Pharmacokinetics and targeting property of TFu-loaded liposomes with different sizes after intravenous and oral administration

The purpose of the study was to develop the liposomal formulations of TFu for oral and intravenous (i.v.) administration, clarify the biodistribution characteristics and in vivo pharmacokinetic behaviors of TFu-loaded liposomes. Four TFu-loaded liposomes of different sizes were prepared and characterized. The pharmacokinetic characteristics and the biodistribution of TFu-loaded liposomes with different sizes were investigated after i.v. or oral administration to mice. The pharmacokinetic studies indicated that TFu-loaded liposomes with different sizes all resulted in higher bioavailabilities than the TFu suspension after oral administration, and the gastrointestinal absorption increased with the reduction in liposome sizes. Following i.v. administration to mice, larger TFu-loaded liposomes (530 and 400 nm) showed higher hepatic and splenic targeting properties and lower cardiac and renal accumulations, while smaller sized liposomes (180 nm) significantly enhanced drug plasma concentration, bioavailability and prolonged retention time in circulation. Therefore, it can be concluded that both the oral and the injectable TFu-loaded liposomes are promising anticancer formulations for improved bioavailability; larger sized liposomes are potential passive targeting therapeutic agents for hepatoma and splenoma through i.v. administration while smaller liposomes might be preferable for oral administration due to its enhancing oral absorption possibility. Consequently, TFu-loaded liposomes with different sizes might have different clinical applications according to different goals of treatment.     

Genistein-loaded poloxamer 403/407 mixed micelles: preparation and pharmacokinetic study in rats

In the present study, we aimed to prepare poloxamer 403/407 mixed micelles in order to improve the solubility and oral bioavailability of genistein.Genistein was incorporated in the mixed poloxamer micelles by thin-film hydration method, and its physicochemical properties, including particle size, zeta potential, entrapment efficiency and drug loading, were investigated.In vitro release of genistein from the mixed micelles was monitored by dialysis method, and pharmacokinetic study of genistein loaded mixed micelles was carried out in rats. We found that the particle size and zeta potential of mixed micelles were (20.31±0.43) nm and (–8.94±0.35) mV, with encapsulation efficiency 90.59%±0.67% and drug loading 7.74%±0.05%. Solubility of genistein in mixed micelles reached 3.80 mg/mL, which was about 130 times higher than that in water.Genistein-loaded mixed micelles showed sustained release characteristics in vitro with no burst release phenomenon, but it was faster than suspension.The AUC_0–t andAUC_0–∞ of mixed micelles were 196.74% and 204.62% greater than that of genisein suspension, respectively.Consequently,poloxamer 403/407 mixed micelles significantly improved the solubility and oral bioavailability of genistein, which could be used as an effective drug delivery system for oral administration of poorly soluble drugs.     

Development and pharmacokinetics of nimodipine-loaded liposomes

In order to improve the water solubility of nimodipine and prolong the time of the drug in the circulation, nimodipine-loaded liposomes with a small size and high entrapment efficiency were prepared by a method that was easy to scale up (the modified ethanol injection method). The nimodipine liposome dispersions were characterized with respect to particle size distribution, zeta potential and entrapment efficiency. Liposomal nimodipine and nimodipine solution were intravenously administered to mice as a single dose of 4 mg kg-1. The pharmacokinetic parameters of nimodipine changed significantly when encapsulated in liposomes. The clearance of nimodipine encapsulated in liposomes was reduced and the elimination half-life was prolonged. The ratios of the area under the curve values of nimodipine liposomes to nimodipine solution were 1.78 and 1.90 in plasma and cerebral tissue, respectively. The drug concentration in cerebral tissue and in plasma showed a good linear correlation, which showed that liposomes could efficiently deliver nimodipine into brain tissue. These findings suggest that intravenous administration of liposomal nimodipine produces higher and more stable plasma and cerebral drug concentrations compared with nimodipine solution. In conclusion, liposomal nimodipine is a promising alternative to the solution preparation.     

Investigation of lectin-modified insulin liposomes as carriers for oral administration

The aim of this study was to design and characterize lectin-modified liposomes containing insulin and to evaluate the potential of these modified colloidal carriers for oral administration of peptide and protein drugs. Wheat germ agglutinin (WGA), tomato lectin (TL), or Ulex europaeus agglutinin 1 (UEA1) were conjugated by coupling their amino groups to carbodiimide-activated carboxylic groups of N-glutaryl-phosphatidylethanolamine (N-glut-PE). Insulin liposomes dispersions were prepared by the reverse-phase evaporation technique and modified with the lectin-N-glut-PE conjugates. Lectin-modified liposomes were characterized according to particles size, zeta potential and entrapment efficiency. The hypoglycemic effect indicated by pharmacological bioavailability of insulin liposomes modified with WGA, TL and UEA1 were 21.40, 16.71 and 8.38% in diabetic mice as comparison with abdominal cavity injection of insulin, respectively. After oral administration of the insulin liposomes modified with WGA, TL and UEA1 to rats, the relative pharmacological bioavailabilities were 8.47, 7.29 and 4.85%, the relative bioavailability were 9.12, 7.89 and 5.37% in comparison with subcutaneous injection of insulin, respectively. In the two cases, no remarkable hypoglycemic effects were observed with the conventional insulin liposomes. These results confirmed that lectin-modified liposomes promote the oral absorption of insulin due to the specific-site combination on GI cell membrane.     

Preparation and characterization of liposomes encapsulating chitosan nanoparticles

Liposomes are an important colloidal carrier system for controlled drug delivery. However some highly hydrophilic small molecules are difficult to entrap into liposomes and store stably, resulting in poor encapsulation efficiency and fast leakage. In the present work, fluorescein sodium (FS) was used as a model drug that was loaded into chitosan nanoparticles and then encapsulated into liposomes by reverse-phase evaporation (RPV). The encapsulation efficiency, particle size, zeta potential, release in vitro and pharmacokinetics in rats were determined in order to characterize the novel drug delivery system. The entrapment efficiency was above 80% in nanoparticles (Np) and 95% in liposomes encapsulating the nanoparticles (Lip-Np). The Lip-Np was composed of soybean phospholipids, cholesterol and chitosan, which the average diameter was 202.6 nm and zeta potential was -34.8 mV. The release rate of fluorescein sodium from Lip-Np was slower than from Np and liposomes. FS in Lip-Np administered to rats exhibited prolonged circulation and higher bioavailability than FS in Np. The results indicated that liposomal release kinetics can be controlled by encapsulating nanoparticles and thus solid-cored liposomes can be used as a potential drug delivery system.     

Solid lipid nanoparticles (SLNs) to improve oral bioavailability of poorly soluble drugs

The purpose of this work was to improve the oral bioavailability of poorly soluble drugs by incorporation into solid lipid nanoparticles (SLNs). All-trans retinoic acid (ATRA) was used as a poorly soluble model drug. Different formulations of SLNs loaded with ATRA were successfully prepared by a high-pressure homogenization method and using Compritol 888 ATO as lipid matrix. The particle size and distribution, drug loading capacity, drug entrapment efficiency (EE %), zeta potential, and long-term physical stability of the SLNs were investigated in detail. Drug release from two sorts of ATRA-SLN was studied and compared with the diffusion from ATRA solution in 0.1 M HCl, distilled water and phosphate buffer (pH 7.40), using a dialysis bag method. A pharmacokinetic study was conducted in male rats after oral administration of 8 mg kg(-1) ATRA in different formulations and it was found that the relative bioavailability of ATRA in SLNs was significantly increased compared with that of an ATRA solution. The amount of surfactant also had a marked effect on the oral absorption of ATRA with SLN formulations. Although an emulsion formulation also increased ATRA absorption, it was too unstable for use in clinical situations. The absorption mechanism of the SLN formulations was discussed. These results indicate that ATRA absorption is enhanced significantly by employing SLN formulations. SLNs offer a new approach to improve the oral bioavailability of poorly soluble drugs.     

Studies on binary lipid matrix based solid lipid nanoparticles of repaglinide: in vitro and in vivo evaluation

The purpose of present study is to examine effect of binary lipid matrix (combination of lipids) on the entrapment and storage stability of repaglinide (RG) loaded solid lipid nanoparticles (SLN). Solid lipid nanoparticles were prepared by modified solvent injection method for oral delivery to improve the bioavailability of RG, an antidiabetic drug. The stearic acid and tristearin were used to form lipid core materials, and Pluronic-F68 was used as a stabilizer. Nanoparticles were characterized by evaluating their particle size, zeta potential, entrapment efficiency, drug loading, solid-state studies (differential scanning calorimetry, X-ray diffraction), in vitro drug release, particle surface (transmission electron microscopy analysis with electron diffraction pattern), stability study in gastrointestinal fluids (GIFs) and storage stability at 30 °C/65% RH for 3 months. The characterization of SLN suggested that binary lipid matrix based nanoparticles had better drug entrapment and loading, desired release characteristics, stable in GIFs and significantly higher storage stability compared with single lipid formulations. Pharmacodynamic (blood glucose, blood cholesterol, blood triglyceride levels) and pharmacokinetic (AUC, T(max), peak plasma concentrations, K, t(1/2), mean residence time and relative bioavailabilities) studies were performed for the selected formulations. These studies indicate that the formulation based on binary lipid matrix significantly improves the oral bioavailability of RG.     

洛伐他汀自组装前体脂质体的制备及其理化性质的研究

目的:为研究洛伐他汀新剂型,制备洛伐他汀新型前体脂质体,并对其质量进行考察。方法:采用一种新型前体脂质体制备方法将洛伐他汀制成自组装前体脂质体,对水合后脂质体的形态、粒径、Zeta电位、包封率、自组装速度、稳定性等进行考察,验证这种新型前体脂质体制备方法用于制备洛伐他汀脂质体的可行性。结果:所形成的洛伐他汀脂质体包封率为95.4%±6.7%,平均粒径为(327.4±29.6)nm,Zeta电位值为-(22.4±1.5)mV。洛伐他汀自组装前体脂质体可在60 s内自发形成脂质体并达到分散平衡;以人工胃液为稀释介质,洛伐他汀脂质体在12 h内稳定。结论:采用新型前体脂质体制备方法可将洛伐他汀制成洛伐他汀脂质体,形成的脂质体包封率较高且具有良好的稳定性。     

In vivo and cytotoxicity evaluation of repaglinide-loaded binary solid lipid nanoparticles after oral administration to rats

The purpose of this work was to develop prolonged release binary lipid matrix-based solid lipid nanoparticles (SLN) of repaglinide (RG) for oral intestinal delivery and to improve the bioavailability of RG. SLN were designed by using glycerol monostearate and tristearin as lipid core materials and Pluronic-F68 as stabilizer. SLN were characterised by their particle size, zeta potential, entrapment efficiency, solid-state studies, in vitro drug release, particle surface and storage stability at 30 °C/65% relative humidity for 3 months. Pharmacodynamic (PD) and pharmacokinetic (PK) studies were also performed in diabetes-induced rat. Moreover, an in vitro toxicity study was performed in rat macrophage cells to establish the safety of the prepared SLN. It was observed that binary lipid matrix-based SLN had better drug entrapment, desired release characteristics, spherical shape and maximum storage stability. Pharmacodynamic study indicated that RG delivered through binary SLN significantly reduces blood glucose, blood cholesterol and blood triglycerides level. The area under the curves after oral administration of optimised RG-SLN formulation and RG control were 113.36 ± 3.01 and 08.08 ± 1.98 h/(ng · mL), respectively. The relative bioavailability of RG was enhanced with optimised SLN formulation when compared with RG control. There was a direct correlation found between the plasma drug level (drug concentration) and the peak response (% blood glucose inhibition) in optimised RG-SLN batch. The in vitro toxicity study indicated that the SLN were well tolerated.     

槲皮素前体脂质体的质量考察

目的制备液体型槲皮素前体脂质体,并对制剂质量进行考察。方法采用一种新型前体脂质体制备方法制备液体型槲皮素前体脂质体,将脂质体膜材和药物等以一定比例溶于分散介质中,形成一种无水的澄明溶液。考察其水合后粒子形态、粒径、电位、包封率及自组装速度等理化性质,并评价其体外释药性质。结果槲皮素前体脂质体遇水即可快速自组装成纳米级含药脂质体混悬液,水合后形态多为类球形,平均粒径为228.7nm,Zeta电位为21.2 mV,包封率可达90%以上,体外释药符合Higuchi方程。结论槲皮素口服前体脂质体制备工艺简单可行,包封率高,具有一定的缓释效果。     

Pharmacokinetic behavior and efficiency of acetylcholinesterase inhibition in rat brain after intranasal administration of galanthamine hydrobromide loaded flexible liposomes

Galanthamine hydrobromide (GH) has been approved for symptomatic treatment of Alzheimer's disease (AD) and vascular dementia. Hence, the effects of intranasal administration of GH loaded flexible liposomes have been investigated for the first time on the efficiency of acetylcholinesterase inhibition, as well as the pharmacokinetic behavior of GH in rat brain. The GH loaded flexible liposomes were characterized for shape, entrapment capacity, size distribution and zeta potential by transmission electron microscopy (TEM), ultracentrifugation and dynamic light scattering (DLS), respectively. The inhibition of acetylcholinesterase was investigated using rat brain homogenates as an enzyme resource and microdialysis was used to determine the pharmacokinetic behavior of GH in rats brain. The rat pheochromocytoma PC-12 cell line was used to evaluate the cytotoxicity of GH loaded flexible liposomes. The results revealed that: (i) the efficiency of acetylcholinesterase inhibition of GH was greatly enhanced by intranasal administration compared with oral administration, especially GH loaded in flexible liposomes; (ii) the C(max) and AUC(0→10) for intranasal administration of GH loaded flexible liposomes were 3.52 and 3.36 times higher than those of orally administered GH, moreover, the T(max) was greatly shortened from 1.5h for oral administration to 0.75h for intranasal administration of GH loaded flexible liposomes; and (iii) PC-12 cells viability tests showed that the flexible liposome carrier is not toxic to the cultured cells and the cytotoxicity of GH to cells was clearly decreased by loading in flexible liposomes. These results indicate that intranasal administration of GH loaded flexible liposomes could readily transport GH into brain tissues, suggesting some promise for this approach in successful brain-drug targeting in AD treatment.     

Preparation,characterization and tissue distribution of brucine stealth liposomes with different lipid composition

Objective: To improve the therapeutic index of brucine, the novel stealth liposomes (SLS-n), composed of naturally unsaturated and hydrogenated soy phosphatidylcholines, with significant difference of phase transition temperature, were developed to encapsulate brucine.

Methods: Brucine-loaded stealth liposomes with different lipid compositions were prepared and characterized for their entrapment efficiency (EE), particle size, zeta potential and in vitro drug release profile. Tissue distribution after intravenous administration of different brucine formulations was further compared in tumor-bearing mice.

Results: Compared with the conventional stealth liposomes composed of SPC (SLS-s) or HSPC (SLS-h), EE and zeta potential of SLS-n were increased slightly, and the size was decreased slightly. The results of drug release showed that SLS-n were more stable than SLS-s. After intravenous administration, tumor AUC in SLS-s, SLS-n and SLS-h treated animals were 1.33, 1.72 and 2.59-fold higher than in mice treated with the same dose of free brucine, respectively. Compared with brucine solution, administration of SLS-s and SLS-n could significantly decrease brucine concentration in brain, but administration of SLS-h resulting in significantly increased (2.75-fold) concentration in 10?min.

Conclusion: Since brucine has severe central nervous system toxicity, our study indicated that SLS-n could considerably improve the therapeutic index of brucine.     

用四阶导数光谱法测定A-OT-Fu小鼠代谢物的血药浓度

本文采用四阶导数光谱测定了小鼠口服A-OT-Fu淀粉液后的主要代谢产物TFu和5-Fu的血药浓度—时间曲线。当TFu和5-Fu浓度为5～50μg/ml时,浓度与252nm和289 nm对零轴间的振幅有良好的线性关系。在本测试条件下TFu和5-Fu的回收率约95%以上,实验结果表明,TFu和5-Fu达到最高血药浓度的时间分别为1和2 h。     

Trans-nasal zolmitriptan novasomes: in-vitro preparation,optimization and in-vivo evaluation of brain targeting efficiency

Migraine attack is a troublesome physiological condition associated with throbbing, intense headache, in one half of the head. Zolmitriptan is a potent second-generation triptan, prescribed for patients with migraine attacks, with or without an aura, and cluster headaches. The absolute bioavailability of zolmitriptan is about 40% for oral administration; due to hepatic first metabolism. Nasal administration would circumvent the pre-systemic metabolism thus increasing the bioavailability of zolmitriptan. In addition, due to the presence of microvilli and high vasculature, the absorption is expected to be faster compared to oral route. However, the bioavailability of nasal administered drugs is particularly restricted by poor membrane penetration. Thus, the aim of this work is to explore the potential of novel nanovesicular fatty acid enriched structures (novasomes) for effective and enhanced nasal delivery of zolmitriptan and investigate their nose to brain targeting potential. Novasomes were prepared using nonionic surfactant, cholesterol in addition to a free fatty acid. A 2³ full factorial design was adopted to study the influence of the type of surfactant, type of free fatty acid and ratio between the free fatty acid and the surfactant on novasomes properties. The particle size, entrapment efficiency, polydispersity index, zeta potential and % zolmitriptan released after 2?h were selected as dependent variables. Novasomes were further optimized using Design Expert® software (version 7; Stat-Ease Inc., Minneapolis, MN), and an optimized formulation composed of Span® 80:Cholesterol:stearic acid (in the ratio 1:1:1) was selected. This formulation showed zolmitriptan entrapment of 92.94%, particle size of 149.9?nm, zeta potential of ?55.57?mV, and released 48.43% zolmitriptan after 2?h. The optimized formulation was further examined using transmission electron microscope, which revealed non-aggregating multi-lamellar nanovesicles with narrow size distribution. DSC, XRD examination of the optimized formulation confirmed that the drug have been homogeneously dispersed throughout the novasomes in an amorphous state. In-vivo bio-distribution studies of ^99mTc radio-labeled intranasal zolmitriptan loaded novasomes were done on mice, the pharmacokinetic parameters were compared with those following administration of intravenous ^99mTc-zolmitriptan solution. Results revealed the great enhancement in zolmitriptan targeting to the brain, with drug targeting potential of about 99% following intranasal administration of novasomes compared with the intravenous drug solution. Zolmitriptan loaded novasomes administered via the nasal route may therefore constitute an advance in the management of acute migraine attacks.     

A lipid microsphere vehicle for vinorelbine: Stability, safety and pharmacokinetics

A lipid microsphere vehicle for vinorelbine (VRL) was designed to reduce the severe venous irritation caused by the aqueous intravenous formulation of VRL. Lipid microspheres (LMs) were prepared by high pressure homogenization. The physical stability was monitored by the appearance, particle size and zeta potential changes while the chemical stability was achieved by using effective antioxidants and monitored by long-term investigations. Safety tests were performed by testing rabbit ear vein irritation and a guinea pig hypersensitivity reaction. A pharmacokinetic study was performed by determining the drug levels in plasma up to 24h after intravenous administration of VRL-loaded LMs and conventional VRL aqueous injection separately. The VRL-loaded LMs had a particle size of 180.5+/-35.2nm with a 90% cumulative distribution less than 244.1nm, while the drug entrapment efficiency was 96.8%, and it remained stable for 12 months at 6+/-2 degrees C. The VRL-loaded LMs were less irritating and toxic than the conventional VRL aqueous injection. The pharmacokinetic profiles were similar and the values of AUC(0-t) were very close for the two formulations. A stable and easily mass-produced VRL-loaded LM preparation has been developed. It produces less venous irritation and is less toxic but has similar pharmacokinetics in vivo to the VRL aqueous injection currently commercially available.     

Injectable actarit-loaded solid lipid nanoparticles as passive targeting therapeutic agents for rheumatoid arthritis

This work systematically studied the intravenous injection formulation of solid lipid nanoparticles (SLNs) loaded with actarit, a poor water soluble anti-rheumatic drug. The goal of this study was to design passive targeting nanoparticles which could improve therapeutic efficacy and reduce side-effects such as nephrotoxicity and gastrointestinal disorders commonly associated with oral formulations of actarit. Based on the optimized results of single-factor and orthogonal design, actarit-loaded SLNs were prepared by a modified solvent diffusion-evaporation method. The formulated SLNs were found to be relatively uniform in size (241+/-23 nm) with a negative zeta potential (-17.14+/-1.6 mV). The average drug entrapment efficiency and loading were (50.87+/-0.25)% and (8.48+/-0.14)%, respectively. The actarit-loaded SLNs exhibited a longer mean retention time in vivo (t(1/2(beta)), 9.373 h; MRT, 13.53 h) compared with the actarit 50% propylene glycol solution (t(1/2(ke)), 0.917 h; MRT, 1.323 h) after intravenous injection to New Zealand rabbits. The area under curve of plasma concentration-time (AUC) of actarit-loaded SLNs was 1.88 times greater than that of the actarit in 50% propylene glycol solution. The overall targeting efficiency (TE(C)) of the actarit-loaded SLNs was enhanced from 6.31% to 16.29% in spleen while the renal distribution of actarit was significantly reduced as compared to that of the actarit solution after intravenous administration to mice. These results indicated that injectable actarit-loaded solid lipid nanoparticles were promising passive targeting therapeutic agents for rheumatoid arthritis.     

米诺地尔醇脂质体的制备

目的制备米诺地尔醇脂质体并评价其质量。方法采用乙醇注入法制备米诺地尔醇脂质体,以包封率为评价指标进行正交试验筛选出最佳的处方和工艺。采用HPLC测定主药含量、透析袋法测定醇脂质体的包封率。并对其粒径、电位、包封率等理化性质进行研究。结果各因素最佳的水平组合：药脂重量比为1∶10、胆固醇与大豆磷脂的重量比为1∶2、无水乙醇为处方量的30%。所制醇脂质体为乳黄色,平均粒径为1.103μm,Zeta电位为-3.69 mV,平均包封率为66.7%。结论米诺地尔醇脂质体的制备工艺简便可行,质量稳定可控,为开发新剂型奠定了实验基础。     

PEG-PLGA- hybrid nanoparticles loaded with etoricoxib – phospholipid complex for effective treatment of inflammation in rat model

The aim of the present study was to increase the bioavailability of the etoricoxib by making PEG-PLGA-Hybrid nanoparticles using emulsion solvent evaporation method. Then the prepared nanoparticles were further characterised using TEM, particle size, PDI, zeta potential, encapsulation efficiency and drug release study. Lipid (Phospholipon 90-G) and drug thermal behaviour were studied using DSC, TGA. The results of optimised formulation of Particle size, PDI and zeta potential was found 216.6?±?4.0?nm, 0.24?±?0.19 and +36.3?±?1.9?mV. Encapsulation efficiency was found in the range of 77.15% w/v to 93.88% w/v. In-vivo study shows that the optimised formulation at a particular dose decreases the swelling index and number of writhes. Stability study indicated that the nanoparticles can be stored at a temperature of 4?±?2?°C/60?±?5% RH in well-closed container, away from heat and damp places. The prepared formulation has significantly increased the bioavailability of etoricoxib via oral administration.     

胰岛素乳酸/羟基乙酸共聚物纳米粒的制备及口服药效学研究

目的探索可生物降解乳酸/羟基乙酸共聚物［poly(lactic-co-glycolic acid),PLGA］纳米粒作为大分子蛋白质类口服给药系统的可能性。方法用复乳溶剂挥发法制备了胰岛素乳酸/羟基乙酸共聚物纳米粒(INS-PLGA-NPs);光子相关光谱法测定了平均粒径;HPLC法测定了胰岛素的包封率;放射免疫法研究了纳米粒的载药方式;考察了INS-PLGA-NPs的体外释放特性;评价了口服给予纳米粒对糖尿病大鼠降血糖作用。结果以1% poloxamer 188为乳化剂制备的纳米粒,平均粒径为149.6 nm,多分散度为0.09,包封率为42.8%;同时抗体捕捉实验发现纳米粒主要以吸附方式载药;胰岛素的体外释放分为两相;以10 u·kg^-1的剂量给予该纳米粒,4 h后血糖浓度显著降低(P<0.05),10 h血糖降至最低,药理相对生物利用度(10.3±0.8)%。结论PLGA-NPs可能成为大分子蛋白质药物口服给药的新型载体。     

A gamma scintigraphy study to investigate uterine targeting efficiency of raloxifene-loaded liposomes administered intravaginally in New Zealand white female rabbits

Context: Raloxifene hydrochloride (RLH), a selective estrogen receptor modulator, shows antiproliferative and apoptotic effects on Leiomyoma. Its extensive first pass metabolism leads to oral bioavailability of 2%.

Objective: The aim of this investigation was to formulate RLH-loaded liposomes and study its uterine-targeting efficiency after intravaginal administration.

Materials and methods: Liposomes were prepared by thin film hydration method using 1:1 molar ratio of DSPC:Cholesterol and characterized for vesicle size, zeta potential, %entrapment efficiency, loading, drug release and transmission electron microscopy. Radiolabeling of RLH was performed with reduced technetium-99m (^99mTc). Binding affinity of ^99mTc-labeled complexes was assessed by diethylene triamine penta acetic acid (DTPA) challenge test. Biodistribution study was done in New Zealand white female rabbits by administering the formulation intravaginally.

Results and discussion: Spherical and discrete liposomes of size 119?nm were seen in TEM results. Liposomes had high entrapment efficiency of 90.96% with drug loading of 27.25%w/w. Liposomes were able to sustain the drug release for 6 days. ^99mTc-labeled complexes showed high labeling efficiency and stability both in saline and serum. DTPA challenge test confirmed low transchelation of ^99mTc-labeled complexes. Biodistribution study by gamma scintigraphy revealed the preferential uptake of the formulation by uterus when administered vaginally. Compared to plain drug, liposomes were concentrated and retained within the uterus for a longer period of time.

Conclusion: Uterine targeting of RLH-loaded liposomes indicates its potential to overcome the limitations of marketed formulation. Drug targeting to site of action anticipates dose reduction needed to elicit the therapeutic effect.