Multivesicular liposomes for sustained release of naltrexone hydrochloride: design,characterization and in vitro/in vivo evaluation

Multivesicular liposomes containing naltrexone hydrochloride (DepoNTX) was prepared by using the traditional DepoFoam technology and the key formulation factors on encapsulation efficiency and particle size were investigated. A morphological characterization and in vitro/in vivo release assay was also carried out. NTX was successfully encapsulated in DepoNTX with good yield and showing the spherical, smooth and multivesicular characteristics of particle by a light microscope. The in vitro studies in human plasma and sodium chloride showed that 80–85% of NTX encapsulated in MVLs released slowly from particles over 5 days. In vivo study, after a single dose of 2.0?mg/kg of DepoNTX formulation administered subcutaneously in rats, plasma NTX levels were maintained at a relatively constant level above 10?ng/mL for approximately 120?h, while after administered NTX solution, NTX level was quickly decreased below 10?ng/mL within 20?h. The results of the study demonstrated that DepoNTX was very promising candidate for sustained release delivery of naltrexone hydrochloride.     

Melittin liposomes surface modified with poloxamer 188: in vitro characterization and in vivo evaluation

Melittin liposomes surface modified with poloxamer 188 were developed, and the effect of poloxamer 188 was investigated with regard to anti-cancer effect and vascular stimulation. Melittin liposomes surface modified with poloxamer 188 at different concentrations (0%, 2%, and 5%) were prepared using the adsorption method, followed by in vitro characterization, including entrapment efficiency, zeta potential, particle size, and morphology. Subsequently, the influence of repeated freeze-thawing on the liposomes was investigated, and the effect of poloxamer 188 on the repeated freeze-thawing process was explored. Vascular stimulation effects of MLT, and MLT liposome that surface coated with or without poloxamer were all studied. Pharmacokinetics of the different MLT preparations were determined and the anticancer activity of the MLT formulations was investigated. The particle size of the liposomes gradually increased with increasing poloxamer 188 content, while the entrapment efficiency did not change significantly. After the first freeze-thaw cycle, size and PDI were both markedly reduced, entrapment efficiency rose, and there was no significant change of zeta potential. The vascular irritation caused by MLT could be reduced to an extent by encapsulation in liposome, but not completely eliminated, while liposomes coated with poloxamer 188 can effectively abolish the phenomenon. Melittin liposomes with surface modified by poloxamer exhibit enhanced bioavailability, effective anticancer activity, and reduced side effects compared with melittin solution. Poloxamer plays an important role in melittin liposomes.     

Development, characterization and in vivo evaluation of benzocaine-loaded liposomes.

This study reports the development and in vivo evaluation of a liposomal formulation of the local anaesthetic benzocaine. Multi-lamellar (MLV) and small uni-lamellar (SUV) vesicles entrapping benzocaine were prepared using 50:50 w/w phosphatidylcholine-cholesterol as lipophilic phase and 50:50 v/v ethanol-water as hydrophilic phase. Liposome size, Zeta-potential, encapsulation efficiency and skin penetration properties were determined. Drug permeation from liposomal dispersions, as such or formulated in Carbopol gel, was evaluated through artificial lipophilic membranes and excised abdominal rat skin, whereas in vivo anaesthetic effect was tested on rabbits. Interestingly, addition of the drug into the hydrophilic phase, rather than into the lipophilic one, during liposome preparation enabled an improvement of the MLV's entrapment efficiency from 29.7% to 82.3%. On the other hand, sonication conditions to obtain SUV influenced size and polydispersity index of the vesicles and reduced the entrapment efficiency by about 30%. All liposomal-benzocaine formulations showed sustained release properties and a more intense anaesthetic effect than plain drug. Permeation experiments from drug solutions in gel containing the same amount of ethanol as in the liposomal formulations made it possible to exclude a possible enhancer effect of this solvent, at least when not used in liposomal formulations. MLV with the drug added into the hydrophilic phase gave the most effective formulation, showing a permeability coefficient value 2.5 times higher than that of the plain drug and allowing a significant improvement (P<0.01) not only of intensity but also of duration of anaesthetic effect of benzocaine. These results suggest that a suitably developed liposomal formulation of benzocaine can be of actual value for improving its clinical effectiveness in topical anaesthesia.     

盐酸拓扑替康脂质体的体外细胞毒及体内抗肿瘤作用

目的对抗癌药物盐酸拓扑替康普通脂质体(Plain L)及PEG修饰脂质体(PEG L)的体外细胞毒及体内抗肿瘤作用进行研究。方法采用噻唑蓝(MTT)比色法测定Plain L与PEG L对人卵巢癌细胞A2780和人结肠直肠癌细胞HCT 8的抑制作用;对荷肝癌H22小鼠尾静脉注射给药进行Plain L、PEG L的体内抑瘤试验。结果与游离药物相比,Plain L、PEG L的细胞毒作用增强,对体外培养的人卵巢癌A2780细胞的IC50分别为(9.26±2.14)mg.L-1和(2.36±1.08)mg.L-1,相比于游离药物[IC50=(25.45±1.69)mg.L-1]分别降低了63.6%(P<0.005)和90.7%(P<0.001);对HCT 8细胞,Plain L[IC50=(10.66±1.25)mg.L-1]与PEG L[IC50=(4.50±0.31)mg.L-1]的细胞毒作用也强于游离药物[IC50=(16.72±2.45)mg.L-1],分别是游离药物的1.5倍(P<0.001)和3.6倍(P<0.005)。体内抑瘤实验结果表明,游离药物、Plain L与PEG L体积抑瘤率分别为58.2%、67.6%、83.5%,质量抑瘤率分别为56.3%、69.6%、85.7%;与游离药物相比,Plain L与PEG L的体内抗肿瘤作用明显提高。结论与游离药物相比,脂质体包封提高了盐酸拓扑替康的体外细胞毒作用及体内抗肿瘤效果,而经PEG修饰的脂质体相比于普通脂质体体内、外抗肿瘤效果更强。     

Preparation and in vitro/in vivo evaluation of revaprazan hydrochloride nanosuspension

Revaprazan hydrochloride (RH) is a new reversible proton pump inhibitor. However, due to poor water solubility, oral bioavailability of the drug was relatively low. To investigate the particle size reduction effect of RH on dissolution and absorption, three suspensions that containing different sized particles were prepared by high pressure homogenization and in vitro/in vivo evaluations were carried out. DSC and powder X-ray diffraction were used to study crystalline state of freeze dried powder of RH suspensions and the results showed that particles of RH microsuspension and nanosuspension remained in the same crystalline state as coarse suspension, but had lower lattice energy. In the in vitro dissolution test, both microsuspension and nanosuspension showed increased dissolution rate. In the in vivo evaluation, compared to coarse suspension, RH nanosuspension exhibited significant increase in AUC(0-t), C(max) and decrease in T(max), MRT. Nevertheless, RH microsuspension did not display any significant differences in these pharmacokinetic parameters compared to the coarse suspension. The findings revealed that particle size reduction can influence RH absorption in gastrointestinal tract and nanosuspension can enhance oral bioavailability of RH in rats.     

Formulation and optimization of duloxetine hydrochloride buccal films: in vitro and in vivo evaluation

Duloxetine hydrochloride (DH) is a serotonin–norepinephrine reuptake inhibitor (SSNRI) indicated for the treatment of depression. Duloxetine suffers from reduced oral bioavailability (≈50%) due to hepatic metabolism. This study aims to develop DH buccoadhesive films to improve its bioavailability. DH buccoadhesive films were prepared adopting the solvent casting method using hydroxypropyl methylcellulose (HPMC) and polyvinyl alcohol (PVA). The prepared films were evaluated for weight uniformity, drug content, surface pH, swelling index, mucoadhesion strength and drug release percentages. Accelerated stability and bioavailability studies in healthy human volunteers were also performed for the selected films. Results of the evaluation tests showed that the optimum physicochemical characters were obtained by the films prepared with 2% HPMC using 10% propylene glycol (F2 films). Accelerated stability studies revealed that DH showed proved stability throughout the experiment time. DH bioavailability from F2 films was determined and compared with that of the marketed oral capsules (Cymbalta^® 30?mg). The pharmacokinetic results showed that C_max for F2 was higher than the market product. In addition, ANOVA analysis showed that a T_max of F2 film was significantly lower, while, the AUC_0–72 of F2 was significantly higher than that of Cymbalta capsules. The percentage relative bioavailability of DH from F2 was found to be 296.39%. Therefore, the prepared buccal films offer an alternative route for the administration of DH with the possibility of improving its bioavailability.     

In vitro and in vivo evaluation of mPEG-PLA modified liposomes loaded glycyrrhetinic acid

In order to prolong the in vivo residence of glycyrrhetinic acid, a liposomes with surface modified by methoxy poly(ethyleneglycol) (mPEG)-PLA was prepared for the first time. The liposomes (C-LP) and long-circulating liposomes (LC-LP) were prepared by film-dispersion method using soybean phospholipid/cholesterol mixture (1:0.5 mol/mol), containing 5% (w/w) sodium deoxycholate, and 2% (w/w) mPEG-PLA (only for LC-LP). The diameter of LC-LP was 243.3+/-17.1 nm. The pharmacokinetics behaviors of the conventional injection and liposomes (C-LP and LC-LP) were compared after a single intravenous injection to rats. Pharmacokinetic parameters were calculated based on a two-compartment open model analysis. LC-CP had a 1.7-fold longer residence time (MRT), a 2.75-fold larger AUC and a 0.4-fold lower clearance compared with conventional injection, respectively. These results combined suggested that the LC-CP had a well-improved residence in rats.     

Preparation and in vitro/in vivo evaluation of sustained-release venlafaxine hydrochloride pellets

The objective of this study was to prepare different venlafaxine hydrochloride sustained-release products and to elucidate the influence of composition of the coating film on the in vitro drug release profiles and in vivo pharmacokinetics. Pellets were prepared by a standardized process of extrusion/spheronization. A selected fraction size (0.8-1.0 mm diameter) of pellets of each formulation was coated with Eudragit NE30D or ethylcellulose (10 cps). Many efforts have been made to tailor drug release rate by choosing different coating materials, different percent of pore forming components and coating weight variation to achieve a desired sustained-release effect. The dissolution studies were performed and data were analyzed in terms of cumulative release as a function of time. The influence on the release of venlafaxine from sustained-release capsules was observed in dissolution media of different pH and gradient pH. Scanning electron microscope (SEM) micrographs revealed morphological changes of the pellet coating surface which were related to in vitro drug release profiles. The relative bioavailability for Formulation 1 and Formulation 2 was evaluated in six healthy beagle dogs after oral administration in a fast state using sustained-release capsules (Effexor XR) as a reference. The results suggested that Formulation 1 and Formulation 2 both had better bioavailability compared with Effexor XR. It could be found that there existed quite difference in the in vivo release and oral absorption performances, despite the similar in vitro drug release behavior for the two formulations. It might be attributable to complex in vivo environment and then variation in the release behavior. Thus differences in the film micro-structure and surface roughness caused by aqueous dispersion and organic solvent coating techniques strongly influence the in vivo release and oral absorption performances.     

In vitro and in vivo evaluation of ranitidine hydrochloride ethyl cellulose floating microparticles

The real issue in the development of oral controlled release dosage forms is not just to prolong the delivery of drugs but also to prolong the presence of dosage forms in the stomach in order to improve the bioavailability of drugs with a 'narrow absorption window'. In the present study, an anti-ulcer drug, ranitidine hydrochloride, is delivered through a gastroretentive ethyl cellulose-based microparticulate system capable of floating on simulated gastric fluid for > 12 h. Preparation of microparticles is done by solvent evaporation technique with modification by using an ethanol co-solvent system. The formulated microspheres were free flowing with good packability and encapsulation efficiencies were up to 96%. Scanning electron microscopy confirmed porous, spherical particles in the size range 300-750 microm. Microspheres showed excellent buoyancy and a biphasic controlled release pattern with 12h. In vivo bioavailability studies performed on rabbits and T(max), C(max), AUC were calculated and confirmed significant improvement in bioavailability. The data obtained thus suggests that a microparticulate floating delivery system can be successfully designed to give controlled drug delivery, improved oral bioavailability and many other desirable characteristics.     

Water/oil type microemulsion systems containing lidocaine hydrochloride: in vitro and in vivo evaluation

Abstract

The purpose of this study was to develop a water/oil microemulsion containing lidocaine hydrochloride (4%) and to compare its local anaesthetic efficacy with commercial products. A pseudoternary diagram (K_m:1/1 or 1/2) was constructed using lecithin/ethanol/oil/water. The droplet size, viscosity and release of the microemulsions were evaluated. Tail flick tests were conducted for in vivo effectiveness; the initiation time of effect, maximum effect, time to reach maximum effect, and relative efficacy were evaluated. The drug caused a significant increase in droplet size. The use of olive oil resulted in a decrease in the solubilisation parameter, as well as a reduction in the release. The droplet size and viscosity of the microemulsion composed of Miglyol/lecithin/ethanol/water/drug (K_m:1/2) was lower than other microemulsions (8.38?nm, 6.9 mPa), and its release rate (1.61?mg/h) was higher. This system had a faster and more efficient anaesthetic effect than the other microemulsions and commercial products. Results indicate that a water/oil type microemulsion (Miglyol/lecithin/ethanol/water) has promising potential to increase the local anaesthetic effect.     

Controlled release effervescent buccal discs of buspirone hydrochloride: in vitro and in vivo evaluation studies

Abstract

In the present study controlled release effervescent buccal discs of buspirone hydrochloride (BS) were designed using HPMC as rate controlling and bioadhesive polymer by direct compression method. Sodium bicarbonate and citric acid were used in varying amounts as effervescence forming agents. Carbon dioxide evolved due to reaction of sodium bicarbonate and citric acid was explored for its potential as buccal permeation enhancer. The designed buccal discs were evaluated for physical characteristics and in vitro drug release studies. Bioadhesive behavior of designed buccal discs was assessed using texture analyzer. In vivo animal studies were performed in rabbits to study bioavailability of BS in the designed buccal discs and to establish permeation enhancement ability of carbon dioxide. It was observed that effervescent buccal discs have faster drug release compared to non-effervescent buccal discs in vitro and effervescent buccal discs demonstrated significant increase in bioavailability of drug when compared to non-effervescent formulation. Hence, effervescent buccal discs can be used as an alternative to improve the drug permeation resulting in better bioavailability. However, the amount of acid and base used for generation of carbon dioxide should be selected with care as this may damage the integrity of bioadhesive dosage form.     

In vitro and in vivo evaluation of ranitidine hydrochloride ethyl cellulose floating microparticles

The real issue in the development of oral controlled release dosage forms is not just to prolong the delivery of drugs but also to prolong the presence of dosage forms in the stomach in order to improve the bioavailability of drugs with a ‘narrow absorption window’. In the present study, an anti-ulcer drug, ranitidine hydrochloride, is delivered through a gastroretentive ethyl cellulose-based microparticulate system capable of floating on simulated gastric fluid for?>?12 h. Preparation of microparticles is done by solvent evaporation technique with modification by using an ethanol co-solvent system. The formulated microspheres were free flowing with good packability and encapsulation efficiencies were up to 96%. Scanning electron microscopy confirmed porous, spherical particles in the size range 300–750 µm. Microspheres showed excellent buoyancy and a biphasic controlled release pattern with 12 h. In vivo bioavailability studies performed on rabbits and T_max, C_max, AUC were calculated and confirmed significant improvement in bioavailability. The data obtained thus suggests that a microparticulate floating delivery system can be successfully designed to give controlled drug delivery, improved oral bioavailability and many other desirable characteristics.     

盐酸利多卡因多囊脂质体的制备和质量评价

目的:制备具有缓释特性的盐酸利多卡因多囊脂质体,考察其理化性质。方法:以卵磷脂和胆固醇为膜材,采用复乳法制备盐酸利多卡因多囊脂质体,用透射电镜观察其外观形态,用激光粒度分析仪测定粒径,检测包封率和体外释药特性。结果:盐酸利多卡因多囊脂质体的外观形态圆整、规则,粒径分布在300～700nm及1～6μm两区域,包封率为(27.10±0.66)%。多囊脂质体在pH 7.4的磷酸盐缓冲液中,24h的累积释药百分率为(92.7±3.6)%。结论:盐酸利多卡因多囊脂质体具有一定的缓释特性。     

Preparation and in vitro/in vivo evaluation of sustained-release metformin hydrochloride pellets.

In this study, metformin hydrochloride (MH) sustained-release pellets were successfully prepared by centrifugal granulation. Seed cores preparation, drug layering, talc modification and coating of polymeric suspensions were carried out in a centrifugal granulator. Talc modification was performed before coating in order to overcome the high water solubility of metformin. The influence of surface modification by talc, the effects of Eudragit types and ratios, as well as the correlation between in vitro release and in vivo absorption were investigated in detail. Experimental results indicated that talc modification made a decisive contribution to controlling the drug release by avoiding drug dumping. Three dissolution media: 0.1 M HCl, distilled water and pH 6.8 phosphate buffer were employed to determine the in vitro release behaviors of the above metformin hydrochloride pellets. The relative bioavailability of the sustained-release pellets was studied in 12 healthy volunteers after oral administration in a fast state using a commercially available immediate release tablet (Glucophage) as a reference. Following coating with a blend of Eudragit L30D-55 and Eudragit NE30D (1:20), at 7% or 10% coating level, respectively (referred to as F-2, F-3), the pellets acquired perfect sustained-release properties and good relative bioavailability. The Cmax, Tmax and relative bioavailability for F-2 and F-3 coated pellets were 1.21 microg/ml, 6 h, 97.6% and 1.65 microg/ml, 8 h, 165%, respectively. Combined use of two Eudragit polymers with different features as coating materials produced the desired results. Restricted delivery of metformin hydrochloride to the small intestine from differently coated pellets resulted in increased relative bioavailability and a sustained release effect. The adoption of several different pH dissolution media established a better relationship between the in vitro release and in vivo absorption of the sustained-release pellets.     

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.     

棓丙酯脂质体的制备与表征

目的制备棓丙酯脂质体,并对其进行理化性质的表征和释放度的评价。方法采用薄膜分散法制备棓丙酯脂质体,超滤离心法测定脂质体的包封率,正交设计优化处方,并对其包封率、粒径、Zeta电位、形态及体外释放行为进行综合评价。结果正交设计优化最终处方为磷脂浓度5 mg.mL-1、药脂比1∶5、磷脂胆固醇比5∶1、水化介质离子强度20 mmol.mL-1,所得脂质体包封率为89.6%、粒径为181.3 nm、Zeta电位为-21.8 mV、4 h体外释放达到80%。结论制备的棓丙酯脂质体包封率高,粒径小而均一,体外释放完全。     

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 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.