Krutika K. Sawant

Antibody derivatization and conjugation strategies: Application in preparation of stealth immunoliposome to target chemotherapeutics to tumor

A great deal of effort has been made over the years to develop liposomes that have targeting vectors (oligosaccharides, peptides, proteins and vitamins) attached to the bilayer surface. Most studies have focused on antibody conjugates since procedures for producing highly specific monoclonal antibodies are well established. Antibody conjugated liposomes have recently attracted a great deal of interest, principally because of their potential use as targeted drug delivery systems and in diagnostic applications. A number of methods have been reported for coupling antibodies to the surface of stealth liposomes. The objective of this review is to enumerate various strategies which are employed in the modification and conjugation of antibodies to the surface of stealth liposomes. This review also describes various derivatization techniques of lipids prior and after their use in the preparation of liposomes. The use of single chain variable fragments and affibodies as targeting ligands in the preparation of immunoliposomes is also discussed.

Rivastigmine-loaded PLGA and PBCA nanoparticles: preparation, optimization, characterization, in vitro and pharmacodynamic studies.

Sustained release nanoparticulate formulations of Rivastigmine tartrate (RT) were prepared, optimized (using factorial design) and characterized using the biodegradable polymers, PLGA and PBCA as carriers. The pharmacodynamic performances of the nanoparticles (NPs) were evaluated for brain targeting and memory improvement in scopolamine-induced amnesic mice using Morris Water Maze Test. PLGA NPs were prepared by nanoprecipitation technique, while PBCA NPs were prepared by emulsion polymerization technique. Effect of key formulation variables on particle size (PS) and percentage drug entrapment (PDE) of NPs was studied by using factorial design. PLGA NPs showed PS of 135.6±4.2nm and PDE of 74.46±0.76 %, whereas PBCA NPS showed PS of 146.8±2.6nm and PDE of 57.32±0.91%. FTIR and GPC characterization confirmed complete polymerization of n-butyl cyanoacrylate (nBCA) monomer into PBCA. DSC thermograms indicated that RT was dispersed as amorphous state in both PLGA and PBCA NPs. TEM studies indicated that the NPs were spherical. In vitro studies showed 30.86±2.07% and 43.59±3.80% release from PLGA and PBCA NPs in 72h, respectively. Pharmacodynamic study demonstrated faster regain of memory loss in amnesic mice with both PLGA and PBCA NPs when compared to RT solution. This indicates rapid and higher extent of transport of RT into the mice brain and thus shows the suitability of both NPs as potential carriers for providing sustained brain delivery of RT.

Oral Bioavailability Enhancement of Acyclovir by Self-Microemulsifying Drug Delivery Systems (SMEDDS)

Acyclovir is a potent anti-viral agent useful in the treatment of Herpes Simplex Virus (HSV) infections. Acyclovir exerts its antiviral activity by competitive inhibition of viral DNA through selective binding of acyclovir to HSV-thymidine kinase. The main purpose of this work was to develop self-microemulsifying drug delivery system (SMEDDS) for oral bioavailability enhancement of acyclovir. Solubility of acyclovir was determined in various vehicles. SMEDDS is mixture of oils, surfactants, and co-surfactants, which are emulsified in aqueous media under conditions of gentle agitation and digestive motility that would be encountered in the gastro-intestinal (GI) tract. Pseudoternary phase diagrams were constructed to identify the efficient self-emulsifying region dilution study was also performed for optimization of formulation. SMEDDS was evaluated for its percentage transmittance, Assay of SMEDDS, phase separation study, droplet size analysis, zeta potential, electrophoretic mobility, and viscosity. The developed SMEDDS formulation contained acyclovir (50 mg), Tween 60 (60%), glycerol (30%) and sunflower oil (9%) was compared with the pure drug solution by oral administrating to male albino rats. The absorption of acyclovir from SMEDDS form resulted about 3.5 fold increase in bioavailability compared with the pure drug solution. Our studies illustrated the potential use of SMEDDS for the delivery of hydrophobic compounds such as acyclovir by oral route.

Development, evaluation and clinical studies of Acitretin loaded nanostructured lipid carriers for topical treatment of psoriasis

The objective of the present study was to formulate and characterize Acitretin loaded Nanostructured Lipid Carriers (ActNLCs), to understand in vitro drug release and clinically evaluate the role of the developed gel in the topical treatment of psoriasis. ActNLCs were prepared by solvent diffusion technique using 3(2) full factorial design. The mean diameter and surface morphology of ActNLC was evaluated. ActNLCs were lyophilized and crystallinity of NLC was characterized by Differential Scanning Calorimtery (DSC) and powder X-Ray Diffraction (XRD). The NLCs were incorporated in 1% w/w Carbopol 934 P gel base and in vitro skin deposition studies in Human Cadaver Skin and double-blind clinical studies in psoriatic patients were conducted. The optimized ActNLCs were spherical in shape, with average particle size of 223(±8.92)nm, zeta potential of -26.4 (±0.86) mV and EE of 63.0(±1.54)%. DSC and XRD data confirmed the formation of NLCs. Significantly higher deposition of Acitretin was found in human cadaver skin from ActNLC gel (81.38 ±1.23%) as compared to Act plain gel (47.28±1.02%). Clinical studies demonstrated significant improvement in therapeutic response and reduction in local side effects with ActNLCs loaded gel indicated its effectiveness in the topical treatment of Psoriasis.

Brain targeting of risperidone-loaded solid lipid nanoparticles by intranasal route

Intranasal drug delivery is known to overcome the blood–brain barrier (BBB) for delivery of drugs to brain. The objective of this study was to prepare risperidone (RSP)-loaded solid lipid nanoparticles (RSLNs) and explore the possibility of brain targeting by nose-to-brain delivery. RSLNs were prepared by solvent emulsification–solvent evaporation method and characterized for drug content, particle size and size distribution, zeta potential, and in vitro drug-release study. The pharmacodynamic study of RSLNs, which was performed by paw test using Perspex platform, showed higher hindlimb retraction time (HRT) values as compared with RSP solution (RS) indicating the superiority of RSLNs over the RS for brain targeting. The pharmacokinetics and biodistribution studies in mice showed that brain/blood ratio 1 h post-administration of RSLNs (i.n.) was found to be 1.36 ± 0.06 (nearly 10- and 5-fold higher) as compared with 0.17 ± 0.05 for RS (i.v.) and 0.78 ± 0.07 for RSLNs (i.v.), respectively. Gamma scintigraphy imaging of mice brain following intravenous and intranasal administration confirmed the localization of drug in brain. This finding substantiates the existence of direct nose-to-brain delivery route for nanoparticles administered to the nasal cavity.

Recent Advances and Patents on Solid Lipid Nanoparticles

Solid Lipid Nanoparticles (SLNs) have attracted increasing scientific and commercial attention as colloidal drug carriers during the last decade. They have emerged as a potential alternative compared to other colloidal systems like polymeric nanoparticles, liposomes and fat emulsions, as they have been claimed to combine their advantages but successfully overcome their drawbacks. SLN formulations are extensively developed and characterized for their in vitro and in vivo applications by various routes like parenteral, oral, pulmonary, ocular, and dermal. SLNs are being widely investigated as carriers for delivery of macromolecules like proteins, oligonucleotides and DNA. SLNs have already been taken up for medium and large scale production using two of its reported production methods. In fact, the first SLN based product has recently been introduced in the Poland market as a topically applied moisturizer. Newer methods for production of SLNs and their applications are being reported and patented. Nanostructured lipid carriers (NLC) are mixture of solid lipid and liquid lipid while Lipid Drug Conjugates (LDC) are water insoluble lipid carrier for loading of poorly lipid soluble drugs. These new generation of lipid nanoparticles have been claimed to overcome the shortcomings of SLNs. This article reviews the formulation, characterization, applications, and patents on the advances and research on SLNs, NLC and LDC.

Development of solid lipid nanoparticles based controlled release system for topical delivery of terbinafine hydrochloride

The study describes the development and evaluation of solid lipid nanoparticles (SLNs) of terbinafine hydrochloride (TH) for sustained release and skin targeting. TH-loaded SLNs were prepared by solvent-injection technique and optimized using 3(3) full-factorial design. Effect of drug:lipid ratio, surfactant concentration and volume of organic solvent were studied on % entrapment efficiency (%EE) and particle size (PS). The optimum formulation based on desirability (0.945) exhibited %EE of 73.74% and PS of 300 nm. Optimized SLNs were incorporated into Carbopol gel and evaluated for drug content, pH, in vitro release, ex vivo retention, in vivo pharmacodynamic and stability studies. Drug release from SLNs dispersion followed Korsmeyer-Peppas model, indicating Fickian drug release, while that from the gel followed Higuchi model. The ex vivo studies through rat abdominal skin indicated skin retention ability of SLNs as compared to commercial product. In vivo pharmacodynamic studies showed that the SLNs based gel reduced fungal burden of Candida albicans in rats as compared to commercial product in shorter duration of time. The SLNs dispersion and gel exhibited physicochemical stability under refrigeration upto 3 months. It was concluded that SLNs incorporated Carbopol gel had skin targeting ability and may serve as a promising carrier in treatment of fungal skin infections.

Formulation optimization of etoposide loaded PLGA nanoparticles by double factorial design and their evaluation.

Etoposide is one of the most commonly used drugs in chemotherapy of acute lymphocytic leukemia and acute myelogenous leukaemia. Etoposide has variable oral bioavailability ranging from 24-74% and has terminal half life of 1.5 hours by intravenous route. The conventional parenteral therapy causes inconvenience and pain to the patients as it has to be given through a continuous IV infusion over 24-34 h. The present investigation was aimed at developing etoposide loaded biodegradable nanoparticles which would be a sustained release formulation and replace the conventional therapy of continuous intravenous administration. Nanoparticles were prepared by emulsion solvent evaporation method using high pressure homogenization. The process parameters like homogenization cycles (four) and homogenization pressure (10000 psi) were first optimized using a 3(2) factorial design based on response Y1(mean particle size of 98+/-1nm). Then a 32 factorial design was carried out to study the effect of two independent variables, ratio of drug and polymer (X1) and surfactant concentration (X2) on the two responses to obtain their optimized values, percentage entrapment efficiency (Y2, 83.12+/-8.3%) and mean particle size (Y3, 105+/-5.4 nm) for Etoposide loaded PLGA Nanoparticles. Contour plots and response surface plots showed visual representation of relationship between the experimental responses and the set of input variables. The adequacy of the regression model was verified by a check point analysis. The zeta potential values ranged between -23.0 to -34.2 mV, indicating stability. Sucrose was used as cryoprotectant during lyophilization. DSC and XRD studies indicated that etoposide was present in the amorphous phase and may have been homogeneously dispersed in the PLGA matrix. The electron micrographs showed spherical, discrete and homogenous particles. Drug release study showed that etoposide loaded PLGA nanoparticles sustained release up to 72h. The release from the nanoparticles followed first order kinetics and mechanism of drug release was Fickian. Stability studies indicated that it was best to store nanoparticle formulations in the freeze dried state at 2-8 degrees C where they remained stable in terms of both size and drug content upto three months.

Development, optimization and in vitro evaluation of alginate mucoadhesive microspheres of carvedilol for nasal delivery.

Abstract The present research work was aimed at development and optimization of alginate mucoadhesive microspheres of carvedilol for nasal delivery to avoid first pass metabolism and to improve the therapeutic efficacy in the treatment of hypertension and angina pectoris. The microspheres were prepared by a water-in-oil (w/o) emulsification technique. A 23 factorial design was employed with drug : polymer ratio, calcium chloride concentration and cross-linking time as independent variables while particle size of the microspheres and in vitro mucoadhesion were the dependent variables. Regression analysis was performed to identify the best formulation conditions. Particle size was analysed by dynamic laser light diffraction technique and found to be in the range of 26.36–54.32 µm, which is favourable for intranasal absorption. The shape and surface characteristics were determined by scanning electron microscopy (SEM) which depicted the spherical nature and nearly smooth surfaces of the microspheres. The percentage encapsulation efficiency was found to be in the range between 36.62–56.18. In vitro mucoadhesion was performed by adhesion number using sheep nasal mucosa and was observed in a range from 69.25–85.28. Differential scanning calorimetry and X-ray diffraction results indicated a molecular level dispersion of carvedilol in the microspheres. In vitro release studies in pH 6.2 phosphate buffer indicated non-Fickian or anomalous type of transport for the release of carvedilol from the microspheres.

Nimodipine loaded PLGA nanoparticles: formulation optimization using factorial design, characterization and in vitro evaluation.

The present study was aimed at developing a sustained release formulation of Nimodipine (NIM) nanoparticles using the biodegradable polymers, poly (lactide-co-glycolide) (PLGA 50:50 and 85:15) as carrier. NIM is a widely used calcium channel blocker which has to be administered as an intravenous infusion for a prolonged period of 1-2 weeks in the treatment of cerebral vasospasm. A sustained release biodegradable formulation would serve to replace this conventional therapy of continuous intravenous administration. PLGA nanoparticles were prepared by a modified precipitation method using high pressure homogenizer at 10,000 to 14,000 psi. A 3(2) factorial design was applied for optimization of the formulation parameters and for studying the effect of two independent variables [drug: polymer ratio and concentration of surfactant (Pluronic F 127)] on entrapment efficiency and mean particle size (response variables). Contour plots were plotted which gave a visual representation of the two variables on the dependent variables and also indicated non-linear relationship between them. The nanoparticles had particle size of 131+/-1.9 nm for PLGA 50:50 and 196+/-2.2 nm for PLGA 85:15. Scanning Electron Microscopy studies indicated that nanoparticles had spherical shape with a regular surface. The nanoparticles had high entrapment efficiency (96.42+/-2.09% for PLGA 50:50 and 94.50+/-1.25% for PLGA 85:15). DSC thermograms indicated that NIM was dispersed as an amorphous state in the nanoparticles. In vitro drug release from the lyophilized nanoparticles showed 94.35 +/- 3.8% NIM release from PLGA (50:50) nanoparticles and 63.32 +/- 4.6% release from PLGA (85:15) nanoparticles in 25 days. The release was first ordered and fickian diffusion kinetics in both the cases. These preliminary results indicate that NIM loaded PLGA nanoparticles could be effective in sustaining its release for a prolonged period. However, further studies are needed to confirm its performance in vivo.