.68)%,在(6±2)和(25±2)℃条件下放置6个月稳定。结论:制备工艺可行,制剂理化性质稳定,符合静脉注射要求。     

Preparation and physical characterization of a novel marine oil emulsion as a potential new formulation vehicle for lipid soluble drugs

Emulsions often contain vegetable oils such as soybean oil. In this study, a 10% (w/w) of marine mammal oil emulsion was prepared. The effect of a group of emulsifying agents on the stability of the 10% of seal oil emulsion was examined. The emulsifying agents studied were hydrogenated castor oil coated with various polyoxyethylene derivatives. It was found that 2.5% of HCO-40 resulted in the most stable seal oil emulsion. The size of the emulsified droplets defined by their diameters was found to be around 240-270 nm. The initial zeta-potential and pH value of the emulsion were found to be around -27 mV and 3.5, respectively, which decreased over time, to about -31 mV and 2.4, respectively. This is believed to be a result of the hydrolysis of triacylglycerides into free fatty acids in the emulsion. The effect of various amounts of Crodasinic LS-30, a negatively charged surfactant, and Incroqal Behenyl TMS, a positively charged surfactant, on the emulsion was investigated. It was shown that Crodasinic LS-30 had very little effect on the particle size, zeta-potential and pH, while the effect of Incroquat Benhenyl TMS was found to be dependent upon the concentration of the surfactant used.     

3-正丁基苯酞静脉注射亚微乳的制备和稳定性考察

目的制备3-正丁基苯酞(NBP)静脉注射亚微乳并考察其稳定性。方法采用高速剪切法制备初乳,二次高压均质法制备终乳。以灭菌前后乳剂的外观性状、粒径变化和稳定性常数(Ke)等为评价指标,考察制剂工艺的影响因素,同时采用正交设计实验优化处方。所得制剂分别在4、25、40℃条件下放置3个月,观察其外观性状、粒径、Zeta电位、pH值、药物含量、游离脂肪酸值和过氧化值等的变化。结果在优化处方及工艺条件下,所制备的NBP亚微乳稳定性良好,平均粒径为(128.0±3.4)nm(n=3),Zeta电位为-(34.3±5.3)mV(n=3)。稳定性实验结果表明,样品放置3个月后pH值降低约0.3,40℃条件下样品略变黄,其余各项指标无明显变化。结论该处方和工艺可行,制备的NBP亚微乳性质稳定,可供静脉使用。     

Preparation, characterization, and pharmacokinetic evaluation of puerarin submicron emulsion

A novel formulation of puerarin was studied. Puerarin submicron emulsion was prepared by complex phase inversion-high-pressure homogenization technology. Characterization, distribution of drug in emulsion, short-term stability, and pharmacokinetics of emulsion were evaluated. The mean diameter and zeta potential of puerarin emulsion were 188.14 nm and -29.45 mv, respectively. The distribution range of puerarin emulsion was very narrow. The concentration of puerarin in the interfacial surface, oil droplet, water, and liposome-micelles were 7.821, 1.079, 0.637 and 0.423 mg/mL, respectively. Puerarin submicron emulsion was stable for a period of 3 months. The area under the whole blood concentration-time curve of rabbits after intravenous administration of puerarin emulsion was 1.718-fold higher than that of rabbits of intravenous administration of puerarin (P < 0.05). And compared with the puerarin group, the elimination rate of puerarin emulsion group was significantly decreased (P < 0.05), and the biological half-life and the mean retention time of puerarin emulsion were markedly increased (P < 0.05).     

Synthesis and in vitro studies on a potential dopamine prodrug

Dopamine delivery to the central nervous system (CNS) undergoes the permeability limitations of blood-brain barrier (BBB) which is a selective interface that excludes most water-soluble molecules from entering the brain. Neutral amino acids permeate the BBB by specific transport systems. Condensation of dopamine with neutral amino acids could afford potential prodrugs able to interact with the BBB endogenous transporters and easily enter the brain. The synthesis and characterization of the dopamine derivative 2-amino-N-[2-(3,4-dihydroxy-phenyl)-ethyl]-3-phenyl-propionamide (7) is described. The chemical and enzymatic stability of 7 was evaluated. The molecular weight (300 Da) and Log Papp (0.76) indicated that the physico-chemical characteristics of compound 7 are adequate to cross biological membranes. Compound 7 was enzymatically cleaved to free dopamine in rat brain homogenate (t1/2 = 460 min). In human plasma, the t1/2 of 7 was estimated comparable to that reported for L-DOPA. In view of a possible oral administration of 7, studies of its chemical behavior under conditions simulating those of the gastrointestinal tract showed that no dopamine production occurred; furthermore, 7 is able to permeate through a simulated intestinal mucosal membrane. The collected data suggest that compound 7 could beconsidered a very valuable candidate for subsequent in vivo evaluation.     

Lyophilized Cheliensisin A submicron emulsion for intravenous injection: characterization, in vitro and in vivo antitumor effect

Growing attentions have been focused on natural antitumor drugs. Recently, a novel and potent antitumor drug Cheliensisin A (GC-51) with broad-spectrum efficiency has been developed. However, due to its poor water solubility and chemical instability, choosing the appropriate dosage form is of great significance. This study aimed at developing a lyophilized submicron emulsion for GC-51 and further improving the therapeutic index of the drug. The resultant lyophilized GC-51 submicron emulsion was much more stable than its solution, which can be stored for years without significant change on physicochemical properties. And its solubility was increased from 6.74 ± 0.14 to 2.00 ± 0.10 mg mL⁻¹. The 50% inhibitory concentration IC₅₀ values were calculated from growth curves by MTT assay on various tumor cell lines. Compared with the IC₅₀ of GC-51 crude drug, that of lyophilized GC-51 submicron emulsion decreased from 24.04 ± 1.97 to 8.23 ± 1.84 μg mL⁻¹ on HepG2, and from 31.08 ± 2.56 to 10.85 ± 2.09 μg mL⁻¹ on CT-26, from 17.90 ± 1.83 to 7.49 ± 1.87 μg mL⁻¹ on HeLa and from 16.38 ± 2.41 to 10.13 ± 2.12 μg mL⁻¹ on A549, respectively. In the time-dependent assay of tumor cell viability, lyophilized GC-51 submicron emulsion exhibited significantly lower inhibition rate in the initial action times, but increased gradually afterwards. That means lyophilized submicron emulsion as the vector for GC-51 had some protective and delayed release effect. Further, the in vivo therapeutic efficacy was measured in pulmonary metastasis of colon cancer-bearing BALB/c mice model. An obvious enhanced antitumor activity was observed after administration of lyophilized GC-51 submicron emulsion (P < 0.05), which increased from 22.78 ± 3.5 to 41.42 ± 4.2% compared with GC-51 injection. And the life span of tumor-bearing mice in lyophilized GC-51 submicron emulsion group was significantly longer than that of the mice in GC-51 injection and normal saline groups. Compared with crude drug, the lyophilized GC-51 submicron emulsion showed a significantly higher antitumor efficiency both in vivo and in vitro, suggesting a potential application in tumor chemotherapy.     

Comparative studies on the ocular and dermal irritation potential of surfactants.

Comparative studies on the irritation potential of 18 surfactants were performed using the same stock solution of surfactant for each study. The ocular irritation potential of surfactants was studied using the red blood cell test (RBC), the hen's egg test-chorioallantoic membrane (HET-CAM) and the Skinethic ocular tissue model. The skin irritation potential was assessed based on data obtained from human studies using a 24h epicutaneous patch test (ECT) and a soap chamber test (SCT). The same pH and active substance (AS) content for all surfactants tested was used depending on the test conducted. In general, clusters of substances with varying irritation potential were identified similarly by most tests. These results show that when using standardized test conditions in which pH and % AS are the same for each surfactant tested, there is a good correlation between the in vitro ocular irritation assays themselves as well as between the dermal and ocular irritation assays. In particular the RBC test seems to be not only highly predictive for ocular irritation (H(50)/DI) but also for dermal irritation and changes in barrier function (DI) induced by surfactants.     

Evaluation of the efficacy, toxicity and safety of vinorelbine incorporated in a lipid emulsion

To reduce the severe adverse effects of vinorelbine (VRB) with the aim of improving patient compliance, a parenteral vinorelbine-loaded lipid emulsion (VLE) has been developed. The objective of the present study was to get insight into the preclinical antitumor efficacy, toxicity and safety of VLE, and compare this with that of the commercial product, Navelbine(?) i.v. (VS). Comparable antitumor efficacy of VLE and VS was observed in tumor-bearing nude mouse models inoculated with A549 human lung cancer, hepatoma solidity (Heps) G2 cancer and BCAP-37 human breast cancer cells. The median lethal dose (LD(50)) in mice was 29.3mg/kg (male) and 32.1mg/kg (female) for VLE, while the corresponding value was 30.5mg/kg (male and female) for VS. In the long-term toxicity study, VLE significantly reduced the decreases in RBC, HC, WBC and WBC differential count (DC) levels. Lesions in spleen, thymus, lymph nodes, bone marrow, testis, ovary and injection site induced by VS were much more severe compared with VLE. VLE also exhibited less local venous irritation than VS, as well as no hemolysis or hypersensitivity. Consequently, these observations clearly indicate that the lipid emulsion could be a useful potential parenteral carrier for VRB with equivalent efficacy and lower toxicity.     

Influence of the concentrations of liposomes and a submicron emulsion on the rheological properties of a topical gel

Two different kinds of liposomes and a submicron emulsion were added to a topical hydrogel consisting of alginates. The rheological characteristics of the gels after various dilutions were investigated. The various preparations studied exhibited a similar rheological behaviour. No important interactions were observed by mixing the hydrogel with liposomes or a submicron emulsion. The viscoelastic properties and gel state were preserved, only a decrease in consistency was measured.