匹罗卡品脂质体与凝胶缩瞳作用的实验研究

目的　研究 1%匹罗卡品脂质体与 4 %匹罗卡品凝胶对兔眼的缩瞳作用。方法　家兔 2 4只 ,随机分为 4组 ,每组 6只 ,按 1%匹罗卡品脂质体滴眼液 ,4 %匹罗卡品凝胶 ,1%匹罗卡品滴眼液 ,空白对照分为四组 ,给药后观察兔眼的刺激反映情况并间隔一定时间测量其瞳孔大小。结果　 4组兔眼滴药前瞳孔直径左右眼比较 ,差异无显著性 (P >0 .0 5 )。 1%匹罗卡品滴眼液组滴药后 0 .2 5h ,缩瞳作用最大 (P <0 .0 1) ,滴药后 1h瞳孔开始散大 ,滴药后 5h ,左右眼差异无显著性 (P >0 .0 5 ) ;1%匹罗卡品脂质体滴眼液组 ,滴药后 0 .5h缩瞳作用最大 (P <0 .0 1) ,滴药后 3h瞳孔开始散大 ,滴药后 7h ,左右眼差异无显著性 (P >0 .0 5 ) ;4 %匹罗卡品凝胶组 ,滴药后 0 .5h缩瞳作用最大 (P <0 .0 1) ,滴药后 4h瞳孔开始散大 ,滴药后 5h左右眼差异无显著性(P >0 .0 5 ) ;空白对照组在观察的 7h内左右眼差异无显著性 (P >0 .0 5 )。结论　 1%匹罗卡品脂质体滴眼液具有缓慢释药 ,延长作用时间的优点。其作用时间长于 4 %匹罗卡品凝胶。     

联苯双酯对家兔体内环孢菌素A的药动学影响

目的 :考察联苯双酯 (BFD)与环孢菌素A(CsA)在兔体内合用后联苯双酯对环孢菌素A动力学过程的影响。方法 :用高效液相色谱法测定 6只家兔单用环孢菌素A及合用联苯双酯后环孢菌素A的血药浓度并进行动力学参数的计算与比较。结果 :CsA与BFD合用后 ,CsA在家兔体内的血药浓度普遍降低 ,表观分布容积及清除率显著增大 (P <0 .0 5 ) ,AUC明显小于单用CsA(P <0 .0 5 ,P >0 .0 1)时的AUC ,其余的参数无统计学差异。结论 :BFD可明显降低CsA的血药浓度。     

羟基喜树碱对家兔环孢A代谢和红细胞膜脂流动性的影响

目的　研究羟基喜树碱 (HCPT )对家兔环孢素A(CsA)药物动力学及对红细胞膜流动性 (LFU)的影响。方法　用TDX快速测定CsA全血药物浓度 ,用DPH荧光探针法测定红细胞膜流动性。结果　HCPT可使CsA的a ,V(c) ,K12 及CL(s)降低 ,T1/ 2 (a) 增加 (P <0 0 5 )。联合给药组的CsA血药浓度在给药后的 0 2 5 ,0 5和 1h高于单独给药组 ,且在 1h时差异有显著性 (P <0 0 5 )。联合给药组的LFU值在给药后的 0 5 ,1 0 ,1 5h时高于单独给药组 (P <0 0 5 ) ,与对照组差异无显著性。单独给药组的LFU值在给药后的 0 5 ,1 0 ,1 5h时低于对照组。结论　HCPT与CsA合用可提高CsA的血药浓度 ,有一定的临床应用前景     

双氯酚酸钠脂质体的制备及其眼部药代动力学

目的研究双氯酚酸钠脂质体的制备方法并考察其在家兔眼部的药代动力学特征。方法采用逆相蒸发法制备双氯酚酸钠正电荷脂质体。脂质体和滴眼液滴眼后家兔采用高效液相色谱法测定角膜前、角膜和房水中药物浓度。结果制得的脂质体平均粒径为226.5 nm，多分散度为0.214，ζ电位为+18.1 mV，经均匀设计优化处方，包封率可达到63%。0.1%双氯酚酸钠脂质体和滴眼液两种制剂家兔局部滴眼后的药代动力学研究显示，脂质体可延缓药物在角膜前的清除，增加角膜中药物的浓度，药物在房水中半衰期延长，以滴眼液为参比制剂，相对生物利用度为211%。结论双氯酚酸钠正电荷脂质体可以增加药物在角膜前的滞留时间，提高角膜渗透性及药物在眼部的生物利用度，减少滴眼次数。     

他克莫司滴眼液与环孢素A滴眼液在全角膜移植术后免疫排斥反应的疗效观察

目的　观察 0 .0 5 %他克莫司 (FK5 0 6 )滴眼液与 1%环孢素A(CsA)滴眼液在全角膜移植术后免疫排斥反应的临床疗效。方法　选择 6 2例 (6 2只眼 )全角膜移植术后的患者 ,按随机原则将其分试验组 (FK5 0 6组 )及对照组 (CsA组 )各 31例 31只眼 ,平均年龄 37.8岁。观察应用两种滴眼液后不同时期角膜移植术后角膜免疫排斥的情况。结果　在全角膜移植术后第 6个月FK5 0 6组排斥率为 6 8.4 % ,CsA组排斥率为 92 .1% ,在统计学有显著差异 (P <0 .0 1)。结论　FK5 0 6滴眼液用于角膜移植术后抗排斥反应疗效明显优于CsA滴眼液。经动物试验及临床应用 ,未见有不良反应。     

双氯酚酸钠眼膏在家兔眼部的相对生物利用度

目的 :测定双氯酚酸钠眼膏在家兔眼部的相对生物利用度 ,评价双氯酚酸钠眼膏在眼部的经 -时过程 ,为临床应用提供参考。方法 :48只家兔随机分为两组 ,其眼部分别应用0 1 %双氯酚酸钠眼膏和滴眼液 ,于不同时间抽取房水、分离虹膜 ,采用高效液相色谱法测定眼组织中的药物浓度。结果 :眼膏组较滴眼液组具有较高的组织药物浓度 ,较长的消除半衰期 ,达峰时间与滴眼液相同 ;眼膏在房水和虹膜的相对生物利用度分别为183 33 %和205 68 %。结论 :双氯酚酸钠眼膏吸收程度较滴眼液高并具有缓释作用 ,临床上可减少用药次数 ,特别适用于手术患者或夜间治疗     

霉酚酸酯和环孢素A合用预防和治疗肾移植早期急性排斥反应

目的 :考察霉酚酸酯 (MMF)预防移植肾急性排斥反应的疗效及安全性。方法 :对MMF 1.5 g·d-1联合应用环孢素A(CsA)和皮质类固醇与硫唑嘌呤 (Aza)联合应用环孢素A和皮质类固醇预防和治疗急性排斥反应进行随机比较研究。结果 :MMF组的CsA平均给药量、血药浓度与Aza组统计学检验差异有非常显著性 (P <0 .0 1)。急性排斥反应MMF组发生率为12 % (3/ 2 5 ) ,Aza组为 33% (12 / 36 ) ,急排发生时两组CsA浓度差异有显著性 (P <0 .0 1) ,但平均给药差异无显著性 (P >0 .0 5 )。结论 :MMF可有效地减少急性排斥反应的发生。     

合用盐酸黄连素前后环孢素A的人体药动学

目的 :研究健康受试者合用盐酸黄连素 (berberinehydrochloride ,Ber)前后环孢素A(cyclosporinA ,CsA)的动力学过程 ,以分析两药相互作用发生的部位。方法 :6名健康男性志愿者在单剂口服CsA 3mg·kg-1后开始连续服用Ber 30 0mg ,bid× 10d ,最后一次与单剂CsA 3mg·kg 　 -1同时口服。每次口服CsA后即按时采血 ,用FPIA法测定全血CsA浓度 ,并计算出药动学参数。结果 :在健康志愿者合用Ber后 ,CsA的AUC值增加 19.6 % ,差异具非常显著性 (P <0 .0 1)。结论 :推测Ber对CsA的影响部位可能主要在肠道 ,Ber可能增加CsA的吸收或减少肠代谢。     

厄贝沙坦达稳态时对兔体内环孢素A药动学的影响

目的:研究厄贝沙坦对家兔体内环孢素A(CsA)药动学的影响。方法:采用荧光偏振免疫法测定6只家兔单用CsA及合用厄贝沙坦后CsA的血药浓度,并对2组药动学参数进行统计学分析。结果:合用厄贝沙坦后CsA的峰浓度(Cmax)显著升高(P<0.01),曲线下面积(AUC0→24)显著增大(P<0.01),血浆清除率(CL)及表观分布容积(V)显著降低(P<0.05),其余药动学参数无显著性变化。结论:厄贝沙坦可升高CsA的血药浓度,建议临床上两药合用时须监测CsA的血药浓度,保证治疗安全有效。     

雷公藤甲素对家兔体内环孢菌素A的药物动力学参数的影响

对合并应用TL与CsA后6只家兔体内CsA的药物动力学进行了研究.结果表明:合用TL对家兔体内CsA的AUC以及T_(1/2)无显著性影响(P>0.05),使CsA的Vc及CLs明显增大,差异有统计学意义(P<0.05).可能是由于TL在体内分布广泛,与组织亲和力强,降低了CsA的血浆蛋白结合率所致.提示临床合理地合用,TL有减少CsA体内蓄积的趋势.     

Liposomal ophthalmic drug delivery system. II. Dihydrostreptomycin sulfate

The carrier ability of liposomes for a model hydrophilic compound vas investigated in the rabbit eye. Dihydrostreptomycin sulfate was encapsulated in various types of liposomes, i.e. large and small uni- and multilamellar vesicles having either positive or neutral surface charge. An aqueous solution served as control preparation. Results indicated that liposomal encapsulation reduced the ocular drug con- centration. Addition of empty liposomes to the control solution did not alter drug levels in most of the ocular tissues. Among the liposomal preparations the large multi- and unilamellar vesicles provided higher drug concentration in all ocular tissue than the small unilamellar ones. Introduction of a positive charge on liposome surface enhanced liposome-conjunctiva interactions. The results suggest that liposomal encapsulation alters drug disposition in the eye lepending on the type of liposomes and the physicochemical properties of the encapsulated drug. In the case of the dihydrostreptomycin sulfate and possibly other hydrophilic drugs the liposomal encapsulation provides no advantages as far as drug delivery is concerned.     

Preparation and Characterization of Demeclocycline Liposomal Formulations and Assessment of their Intraocular Pressure-Lowering Effects

ABSTRACT

The objective of the present study is to enhance the ocular permeability and to study the ocular disposition of demeclocycline (DEM), liposomal topical formulation for treatment of elevated intraocular pressure using Male New Zealand albino rabbits as an animal model. Methods: Different liposomal formulations of the DEM were prepared and characterized for their drug entrapment, drug-liposome affinity and the in vivo distribution of DEM in various ocular tissues. Liposomal formulations of promising drug distribution within the various ocular tissues have been scaled up for the in vivo intraocular pressure (IOP) measurements by Pneuma-tonometer using different dosing regimens. Results: The amounts of drug entrapped in the charged liposomal formulations were comparable and lower than that entrapped with neutral ones. DEM was found to be more concentrated (69–95%) in the lipid phase of the liposome. The concentrations of DEM in the cornea, aqueous humor, and conjunctiva were 4.76, 2.18, and 23.32 µg/g of tissue, respectively. Test formulations have shown significant reductions in the IOP on using different treatment protocols. Conclusion: Preparation of liposomal formulations of DEM has substantially enhanced its transcorneal transport. Furthermore, the test formulations have shown promising and long-lasting intraocular pressure-lowering effect comparable with that of pilocarpine formulation as a control.     

Preparation and ocular pharmacokinetics of ganciclovir liposomes

Ophthalmic liposomes of ganciclovir (GCV) were prepared by the reverse phase evaporation method, and their ocular pharmacokinetics in albino rabbits were compared with those obtained after dosing with GCV solution. The in vitro transcorneal permeability of GCV liposomes was found to be 3.9-fold higher than that of the solution. After in vivo instillation in albino rabbits, no difference was found in the precorneal elimination rate of GCV from liposome vs solution dosing. The aqueous humor concentration-time profiles of both liposomes and solution were well described by 2-compartmental pharmacokinetics with first-order absorption. The area under the curve of the aqueous humor concentration-time profiles of GCV liposomes was found to be 1.7-fold higher than that of GCV solution. Ocular tissue distribution of GCV from liposomes was 2 to 10 times higher in the sclera, cornea, iris, lens, and vitreous humor when compared with those observed after solution dosing. These results suggested that liposomes may hold some promise in ocular GCV delivery.     

Characterization of calcitonin-containing liposome formulations for intranasal delivery

Calcitonin-containing liposome formulations were characterized to obtain information for evaluation of their feasibility in intranasal delivery. The parameters of liposomal charge characteristics, charge inducing agent concentration, calcitonin concentration and pH of the medium on the loading efficiency and leakage behaviour, and the chemical stability of calcitonin in liposomes were investigated. Results showed that the loading efficiency of calcitonin increased with increasing the added concentration of calcitonin. The magnitude of the loading efficiency due to the liposomal charge of negative, positive and neutral characteristics was in the order of negatively charged liposome > neutral liposome > positively charge liposome. The increase of molar ratio of phosphatidylserine in liposomes showed an increase of loading efficiency; while, the increase of molar ratios of stearylamine showed a decrease of loading efficiency. The loading efficiency at pH 7.4 was greater than that at pH 4.3. The leakage of positively charged liposomes was greater than that of neutral and negatively charged liposomes. The leakage at pH 4.3 was faster than that at pH 7.4. The leakage of positively charged liposomes increased as temperature increased. The chemical stability of calcitonin in both solution and liposomes demonstrated a pseudo-first-order kinetic degradation. Less degradation was observed at pH 3.4 and 4 degrees C. The degradation rate of calcitonin in solution, or in positively charged, negatively charged, and neutral liposomes, exhibited no significant difference. The particle size of the calcitonin-containing liposomes after storage for 1 month at pH 4.3 and 4 degrees C showed little change.     

Characterization of calcitonin-containing liposome formulations for intranasal delivery

Calcitonin-containing liposome formulations were characterized to obtain information for evaluation of their feasibility in intranasal delivery. The parameters of liposomal charge characteristics, charge inducing agent concentration, calcitonin concentration and pH of the medium on the loading efficiency and leakage behaviour, and the chemical stability of calcitonin in liposomes were investigated. Results showed that the loading efficiency of calcitonin increased with increasing the added concentration of calcitonin. The magnitude of the loading efficiency due to the liposomal charge of negative, positive and neutral characteristics was in the order of negatively charged liposome &gt; neutral liposome &gt; positively charge liposome. The increase of molar ratio of phosphatidylserine in liposomes showed an increase of loading efficiency; while, the increase of molar ratios of stearylamine showed a decrease of loading efficiency. The loading efficiency at pH7.4 was greater than that at pH4.3. The leakage of positively charged liposomes was greater than that of neutral and negatively charged liposomes. The leakage at pH4.3 was faster than that at pH7.4. The leakage of positively charged liposomes increased as temperature increased. The chemical stability of calcitonin in both solution and liposomes demonstrated a pseudo-first-order kinetic degradation. Less degradation was observed at pH3.4 and 4°C. The degradation rate of calcitonin in solution, or in positively charged, negatively charged, and neutral liposomes, exhibited no significant difference. The particle size of the calcitonin-containing liposomes after storage for 1 month at pH4.3 and 4°C showed little change.     

Ocular pharmacokinetics and safety of ciclosporin, a novel topical treatment for dry eye

Ciclosporin is a potent immunomodulator that acts selectively and locally when administered at the ocular surface. 0.05% ciclosporin ophthalmic emulsion has recently been approved by the US FDA for treatment of keratoconjunctivitis sicca (KCS) [dry-eye disease]. After topical application, ciclosporin accumulates at the ocular surface and cornea, achieving concentrations (>/=0.236 microg/g) that are sufficient for immunomodulation. Very little drug penetrates through the ocular surface to intraocular tissues. Ciclosporin is not metabolised in rabbit or dog eyes and may not be prone to metabolism in human eyes. Cultured human corneal endothelial and stromal cells exposed to ciclosporin in vitro exhibited no adverse effects and only minor effects on DNA synthesis. No ocular or systemic toxicity was seen with long-term ocular administration of ciclosporin at concentrations up to 0.4%, given as many as six times daily for 6 months in rabbits and 1 year in dogs. Systemic blood ciclosporin concentration after ocular administration was extremely low or undetectable in rabbits, dogs and humans, obviating concerns about systemic toxicity. In 12-week and 1-year clinical safety studies in dry-eye patients, the most common adverse event associated with the ophthalmic use of ciclosporin emulsion was ocular burning. No serious drug-related adverse events occurred.These data from in vitro, nonclinical and clinical studies indicate effective topical delivery of ciclosporin to desired target tissues along with a favourable safety profile, making 0.05% ciclosporin ophthalmic emulsion a promising treatment for KCS.     

In vivo gene transfection via intravitreal injection of cationic liposome/plasmid DNA complexes in rabbits

To optimize the in vivo ocular transfection efficiency of plasmid DNA (pDNA)/cationic liposome complexes, N-[1-(2,3-dioleyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTMA)/dioleoylphosphatidylethanolamine (DOPE) (1:1 molar ratio) liposomes and DOTMA/cholesterol (Chol) (1:1 molar ratio) liposomes were prepared with varying amounts of pDNA. pDNA/cationic liposome complexes were intravitreally injected (100 microL) in rabbits, and luciferase activity in the cornea, aqueous humor, iris-ciliary body, lens, vitreous body, and retina was measured. Transfection efficiency of pDNA alone did not change with pDNA ranging from 40 to 85 mg. In contrast, transfection efficiency of pDNA complexed with DOTMA/Chol liposomes significantly increased with the amount of pDNA ranging from 40 to 85 microg (P < 0.05). pDNA complexed with DOTMA/DOPE liposomes could not be prepared with pDNA greater than 60 microg. Among these experiments, pDNA (85 microg) complexed with DOTMA/Chol liposomes (pDNA:cationic liposome charge ratio (- : +) = 1.0:2.0) showed the highest transfection efficiency in the ocular tissue and its transfection-mediated luciferase activity peaked at 3 days. Among the ocular tissues, the highest gene expression was observed in the aqueous humor.     

Thiolated nanostructured lipid carriers as a potential ocular drug delivery system for cyclosporine A: Improving in vivo ocular distribution

Ophthalmic drug delivery with long pre-corneal retention time and high penetration into aqueous humor and intraocular tissues is the key-limiting factor for the treatment of ocular diseases and disorders. Within this study, the conjugate of cysteine-polyethylene glycol monostearate (Cys-PEG-SA) was synthesized and was used to compose the thiolated nanostructured lipid carrier (Cys-NLC) as a potential nanocarrier for the topical ocular administration of cyclosporine A (CyA). The rapid cross-linking process of Cys-PEG-SA in vitro was found in simulated physiological environment. The in vitro CyA release from Cys-NLC was slower than that of non-thiolated nanostructured lipid carriers (NLC) due to the cross-linking of thiomers on the surface of nanocarriers. After topical ocular administration in rabbits, the in vivo ocular distribution of CyA was investigated in comparison of Cys-NLC with non-thiolated NLCs and oil solution. The results showed that CyA concentration in systemic blood was very low and close to the detection limit. The area-under-the-curve (AUC(0-24h)) and mean retention time (MRT(0-24h)) of Cys-NLC group in aqueous humor, tear and eye tissues were significantly higher than that of oil solution, non-thiolated NLCs (p<0.05). These results demonstrated that the thiolated NLC could deliver high level of CyA into intraocular tissues due to its bioadhesive property and sustained release characteristics.     

Pharmacokinetics of falintolol II. Absorption, distribution and elimination from tissues and organs following ocular administration and intravenous injection of falintolol in albino rabbits

The absorption, distribution and elimination of falintolol maleate was studied in various ocular and extraocular tissues and organs following ocular instillation, intravenous injection of a 0.5% 14C-falintolol ophthalmic solution and repeated ocular instillations of a 1% non-labeled falintolol ophthalmic solution into albino New Zealand rabbits. Falintolol was distributed in all studied tissues and organs after both routes of administration. After ocular instillation, levels of total radioactivity were distinctly higher in ocular tissues than after intravenous injection. Thus, the level was 475 times more important in cornea, 72 times in aqueous humor and 36 times in iris and ciliary body after ocular instillation. On the other hand, levels of total radioactivity in extraocular tissues and organs were 30-50% higher after intravenous injection compared to ocular instillation of the same dose. Peak levels of total radioactivity were generally achieved between 30 min and 1 h after ocular instillation, while 1.5 h after intravenous injection an increase in the declining part of the curve occurred. This increase, characteristic of an enterohepatic reabsorption, was also observed in blood and plasma 1 h after intravenous injection. Urinary elimination was the major means of excretion since 79.6% of total radioactivity was found in urine 6 h after intravenous injection and 74.5% 12 h after ocular instillation. But after ocular instillation, only 5% was excreted as unchanged falintolol. Whatever the route of administration, after single or repeated application, no drug accumulation was evident.