Design and in vivo pharmacodynamic evaluation of nanostructured lipid carriers for parenteral delivery of artemether: Nanoject

Bio-inspired artemether-loaded human serum albumin nanoparticles for effective control of malaria-infected erythrocytes

AIM

The intra-erythrocytic development of the malarial parasite is dependent on active uptake of nutrients, including human serum albumin (HSA), into parasitized red blood cells (pRBCs). We have designed HSA-based nanoparticles as a potential drug-delivery option for antimalarials.

METHODS

Artemether-loaded nanoparticles (AANs) were designed and antimalarial activity evaluated in vitro/in vivo using Plasmodium falciparum/Plasmodium berghei species, respectively.

RESULTS

Selective internalization of AAN into Plasmodium-infected RBCs in preference to healthy erythrocytes was observed using confocal imaging. In vitro studies showed 50% dose reduction for AAN as compared with drug-only controls to achieve IC₅₀ levels of inhibition. The nanoparticles exhibited twofold higher peak drug concentrations in RBCs with antimalarial activity at 50% of therapeutic doses in P. bergei infected mice.

CONCLUSION

Novel HSA-based nanoparticles offer safe and effective approach for selective targeting of antimalarial drugs.

Nanostructured lipid carriers of artemether-lumefantrine combination for intravenous therapy of cerebral malaria

Patients with cerebral malaria (CM) are unable to take oral medication due to impaired consciousness and vomiting thus necessitating parenteral therapy. Quinine, artemether, and artesunate which are currently used for parenteral malaria therapy have their own drawbacks. The World Health Organization (WHO) has now banned monotherapy and recommends artemisinin-based combination therapy for malaria treatment. However, presently there is no intravenous formulation available for combination therapy of malaria. Artemether-Lumefantrine (ARM-LFN) is a WHO approved combination for oral malaria therapy. However, the low aqueous solubility of ARM and LFN hinders their intravenous delivery. The objective of this study was to formulate ARM-LFN nanostructured lipid carriers (NLC) for intravenous therapy of CM. ARM-LFN NLC were prepared by microemulsion template technique and characterized for size, drug content, entrapment efficiency, drug release, crystallinity, morphology, amenability to autoclaving, compatibility with infusion fluids, stability, antimalarial efficacy in mice, and toxicity in rats. The ARM-LFN NLC showed sustained drug release, amenability to autoclaving, compatibility with infusion fluids, good stability, complete parasite clearance and reversal of CM symptoms with 100% survival in Plasmodium berghei-infected mice, and safety in rats. The biocompatible ARM-LFN NLC fabricated by an industrially feasible technique offer a promising solution for intravenous therapy of CM.

Nanostructured lipid carriers for oral bioavailability enhancement of raloxifene: Design and in vivo study

The objective of present work was to utilize potential of nanostructured lipid carriers (NLCs) for improvement in oral bioavailability of raloxifene hydrochloride (RLX). RLX loaded NLCs were prepared by solvent diffusion method using glyceryl monostearate and Capmul MCM C8 as solid lipid and liquid lipid, respectively. A full 3(2) factorial design was utilized to study the effect of two independent parameters namely solid lipid to liquid lipid ratio and concentration of stabilizer on the entrapment efficiency of prepared NLCs. The statistical evaluation confirmed pronounced improvement in entrapment efficiency when liquid lipid content in the formulation increased from 5% w/w to 15% w/w. Solid-state characterization studies (DSC and XRD) in optimized formulation NLC-8 revealed transformation of RLX from crystalline to amorphous form. Optimized formulation showed 32.50 ± 5.12 nm average particle size and -12.8 ± 3.2 mV zeta potential that impart good stability of NLCs dispersion. In vitro release study showed burst release for initial 8 h followed by sustained release up to 36 h. TEM study confirmed smooth surface discrete spherical nano sized particles. To draw final conclusion, in vivo pharmacokinetic study was carried out that showed 3.75-fold enhancements in bioavailability with optimized NLCs formulation than plain drug suspension. These results showed potential of NLCs for significant improvement in oral bioavailability of poorly soluble RLX.

Intra-articular delivery of a methotrexate loaded nanostructured lipid carrier based smart gel for effective treatment of rheumatic diseases

A nanostructured lipid carrier (NLC) based smart gel of methotrexate (MTX) was developed as a potential system for the treatment of rheumatic diseases (RD).

Development, characterization and antimalarial efficacy of dihydroartemisinin loaded solid lipid nanoparticles

Effective use of dihydroartemisinin (DHA) is limited by poor water-solubility, poor pharmacokinetic profile and unsatisfactory clinical outcome especially in monotherapy. To reduce such limitations, we reformulated DHA into solid lipid nanoparticles (SLNs) as a nanomedicine drug delivery system. DHA-SLNs were characterized for physical parameters and evaluated for in vitro and in vivo antimalarial efficacy. DHA-SLNs showed desirable particle characteristics including particle size (240.7 nm), particle surface charge (+17.0 mV), drug loadings (13.9 wt %), encapsulation efficacy (62.3%), polydispersity index (0.16) and a spherical appearance. Storage stability up to 90 days and sustained release of drug over 20 h was achieved. Enhanced in vitro (IC50 0.25 ng/ml) and in vivo (97.24% chemosuppression at 2mg/kg/day) antimalarial activity was observed. Enhancement in efficacy was 24% when compared to free DHA. These encouraging results show potential of using the described formulation for DHA drug delivery for clinical application.

FROM THE CLINICAL EDITOR

Malaria still poses a significant problem worldwide. One of the current drugs, artemisinin has been shown to be effective, but has poor water-solubility. The authors here described their formulation of making dihydroartemisinin (DHA) into solid lipid nanoparticles, with subsequent enhancement in efficacy. These results would have massive potential in the clinical setting.

Pharmacokinetics of a novel sublingual spray formulation of the antimalarial drug artemether in healthy adults

The pharmacokinetics of sublingual artemether (ArTiMist) was investigated in two open-label studies. In study 1, 16 healthy males were randomized to each of four single-dose treatments administered in random order: (i) 15.0 mg of sublingual artemether (5 × 3.0 actuations), (ii) 30.0 mg of sublingual artemether (10 × 3.0 mg), (iii) 30.0 mg of sublingual artemether (5 × 6.0 mg), and (iv) 30.0 mg of artemether in tablet form. In study 2, 16 healthy males were randomized to eight 30.0-mg doses of sublingual artemether given over 5 days as either 10 3.0-mg or 5 6.0-mg actuations. Frequent blood samples were drawn postdose. Plasma artemether and dihydroartemisinin levels were measured using liquid chromatography-mass spectrometry. Population compartmental pharmacokinetic models were developed. In study 1, sublingual artemether absorption was biphasic, with both rate constants being greater than that of the artemether tablets (1.46 and 1.66 versus 0.43/h, respectively). Relative to the tablets, sublingual artemether had greater bioavailability (≥1.24), with the greatest relative bioavailability occurring in the 30.0-mg dose groups (≥1.58). In study 2, there was evidence that the first absorption phase accounted for between 32% and 69% of the total dose and avoided first-pass (FP) metabolism, with an increase in FP metabolism occurring in later versus earlier doses but with no difference in bioavailability between the dose actuations. Sublingual artemether is more rapidly and completely absorbed than are equivalent doses of artemether tablets in healthy adults. Its disposition appears to be complex, with two absorption phases, the first representing pregastrointestinal absorption, as well as dose-dependent bioavailability and autoinduction of metabolism with multiple dosing.

A Review of In Vitro Drug Release Test Methods for Nano-Sized Dosage Forms

This review summarizes the methods used to study real-time (37°C) drug release from nanoparticulate drug delivery systems and establish an IVIVC. Since no compendial standards exist, drug release is currently assessed using a variety of methods including sample and separate (SS), continuous flow (CF), dialysis membrane (DM) methods, and a combination thereof, as well as novel techniques like voltametry and turbidimetry. This review describes the principle of each method along with their advantages and disadvantages, including challenges with set-up and sampling. The SS method allows direct measurement of drug release with simple set-up requirements, but sampling is cumbersome. With the CF method, sampling is straightforward but the set-up is time consuming. Set-up as well as sampling is easier with the DM, but it may not be suitable for drugs that bind to the membrane. Novel methods offer the possibility of real-time drug release measurement but may be restricted to certain types of drugs. Of these methods, Level A IVIVCs have been obtained with dialysis, alone or in combination with the sample and separate technique. Future efforts should focus on developing mathematical models that describe drug release mechanisms as well as facilitate formulation development of nano-sized dosage forms.

Liquid chromatography/tandem mass spectrometry method for quantitative estimation of solutol HS15 and its applications

A rapid, sensitive and selective pseudoMRM (pMRM)-based method for the determination of solutol HS15 (SHS15) in rat plasma was developed using liquid chromatography/tandem mass spectrometry (LC–MS/MS). The most abundant ions corresponding to SHS15 free polyethyleneglycol (PEG) oligomers at m/z 481, 525, 569, 613, 657, 701, 745, 789, 833, 877, 921 and 965 were selected for pMRM in electrospray mode of ionization. Purity of the lipophilic and hydrophilic components of SHS15 was estimated using evaporative light scattering detector (ELSD). Plasma concentrations of SHS15 were measured after oral administration at 2.50 g/kg dose and intravenous administration at 1.00 g/kg dose in male Sprague Dawley rats. SHS15 has poor oral bioavailability of 13.74% in rats. Differences in pharmacokinetics of oligomers were studied. A novel proposal was conveyed to the scientific community, where formulation excipient could be analyzed as a qualifier in the analysis of new chemical entities (NCEs) to address the spiky plasma concentration profiles.

Effect of the excipient concentration on the pharmacokinetics of PM181104, a novel antimicrobial thiazolyl cyclic peptide antibiotic, following intravenous administration to mice

Thiazolyl cyclic peptide antibiotics are known for their poor aqueous solubility and unfavorable pharmacokinetics (PK) and hence pose challenging tasks in developing these antibiotics as clinical candidates. In the current paper, we report a possible way to address these challenges with exemplification of our antibiotic PM181104. The approach was to prepare formulations with known excipients, Polysorbate 80 (Tween 80, T-80) and PEG 400 through their varied stiochiometric combination in appropriate ratio to achieve acceptable osmolarity, pH and particle size of the formulation. Two different sets of formulations were prepared with two distinct average particle diameters ranging from 32.8 to 465.4 nm. First, semi-transparent solutions with a particle size of >100 nm were achieved by keeping concentration of PEG 400 constant at 8% (w/v) and decreasing the amounts of T-80. Second, clear colorless solutions with a particle size of <100 nm were achieved by keeping concentration of T-80 constant at 8% (w/v) and decreasing the amounts of PEG 400. In PK studies, intravenous administration of formulation with particle size <100 nm to mice resulted in a two-fold increase in area under the plasma concentration-time curve (AUC_last) and concentration at time zero (C₀), there by facilitating the selection of suitable formulation for further efficacy studies.

Influence of surfactant and lipid type on the physicochemical properties and biocompatibility of solid lipid nanoparticles

Nine types of solid lipid nanoparticle (SLN) formulations were produced using tripalmitin (TPM), glyceryl monostearate (GM) or stearic acid (SA), stabilized with lecithin S75 and polysorbate 80. Formulations were prepared presenting PI values within 0.25 to 0.30, and the physicochemical properties, stability upon storage and biocompatibility were evaluated. The average particle size ranged from 116 to 306 nm, with a negative surface charge around −11 mV. SLN presented good stability up to 60 days. The SLN manufactured using SA could not be measured by DLS due to the reflective feature of this formulation. However, TEM images revealed that SA nanoparticles presented square/rod shapes with an approximate size of 100 nm. Regarding biocompatibility aspects, SA nanoparticles showed toxicity in fibroblasts, causing cell death, and produced high hemolytic rates, indicating toxicity to red blood cells. This finding might be related to lipid type, as well as, the shape of the nanoparticles. No morphological alterations and hemolytic effects were observed in cells incubated with SLN containing TPM and GM. The SLN containing TPM and GM showed long-term stability, suggesting good shelf-life. The results indicate high toxicity of SLN prepared with SA, and strongly suggest that the components of the formulation should be analyzed in combination rather than separately to avoid misinterpretation of the results.

Lipid nanoparticles as carriers for RNAi against viral infections: current status and future perspectives

The efforts made to develop RNAi-based therapies have led to productive research in the field of infections in humans, such as hepatitis C virus (HCV), hepatitis B virus (HBV), human immunodeficiency virus (HIV), human cytomegalovirus (HCMV), herpetic keratitis, human papillomavirus, or influenza virus. Naked RNAi molecules are rapidly digested by nucleases in the serum, and due to their negative surface charge, entry into the cell cytoplasm is also hampered, which makes necessary the use of delivery systems to exploit the full potential of RNAi therapeutics. Lipid nanoparticles (LNP) represent one of the most widely used delivery systems for in vivo application of RNAi due to their relative safety and simplicity of production, joint with the enhanced payload and protection of encapsulated RNAs. Moreover, LNP may be functionalized to reach target cells, and they may be used to combine RNAi molecules with conventional drug substances to reduce resistance or improve efficiency. This review features the current application of LNP in RNAi mediated therapy against viral infections and aims to explore possible future lines of action in this field.

Development of artemether and lumefantrine co-loaded nanostructured lipid carriers: physicochemical characterization and in vivo antimalarial activity

CONTEXT

Artemether and lumefantrine combination therapy is well-accepted for uncomplicated malaria treatment. However, the current available formulation has several pharmacokinetic mismatches such as drug degradation in gastrointestinal tract, erratic absorption, etc. Hence, need of the hour is the injectable formulation, which can overcome the pharmacokinetic mismatch associated with current available formulation in the market.

OBJECTIVE

To fabricate artemether and lumefantrine co-loaded injectable nanostructured lipid carriers (NLCs) formulation.

MATERIALS AND METHODS

Artemether and lumefantrine co-loaded NLCs were fabricated using homogenization followed by ultra-sonication method. Fabricated NLCs were evalauated for their physicochemical characteristics, and suitability of the formulation for malaria treatment was evaluated using in vivo animal model (Plasmodium berghei-infected mice). Results, discussion and conclusion: Artemether and lumefantrine co-loaded NLCs had a hydrodynamic diameter of ∼ 145 nm with the surface charge of -66 mV. Due to the lipophilic nature of both antimalarial drugs, both single drugs-loaded and co-loaded NLCs have shown high encapsulation efficiency, which is 84% for artemether and 79% for lumefantrine. In vitro drug release study has shown a biphasic drug release pattern, which has shown 63% artemether release and 45% of lumefantrine release over a time period of 30 h. Plasmodium berghei-infected mice treated with artemether and lumefantrine co-loaded NLCs showed better antimalarial activity with respect to parasitemia progression and survivability period.

Nanostructured lipid carriers as a novel oral delivery system for triptolide: induced changes in pharmacokinetics profile associated with reduced toxicity in male rats

After oral administration in rodents, triptolide (TP), a diterpenoid triepoxide compound, active as anti-inflammatory, immunosuppressive, anti-fertility, anti-cystogenesis, and anticancer agent, is rapidly absorbed into the blood circulation (from 5.0 to 19.5 minutes after dosing, depending on the rodent species) followed by a short elimination half-life (from about 20 minutes to less than 1 hour). Such significant and rapid fluctuations of TP in plasma likely contribute to its toxicity, which is characterized by injury to hepatic, renal, digestive, reproductive, and hematological systems. With the aim of prolonging drug release and improving its safety, TP-loaded nanostructured lipid carriers (TP-NLCs), composed of Compritol® 888 ATO (solid lipid) and Capryol™ 90 (liquid lipid), were developed using a microemulsion technique. The formulated TP-NLCs were also characterized and in vitro release was evaluated using the dialysis bag diffusion technique. In addition, the pharmacokinetics and toxicology profiles of TP-NLCs were compared to free TP and TP-loaded solid lipid nanoparticles (TP-SLNs; containing Compritol 888 ATO only). Results demonstrate that TP-NLCs had mean particle size of 231.8 nm, increased drug encapsulation with a 71.6% efficiency, and stable drug incorporation for over 1-month. TP-NLCs manifested a better in vitro sustained-release pattern compared to TP-SLNs. Furthermore, TP-NLCs prolonged mean residence time (MRT)_0–t (P<0.001, P<0.001), delayed T_max (P<0.01, P<0.05) and decreased C_max (P<0.01, P<0.05) compared to free TP and TP-SLNs, respectively, which was associated with reduced subacute toxicity in male rats. In conclusion, our data suggest that TP-NLCs are superior to TP-SLNs and could be a promising oral delivery system for a safer use of TP.

Optimization of artemether-loaded NLC for intranasal delivery using central composite design

The objective of the study was to optimize artemether-loaded nanostructured lipid carriers (ARM-NLC) for intranasal delivery using central composite design. ARM-NLC was prepared by microemulsion method with optimized formulation having particle size of 123.4 nm and zeta potential of -34.4 mV. Differential scanning calorimetry and powder X-ray diffraction studies confirmed that drug existed in amorphous form in NLC formulation. In vitro cytotoxicity assay using SVG p12 cell line and nasal histopathological studies on sheep nasal mucosa indicated the developed formulations were non-toxic and safe for intranasal administration. In vitro release studies revealed that NLC showed sustained release up to 96 h. Ex vivo diffusion studies using sheep nasal mucosa revealed that ARM-NLC had significantly lower flux compared to drug solution (ARM-SOL). Pharmacokinetic and brain uptake studies in Wistar rats showed significantly higher drug concentration in brain in animals treated intranasally (i.n.) with ARM-NLC. Brain to blood ratios for ARM-NLC (i.n.), ARM-SOL (i.n.) and ARM-SOL (i.v.) were 2.619, 1.642 and 0.260, respectively, at 0.5 h indicating direct nose to brain transport of ARM. ARM-NLC showed highest drug targeting efficiency and drug transport percentage of 278.16 and 64.02, respectively, which indicates NLC had better brain targeting efficiency compared to drug solution.

Targeting of diacerein loaded lipid nanoparticles to intra-articular cartilage using chondroitin sulfate as homing carrier for treatment of osteoarthritis in rats

Targeted delivery of antiosteoarthritic drug diacerein to articular tissue could be a major achievement and soluble polysaccharide chondroitin sulfate (ChS) may be a suitable agent for this. Therefore, diacerein loaded solid lipid nanoparticles modified with ChS (ChS-DC-SLN) were prepared for synergistic effect of these agents to combat multidimensional pathology of osteoarthritis (OA). Prepared formulation were of size range 396±2.7nm, showed extended release up to 16h and increased bioavailability of diacerein by 2.8 times. ChS-DC-SLN were evaluated for their effect on histopathology of femoro-tibial joint of rat knee and amount of ChS and rhein (an active metabolite of diacerein) at targeted site. Concentration of rhein was significantly higher in case of ChS-DC-SLN (7.8±1.23μg/ml) than that of drug dispersion (2.9±0.45μg/ml). It can be stated that ChS served as homing to articular cartilage for targeting of drug. Thus, ChS-DC-SLN have great potential to enhance the overall efficacy of treatment for OA.

FROM THE CLINICAL EDITOR

This study demonstrates the feasibility of targeted delivery of diacerein to articular tissue using soluble polysaccharide chondroitin sulfate as the targeting vector. This approach has the potential to significantly increase anti-arthritic drug concentration in joints without leading to systemic toxicity.

Advances in nanomedicines for malaria treatment

Malaria is an infectious disease that mainly affects children and pregnant women from tropical countries. The mortality rate of people infected with malaria per year is enormous and became a public health concern. The main factor that has contributed to the success of malaria proliferation is the increased number of drug resistant parasites. To counteract this trend, research has been done in nanotechnology and nanomedicine, for the development of new biocompatible systems capable of incorporating drugs, lowering the resistance progress, contributing for diagnosis, control and treatment of malaria by target delivery. In this review, we discussed the main problems associated with the spread of malaria and the most recent developments in nanomedicine for anti-malarial drug delivery.

Tamoxifen-loaded nanostructured lipid carrier as a drug delivery system: characterization, stability assessment and cytotoxicity

Cancer nanotherapeutics is beginning to overwhelm the global research and viewed to be the revolutionary treatment regime in the medical field. This investigation describes the development of a stable nanostructured lipid carrier (NLC) system as carrier for Tamoxifen (TAM). The TAM-loaded NLC (TAM-NLC) developed with 200mg of TAM showed a spherical particle with the size of 46.6nm, polydispersity index of 0.267, entrapment efficiency of 99.74% and with the zeta potential of -23.78mV. Besides, the equivalent cytotoxicity of TAM and TAM-NLC to human (MCF-7) and mice (4T1) mammary breast cancer cell lines were observed. Incubating the formulation at the physiological pH resulted into reduced Ostwald ripening rate but without any significant change in the absorptivity. When coupled with the measurements of zeta potential and Ostwald ripening rate, the absorbance assay may be used to predict the long-term stability of drug-loaded nanoparticle formulations. The results of the study also suggest that TAM-NLC is a promising drug delivery system for breast cancer therapy. This is the first encouraging report on the in vitro effect of TAM-NLC against human and mouse mammary adenocarcinoma cell lines.

Development of ionic-complex-based nanostructured lipid carriers to improve the pharmacokinetic profiles of breviscapine

AIM

Breviscapine isolated from the Chinese herb Erigeron breviscapus (Vant) Hand-Mazz is widely used to treat cardiovascular and cerebrovascular diseases. The aim of this study was to improve the pharmacokinetic profiles of breviscapine using nanostructured lipid carrier based on an ionic complex formation.

METHODS

Breviscapine nanostructured lipid carrier (Bre-NLC) was prepared using the thin film homogenization method. The morphology of Bre-NLCs was determined using transmission electron microscopy. The mean particle size, polydispersity index, zeta-potential analysis and entrapment efficiency were analized. In vitro release was studied using the dialysis method. In vitro stability was studied in fresh plasma and liver slurry of rats. In vivo pharmacokinetics was analyzed in rats after intravenous injection of a dose equivalent to breviscapine (10 mg/kg).

RESULTS

The Bre-NLCs were spherical with a mean particle size of ~170 nm, a zeta potential of ∼20 mV and a high entrapment efficiency of ~89%. Compared with a commercially available solution, a substantial decrease in the cumulative release of breviscapine was found for the Bre-NLCs. The NLC has a significantly protective effect against the liver enzyme degradation of breviscapine. After intravenous administration in rats, the Bre-NLCs exhibited a 32 times increase in the AUC0-t and a 12 times increase in T1/2 as compared to the commercially available breviscapine solution.

CONCLUSION

The results demonstrate that the NLC has great potential to use as a novel sustained release system for breviscapine.

Modulation of cerebral malaria by curcumin as an adjunctive therapy

Cerebral malaria is the most severe and rapidly fatal neurological complication of Plasmodium falciparum infection and responsible for more than two million deaths annually. The current therapy is inadequate in terms of reducing mortality or post-treatment symptoms such as neurological and cognitive deficits. The pathophysiology of cerebral malaria is quite complex and offers a variety of targets which remain to be exploited for better therapeutic outcome. The present review discusses on the pathophysiology of cerebral malaria with particular emphasis on scope and promises of curcumin as an adjunctive therapy to improve survival and overcome neurological deficits.

Preparation and optimization of transferrin-modified-artemether lipid nanospheres based on the orthogonal design of emulsion formulation and physically electrostatic adsorption

Artemether has been used for a long time in the treatment of malaria as safe and non expensive drug. It possesses potent anticancer effects in cancer cell lines. Our aim was to develop transferrin-modified-artemether lipid nanospheres as targeted anticancer drug delivery system. In this study, artemether intravenous delivery system was prepared by emulsifying method as lipid nanospheres containing mixture of soya oil and crodamol as the core and soya lecithin and Tween 80 as coating layer. According to the physicochemical characterization, the process and formulation variables were optimized by orthogonal design and ANOVA analysis. Based on the electrostatic interaction, transferrin (TR) was physically adsorbed onto the coating layer; the effect of medium pH and the charge of the nanocarriers on the adsorption were investigated. The in vitro characterizations were carried out including, the zeta potential, AFM, TEM, FTIR, (1)H NMR and gel filtration. ART-LNSs with high entrapment efficiency, small size of about 50 nm and monodispersity were formulated. Optimized and stable TR-LNSs, a lipoprotein like structure and size, were produced. We showed a method by which TR can be bound to lipid nanospheres without the need for chemical modification as a base for the development of safe, effective and non expensive anticancer drug delivery system.

Long chain lipid based tamoxifen NLC. Part I: preformulation studies, formulation development and physicochemical characterization

Tamoxifen citrate (Tmx) was formulated in nanostructured lipid carrier system (NLC) using long chain solid lipids (LCSL) and oils (LCO) with the aim to target lymphatic system to improve its bioavailability in plasma and lymphnode (initial sites for metastasis) and reduce its drug associated toxicity. Tamoxifen loaded NLC (Tmx-NLC) was formulated using solvent diffusion technique. Preformulation studies comprised evaluation of drug-excipients compatibility. Solubility of Tmx was screened in LCSL and LCO, surfactants and co-surfactants to identify NLC components. Surfactant co-surfactant combinations were studied for their ability to stabilize the system. Tmx-NLC was physicochemically characterized by TEM, DSC, XRD, and FTIR studies. Drug-excipients chemical compatibility study facilitated anticipation of excipients induced oxidative degradation of Tmx. Suitable storage condition below 30°C could stabilize Tmx. Tmx-NLC with >90% entrapment efficiency and 215.60 ± 7.98 nm particle size were prepared and freeze dried. Freeze dried Tmx-NLC could withstand various gastrointestinal tract (GI) media (pH 1.2, pH 3.5, pH 4.5, pH 6.8, pH 7.4). Dissolution profile of Tmx-NLC in various media showed sustained release pattern irrespective of pH of medium. No significant change in characteristics of Tmx-NLC was observed after 3 months of accelerated stability studies.

Comparative in vitro and in vivo evaluation of lipid based nanocarriers of Huperzine A

The purpose of the present investigation was to explore feasibility of nanocarrier based transdermal delivery of Huperzine A (HupA) for the treatment of Alzheimer's disease. For this investigation, microemulsion (ME), solid lipid nanoparticles (SLNs), and nanostructured lipid carriers (NLCs) were formulated and characterized for physicochemical parameters. The pseudo-ternary phase diagrams for microemulsion region were developed using generally recognized as safe (GRAS) excipients. The SLNs and NLCs were prepared by microemulsion template technique. These nanodispersions were formulated into gels for transdermal application and evaluated for various physicochemical parameters. In vitro permeation profiles in rat skin exhibited zero-order kinetics. HupA loaded ME exhibited superior permeation than NLCs followed by SLNs and cumulative amount permeated after 24h was found to be 147.68±9.42 μg/cm(2), 129.11±32.76 μg/cm(2) and 10.74±0.68 μg/cm(2), respectively. Furthermore, optimized gels were subjected to primary skin irritation testing over a period of 48 h and were found to be safe for skin application. In vivo efficacy tested in scopolamine induced amnesia model indicated significant improvement in cognitive function in mice group treated with developed nanocarrier based formulations as compared to the control group.

In Vitro Dissolution Testing Strategies for Nanoparticulate Drug Delivery Systems: Recent Developments and Challenges

Nanoparticulate systems have emerged as prevalent drug delivery systems over the past few decades. These delivery systems (such as liposomes, emulsions, nanocrystals, and polymeric nanocarriers) have been extensively used to improve bioavailability, prolong pharmacological effects, achieve targeted drug delivery, as well as reduce side effects. Considering that any unanticipated change in product performance of such systems may result in toxicity and/or change in vivo efficacy, it is essential to develop suitable in vitro dissolution/release testing methods to ensure product quality and performance, and to assist in product development. The present review provides an overview of the current in vitro dissolution/release testing methods such as dialysis, sample and separate, as well as continuous flow methods. Challenges and future directions in the development of standardized and biorelevant in vitro dissolution/release testing methods for novel nanoparticulate systems are discussed.

Design and in vitro haemolytic evaluation of cryptolepine hydrochloride-loaded gelatine nanoparticles as a novel approach for the treatment of malaria

Cryptolepine hydrochloride-loaded gelatine nanoparticles were developed and characterised as a means of exploring formulation techniques to improve the pharmaceutic profile of the compound. Cryptolepine hydrochloride-loaded gelatine-type (A) nanoparticles were developed base on the double desolvation approach. After optimisation of formulation parameters including temperature, stirring rate, incubation time polymer and cross-linker (glutaraldehyde) concentrations, the rest of the study was conducted at two different formulation pH values (2.5 and 11.0) and by two different approaches to drug loading. Three cryoprotectants--sucrose, glucose and mannitol--were investigated for possible use for the preparation of freeze-dried samples. Nanoparticles with desired size mostly less than 350 nm and zeta potential above ±20 were obtained when formulation pH was between 2.5 and 5 and above 9. Entrapment efficiency was higher at pH 11.0 than pH 2.5 and for products formulated when drug was loaded during the second desolvation stage compared to when drug was loaded onto pre-formed nanoparticles. Further investigation of pH effect showed a new isoelectric point of 6.23-6.27 at which the zeta potential of nanoparticles was zero. Sucrose and glucose were effective in low concentrations as cryoprotectants. The best formulation produced an EC(50) value of 227.4 μM as a haemolytic agent compared to 51.61 μM by the free compound which is an indication of reduction in haemolytic side effect. There was sustained released of the compound from all formulation types over a period of 192 h. Stability data indicated that the nanosuspension and freeze-dried samples were stable at 4 and 25°C, respectively, over a 52-week period, but the former was less stable at room temperature. In conclusion, cryptolepine hydrochloride-loaded gelatine nanoparticles exhibited reduced haemolytic effect compared to the pure compound and can be developed further for parenteral delivery.

Development and evaluation of artemether parenteral microemulsion

The objective of the present investigation was to develop a parenteral microemulsion delivering artemether, a hydrophobic antimalarial drug and to evaluate antimalarial activity of the microemulsion in comparison to the marketed oily injection of artemether (Larither^®). The microemulsion was evaluated for various parameters such as globule size, ability to withstand centrifugation and freeze-thaw cycling and effect of sterilization method on the drug content and globule size. The in vivo antimalarial activity of the microemulsion was evaluated in P. berghei infected mice in comparison to the Larither^;. The stability of the microemulsion was evaluated at 5º for 1 month. The microemulsion exhibited globule size of 113 nm and it could successfully withstand centrifugation and freeze-thaw cycling. The method of sterilization did not have any significant effect on the artemether content and globule size of the microemulsion. The microemulsion showed around 1.5-fold higher antimalarial activity and higher survival as compared to that of marketed artemether injection Larither^® and it showed a good stability at the end of 1 month.

Physicochemical characterization and in vivo bioluminescence imaging of nanostructured lipid carriers for targeting the brain: apomorphine as a model drug

Nanostructured lipid carriers (NLCs) were prepared to investigate whether the duration of brain targeting and accumulation of drugs in the brain can be improved by intravenous delivery. NLCs were developed using cetyl palmitate as the lipid matrix, squalene as the cationic surfactant, and Pluronic F68, polysorbate 80 and polyethylene glycol as the interfacial additives. Solid lipid nanoparticles (SLNs) and lipid emulsions (LEs) were also prepared for comparison. An anti-Parkinson's drug, apomorphine, was used as the model drug. Nuclear magnetic resonance and differential scanning calorimetry showed possible interactions between the solid and liquid lipids in the inner core. The lipid nanoparticles with different compositions were characterized by mean size, zeta potential, apomorphine encapsulation and in vitro drug release. NLCs were 370-430 nm in size, which was between the sizes of the SLNs and LEs. A cationic surfactant was used to produce a positive surface charge of 42-50 mV. The base form of apomorphine was successfully entrapped by NLCs with an entrapment percentage of > 60%. The loading of apomorphine in nanoparticles resulted in a slower release behavior compared to the aqueous solution, with LEs showing the lowest release. In vivo real-time bioluminescence imaging of the rat brain revealed that NLCs could be targeted, through certain vessels, to selected brain regions. This effect was further confirmed by imaging the entire brain and brain slices. The results indicated that NLCs with moderate additives are a promising controlled-release and drug-targeting system.

Self-microemulsifiyng suppository formulation of β-artemether

Parasitic diseases are of immense global significance as around 30% of world's population experiences parasitic infections. Among these, malaria is the most life-threatening disease. Various routes of administration have been explored for delivering antimalarial actives. The present investigation aims at formulating self-microemulsifying suppositories of β-artemether with faster onset of action and prolonged effect to be administered by rectal route. These were compared with conventional polyethylene glycol suppositories with respect to melting range, rheology, texture analysis, disintegration time, self microemulsification time, particle size, and drug content. In vitro drug release was studied by using USP apparatus II. Further, the suppositories were evaluated in murine model against virulent rodent malaria parasite Plasmodium berghei wherein the developed self-microemulsifying suppositories could sustain the activity (94%) for 20 days post infection. The survival of animals was also better as compared to the conventional formulation.

Nanotechnology applied to the treatment of malaria

Despite the fact that we live in an era of advanced technology and innovation, infectious diseases, like malaria, continue to be one of the greatest health challenges worldwide. The main drawbacks of conventional malaria chemotherapy are the development of multiple drug resistance and the non-specific targeting to intracellular parasites, resulting in high dose requirements and subsequent intolerable toxicity. Nanosized carriers have been receiving special attention with the aim of minimizing the side effects of drug therapy, such as poor bioavailability and the selectivity of drugs. Several nanosized delivery systems have already proved their effectiveness in animal models for the treatment and prophylaxis of malaria. A number of strategies to deliver antimalarials using nanocarriers and the mechanisms that facilitate their targeting to Plasmodium spp.-infected cells are discussed in this review. Taking into account the peculiarities of malaria parasites, the focus is placed particularly on lipid-based (e.g., liposomes, solid lipid nanoparticles and nano and microemulsions) and polymer-based nanocarriers (nanocapsules and nanospheres). This review emphasizes the main requirements for developing new nanotechnology-based carriers as a promising choice in malaria treatment, especially in the case of severe cerebral malaria.

Nanostructured lipid carriers constituted from high-density lipoprotein components for delivery of a lipophilic cardiovascular drug

To investigate the possibility of reconstituted protein-free high-density lipoprotein (HDL) being a carrier for delivering a lipophilic cardiovascular drug, Tanshinone IIA-loaded HDL-like nanostructured lipid carriers (TA-NLC) were prepared by a nanoprecipitation/solvent diffusion method. The physicochemical parameters of TA-NLC were characterized in terms of particle size, zeta potential, morphology, entrapment efficiency, differential scanning calorimetry (DSC) and stability. A novel two-step method has been employed to determine entrapment efficiency of TA-NLC. The binding properties of TA-NLC to apolipoproteins were investigated by in vitro incubation competition assay in the presence of native HDL and electrophoresis test. Phagocytosis and cytotoxicity was evaluated using mouse macrophage cell line RAW 264.7 with TA-NLC and incubated TA-NLC with native HDL (TA-NLC-apo). The results showed that TA-NLC had an average diameter of 8.0+/-1.2 nm, zeta potential of -29.0+/-0.0 mV, drug loading of 6.17+/-0.3% and entrapment efficiency of 97.84+/-1.2%. TA-NLC were demonstrated spheres with drug incorporated in lipid core forming a shell-core structure. DSC analysis showed that TA was dispersed in NLC in an amorphous state. The incorporation of glycerol trioleate to NLC led to crystal order disturbance. Agarose gel electrophoresis and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-SPAGE) patterns indicated that TA-NLC could bind to apolipoprotein A-I (apoA-I) specifically in vitro. Phagocytosis studies showed significant differences in uptake between TA-NLC and TA-NLC-apo and demonstrated that TA-NLC incubated with native HDL could turn endogenous by association to apolipoproteins, which cannot trigger immunological responses and could escape from recognition by macrophages.

Chapter 6 - Solid lipid nanoparticle formulations pharmacokinetic and biopharmaceutical aspects in drug delivery

Solid lipid nanoparticles (SLNs) have emerged as important tools to modify the release profile for a large number of drugs including protein and peptide molecules. SLNs are produced from biocompatible and biodegradable lipid materials, making them a promising therapeutic strategy for drug targeting and delivery, and surmounting the inherent limitations of regulation acceptance. Due to their versatility in loading both lipophilic and hydrophilic molecules in the solid lipid matrix, SLNs depict the ability to prolong, extend or sustain the release profile of the loaded molecules, therefore reducing the repeated administration, and increasing the therapeutic value of a certain treatment. Additional advantages include reduction of drug toxicity and increase of drug bioavailability. To develop SLN formulations for drug targeting and delivery, a basic pharmacokinetic understanding of drug distribution is of major relevance, as well as the biopharmaceutical aspects of the administration route. This chapter provides a fundamental understanding of the pharmacokinetic properties of SLNs, which influence both biopharmaceutical and clinical profiles of the loaded molecules.