Improvement of antischistosomal activity of praziquantel by incorporation into phosphatidylcholine-containing liposomes

Nanotechnological approaches in the treatment of schistosomiasis: an overview

Schistosomiasis causes over 200,000 deaths annually. The current treatment option, praziquantel, presents limitations, including low bioavailability and resistance. In this context, nanoparticles have emerged as a promising option for improving schistosomiasis treatment. Several narrative reviews have been published on this topic. Unfortunately, the lack of clear methodologies presented in these reviews leads to the exclusion of many important studies without apparent justification. This integrative review aims to examine works published in this area with a precise and reproducible method. To achieve this, three databases (i.e., Pubmed, Web of Science, and Scopus) were searched from March 31, 2022, to March 31, 2023. The search results included only original research articles that used nanoparticles smaller than 1 µm in the treatment context. Additionally, a search was conducted in the references of the identified articles to retrieve works that could not be found solely using the original search formula. As a result, 65 articles that met the established criteria were identified. Inorganic and polymeric nanoparticles were the most prevalent nanosystems used. Gold was the primary material used to produce inorganic nanoparticles, while poly(lactic-co-glycolic acid) and chitosan were commonly used to produce polymeric nanoparticles. None of these identified works presented results in the clinical phase. Finally, based on our findings, the outlook appears favorable, as there is a significant diversity of new substances with schistosomicidal potential. However, financial efforts are required to advance these nanoformulations.

Praziquantel Fifty Years on: A Comprehensive Overview of Its Solid State

This review discusses the entire progress made on the anthelmintic drug praziquantel, focusing on the solid state and, therefore, on anhydrous crystalline polymorphs, amorphous forms, and multicomponent systems (i.e., hydrates, solvates, and cocrystals). Despite having been extensively studied over the last 50 years, new polymorphs and the greater part of their cocrystals have only been identified in the past decade. Progress in crystal engineering science (e.g., the use of mechanochemistry as a solid form screening tool and more strategic structure-based methods), along with the development of analytical techniques, including Synchrotron X-ray analyses, spectroscopy, and microscopy, have furthered the identification of unknown crystal structures of the drug. Also, computational modeling has significantly contributed to the prediction and design of new cocrystals by considering structural conformations and interactions energy. Whilst the insights on praziquantel polymorphs discussed in the present review will give a significant contribution to controlling their formation during manufacturing and drug formulation, the detailed multicomponent forms will help in designing and implementing future praziquantel-based functional materials. The latter will hopefully overcome praziquantel's numerous drawbacks and exploit its potential in the field of neglected tropical diseases.

Mefloquine loaded niosomes as a promising approach for the treatment of acute and chronic toxoplasmosis

Toxoplasmosis is a disease with a worldwide distribution and significant morbidity and mortality. In search of effective treatment, mefloquine (MQ) was repurposed and loaded with niosomes to treat acute and chronic phases of toxoplasmosis in experimental mice. Mice were orally inoculated with 20 cysts of Toxoplasma gondii (ME 49 strain) for the acute model of infection and 10 cysts for the chronic model of infection. Infected mice were dosed with MQ solution or MQ-niosomes at 50 mg/kg/day, starting from the second day post-infection (PI) (acute model) or the fifth week PI (chronic model), and this was continued for six consecutive days. The effects of MQ solution and MQ-niosomes were compared with a pyrimethamine/sulfadiazine (PYR/SDZ) dosing combination as mortality rates, brain cyst number, inflammatory score, and immunohistochemical studies that included an estimation of apoptotic cells (TUNEL assays). In the acute infection model, MQ solution and MQ-niosomes significantly reduced the mortality rate from 45% to 25 and 10%, respectively, compared with infected untreated controls, and decreased the number of brain cysts by 51.5% and 66.9%, respectively. In the chronic infection model, cyst reduction reached 80.9% and 12.3% for MQ solution and MQ-niosomes treatments, respectively. MQ-niosomes significantly decreased inflammation induced by acute or chronic T. gondii infection. Additionally, immunohistochemical analysis revealed that MQ solution and MQ-niosomes significantly increased the number of TUNEL-positive cells in brain tissue, indicative of induction of apoptosis. Collectively, these results indicate that MQ-niosomes may provide a useful delivery strategy to treat both acute and chronic toxoplasmosis.

Potential application of nanotechnology in the treatment, diagnosis, and prevention of schistosomiasis

Schistosomiasis is one of the neglected tropical diseases that affect millions of people worldwide. Globally, it affects economically poor countries, typically due to a lack of proper sanitation systems, and poor hygiene conditions. Currently, no vaccine is available against schistosomiasis, and the preferred treatment is chemotherapy with the use of praziquantel. It is a common anti-schistosomal drug used against all known species of Schistosoma. To date, current treatment primarily the drug praziquantel has not been effective in treating Schistosoma species in their early stages. The drug of choice offers low bioavailability, water solubility, and fast metabolism. Globally drug resistance has been documented due to overuse of praziquantel, Parasite mutations, poor treatment compliance, co-infection with other strains of parasites, and overall parasitic load. The existing diagnostic methods have very little acceptability and are not readily applied for quick diagnosis. This review aims to summarize the use of nanotechnology in the treatment, diagnosis, and prevention. It also explored safe and effective substitute approaches against parasitosis. At this stage, various nanomaterials are being used in drug delivery systems, diagnostic kits, and vaccine production. Nanotechnology is one of the modern and innovative methods to treat and diagnose several human diseases, particularly those caused by parasite infections. Herein we highlight the current advancement and application of nanotechnological approaches regarding the treatment, diagnosis, and prevention of schistosomiasis.

Tunable Polymeric Mixed Micellar Nanoassemblies of Lutrol F127/Gelucire 44/14 for Oral Delivery of Praziquantel: A Promising Nanovector against Hymenolepis nana in Experimentally-Infected Rats

Hymenolepiasis represents a parasitic infection of common prevalence in pediatrics with intimidating impacts, particularly amongst immunocompromised patients. The present work aimed to snowball the curative outcomes of the current mainstay of hymenolepiasis chemotherapy, praziquantel (PRZ), through assembly of polymeric mixed micelles (PMMs). Such innovative nano-cargo could consolidate PRZ hydrosolubility, extend its circulation time and eventually upraise its bioavailability, thus accomplishing a nanoparadigm for hymenolepiasis tackling at lower dose levels. For consummating this goal, PRZ-PMMs were tailored via thin-film hydration technique integrating a binary system of Lutrol F127 and Gelucire 44/14. Box-Behnken design was planned for optimizing the nanoformulation variables employing Design-Expert^® software. Also, in Hymenolepis nana-infected rats, the pharmacodynamics of the optimal micellar formulation versus the analogous crude PRZ suspension were scrutinized on the 1st and 3rd days after administration of a single oral dose (12.5 or 25 mg/kg). Moreover, in vitro ovicidal activity of the monitored formulations was estimated utilizing Fuchsin vital stain. Furthermore, the in vivo pharmacokinetics were assessed in rats. The optimum PRZ-PMMs disclosed conciliation between thermodynamic and kinetic stability, high entrapment efficiency (86.29%), spherical nanosized morphology (15.18 nm), and controlled-release characteristics over 24 h (78.22%). ¹H NMR studies verified PRZ assimilation within the micellar core. Additionally, the in vivo results highlighted a significant boosted efficacy of PRZ-PMMs manifested by fecal eggs output and worm burden reduction, which was clearly evident at the lesser PRZ dose, besides a reversed effect for the intestinal histological disruptions. At 50 µg/mL, PRZ-PMMs increased the percent of non-viable eggs to 100% versus 47% for crude PRZ, whilst shell destruction and loss of embryo were only clear with the applied nano-cargo. Moreover, superior bioavailability by 3.43-fold with elongated residence time was measured for PRZ-PMMs compared to PRZ suspension. Practically, our results unravel the potential of PRZ-PMMs as an oral promising tolerable lower dose nanoplatform for more competent PRZ mass chemotherapy.

In Vivo Evaluation of Praziquantel-Loaded Solid Lipid Nanoparticles against S. mansoni Infection in Preclinical Murine Models

This study aimed to develop and assess the long-term stability of drug-loaded solid lipid nanoparticles (SLNs). The SLNs were designed to extend the release profile, overcome the problems of bioavailability and solubility, investigate toxicity, and improve the antischistosomal efficacy of praziquantel. The aim was pursued using solvent injection co-homogenization techniques to fabricate SLNs in which Compritol ATO 888 and lecithin were used as lipids, and Pluronic F127 (PF127) was used as a stabilizer. The long-term stability effect of the PF127 as a stabilizer on the SLNs was evaluated. Dynamic light scattering (DLS) was used to determine the particle size, stability, and polydispersity. The morphology of the SLNs was examined through the use of transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The chemical properties, as well as the mechanical, thermal, and crystal behaviours of SLNs were evaluated using FTIR, ElastoSens Bio2, XRPD, DSC, and TGA, respectively. SLNs with PF127 depicted an encapsulation efficiency of 71.63% and a drug loading capacity of 11.46%. The in vitro drug release study for SLNs with PF127 showed a cumulative release of 48.08% for the PZQ within 24 h, with a similar release profile for SLNs' suspension after 120 days. DLS, ELS, and optical characterization and stability profiling data indicate that the addition of PF127 as the surfactants provided long-term stability for SLNs. In vitro cell viability and in vivo toxicity evaluation signify the safety of SLNs stabilized with PF127. In conclusion, the parasitological data showed that in S. mansoni-infected mice, a single (250 mg/kg) oral dosage of CLPF-SLNs greatly improved PZQ antischistosomal efficacy both two and four weeks post-infection. Thus, the fabricated CLPF-SLNs demonstrated significant efficiency inthe delivery of PZQ, and hence are a promising therapeutic strategy against schistosomiasis.

Itraconazole, a cytochrome P450 inhibitor, enhanced the efficacy of praziquantel against Schistosoma mansoni infection and alleviated liver injury in mice

Treatment of schistosomiasis is heavily reliant on the single antischistosomal drug praziquantel (PZQ). The use of synergistic drug-drug interactions is one possible solution, which could be used to mitigate PZQ's poor and variable bioavailability. Itraconazole (ITZ), a triazole antifungal agent, is a potent CYP3A inhibitor that can cause significant drug-drug interactions when used with CYP3A substrates. This study investigates the effect of ITZ as adjuvant therapy with PZQ on worm load, egg deposition and maturation, and the consequent histopathology and biochemical abnormalities in the liver during the immature and mature stages of Schistosoma mansoni (S. mansoni) infection. S. mansoni-infected mice were divided into five groups of eight-ten mice each: (I) infected untreated, (II) infected and treated with PZQ 3 weeks PI, (III) infected and treated with both ITZ and PZQ 3 weeks PI, (IV) infected and treated with PZQ 7 weeks PI, and (V) infected and treated with both ITZ and PZQ 7 weeks PI. All mice were killed by rapid decapitation 9 weeks PI. Data revealed that ITZ in combination with PZQ at both immature and mature stages improved the parasitological criteria of cure, and greatly reduced inflammation, granuloma and fibrotic tissue formation, and apoptosis versus PZQ alone. Furthermore, it showed the greatest impact on improving liver injury and oxidative stress markers. Notably, the effect was considerably stronger at the mature stage of S. mansoni infection. These findings support the notion that ITZ increased PZQ's antischistosomal activity by inhibiting CYP450 expression, potentially reducing PZQ metabolism and increasing systemic exposure.

Recent trends in praziquantel nanoformulations for helminthiasis treatment

INTRODUCTION

Infections caused by parasitic flatworms impose a considerable worldwide health burden. Recently, World Health Organization launched its roadmap for neglected diseases for the period 2021 to 2030 and oral treatment with praziquantel (PZQ) in tablet form is the main drug therapy for combating these diseases, but its use is limited by many drawbacks, including the high therapeutic dose due to the drug's low solubility and bioavailability. Among the strategies to improve PZQ performance, the use of drug nanocarriers has been cited as an interesting approach to overcome these pharmacological issues.

AREAS COVERED

This review focuses on the various types of nanomaterials (polymeric, lipidic, inorganic nanoparticles, and nanocrystals) which have been recently used to improve PZQ therapy. In addition, recent advances in PZQ nanoformulations, developed to overcome the barriers of the conventional drug are described.

EXPERT OPINION

Considering the poor rate of discovery in the anthelmintic segment observed in recent decades, the effective management of existing drugs has become essential. The application of new strategies based on nanotechnology can extend the useful life of PZQ in new and more effective formulations. Pharmaceutical nanotechnology can solve the pharmacokinetic challenges characteristic of PZQ and improve its solubility and bioavailability.

Synthesis and therapeutic delivery approaches for praziquantel: a patent review (2010-present)

INTRODUCTION

: Among all the anti-schistosomal drugs, praziquantel has been the most widely used. However, some major challenges have been faced using the drug in the treatment of schistosome infections.

AREAS COVERED

: Several approaches used in the synthesis of praziquantel aimed at reducing the time and cost of production, the toxicity and experimental harsh conditions are discussed. Also, patented methods involved in the pharmaceutical reformulation of praziquantel in the treatment of diverse endoparasitic infestations are reported. Additionally, future perspectives in terms of nanomedicine approach in the formulation of praziquantel are highlighted.

EXPERT OPINION

: Lipid-based nanosystems (LBNSs) formulations can be used to overcome the shortcomings associated with the use of praziquantel in the schistosomiasis treatment due to their amphipathic nature. This could be a promising vehicle for the delivery of praziquantel, which could in turn improve the bioavailability, as well as reduce the frequent dose of the drug and improve patient compliance. This may sustain the release of the drug and improve the rapid conversion of the drug into inactive metabolite due to rapid metabolism. Additionally, LBNSs approach could increase and improve the lipophilicity of the drug, which could make it easier to interact with the hydrophobic cores of the worm tegument.

Nanostructured lipid carriers for enhanced in vitro and in vivo schistosomicidal activity of praziquantel: effect of charge

WHO considers praziquantel (PZQ) as the drug of choice for treatment of Schistosoma mansoni infection but this requires high dose due to poor solubility and first pass metabolism. The aim of this work was to optimize nanostructured lipid carriers (NLCs) for enhanced PZQ oral delivery. The optimization involved testing the effect of surface charge of NLCs. NLCs comprised precirol ATO as solid lipid with oleic acid, Span 60 and Tween 80 as liquid components. Dicetyl phosphate and stearyl amine were the negative and positive charging agents, respectively. NLCs were prepared by microemulsification technique and were characterized. The schistosomicidal activity of PZQ loaded NLCs was monitored in vitro and in vivo using infected mice. PZQ showed high entrapment efficiency in all types of NLCs (ranged from 93.97 to 96.29%) with better PZQ loading in standard NLCs. This was clarified by thermal analysis which reflected displacement of PZQ by charging agents. In vitro schistosomicidal study revealed the superiority of PZQ loaded positively charged NLCs (LC50 and LC95 equal 0.147 and 0.193 µg/ml respectively) with traditional and negatively charged NLCs being inferior to simple PZQ solution after short incubation period. Scanning electron micrographs showed that PZQ loaded positively charged NLCs resulted in more intense ultrastructural changes in worms. The superiority of positively charged NLCs was confirmed by in vivo assessment as they showed better improvement in histopathological features of the liver of the infected mice compared with other formulations. The study introduced positively charged NLCs as promising carriers for oral delivery of PZQ.

Praziquantel-Clays as Accelerated Release Systems to Enhance the Low Solubility of the Drug

Praziquantel is an antiparasitic drug indicated for the treatment of the schistosomiasis disease. This drug has very low aqueous solubility, requiring high oral doses for its administration which gives rise to side effects, therapeutic noncompliance and the appearance of resistant forms of the parasite. Clay minerals, like sepiolite and montmorillonite, are innocuous, non-toxic, biocompatible and low-cost excipients. Additionally, clays have high adsorbent properties that allow them to encapsulate drugs in nanometric spaces present in the channels in the case of the sepiolite or between the layers in the case of the montmorillonite. The interactions between the drug and clay minerals are studied experimentally with the strategy for preparing interactions products in organic solvents (ethanol, acetonitrile and dichloromethane) so that the interaction will be more effective and will be enhanced the aqueous solubility of praziquantel. The results showed that in the interaction products, the drug interacted with both clay minerals, which produced the loss of the crystallinity of the drug demonstrated by different techniques. This led to a significant increase in the dissolution rate of the praziquantel in all the interaction products in the simulated gastrointestinal tract media, except for the praziquantel–montmorillonite product prepared in dichloromethane that presented a controlled release in acid medium. Moreover, in vitro cytotoxicity and cell cycle studies were performed in the interaction products prepared with ethanol. The interaction product with sepiolite was biocompatible with the HTC116 line cells, and it did not produce alterations in the cell cycle. However, interaction products with montmorillonite did not produce cell death, but they showed affectation and damage of cells in the cell cycle study at the highest concentration tested (20–100 µM). Therefore, the different organic solvents used are adequate for the improvement of the biopharmaceutical profile of praziquantel. Drug–clay interaction products, specifically with sepiolite, showed very promising results in which new accelerated oral release systems of the praziquantel were obtained.

First steps in the formulation of praziquantel nanosuspensions for pharmaceutical applications

Praziquantel (PZQ), a broad spectrum anthelmintic drug, cannot be found in acceptable dosage forms for elderly patients, paediatric patients, and for veterinary use. In fact, very little has been done up to now in the formulation of liquid dosage forms, being they always formulated for parenteral administration. To beat this important challenge, it was accomplished a comprehensive analysis of the influence of two elementary physicochemical aspects, i.e. surface thermodynamic and electrokinetic properties, on the colloidal stability of PZQ nanosuspensions. The hydrophobic character of the drug, intensely determining the flocculation curves, was confirmed by the thermodynamic characterization. The electrophoretic characterization, in combination with the sedimentation and relative absorbance versus time curves, highlighted that the electrical double layer thickness and the surface charge can play an essential role in the stability of the pharmaceutical colloid. Finally, it was demonstrated that controlling the pH values and the incorporation of electrolytes can help in formulating PZQ aqueous nanosuspensions with appropriate stability and redispersibility behaviours for pharmaceutical use.

Drug discovery technologies: Caenorhabditis elegans as a model for anthelmintic therapeutics

Helminthiasis is one of the gravest problems worldwide. There is a growing concern on less available anthelmintics and the emergence of resistance creating a major threat to human and livestock health resources. Novel and broad-spectrum anthelmintics are urgently needed. The free-living nematode Caenorhabditis elegans could address this issue through automated high-throughput technologies for the screening of large chemical libraries. This review discusses the strong advantages and limitations for using C elegans as a screening method for anthelmintic drug discovery. C elegans is the best model available for the validation of novel effective drugs in treating most, if not all, helminth infections, and for the elucidation the mode of action of anthelmintic candidates. This review also focuses on available technologies in the discovery of anthelmintics published over the last 15 years with particular attention to high-throughput technologies over conventional screens. On the other hand, this review highlights how combinatorial and nanomedicine strategies could prolong the use of anthelmintics and control resistance problems.

A Review of Nanotechnology for Targeted Anti-schistosomal Therapy

Schistosomiasis is one of the major parasitic diseases and second most prevalent among the group of neglected diseases. The prevalence of schistosomiasis may be due to environmental and socio-economic factors, as well as the unavailability of vaccines for schistosomiasis. To date, current treatment; mainly the drug praziquantel (PZQ), has not been effective in treating the early forms of schistosome species. The development of drug resistance has been documented in several regions globally, due to the overuse of PZQ, rate of parasitic mutation, poor treatment compliance, co-infection with different strains of schistosomes and the overall parasite load. Hence, exploring the schistosome tegument may be a potential focus for the design and development of targeted anti-schistosomal therapy, with higher bioavailability as molecular targets using nanotechnology. This review aims to provide a concise incursion on the use of various advance approaches to achieve targeted anti-schistosomal therapy, mainly through the use of nano-enabled drug delivery systems. It also assimilates the molecular structure and function of the schistosome tegument and highlights the potential molecular targets found on the tegument, for effective specific interaction with receptors for more efficacious anti-schistosomal therapy.

Nanoparticles for antiparasitic drug delivery

As an emerging novel drug carrier, nanoparticles provide a promising way for effective treatment of parasitic diseases by overcoming the shortcomings of low bioavailability, poor cellular permeability, nonspecific distribution and rapid elimination of antiparasitic drugs from the body. In recent years, some kinds of ideal nanocarriers have been developed for antiparasitic drug delivery. In this review, the progress of the enhanced antiparasitic effects of different nanoparticles payload and their influencing factors were firstly summarized. Secondly, the transport and disposition process in the body were reviewed. Finally, the challenges and prospects of nanoparticles for antiparasitic drug delivery were proposed. This review will help scholars to understand the development trend of nanoparticles in the treatment of parasitic diseases and explore strategies in the development of more efficient nanocarriers to overcome the difficulty in the treatment of parasite infections in the future.

Ground Calcium Carbonate as a Low Cost and Biosafety Excipient for Solubility and Dissolution Improvement of Praziquantel

Calcium carbonate is an abundant mineral with several advantages to be a successful carrier to improve oral bioavailability of poorly water-soluble drugs, such as praziquantel. Praziquantel is an antiparasitic drug classified in group II of the Biopharmaceutical Classification System hence characterized by high-permeability and low-solubility. Therefore, the dissolution rate is the limiting factor for the gastrointestinal absorption that contributes to the low bioavailability. Consequently, the therapeutic dose of the praziquantel must be high and big tablets and capsules are required, which are difficult to swallow, especially for pediatric and elderly patients. Mixtures of praziquantel and calcium carbonate using solid-solid physical mixtures and solid dispersions were prepared and characterized using several techniques (X-ray diffraction differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, laser diffraction, Fourier transform infrared and Raman spectroscopies). Solubility of these formulations evidenced that the solubility of praziquantel-calcium carbonate interaction product increased in physiological media. In vitro dissolution tests showed that the interaction product increased the dissolution rate of the drug in acidic medium. Theoretical models were studied to understand this experimental behavior. Cytotoxicity and cell cycle studies were performed, showing that praziquantel-calcium carbonate physical mixture and interaction product were biocompatible with the HTC116 cells, because it did not produce a decrease in cell viability or alterations in the cell cycle.

Effect of nanoparticles on the therapeutic efficacy of praziquantel against Schistosoma mansoni infection in murine models

Praziquantel (PZQ) is the main treatment of Schistosomiasis mansoni. However, resistance to it was described. So, there is a necessity to develop novel drugs or to enhance the present drugs. This work aimed to assess the efficacy of PZQ alone and when loaded on liposomes in treatment of S. mansoni infection by parasitological and histopathological studies in experimental murine models. 112 male laboratories bred Swiss Albino mice were used in this work. They were divided into four groups: Group 1: control group; Group 2: infected then treated by PZQ (500 mg/kg) at 7, 30 and 45 days post infection; Group 3: infected then treated by liposome encapsulated PZQ (lip.PZQ) (500 mg/kg) at 7, 30 and 45 days post infection; Group 4: infected then treated by free liposomes at 7, 30 and 45 days post infection. The results showed that G3 caused the highest significant reduction of the total worm count, eggs/gram liver tissue and intestine (97.2%, 99.3%, 99.5%) respectively. Followed by G2 (85.1%, 97.6%, 89.8%) respectively. Regarding the histopathological studies, G3 showed the highest significant reduction in number and diameter of hepatic granuloma (97.6% and 98.1%), followed by G2 (77.2% and 75%) when compared to other groups. In conclusion, lip.PZQ is more effective than free PZQ from all aspects especially when administered 45 days PI.

In vivo treatment of experimental neurocysticercosis with praziquantel nanosuspensions-a metabolic approach

Neurocysticercosis is the most common parasitic infection of the nervous system and currently represents a serious public health issue in many regions of Latin America, Asia, and Africa. To date, praziquantel is one of the chosen drugs for the treatment of neurocysticercosis. Its mechanism of action is based on the inhibition of different biochemical pathways within the parasite which contribute to its death. Thus, the aim of this work was to analyze, for the first time, whether the nanoformulations of praziquantel would modify the energetic pathway of Taenia crassiceps cysticerci, after an intracranial inoculation in BALB/c mice. Praziquantel nanosuspensions were formulated with polyvinyl alcohol, poloxamer 188, and poloxamer 407, as stabilizers. These formulations exhibited particle size in a range of 74-285 nm and zeta potential values in a range of - 8.1/- 13.2 depending on the type of stabilizer. Physical stability study at both 4 ± 2 and 25 ± 2 °C indicated that praziquantel (PZQ) nanoparticles were stable in terms of solubility and particle size after 120-day storage. In vivo studies demonstrated that those nanosystems were able to produce significant modifications on the concentrations of oxaloacetate, citrate, pyruvate, alpha-ketoglutarate, malate, succinate, lactate, beta-hydroxybutyrate, fumarate, and propionate involved in the metabolism of Taenia crassiceps cysticerci. Therefore, these nanoformulations may be considered as a promising tool to deliver praziquantel to the brain for the effective management of neurocysticercosis.

Chitosan-based nanodelivery systems applied to the development of novel triclabendazole formulations

Triclabendazole is a poorly-water soluble (0.24 μg/mL) compound classified into the Class II/IV of the Biopharmaceutical Classification System. It is the drug of choice to treat fascioliasis, a neglected parasitic disease worldwide disseminated. Triclabendazole is registered as veterinary medicine and it is only available for human treatment as 250 mg tablets. Thus, the aim of this work was to develop novel drug delivery systems based on nanotechnology approaches. The chitosan-based nanocapsules and nanoemulsions of triclabendazole were fully characterized regarding their particle size distribution, polydispersity index and zeta potential, in-vitro release and stability in biological media. Cytotoxicity evaluation and cellular uptake studies using CaCo-2 cell line were also investigated. The results indicated an average hydrodynamic size around ~160 nm were found for unloaded nanoemulsions which were slightly increased up to ~190 nm for loaded one. In contrast, the average hydrodynamic size of the nanocapsules increased from ~160 nm up to ~400 nm when loaded with triclabendazole. The stability studies upon 30 days storage at 4, 25 and 37°C showed that average size of nanoemulsions was not modified with varying amounts of loaded TCBZ while an opposite result was seen in case of loaded nanocapsules. In addition, a slight reduction of zeta potential values over time was observed in both triclabendazole nanosystems. Release of TCBZ from nanoformulations over 6 h in simulated gastric fluid was 9 to 16-fold higher than with untreated TCBZ dispersion. In phosphate buffer saline solution there was no drug release for neither nanocapsules nor nanoemulsions. Cell viabilities studies indicated that at certain concentrations, drug encapsulation can lower its cytotoxic effects when compared to untreated drug. Confocal laser scanning microscopy study has shown that nanocapsules strongly interacted with Caco-2 cells in vitro which could increase the passage time of triclabendazole after oral administration. The results of this study constitute the first step towards the development of nanoformulations intended for the oral delivery of anti-parasitic drugs of enhanced bioavailability.

Praziquantel-lipid nanocapsules: an oral nanotherapeutic with potential Schistosoma mansoni tegumental targeting

Purpose

Lipid nanocapsules (LNCs) have shown potential to increase the bioavailability and efficacy of orally administered drugs. However, their intestinal translocation to distal target sites and their implication in pharmacokinetic (PK)–pharmacodynamic (PD) relationships are yet to be elucidated. In this study, the effect of LNCs on the PD activity and pharmacokinetics of praziquantel (PZQ), the mainstay of schistosomiasis chemotherapy, was investigated.

Materials and methods

The composition of LNCs was modified to increase PZQ payload and to enhance membrane permeability. PZQ–LNCs were characterized in vitro for colloidal properties, entrapment efficiency (EE%), and drug release. PD activity of the test formulations was assessed in Schistosoma mansoni-infected mice 7 days post-oral administration of a single 250 mg/kg oral dose. Pharmacokinetics of the test formulations and their stability in simulated gastrointestinal (GI) fluids were investigated to substantiate in vivo data.

Results

PZQ–LNCs exhibited good pharmaceutical attributes in terms of size (46–62 nm), polydispersity index (0.01–0.08), EE% (>95%), and sustained release profiles. Results indicated significant efficacy enhancement by reduction in worm burden, amelioration of liver pathology, and extensive damage to the fluke suckers and tegument. This was partly explained by PK data determined in rats. In addition, oral targeting of the worms was supported by the stability of PZQ–LNCs in simulated GI fluids and scanning electron microscopy (SEM) visualization of nanostructures on the tegument of worms recovered from mesenteric/hepatic veins. Cytotoxicity data indicated tolerability of PZQ–LNCs.

Conclusion

Data obtained provide evidence for the ability of oral LNCs to target distal post-absorption sites, leading to enhanced drug efficacy. From a practical standpoint, PZQ–LNCs could be suggested as a potential tolerable single lower dose oral nanomedicine for more effective PZQ mass chemotherapy.

Nanomedicine Approaches Against Parasitic Worm Infections

Nanomedicine approaches have the potential to transform the battle against parasitic worm (helminth) infections, a major global health scourge from which billions are currently suffering. It is anticipated that the intersection of two currently disparate fields, nanomedicine and helminth biology, will constitute a new frontier in science and technology. This progress report surveys current innovations in these research fields and discusses research opportunities. In particular, the focus is on: (1) major challenges that helminth infections impose on mankind; (2) key aspects of helminth biology that inform future research directions; (3) efforts to construct nanodelivery platforms to target drugs and genes to helminths hidden in their hosts; (4) attempts in applying nanotechnology to enable vaccination against helminth infections; (5) outlooks in utilizing nanoparticles to enhance immunomodulatory activities of worm-derived factors to cure allergy and autoimmune diseases. In each section, achievements are summarized, limitations are explored, and future directions are assessed.

Evaluation of nanoselenium and nanogold activities against murine intestinal schistosomiasis

Nanomedicine is one of the most important methods used to treat human diseases including parasitic diseases. Schistosomiasis is a major parasitic disease that affects human health in tropical regions. Whilst Praziquantel is the main classic antischistosomal drug, new drugs are required due to the poor effect of the drug on the parasite juveniles and immature worms, and the emergence of drug resistant strains of Schistosoma. The present study aimed to examine the curative roles of both gold and selenium nanoparticles on jejunal tissues of mice infected with Schistosoma mansoni. Transmission electron microscopy was used for characterization of nanoparticles. Gold nanoparticles of 1 mg/kg mice body weight and selenium nanoparticles 0.5 mg/kg body weight were inoculated separately into mice infected with S. mansoni. The parasite induced a significant decrease in glutathione levels; however, the levels of nitric oxide and malondialdehyde were significantly increased. Additionally, the parasite introduced deteriorations in histological architecture of the jejunal tissue. Treatment of mice with metal nanoparticles reduced the levels of body weight changes, oxidative stress and histological impairment in the jejunal tissue significantly. Therefore, our results revealed the protective role of both selenium and gold nanoparticles against jejunal injury in mice infected with S. mansoni.

Effect of gold nanoparticles on mice splenomegaly induced by schistosomiasis mansoni

Schistosomiasis is still one of the main parasitic diseases that affect human health in tropical regions. Whilst praziquantel (PZQ) is the main classic antischistosomal drug, the need for new drugs is still a must due to the low effectiveness of the drug on the schistosome young worms, and the evolving of PZQ resistant strains. Nanotechnology is one of the most important recent and current methods used to treat human diseases including parasitic ones. Therefore, the present study aimed to examine the curative role of gold nanoparticles (GNPs) on splenic tissue of mice infected with Schistosoma mansoni Sambon, 1907. High-resolution transmission electron microscopy was used for characterization of nanoparticles (NP). GNPs of 1 mg/kg mice body weight were inoculated into mice infected with S. mansoni. The parasite caused deteriorations in histological architecture of the spleen tissue, and splenomegaly. Additionally, the parasite induced a significant reduction in splenic tissue glutathione levels; however, the concentrations of nitric oxide and malondialdehyde were significantly increased. Treatment of mice with GNPs reduced the extent of histological impairment and oxidative stress in spleen tissue. Therefore, our results demonstrate the protective role of GNPs against splenic damage in mice infected with S. mansoni.

Nanopharmaceuticals as a solution to neglected diseases: Is it possible?

The study of neglected diseases has not received much attention, especially from public and private institutions over the last years, in terms of strong support for developing treatment for these diseases. Support in the form of substantial amounts of private and public investment is greatly needed in this area. Due to the lack of novel drugs for these diseases, nanobiotechnology has appeared as an important new breakthrough for the treatment of neglected diseases. Recently, very few reviews focusing on filiarasis, leishmaniasis, leprosy, malaria, onchocerciasis, schistosomiasis, trypanosomiasis, and tuberculosis, and dengue virus have been published. New developments in nanocarriers have made promising advances in the treatment of several kinds of diseases with less toxicity, high efficacy and improved bioavailability of drugs with extended release and fewer applications. This review deals with the current status of nanobiotechnology in the treatment of neglected diseases and highlights how it provides key tools for exploring new perspectives in the treatment of a wide range of diseases.

Miltefosine lipid nanocapsules: Intersection of drug repurposing and nanotechnology for single dose oral treatment of pre-patent schistosomiasis mansoni

A dual drug repurposing/nanotechnological approach was used to develop an alternative oral treatment for schistosomiasis mansoni using miltefosine (MFS), an anticancer alkylphosphocholine, and lipid nanocapsules (LNCs) as oral nanovectors. We demonstrated earlier that MFS possesses significant activity against different developmental stages of Schistosoma mansoni in the mouse model using 5 successive 20mg/kg/day oral doses. Moreover, an effective single dose (20mg/kg) oral treatment against the adult stage of S. mansoni in mice was developed using LNCs, particularly modified with CTAB, a positive charge imparting agent (MFS-LNC-CTAB(+)), or oleic acid as membrane permeabilizer (MFS-LNC-OA). Efficacy enhancement involved, at least in part, targeting of the worm tegument with MFS-LNCs as a new therapeutic entity. As the tegument surface charge and composition may differ in pre-patent stages of the parasite, it was of importance in the present study to assess the efficacy of a single oral dose of the two MFS-LNC formulations against invasive and immature stages for potential advantage relative to praziquantel. Results indicated potent schistosomicidal effects against both invasive and immature stages of S. mansoni in infected mice, efficacy being both formulation and developmental stage dependent. This was indicated by the significant reduction in the total worm burden of the invasive stage by 91.6% and 76.8% and the immature stage by 82.7% and 96.7% for MFS-LNC-CTAB+ and MFS-LNC-OA, respectively. Histopathological findings indicated amelioration of hepatic pathology with regression of the granulomatous inflammatory reaction and reduction in granulomas number and size, verifying marked improvement in architecture of hepatic lobules. From a clinical perspective, MFS-LNCs offer potential as an alternative single oral dose nanomedicine with a wide therapeutic profile for the mass chemotherapy of schistosomiasis mansoni.

Effectiveness of hyperbaric oxygen for experimental treatment of schistosomiasis mansoni using praziquantel-free and encapsulated into liposomes: assay in adult worms and oviposition

The treatment of schistosomiasis depends on a single drug: praziquantel (PZQ). However, this treatment presents limitations such as low and/or erratic bioavailability that can contribute to cases of tolerance. Improvements to the available drug are urgently needed and studies with a controlled system of drug release, like liposomes, have been gaining prominence. The present study evaluated the activity and synergy between liposomal-praziquantel (lip.PZQ) and hyperbaric oxygen therapy (HBO). Mice received doses of 60 or 100mg/kg PZQ or lip.PZQ, 50 days post-infection, and after the treatment, were exposed to HBO (3 atmosphere absolute - ATA) for 1h. The viability of adult worms and oviposition were analyzed, by necropsy and Kato-Katz examination performed after 15 days of treatment. A concentration of 100mg/kg of lip.PZQ+HBO was more effective (48.0% reduction of worms, 83.3% reduction of eggs/gram of feces) and 100% of the mice had altered of oograms (indicating interruption of oviposition) compared to other treatments and to the Control group (infected and untreated). It is known that PZQ requires participation of the host immune system to complete its antischistosomal activity and that HBO is able to stimulate the immune system. The drug became more available in the body when incorporated into liposomes and, used with HBO, the HBO worked as an adjuvant. This explains the decreases of oviposition and worms recovered form hepatic portal system.

Nanotechnology-based drug delivery systems for the treatment of Alzheimer's disease

Alzheimer's disease is a neurological disorder that results in cognitive and behavioral impairment. Conventional treatment strategies, such as acetylcholinesterase inhibitor drugs, often fail due to their poor solubility, lower bioavailability, and ineffective ability to cross the blood-brain barrier. Nanotechnological treatment methods, which involve the design, characterization, production, and application of nanoscale drug delivery systems, have been employed to optimize therapeutics. These nanotechnologies include polymeric nanoparticles, solid lipid nanoparticles, nanostructured lipid carriers, microemulsion, nanoemulsion, and liquid crystals. Each of these are promising tools for the delivery of therapeutic devices to the brain via various routes of administration, particularly the intranasal route. The objective of this study is to present a systematic review of nanotechnology-based drug delivery systems for the treatment of Alzheimer's disease.

Praziquantel in a clay nanoformulation shows more bioavailability and higher efficacy against murine Schistosoma mansoni infection

Consideration of existing compounds always simplifies and shortens the long and difficult process of discovering new drugs specifically for diseases of developing countries, an approach that may add to the significant potential cost savings. This study focused on improving the biological characteristics of the already-existing antischistosomal praziquantel (PZQ) by incorporating it into montmorillonite (MMT) clay as a delivery carrier to overcome its known bioavailability drawbacks. The oral bioavailability of a PZQ-MMT clay nanoformulation and its in vivo efficacy against Schistosoma mansoni were investigated. The PZQ-MMT clay nanoformulation provided a preparation with a controlled release rate, a decrease in crystallinity, and an appreciable reduction in particle size. Uninfected and infected mice treated with PZQ-MMT clay showed 3.61- and 1.96-fold and 2.16- and 1.94-fold increases, respectively, in area under the concentration-time curve from 0 to 8 h (AUC0-8) and maximum concentration of drug in serum (Cmax), with a decrease in elimination rate constant (kel) by 2.84- and 1.35-fold and increases in the absorption rate constant (ka) and half-life (t1/2e) by 2.11- and 1.51-fold and 2.86- and 1.34-fold, respectively, versus the corresponding conventional PZQ-treated groups. This improved bioavailability has been expressed in higher efficacy of the drug, where the dose necessary to kill 50% of the worms was reduced by >3-fold (PZQ 50% effective dose [ED50] was 20.25 mg/kg of body weight for PZQ-MMT clay compared to 74.07 mg/kg for conventional PZQ), with significant reduction in total tissue egg load and increase in total immature, mature, and dead eggs in most of the drug-treated groups. This formulation showed better bioavailability, enhanced antischistosomal efficacy, and a safer profile despite the longer period of residence in the systemic circulation. Although the conventional drug's toxicity was not examined, animal mortality rates were not different between groups receiving the test PZQ-clay nanoformulation and conventional PZQ.

Triclosan and triclosan-loaded liposomal nanoparticles in the treatment of acute experimental toxoplasmosis

Efficacy of triclosan (TS) and TS-loaded liposomes against the virulent strain of Toxoplasma gondii (T. gondii) was evaluated. Swiss albino mice were intraperitoneally infected with 10(4) tachyzoites of RH HXGPRT(-) strain of T. gondii, then were orally treated with 150 mg/kg TS or 100 mg/kg TS liposomes twice daily for 4 days. Mice mortality, peritoneal and liver parasite burdens, viability, infectivity and ultrastructural changes of peritoneal tachyzoites of infected treated mice were studied, in comparison with those of infected non-treated controls. Drug safety was biochemically assessed by measuring liver enzymes and thyroxin. Both TS and TS liposomes induced significant reduction in mice mortality, parasite burden, viability and infectivity of tachyzoites harvested from infected treated mice. Scanning electron microscopy of treated tachyzoites showed distorted shapes, reduced sizes, irregularities, surface protrusions, erosions and peeling besides apical region distortion. Transmission electron microscopy showed that treated tachyzoites were intracellularly distorted, had cytoplasmic vacuolation, discontinuous plasma membranes, nuclear abnormalities and disrupted internal structures. Besides, in TS liposomes-treated subgroup, most tachyzoites were seen intracellularly with complete disintegration of the parasite plasma and nuclear membranes, with complete destruction of the internal structures. Biochemical safety of TS and TS liposomes was proven. Accordingly, TS can be considered as a promising alternative to the standard therapy for treating acute murine toxoplasmosis. Liposomal formulation of TS enhanced its efficacy and allowed its use in a lower dose.

Intestinal Lymphatic Delivery of Praziquantel by Solid Lipid Nanoparticles: Formulation Design,In VitroandIn VivoStudies

The aim of the present work was to design and develop Praziquantal (PZQ) loaded solid lipid nanoparticles (PZQ-SLN) to improve the oral bioavailability by targeting intestinal lymphatic system. PZQ is practically insoluble in water and exhibits extensive hepatic first-pass metabolism. PZQ SLN were composed of triglycerides, lecithin and various aqueous surfactants; were optimized using hot homogenization followed by ultrasonication method. The optimized SLN had particle size of123±3.41 nm, EE of86.6±5.72%. The drug release of PZQ-SLN showed initial burst release followed by the sustained release. Inspite of zeta potential being around −10 mV, the optimized SLN were stable at storage conditions (5±3°C and25±2°C/60±5% RH) for six months. TEM study confirmed the almost spherical shape similar to the control formulations. Solid state characterization using differential scanning calorimeter (DSC) and powder X-ray diffraction (PXRD) analysis confirmed the homogeneous distribution of PZQ within the lipid matrix. The 5.81-fold increase inAUC0→∞, after intraduodenal administration of PZQ-SLN in rats treated with saline in comparison to rats treated with cycloheximide (a blocker of intestinal lymphatic pathway), confirmed its intestinal lymphatic delivery. The experimental results indicate that SLN may offer a promising strategy for improving the therapeutic efficacy and reducing the dose.

Liposomal-praziquantel: efficacy against Schistosoma mansoni in a preclinical assay

Currently, schistosomiasis mansoni is treated clinically with praziquantel (PZQ). Nevertheless, cases of tolerance and resistance to this drug have been reported, creating the need to develop new drugs or to improve existing drugs. Considering the small number of new drugs against Schistosoma mansoni, the design of nanotechnology-based drug delivery systems is an important strategy in combating this disease. The aim of this study was to evaluate the activity of PZQ containing liposome (lip.PZQ) on S. mansoni, BH strain. Mice were treated orally with different concentrations of PZQ and lip.PZQ 30 and 45 days following infection. The number of worms, recovered by perfusion of the hepatic portal system, and the number of eggs found in the intestine and liver were analysed. Parasite egg counts were also performed. The most active formulation for all parameters was 300mg/kg of lip.PZQ, since as it decreased the total number of worms by 68.8%, the number of eggs in the intestine by 79%, and the number of hepatic granulomas by 98.4% compared to untreated controls. In addition, this concentration decreased egg counts by 55.5%. The improved efficacy of the treatment with lip.PZQ, especially when administered 45 days following infection, compared with the positive-control group (untreated) and the groups that received free PZQ, can be explained by greater bioavailability in the host organism; the preferred target of lip.PZQ is the liver, and lip.PZQ is better absorbed by the tegument of S. mansoni, which has an affinity for phospholipids.

Enhanced oral bioavailability and tissue distribution of a new potential anticancer agent, Flammulina velutipes sterols, through liposomal encapsulation

This study innovatively investigated the anticancer effect of Flammulina velutipes sterols (FVSs), the in vivo pharmacokinetics, and the tissue distribution of FVS-loaded liposomes. The FVS consisting of mainly 54.8% ergosterol and 27.9% 22,23-dihydroergosterol exhibited evident in vitro antiproliferative activity (liver HepG-2, IC50 = 9.3 μg mL(-1); lung A549, IC50 = 20.4 μg mL(-1)). To improve the poor solubility of FVS, F. velutipes sterol liposome (FVSL) was originally prepared. The encapsulation efficiency of ergosterol was 71.3 ± 0.1% in FVSL, and the encapsulation efficiency of 22,23-dihydroergosterol was 69.0 ± 0.02% in FVSL. In comparison to its two free sterol counterparts, the relative bioavailability of ergosterol and 22,23-dihydroergosterol in FVSL was 162.9 and 244.2%, respectively. After oral administration in Kunming mice, the results of tissue distribution demonstrated that the liposomal FVS was distributed mostly in liver and spleen. The drug was eliminated rapidly within 4 h. These findings support the fact that FVS, a potential nutraceutical and an effective drug for the treatment of liver cancer, could be encapsulated in liposomes for improved solubility and bioavailability.

Preparation and characterisation of Dextran-70 hydrogel for controlled release of praziquantel

A hydrogel was developed from 70 kDa dextran (DEX-70) and praziquantel (PZQ) incorporated as a model drug. Biopharmaceutical properties, such as solubility and dissolution rate, were analysed in the design of the hydrogel. Furthermore, the hydrogel was also characterized by IR spectroscopy and DSC. Tests of the swelling rate showed that the hydrogel swelled slowly, albeit faster than the rate for the free polymer. In dissolution tests, the hydrogel released the drug slowly and continuously. This slow release was similar to that observed in the swelling tests and resulted in controlled release of the drug. Thus, this dextran is a suitable polymer for the development of hydrogels as vehicles for the controlled release of drugs.

Solid lipid nanoparticle suspension enhanced the therapeutic efficacy of praziquantel against tapeworm

Hydatid disease caused by tapeworm is an increasing public health and socioeconomic concern. In order to enhance the therapeutic efficacy of praziquantel (PZQ) against tapeworm, PZQ-loaded hydrogenated castor oil solid lipid nanoparticle (PZQ-HCO-SLN) suspension was prepared by a hot homogenization and ultrasonication method. The stability of the suspension at 4°C and room temperature was evaluated by the physicochemical characteristics of the nanoparticles and in-vitro release pattern of the suspension. Pharmacokinetics was studied after subcutaneous administration of the suspension in dogs. The therapeutic effect of the novel formulation was evaluated in dogs naturally infected with Echinococcus granulosus. The results showed that the drug recovery of the suspension was 97.59% ± 7.56%. Nanoparticle diameter, polydispersivity index, and zeta potential were 263.00 ± 11.15 nm, 0.34 ± 0.06, and −11.57 ± 1.12 mV, respectively and showed no significant changes after 4 months of storage at both 4°C and room temperature. The stored suspensions displayed similar in-vitro release patterns as that of the newly prepared one. SLNs increased the bioavailability of PZQ 5.67-fold and extended the mean residence time of the drug from 56.71 to 280.38 hours. Single subcutaneous administration of PZQ-HCO-SLN suspension obtained enhanced therapeutic efficacy against tapeworm in infected dogs. At the dose of 5 mg/kg, the stool-ova reduction and negative conversion rates and tapeworm removal rate of the suspension were 100%, while the native PZQ were 91.55%, 87.5%, and 66.7%. When the dose reduced to 0.5 mg/kg, the native drug showed no effect, but the suspension still got the same therapeutic efficacy as that of the 5 mg/kg native PZQ. These results demonstrate that the PZQ-HCO-SLN suspension is a promising formulation to enhance the therapeutic efficacy of PZQ.

Formulation, characterization and pharmacokinetics of praziquantel-loaded hydrogenated castor oil solid lipid nanoparticles

Aim: The purpose of this study was to formulate praziquantel (PZQ)-loaded hydrogenated castor oil (HCO) solid lipid nanoparticles (SLN) to enhance the bioavailability and prolong the systemic circulation of the drug. Materials & methods: PZQ was encapsulated into HCO nanoparticles by a hot homogenization and ultrasonication method. The physicochemical characteristics of SLN were investigated by optical microscope, scanning electron microscopy and photon correlation spectroscopy. Pharmacokinetics were studied after oral, subcutaneous and intramuscular administration in mice. Results: The diameter, polydispersivity index, ζ potential, encapsulation efficiency and loading capacity of the nanoparticles were 344.0 ± 15.1 nm, 0.31 ± 0.08, -16.7 ± 0.5 mV, 62.17 ± 6.53% and 12.43 ± 1.31%, respectively. In vitro release of PZQ-loaded HCO-SLN exhibited an initial burst release followed by a sustained release. SLN increased the bioavailability of PZQ by 14.9-, 16.1- and 2.6-fold, and extended the mean residence time of the drug from 7.6, 6.6 and 8.2 to 95.9, 151.6 and 48.2 h after oral, subcutaneous and intramuscular administration, respectively. Conclusion: The PZQ-loaded HCO-SLN could be a promising formulation to enhance the pharmacological activity of PZQ.

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.

Comparison of systemic availability of curcumin with that of curcumin formulated with phosphatidylcholine

PURPOSE

Curcumin, a major constituent of the spice turmeric, suppresses expression of the enzyme cyclooxygenase 2 (Cox-2) and has cancer chemopreventive properties in rodents. It possesses poor systemic availability. We explored whether formulation with phosphatidylcholine increases the oral bioavailability or affects the metabolite profile of curcumin.

METHODS

Male Wistar rats received 340 mg/kg of either unformulated curcumin or curcumin formulated with phosphatidylcholine (Meriva) by oral gavage. Rats were killed at 15, 30, 60 and 120 min post administration. Plasma, intestinal mucosa and liver were analysed for the presence of curcumin and metabolites using HPLC with UV detection. Identity of curcumin and metabolites was verified by negative ion electrospray liquid chromatography/tandem mass spectrometry.

RESULTS

Curcumin, the accompanying curcuminoids desmethoxycurcumin and bisdesmethoxycurcumin, and the metabolites tetrahydrocurcumin, hexahydrocurcumin, curcumin glucuronide and curcumin sulfate were identified in plasma, intestinal mucosa and liver of rats which had received Meriva. Peak plasma levels and area under the plasma concentration time curve (AUC) values for parent curcumin after administration of Meriva were fivefold higher than the equivalent values seen after unformulated curcumin. Similarly, liver levels of curcumin were higher after administration of Meriva as compared to unformulated curcumin. In contrast, curcumin concentrations in the gastrointestinal mucosa after ingestion of Meriva were somewhat lower than those observed after administration of unformulated curcumin. Similar observations were made for curcumin metabolites as for parent compound.

CONCLUSION

The results suggest that curcumin formulated with phosphatidylcholine furnishes higher systemic levels of parent agent than unformulated curcumin.

Assessment of a liposomal formulation of ivermectin in rabbit after a single subcutaneous administration

Ivermectin is a member of the macrocyclic lactone family widely used in livestock, pets, and humans as a potent parasiticide. Slight differences in formulation may change the plasma kinetics and efficacy of these compounds. The aim of the study is to evaluate the ability of a liposomal formulation of ivermectin to generate an efficient exposure of the animal to the drug. Ten rabbits were subcutaneously administered with 0.3 mg kg(-1) of ivermectin using Ivomec (n=5) or a liposomal formulation (n=5). The areas under serum concentration-time curve were similar after both treatments, indicating the same bioavailability for the two formulations. However, the liposomal formulation gave a higher C(max) value (33.33 ng ml(-1)) compared with Ivomec (20.82 ng ml(-1)) and a significantly faster absorption as indicated by the T(max) of 0.23 days compared with 1.13 days for the Ivomec formulation. The use of liposomal formulation shows promise as this system improves the efficacy of ivermectin and related drugs.