Lipid nanoparticles enhance the absorption of cyclosporine A through the gastrointestinal barrier: In vitro and in vivo studies

The Current and Promising Oral Delivery Methods for Protein- and Peptide-Based Drugs

Drugs based on peptides and proteins (PPs) have been widely used in medicine, beginning with insulin therapy in patients with diabetes mellitus over a century ago. Although the oral route of drug administration is the preferred one by the vast majority of patients and improves compliance, medications of this kind due to their specific chemical structure are typically delivered parenterally, which ensures optimal bioavailability. In order to overcome issues connected with oral absorption of PPs such as their instability depending on digestive enzymes and pH changes in the gastrointestinal (GI) system on the one hand, but also their limited permeability across physiological barriers (mucus and epithelium) on the other hand, scientists have been strenuously searching for novel delivery methods enabling peptide and protein drugs (PPDs) to be administered enterally. These include utilization of different nanoparticles, transport channels, substances enhancing permeation, chemical modifications, hydrogels, microneedles, microemulsion, proteolytic enzyme inhibitors, and cell-penetrating peptides, all of which are extensively discussed in this review. Furthermore, this article highlights oral PP therapeutics both previously used in therapy and currently available on the medical market.

The Study of Cyclosporin A Nanocrystals Uptake and Transport across an Intestinal Epithelial Cell Model

Cyclosporin A nanocrystals (CsA-NCs) interaction with Caco-2 cells were investigated in this study, including cellular uptake and transport across Caco-2 cell monolayers. CsA-NCs of 165 nm, 240 nm and 450 nm were formulated. The dissolution of CsA-NCs was investigated by paddle method. The effect of size, concentration and incubation time on cellular uptake and dissolution kinetics of CsA-NCs in cells were studied. Uptake mechanisms were also evaluated using endocytotic inhibitors and low temperature (4 °C). The cell monolayers were incubated with each diameter CsA-NCs to evaluate the effect of size on the permeation characteristics of CsA across the intestinal mucosa. The results of dissolution study showed that 165 nm CsA-NC had the highest dissolution rate followed by 240 CsA-NC and finally 450 nm CsA-NC. The saturation of cell uptake of CsA-NCs was observed with the increase of incubation concentration and time. 240 nm and 450 nm CsA-NCs had the lowest and highest uptake efficiency at different time and drug concentration, respectively. The uptake of all three-sized CsA-NCs declined significantly in some different degree after the pre-treatment with different endocytosis inhibitors. 165 nm CsA-NC showed a highest transport capacity across monolayers at the same concentration and time. The results suggest that the size of CsA-NCs can not only affect the efficiency of cellular uptake, but also the type of endocytosis. Decreasing particle size of CsA-NCs can improve transport capacity of CsA through cell monolayer.

The Effect of Particle Size on the Absorption of Cyclosporin A Nanosuspensions

Background

Cyclosporin A (CsA) is a hydrophobic drug widely used as an immunosuppressant and anti-rejection drug in solid organ transplantation. On the market, there are two oral CsA formulations available containing polyoxyethylene castor oil, which can cause serious allergic reactions and nephrotoxicity. In order to eliminate polyoxyethylene castor oil, CsA was formulated into a nanosuspension. This study aimed to design an oral cyclosporin A nanosuspensions (CsA-NSs) and investigate the effect of particle size on absorption of CsA-NSs.

Methods

CsA-NSs were prepared using a wet bead milling method. Particle size, morphology and crystallinity state of CsA-NSs were characterized. The in vitro dissolution, the intestinal absorption properties and pharmacokinetic study of CsA-NSs were investigated.

Results

CsA-NSs with sizes of 280 nm, 522 nm and 2967 nm were prepared. The shape of CsA-NSs with smaller size was similar to that of spheres. The crystallinity of CsA in nanocrystals was reduced. The dissolution rate of CsA-NSs (280 nm) was greater than that of CsA-NSs (522 nm) and CsA-NSs (2967 nm). CsA-NSs (280 nm) showed higher absorption rate constants (K_α) and effective permeability coefficients (P_eff) of different intestinal segments compared with that of CsA-NSs (522 nm) and CsA-NSs (2967 nm). AUC_0-48h of 280 nm CsA-NSs was about 1.12-fold of that of 522 nm CsA-NSs, and about 1.51-fold of that of 2967 nm CsA-NSs. In particular, the particle size of CsA-NSs was nanoscale, and their bioavailability was bioequivalent with marked self-microemulsion (Sandimmun Neoral^®).

Conclusion

It is feasible to prepare CsA-NSs. The dissolution rate, gastrointestinal transport properties and the oral absorption of CsA-NSs were promoted by reducing size. Considering the cost, efficiency and energy consumption, there should be an optimal particle size range in industrial production.

Evaluation on absorption risks of amentoflavone after oral administration in rats

The present study was aimed to systemically assess the absorption risks of amentoflavone (AMF). Physicochemical properties of AMF were evaluated using in vitro assays including water solubility and stability in both simulated gastric and intestinal fluids, as well as logD, pka and permeability studies in a monolayer Caco-2 model. The results together suggested that AMF was a compound with moderate intestinal absorption and the poor solubility was the key rate-limiting step for the oral absorption of AMF, and PVP-K30 were thus used as a solubilizer to improve its solubility and oral bioavailability. Furthermore, studies on pharmacokinetics and biliary excretion of AMF with tween 80 or PVP-K30 were performed after oral administration, and the results showed that the percentage of AMF conjugates in bile was determined up to be 96.73% and no AMF conjugates were detected in rat plasma. The above results revealed that the poor oral absorption of AMF may probably be attributed to the low solubility, high level of metabolism and hepatic first-pass effects. The relative bioavailability of AMF solubilized by PVP-K30 was about 2-fold than that of AMF suspended in 1% tween 80. The present study may help provide scientific insights to guide the rational design of AMF into more efficient formulation systems.

Precisely Fabricated Sulpiride-Loaded Nanolipospheres with Ameliorated Oral Bioavailability and Antidepressant Activity

BACKGROUND

Sulpiride (SUL), is a selective antidopaminergic drug that had extensive biological activities. However, its sparingly aqueous solubility and limited gastrointestinal permeability lead to scanty oral bioavailability which hinders its clinical efficacy.

OBJECTIVE

SUL-loaded lipospheres (SUL-LPS) were designed to serve as an oral biocompatible nanovector for improving SUL permeability as well as conquering its low oral absorption and then in turn enhancing its antidepressant action.

METHODS

SUL-LPS were fabricated via two processing techniques namely, melt emulsification and solvent evaporation. The impact of different lipid cores, phospholipid shells together with various surfactant concentrations and types on the lipospheres properties were screened. Detailed physicochemical elucidations were performed followed by ex vivo permeation appraisal using the non-everted intestine model. The pharmacokinetic parameters of SUL-LPS, free SUL and marketed product were assessed following oral administration to healthy rats. Reserpine-induced depression rat model was used to assess the antidepressant action of SUL-LPS on which full behavioural and biochemical analysis was conducted. Safety attributes of nanoencapsulated SUL on the brain and other internal organs were evaluated.

RESULTS

The optimum LPS revealed an excellent nanosize with a narrow PdI, negative zeta potential and acceptable entrapment efficiency of 68.62 nm, 0.242, -30.4 mV and 84.12%, respectively. SUL-LPS showed a sustained release pattern and 2.1-fold enhancement in the intestinal permeation parameters with low mucin interaction. Oral pharmacokinetic appraisal exhibited that LPS provided 3.4-fold improvement in SUL oral bioavailability together with long-circulating properties, relative to the free drug. Pharmacodynamic study confirmed the superior antidepressant action of SUL-LPS as evident by 1.6 and 1.25-fold elevation in the serotonin and dopamine expressions, respectively. Meanwhile, nanotoxicological appraisal proved the biocompatibility of SUL-LPS upon repetitive oral administration.

CONCLUSION

Rationally designed lipospheres hold promising in vitro and in vivo characteristics for efficient delivery of SUL with high oral bioavailability, antidepressant activity together with a good safety profile.

New Nanoparticle Formulation for Cyclosporin A: In Vitro Assessment

Cyclosporin A (CsA) is a molecule with well-known immunosuppressive properties. As it also acts on the opening of mitochondrial permeability transition pore (mPTP), CsA has been evaluated for ischemic heart diseases (IHD). However, its distribution throughout the body and its physicochemical characteristics strongly limit the use of CsA for intravenous administration. In this context, nanoparticles (NPs) have emerged as an opportunity to circumvent the above-mentioned limitations. We have developed in our laboratory an innovative nanoformulation based on the covalent bond between squalene (Sq) and cyclosporin A to avoid burst release phenomena and increase drug loading. After a thorough characterization of the bioconjugate, we proceeded with a nanoprecipitation in aqueous medium in order to obtain SqCsA NPs of well-defined size. The SqCsA NPs were further characterized using dynamic light scattering (DLS), cryogenic transmission electron microscopy (cryoTEM), and high-performance liquid chromatography (HPLC), and their cytotoxicity was evaluated. As the goal is to employ them for IHD, we evaluated the cardioprotective capacity on two cardiac cell lines. A strong cardioprotective effect was observed on cardiomyoblasts subjected to experimental hypoxia/reoxygenation. Further research is needed in order to understand the mechanisms of action of SqCsA NPs in cells. This new formulation of CsA could pave the way for possible medical application.

Cyclosporine CsA—The Physicochemical Characterization of Liposomal and Colloidal Systems

This paper presents an overview of the possibilities of testing various cyclosporine (CsA) formulations with an emphasis on parameters that may be key to improving the stability and biocompatibility. The feasibility of CsA colloidal systems for oral (injection) administration were investigated using different techniques and compared with similar investigations of other researchers. The chosen CsA systems were developed using dipalmitoylphosphocholine (DPPC) and/or cholesterol as a lipid matrix, stabilized with ethanol, with soybean oil or n-tetradecane as oil phase in emulsions, under natural pH, room and physiological temperature. Their integrity was found to be strictly dependent on the stabilizers. The highest CsA penetrability with the system containing phospholipid in the context of its interactions with lipid membranes was shown. Also, the bioavailability of CsA can be enhanced with the biopolymer antibacterial chitosan. This mini-review suggests the suitability of liposome/microemulsion as promising vehicles for CsA delivery. The most hopeful proved to be formulation with the smaller particle size facilitating absorption, but when safety is assessed, relying on just the particle size cannot be the only criteria. Reassumed, the CsA formulation stability known on the basis of the size and zeta potential measurements guarantees a decrease of the individual variations in the drug bioavailability, toxicity and minimizes rejection.

Transport and metabolic profiling studies of amentoflavone in Caco-2 cells by UHPLC-ESI-MS/MS and UHPLC-ESI-Q-TOF-MS/MS

Amentoflavone, a kind of biflavonoid existing in several medicinal plants such as Selaginella moellendorfi and Gingko biloba, possesses anti-inflammatory, antioxidant, anti-virus, anti-tumor activities. In the present study, a new reliable and sensitive UHPLC-ESI-MS/MS method was developed to determine the permeability of amentoflavone under different conditions, and its metabolites in Caco-2 cells were identified by means of UHPLC-Q-TOF-MS/MS method. The results showed that amentoflavone could be considered as a compound with moderate intestinal absorption in Caco-2 cell model and its absorption characteristics might be involved in paracellular passive penetration and clathrin-mediated endocytosis with no participation of efflux transporters. Eight metabolites of amentoflavone were identified in Caco-2 cell model, indicating that the main metabolic pathways were oxidation, reduction, methylation and glucuronide conjugation. This study can provide valuable evidence for an in-depth understanding of absorption mechanism and transformation of amentoflavone in the intestine.

Freeze-Dried Softisan® 649-Based Lipid Nanoparticles for Enhanced Skin Delivery of Cyclosporine A

Inflammatory skin diseases, including psoriasis and atopic dermatitis, affect around one quarter to one third of the world population. Systemic cyclosporine A, an immunosuppressant agent, is included in the current therapeutic armamentarium of these diseases. Despite being highly effective, it is associated with several side effects, and its topical administration is limited by its high molecular weight and poor water solubility. To overcome these limitations, cyclosporine A was incorporated into solid lipid nanoparticles obtained from Softisan^® 649, a commonly used cosmetic ingredient, aiming to develop a vehicle for application to the skin. The nanoparticles presented sizes of around 200 nm, low polydispersity, negative surface charge, and stability when stored for 8 weeks at room temperature or 4 °C. An effective incorporation of 88% of cyclosporine A within the nanoparticles was observed, without affecting its morphology. After the freeze-drying process, the Softisan^® 649-based nanoparticles formed an oleogel. Skin permeation studies using pig ear as a model revealed low permeation of the applied cyclosporine A in the freeze-dried form of the nanoparticles in relation to free drug and the freshly prepared nanoparticles. About 1.0 mg of cyclosporine A was delivered to the skin with reduced transdermal permeation. These results confirm local delivery of cyclosporine A, indicating its promising topical administration.

A Novel Drug Delivery Carrier Comprised of Nimodipine Drug Solution and a Nanoemulsion: Preparation, Characterization, in vitro, and in vivo Studies

Purpose

Nimodipine (NIMO) is used clinically to treat ischemic damage resulting from subarachnoid hemorrhage. However, clinical application of NIMO is limited by poor aqueous solubility and low safety. To overcome these limitations, a novel two-vial NIMO-loaded nanoemulsion (NIMO-TNE) was designed in this study.

Methods

NIMO-TNE was prepared by mixing a nimodipine-polyethylene glycol 400 (NIMO-PEG400) solution and a commercially available 20% injectable blank nanoemulsion (BNE). Drug distribution in NIMO-TNE, physical stability, and dilution stability were evaluated in vitro, and pharmacokinetics and pharmacodynamics were evaluated in vivo. Safety was assessed using the hemolysis test and the intravenous irritation test, and acute toxicity of NIMO-TNE was compared with that of commercial Nimotop injection.

Results

Drug loading (DL) in NIMO-TNE was enhanced 5-fold compared with that in Nimotop injection. The mean particle size of NIMO-TNE was 241.53 ± 1.48 nm. NIMO-TNE and NIMO-TNE diluted in 5% glucose injection and 0.9% sodium chloride was stable for a sufficient duration to allow for clinical use. In addition, NIMO-TNE exhibited a similar pharmacokinetic profile and similar brain ischemia reduction in a rat middle cerebral artery occlusion (MCAO) model compared to Nimotop injection. Furthermore, NIMO-TNE did not induce hemolysis at 37°C, and NIMO-TNE induced less intravenous irritation than Nimotop injection. Moreover, NIMO-TNE could be injected at a 23-fold higher dose than the LD₅₀ of Nimotop injection with no obvious toxicity or side effects.

Conclusion

NIMO-TNE is a promising formulation suitable for intravenous injection, is easy to prepare, and exhibits excellent safety.

The hurdles of nanotoxicity in transplant nanomedicine

Nanomedicine has matured significantly in the past 20 years and a number of nanoformulated therapies are cleared by regulatory agencies for use across the globe. Transplant medicine is one area that has significantly benefited from the advancement of nanomedicine in recent times. However, while nanoparticle-based therapies have improved toxicological profiles of some drugs, there are still a number of aspects regarding the biocompatibility and toxicity of nanotherapies that require further research. The goal of this article is to review toxicological profiles of immunosuppressant therapies and their conversion into nanomedicine formulations as well as introduce future challenges associated with current in vitro and in vivo toxicological models.

Preparation and characterization of nimodipine-loaded nanostructured lipid systems for enhanced solubility and bioavailability

Purpose

Nimodipine (NMP) is a clinical dihydropyridine calcium antagonist. However, the clinical application of NMP is limited by poor water solubility and low oral bioavailability. To overcome these drawbacks, this study designed optimal NMP-incorporated nanostructured lipid carriers (NLCs).

Methods

High-pressure homogenization was successfully applied to prepare NMP-NLC, and the nanoparticle morphology was observed by a transmission electron microscope. The existence form of NMP in NMP-NLC was investigated by powder X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared spectroscopy, respectively. The in vitro release study was performed by the dialysis method, and in vivo studies including in situ intestinal perfusion and pharmacokinetics were investigated in rats with NMP detected by high-performance liquid chromatography.

Results

The obtained NMP-NLC shared a spherical shape of ~70 nm with a smooth surface and high encapsulation efficiency of 86.8%±2.1%. Spectroscopy indicated that the drug was in an amorphous state. The NMP-NLC exhibited a sustained release and diverse release profiles under different release medium, which mimicked the physiological environment. Moreover, an in situ intestinal perfusion experiment revealed that NMP-NLC could be mainly absorbed by the small intestine. Remarkable improvements in C_max and AUC_0-∞ from NMP-NLC were obtained from pharmacokinetic experiments, and the relative bioavailability of NMP-loaded nanostructured lipid systems was 160.96% relative to NMP suspensions.

Conclusion

Collectively, the NLCs significantly enhanced the oral bioavailability of NMP and might provide a promising nanoplatform for hydrophobic drug delivery.

Enhanced Dissolution and Oral Bioavailability of Cyclosporine A: Microspheres Based on αβ-Cyclodextrins Polymers

Cyclosporine (CsA) has a selective property of suppressing various T-lymphocyte functions. This is of utmost importance in preventing allograft rejection by several organ transplantations, as well as in the treatment of systemic and local autoimmune disorders. However, the poor water solubility of CsA can be a major hurdle for its absorption into the blood stream, which leads to low bioavailability and thus less efficacy. The aim of this study was to prepare, characterize, and evaluate in vitro as well as in vivo, the potential of the innovative CsA drug delivery system. The latter contains CsA in spherical amorphous solid dispersion (SASD) which is embedded in an original α-cyclodextrin and β-cyclodextrin polymer mixture (Poly-αβ-CD) as a multifunctional amorphous carrier. The new developed SASD formulation showed that CsA was molecularly dispersed in αβ-cyclodextrins in an amorphous form, as was confirmed by physicochemical characterization studies. Interestingly, the peptide secondary structure, and thus, the drug activity was not impacted by the preparation of SASD as was shown by circular dichroism. Furthermore, the in vitro CsA release profile kinetics was almost identical to the commercially available product Neoral^®. This study presents the first in vivo proof-of-concept for a novel drug delivery system based on Poly-αβ-CD containing CsA, with SASD allowing for increased bioavailibility. The pharmacokinetic parameters of cyclosporine A from the spherical spray-dried dispersion formulation was demonstrated in a “rat” animal model. For comparison, the commercially available Neoral® was studied. Importantly, the pharmacokinetic parameters were improved by extending T_max from 2 to 3 h after the oral administration in rats, and eventually preventing the enterohepatic circulation. All these results clearly demonstrate the improved pharmacokinetic parameters and enhanced bioavailability of CsA in the new developed drug delivery system. These data demonstrated the superiority of the newly developed Poly-αβ-CD formulation for oral administration of the poorly soluble CsA in vivo without altering its secondary structure. Poly-αβ-CD can be a very useful tool for the oral administration of poorly water-soluble drugs.

Enhanced digestion inhibition and mucus penetration of F127-modified self-nanoemulsions for improved oral delivery

Self-nanoemulsifying systems (SNEs) have excellent ability to improve the solubility of poorly water-soluble drugs (PWSD). However, SNEs are likely to be degraded in gastrointestinal (GIT) when their surface is recognized by lipase/co-lipase enzyme complex, resulting in rapid release and precipitation of encapsulated drugs. The precipitates are then captured and removed by intestinal mucus, reducing the delivery efficacy of SNEs. Herein, the amphiphilic polymer Pluronic® F127 was incorporated into long and short-chain triglycerides (LCT, SCT) based SNEs to diminish the recognition and therefore minimized their degradation by enzymes and clearance by mucus. The SNEs were characterized in terms of particle size, zeta potential and stability. Ex vivo multiple particles tracking studies were performed by adding particle solution into fresh rat mucus. Cellular uptake of SNEs were conducted by using E12 cells, the absorption and distribution in small intestine were also studied after oral administration in male Sprague-Dawley (SD) rats. The in vitro digestion rate of SNEs were found to be in following order SCT-SNE > SCT-F127-SNE > LCT-SNE > LCT-F127-SNE. Moreover, the LCT-F127-SNE was found to be most effective in enhancing cellular uptake, resulting in 3.5-fold, 2.1-fold and 1.7-fold higher than that of SCT-SNE, LCT-SNE and SCT-F127-SNE, respectively. After incubating the SNE with E12 cells, the LCT-F127-SNE exhibited the highest amount regarding both mucus penetration and cellular uptake, with an uptake amount number (via bicinchoninic acid (BCA) analysis) of 3.5-fold, 2.1-fold and 1.7-fold higher than that of SCT-SNE, LCT-SNE and SCT-F127-SNE, respectively. The in vivo results revealed that orally administered LCT-F127-SNE could significantly increase the bioavailability of Cyclosporine A (CsA), which was approximately 2.43-fold, 1.33-fold and 1.80-fold higher than that of SCT-SNE, SCT-F127-SNE and LCT-SNE, respectively. We address in this work that F127-modified SNEs have potentials to improve oral drug absorption by significantly reducing gastrointestinal enzymatic degradation and simultaneously enhancing mucus penetration.

In Vivo Fate of Biomimetic Mixed Micelles as Nanocarriers for Bioavailability Enhancement of Lipid-Drug Conjugates

The transformation of lipid-based nanovehicles into mixed micelles (MMs) upon lipolysis plays an indispensable role in enhancement of the oral bioavailability of poorly water-soluble drugs. Therefore, this study employs biomimetic MMs as functional vehicles to enhance the oral bioavailability of the lipid conjugates of a model drug silybin. The main objective is to explore the in vivo fate and underlying mechanisms of facilitated absorption by MMs. Pharmacokinetics in rats indicate bioavailability enhancement by 7-9 folds as compared to a fast-release silybin solid dispersion formulation. Confocal laser scanning microscopy reveals evidence of cellular uptake of integral MMs into the cytoplasm of both Caco-2 and Caco-2/HT29-MTX coculture cells lines. The recovery of a definite amount of prototype silybin but negligible or traces of lipid-silybin conjugates from the cells, as well as the limited trans-monolayer transport, confirms fast disruption of MMs and fast degradation of the conjugates as well. The MMs survive the gastrointestinal environment with relatively high integrity for about 4 h, and are found accumulating in intestinal villi surface layers in higher density but in lower density to the basolateral tissues. By scanning the organs, a small amount of integral MMs are observed to distribute mainly to the livers with peak time around 4-8 h. The total amount of lymphatic absorption monitored by cannulation is negligible. It is concluded that biomimetic MMs might be taken up by enterocytes and be digested there to release the prototype drug, which is further transported to the circulation, and only a limited amount of integral MMs could be absorbed into the circulation.

In vivo fate of lipid-silybin conjugate nanoparticles: Implications on enhanced oral bioavailability

Lipid-drug conjugates (LDCs) of a poorly soluble and poorly permeable drug silybin (SB) and lipids with different chain lengths (6C, 12C, 18C) are synthesized and formulated into solid lipid nanoparticles (SLNs). The in vivo fate of LDCs as well as SLNs is investigated by tracking either SB or LDCs or SLNs. LDCs are prone to be hydrolyzed by lipases either in simulated gastrointestinal media or in Caco-2 cell lines in a lipid chain length-dependent mode. The oral bioavailability of SB is enhanced by 5-7-fold in comparison with a fast-release formulation. No integral LDCs are detected in plasma confirms the readily degradable nature of LDCs. The absorption of LDCs by enteric epithelia and subsequent transportation into circulation might play a leading role in absorption enhancement, whereas the contribution of then M-cell pathway is not as remarkable. A shorter lipid chain favors earlier lipolysis and faster absorption along the intestine-to-circulation path.

Cyclosporine A-loaded lipid nanoparticles in inflammatory bowel disease

Cyclosporine A (CsA) is a well-known immunosuppressive agent used as rescue therapy in severe steroid-refractory ulcerative colitis (UC). However, toxicity issues associated with CsA when administered in its commercially available formulations have been reported in clinical practice. Since nanotechnology has been proposed as a promising strategy to improve safety and efficacy in the treatment of inflammatory bowel disease (IBD), the main purpose of this study was to evaluate the effect of oral administration of CsA-loaded lipid nanoparticles (LN) in the dextran sodium sulfate (DSS)-induced colitis mouse model using Sandimmune Neoral(®) as reference. The results showed that the formulations used did not decrease colon inflammation in terms of myeloperoxidase activity (MPO), tumor necrosis factor (TNF)-α expression, or histological scoring in the acute stage of the disease. However, further studies are needed in order to corroborate the efficacy of these formulations in the chronic phase of the disease.

Cyclosporine A lipid nanoparticles for oral administration: Pharmacodynamics and safety evaluation

The pharmacodynamic effect and the safety of cyclosporine A lipid nanoparticles (CsA LN) for oral administration were investigated using Sandimmune Neoral® as reference. First, the biocompatibility of the unloaded LN on Caco-2 cells was demonstrated. The pharmacodynamic response and blood levels of CsA were studied in Balb/c mice after 5 and 10 days of daily oral administration equivalent to 5 and 15 mg/kg of CsA in different formulations. The in vivo nephrotoxicity after 15 days of treatment at the high dose was also evaluated. The results showed a significant decrease in lymphocyte count (indicator of immunosuppression) for the CsA LN groups which was not observed with Sandimmune Neoral®. CsA blood levels remained constant over the time after treatment with LN, whereas a proportional increase in drug blood concentration was observed with Sandimmune Neoral®. Therefore, CsA LN exhibited a better pharmacological response along with more predictable pharmacokinetic information, diminishing the risk of toxicity. Moreover, a nephroprotective effect against CsA related toxicity was observed in the histopathological evaluation when LN containing Tween® 80 were administered. Therefore, our preliminary findings suggest LN formulations would be a good alternative for CsA oral delivery, enhancing efficacy and reducing the risk of nephrotoxicity.

Reformulating cyclosporine A (CsA): More than just a life cycle management strategy

Cyclosporine A (CsA) is a well-known immunosuppressive agent that gained considerable importance in transplant medicine in the late 1970s due to its selective and reversible inhibition of T-lymphocytes. While CsA has been widely used to prevent graft rejection in patients undergoing organ transplant it was also used to treat several systemic and local autoimmune disorders. Currently, the neuro- and cardio-protective effects of CsA (CiCloMulsion®; NeuroSTAT®) are being tested in phase II and III trials respectively and NeuroSTAT® received orphan drug status from US FDA and Europe in 2010. The reformulation strategies focused on developing Cremophor® EL free formulations and address variable bioavailability and toxicity issues of CsA. This review is an attempt to highlight the progress made so far and the room available for further improvements to realize the maximum benefits of CsA.