Effect of Cremophor RH40, Hydroxypropyl Methylcellulose, and Mixing Speed on Physicochemical Properties of Films Containing Nanostructured Lipid Carriers Loaded with Furosemide Using the Box-Behnken Design.

This study aimed to examine the characteristics of H-K4M hydroxypropyl methylcellulose (HPMC) films containing nanostructured lipid carriers (NLCs) loaded with furosemide. A hot homogenization technique and an ultrasonic probe were used to prepare and reduce the size of the NLCs. Films were made using the casting technique. This study used a Box-Behnken design to evaluate the influence of three key independent variables, specifically H-K4M concentration (X1), surfactant Cremophor RH40 concentration (X2), and mixing speed (X3), on the physicochemical properties of furosemide-loaded NLCs and films. The furosemide-loaded NLCs had a particle size ranging from 54.67 to 99.13 nm, and a polydispersity index (PDI) ranging from 0.246 to 0.670. All formulations exhibited a negative zeta potential, ranging from -7.05 to -5.61 mV. The prepared films had thicknesses and weights ranging from 0.1240 to 0.2034 mm and 0.0283 to 0.0450 g, respectively. The drug content was over 85%. Film surface wettability was assessed based on the contact angle, ranging from 32.27 to 68.94°. Film tensile strength varied from 1.38 to 7.77 MPa, and their elongation at break varied from 124.19 to 170.72%. The ATR-FTIR analysis confirmed the complete incorporation of the drug in the film matrix. Therefore, the appropriate selection of values for key parameters in the synthesis of HPMC films containing drug-loaded NLCs is important in the effective development of films for medical applications.

Fluorescence lifetime imaging and phasor analysis of intracellular porphyrinic photosensitizers applied with different polymeric formulations.

The fluorescence lifetime of a porphyrinic photosensitizer (PS) is an important parameter to assess the aggregation state of the PS even in complex biological environments. Aggregation-induced quenching of the PS can significantly reduce the yield of singlet oxygen generation and thus its efficiency as a medical drug in photodynamic therapy (PDT) of diseased tissues. Hydrophobicity and the tendency to form aggregates pose challenges on the development of efficient PSs and often require carrier systems. A systematic study was performed to probe the impact of PS structure and encapsulation into polymeric carriers on the fluorescence lifetime in solution and in the intracellular environment. Five different porphyrinic PSs including chlorin e6 (Ce6) derivatives and tetrakis(m-hydroxyphenyl)-porphyrin and -chlorin were studied in free form and combined with polyvinylpyrrolidone (PVP) or micelles composed of triblock-copolymers or Cremophor. Following incubation of HeLa cells with these systems, fluorescence lifetime imaging combined with phasor analysis and image segmentation was applied to study the lifetime distribution in the intracellular surrounding. The data suggest that for free PSs, the structure-dependent cell uptake pathways determine their state and emission lifetimes. PS localization in the plasma membrane yielded mostly monomers with long fluorescence lifetimes whereas the endocytic pathway with subsequent lysosomal deposition adds a short-lived component for hydrophilic anionic PSs. Prolonged incubation times led to increasing contributions from short-lived components that derive from aggregates mainly localized in the cytoplasm. Encapsulation of PSs into polymeric carriers led to monomerization and mostly fluorescence emission decays with long fluorescence lifetimes in solution. However, the efficiency depended on the binding strength that was most pronounced for PVP. In the cellular environment, PVP was able to maintain monomeric long-lived species over prolonged incubation times. This was most pronounced for Ce6 derivatives with a logP value around 4.5. Micellar encapsulation led to faster release of the PSs resulting in multiple components with long and short fluorescence lifetimes. The hydrophilic hardly aggregating PS exhibited a mostly stable invariant lifetime distribution over time with both carriers. The presented data are expected to contribute to optimized PDT treatment protocols and improved PS-carrier design for preventing intracellular fluorescence quenching. In conclusion, amphiphilic and concurrent hydrophobic PSs with high membrane affinity as well as strong binding to the carrier have best prospects to maintain their photophysical properties in vivo and serve thus as efficient photodynamic diagnosis and PDT drugs.

Exploiting itraconazole-loaded nanomixed micelles in coated capsules as efficient colon-targeted delivery system for improved antifungal and potential anticancer efficacy.

Chronic Inflammatory bowel diseases are usually accompanied by opportunistic colonic fungal infections. Itraconazole (ITZ), is a highly lipophilic broad-spectrum antifungal drug that is superiorly effective against several fungal species. Box-Behnken design was adopted to design ITZ-nanomixed micelles (ITZ-NMMs), aiming to enhance ITZ solubility, using various concentrations of Pluronic® L121, Cremophor EL, and with either sodium-deoxycholate or Pluronic® F68 through thin film hydration technique. Optimized formula composed of 90 % Pl-L121, 9.1% Cremophor EL, 3.127 % ITZ concentration and SDC as the hydrophilic surfactant and its particle size, Polydispersity index, zeta potential, entrapment efficiency, and release extent after 3 h were found to be 17.82 ± 0.189 nm, 0.26 ± 0.014, -6.72 ± 0.725 mV, 66 ± 7.4%, and 96.3 ± 7.22%, respectively. In vitro ITZ release study implied the ability of optimal ITZ-NMMs to enhance ITZ solubility in comparison to ITZ suspension. Also, augmented anti-fungal and anti-cancer activities were proven as ITZ-NMMs IC50 was 16.5 times that of pure ITZ. Afterwards, lyophilized optimal ITZ-NMMs formula was loaded into Eudragit S100-coated capsules where in vitro release and in vivo X-ray imaging ensured protection of ITZ release in either the stomach or intestine and targeting it to the colon. Such results suggested promising ITZ-NMMs system, capable of enhancing ITZ solubility in the intended target site, therefore, can be used not only in the treatment of colon fungal infections but also augments colon cancer therapy.

The role of autophagy in paclitaxel and cremophor induced damage to rat testis.

The anticancer drug, paclitaxel (PTX), is used to treat a variety of solid tumors, but its effects on normal tissues remain unclear. We investigated the effects of different doses of PTX and its vehicle, cremophor EL, on testis using histochemical, immunohistochemical and biochemical methods. We used 30 adult Wistar albino rats divided randomly into five groups: physiological saline was administered to the control group; the sham 8 group received 8 mg/kg cremophor EL; the sham 16 group received 16 mg/kg cremophor EL; 8 mg/kg PTX was administered to the PTX 8 group; and the PTX 16 group received 16 mg/kg PTX. The cremophore content in PTX groups was the same as in the sham group. All treatments were injected intraperitoneally (i.p.) once/week for 4 weeks. Tissue samples were excised 24 h after the last injection. Tissue sections were prepared and hematoxylin and eosin staining was performed to assess testicular morphology. Expression of Beclin-1, LC3A/B and P62 were assessed using immunohistochemistry. Serum and tissue testosterone levels were determined using ELISA. Light microscopy revealed seminiferous tubule damage, irregularities in germinal epithelium and decreased seminiferous tubule diameter in the PTX treated groups. The immunoreactivity of Beclin-1, LC3A/B, and P62 was increased significantly in the PTX groups compared to the control group. Cremophor EL alone damaged the testis, although not as much as PTX. PTX caused significant damage to testicular tissue and increased autophagy of spermatogenic cells; cremophore EL also may play a role in this effect.

Association of acute thrombocytopenia with anaphylaxis.

A commonly seen phenomenon in the hospital and critical care setting is anaphylaxis. This acute systemic inflammatory reaction can lead to anaphylactic shock in severe cases and potentially be fatal. The role of platelets in anaphylactic reactions is not well established; however, platelets, among other mediators such as platelet-activating factor, have been shown to promote a prothrombotic state shortly after an acute hypersensitivity reaction. In addition, the aggregation of platelets promoted by platelet-activating factor and other mediators can also lead to thrombocytopenia. We present a case of a 57-year-old woman who developed severe anaphylaxis while receiving chemotherapy with paclitaxel suspended in Cremophor, a well-known allergen. She was profoundly thrombocytopenic following the reaction and was treated with therapeutic anticoagulation, with no thrombus formation.

Pharmacokinetic study of an anti-trypanosome agent with different formulations and administration routes in mice by HPLC-MS/MS.

Previously compound 12 showed great anti-trypanosome activity without toxicity in an in vivo study. In the current study, a sensitive and rapid high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed and validated to investigate its pharmacokinetics in mouse plasma. A protein precipitation method was applied to extract the compound, and it was then separated using a Kinetex C18 column with mobile phase consisting of acetonitrile-0.1% formic acid water (50:50, v/v) at a flow rate of 300 µl/min. The analytes were detected with the multiple reaction monitoring in negative electrospray ionization source for quantitative response of the compounds. Compound 12 was detected at m/z 477.0 → 367.2, while the internal standard compound 14 was detected at m/z 499.2 → 268.2. Inter- and intra-day precision was <5.22 and 2.79% respectively, while the accuracy range was within ±9.65%. The method was successfully applied to evaluate the pharmacokinetics of compound 12 in mouse plasma with two formulations (20% Cremophor EL or sesame oil) and drug administration routes (oral and intraperitoneal injection). We observed a better drug serum concentration with the Cremophor formulation, and the two different drug administration routes did not show significant differences from the drug distribution.

Modulation of the anticancer activities of paclitaxel by Cremophor micelles.

The objective of this study was to determine the effect of Cremophor (CrEL) on the antineoplastic effect induced by paclitaxel (PTX). Fluorescence spectroscopy, employing pyrene as a probe, was used to determine the critical micelle concentration (CMC) of CrEL. EL4 murine thymoma cells and MDA-MB-231 human breast cancer cells were treated with PTX in different concentrations of CrEL. G2 arrest with 8 N polyploidy was observed in PTX-treated EL4 cells but not in MDA-MB-231 cells. Cell cycle analysis via propidium iodide (PI) staining showed that the frequency of G2 arrest decreased as the CrEL concentration exceeded 0.02% (w/v), demonstrating the effect of CrEL micelle formation on the antimitotic activity of PTX. CrEL was also shown to enhance PTX-induced cell death in vitro by Annexin V/PI staining. Treatment of C57BL/6 mice with PTX in a lower concentration of CrEL resulted in higher myelosuppression, decreased both Ki-67 expression and survival rate, suggesting that CrEL micelle formation above the CMC may lower the cytotoxic activity of PTX in vivo. The data obtained in this study demonstrate CrEL micelle-mediated modulation of the cell cycle and cell death induced by PTX in vitro and the antineoplastic efficacy of PTX in vivo.

Development of Triamcinolone Acetonide-Loaded Microemulsion as a Prospective Ophthalmic Delivery System for Treatment of Uveitis: In Vitro and In Vivo Evaluation.

Treatment of uveitis (i.e., inflammation of the uvea) is challenging due to lack of convenient ophthalmic dosage forms. This work is aimed to determine the efficiency of triamcinolone acetonide (TA)-loaded microemulsion as an ophthalmic delivery system for the treatment of uveitis. Water titration method was used to construct different pseudo-ternary phase diagrams. Twelve microemulsion formulations were prepared using oleic acid, Cremophor EL, and propylene glycol. Among all tested formulations, Formulation F3, composed of oil: surfactant-co-surfactant (1:1): water (15:35:50% w/w, respectively), was found to be stable and showed acceptable pH, viscosity, conductivity, droplet size (211 ± 1.4 nm), and zeta potential (-25 ± 1.7 mV) and almost complete in vitro drug release within 24 h. The in vivo performance of the optimized formulation was evaluated in experimentally uveitis-induced rabbit model and compared with a commercial TA suspension (i.e., Kenacort®-A) either topically or by subconjunctival injection. Ocular inflammation was evaluated by clinical examination, white blood cell count, protein content measurement, and histopathological examination. The developed TA-loaded microemulsion showed superior therapeutic efficiency in the treatment of uveitis with high patient compliance compared to commercial suspension. Hence, it could be considered as a potential ocular treatment option in controlling of uveitis.

Optimization of transdermal atorvastatin calcium - Loaded proniosomes: Restoring lipid profile and alleviating hepatotoxicity in poloxamer 407-induced hyperlipidemia.

In an attempt to optimize the anti- hyperlipidemic effect and reduce statins induced hepatotoxicity, Atorvastatin Calcium (ATC) transdermal proniosomal gel (PNG) was developed. Different non-ionic surfactants (NISs) (Spans, Tweens, Cremophor RH 40 and Brij 52) were incorporated in the vesicle's lipid bilayer, in combination with lecithin. PNG formulae were characterized for encapsulation efficiency percent (% EE), vesicle size, polydispersity index (PDI) and zeta potential (ZP). Ex-vivo permeation study was performed using full thickness rat skin measuring drug flux and skin permeability coefficients. The pharmacodynamic performance of optimized transdermal ATC- PNG on both lipid profile and liver biomarkers was assessed and compared to oral ATC administration in poloxamer 407-induced hyperlipidemic rats. The liver tissues were subjected to histological examination as well. The results revealed nano-size range vesicles with relatively high ATC entrapment efficiency. Ex-vivo results demonstrated the permeation superiority of ATC proniosomes over free drug. Pharmacodynamic study revealed that transdermal administration of ATC- PNG succeeded in retaining the anti-hyperlipidemic efficacy of orally administered ATC without elevating liver biomarkers. The histological examination signified the role of optimized ATC-PNG in hindering statin- induced hepatocellular damage. The obtained results suggested a promising, easy-to-manufacture and effective ATC proniosomal gel for safe treatment of hyperlipidemia.

Stability of Chlorophyll a Monomer Incorporated into Cremophor EL Nano-Micelles under Dark and Moderate Light Conditions.

In this paper, stability of chlorophyll a monomers encapsulated into the Cremophor EL nano-micelles was studied under dark and moderate light conditions, typical of a room with natural or artificial lighting, in the presence of oxygen. The pigment stability against visible light was determined using the dynamic light scattering and molecular spectroscopy (UV-Vis absorption and stationary fluorescence) methods. Chlorophyll a, at the molar concentration of 10-5 M, was dissolved in the 5 wt% Cremophor emulsion for comparison in the ethanolic solution. The stability of such a self-assembly pigment-detergent nano-system is important in the light of its application on the commercial-scale. The presented results indicate the high stability of the pigment monomeric molecular organization in the nano-emulsion. During the storage in the dark, the half-lifetime was calculated as about 7 months. Additionally, based on the shape of absorption and fluorescence emission spectra, chlorophyll aggregation in the Cremophor EL aqueous solution along with the time was excluded. Moreover, the average size of detergent micelles as chlorophyll carriers was not affected after 70 days of the nano-system storage. Pigment stability against the moderate white light (0.1 mW) did not differ significantly from storage conditions in the dark. The photooxidation products, detected by occurrence of new absorption and fluorescence emission bands, was estimated on the negligible level. The stability of such a self-assembly pigment-detergent nano-system would potentially broaden the field of chlorophyll a (chl a) application in the food industry, medicine or artificial photosynthesis models.

Biosurfactants as a Novel Additive in Pharmaceutical Formulations: Current Trends and Future Implications.

BACKGROUND: Surfactants are an important category of additives that are used widely in most of the formulations as solubilizers, stabilizers, and emulsifiers. Current drug delivery systems comprise of numerous synthetic surfactants (such as Cremophor EL, polysorbate 80, Transcutol-P), which are associated with several side effects though used in many formulations. Therefore, to attenuate the problems associated with conventional surfactants, a new generation of surface-active agents is obtained from the metabolites of fungi, yeast, and bacteria, which are termed as biosurfactants. OBJECTIVES: In this article, we critically analyze the different types of biosurfactants, their origin along with their chemical and physical properties, advantages, drawbacks, regulatory status, and detailed pharmaceutical applications. METHODS: 243 papers were reviewed and included in this review. RESULTS: Briefly, Biosurfactants are classified as glycolipids, rhamnolipids, sophorolipids, trehalolipids, surfactin, lipopeptides & lipoproteins, lichenysin, fatty acids, phospholipids, and polymeric biosurfactants. These are amphiphilic biomolecules with lipophilic and hydrophilic ends and are used as drug delivery vehicles (foaming, solubilizer, detergent, and emulsifier) in the pharmaceutical industry. Despite additives, they have some biological activity as well (anti-cancer, anti-viral, anti-microbial, P-gp inhibition, etc.). These biomolecules possess better safety profiles and are biocompatible, biodegradable, and specific at different temperatures. CONCLUSION: Biosurfactants exhibit good biomedicine and additive properties that can be used in developing novel drug delivery systems. However, more research should be driven due to the lack of comprehensive toxicity testing and high production cost which limits their use.

Applying Biopharmaceutical Classification System criteria to predict the potential effect of Cremophor® RH 40 on fexofenadine bioavailability at higher doses.

Aim: To study the impact of various permeability enhancers on fexofenadine bioavailability. Furthermore, to predict the potential effect of Cremophor® RH 40 on fexofenadine pharmacokinetics at higher doses using Biopharmaceutical Classification System criteria. Experimental methods: The effect of the dose increase (60-360 mg) on the dissolution and permeability behavior of fexofenadine-Cremophor RH 40 formulations was studied in humans. The Biopharmaceutical Classification System criteria of the drug was determined. Results & conclusion: Cremophor RH 40 improved the dissolution and bioavailability of fexofenadine. The pharmacokinetics increased linearly with the dose increase. Absorption number (An) was significantly increased after addition of Cremophor RH 40 in comparison to an unprocessed drug. Similar An values were observed throughout the same dose range. The dose number (D0) values were <1 whereas, all the dissolution number (Dn) values were >1 at the same dose level.

Use of oral paclitaxel for the treatment of bladder tumors in dogs.

An oral paclitaxel formulation that overcomes the hypersensitivity reaction of paclitaxel has been evaluated for safety and efficacy in humans, but not in dogs. We present the first case report on the use of oral paclitaxel in dogs. In this study, oral paclitaxel was well-tolerated in four dogs with either transitional cell carcinoma or prostate cancer; adverse effects were limited to mild neutropenia. Each of the dogs had progressive disease at the end, but clinical responses, including changes in mass size and improvement of clinical symptoms, were confirmed in some of the animals following oral paclitaxel chemotherapy. Although this study is somewhat limited by a small sample size, it suggests that oral paclitaxel may be a chemotherapeutic option for malignant tumors in dogs.

Evaluation of Cytotoxicity of Self-Emulsifying Formulations Containing Long-Chain Lipids Using Caco-2 Cell Model: Superior Safety Profile Compared to Medium-Chain Lipids.

Medium-chain (MC) and long-chain (LC) lipids are used for development of self-emulsifying drug delivery systems (SEDDS). MC lipids are often preferred because of their ability to form stable microemulsions with relatively high drug solubilization capacity. On the other hand, LC lipids could be more biocompatible as most endogenous and dietary lipids are LC glycerides. They also maintain high drug solubilization capacity after digestion. The present study was undertaken to determine the cytotoxicity of LC lipids and their formulations on Caco-2 cells of 1-day, 5-day, and 21-day maturity. The results were compared with the cytotoxicity profiles of MC lipids reported previously from our laboratory. The cell viability and cell membrane integrity were, respectively, determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and the lactate dehydrogenase assay. The cytotoxicity was partially due to lipid surfactant-induced membrane rupture, and it was influenced by cell maturity and formulation composition. The lipid-surfactant combinations showed greater tolerance than surfactants alone, and LC-SEDDS were well-tolerated at almost 10-fold higher concentration than corresponding MC-SEDDS. Furthermore, the cytotoxicity of digestion end products of both LC and MC triglycerides in the presence of 3 mM sodium taurocholate was compared on 21-day Caco-2 cultures by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The LC lipid formulations showed better tolerance than MC lipid formulations after digestion. Thus, although MC and LC lipids are well-tolerated at doses normally administered to humans, LC lipids show much better safety than MC lipids in a cell-culture model.

Potential cross-reactivity of polysorbate 80 and cremophor: A case report.

INTRODUCTION: Anaphylactic and hypersensitivity reactions are known adverse effects of many drug products and may be due to the inactive ingredients of the drug formulation. Specifically for paclitaxel and docetaxel, it is their excipients (cremophor and polysorbate 80, respectively) that have been identified as being most likely responsible for these reactions. CASE REPORT: The patient is a 39-year-old female, with a history of breast cancer and no known allergies, who was scheduled to start chemotherapy. While being administered fosaprepitant, she reported shortness of breath and was noted to be hypotensive and flushed. Two months later, the patient returned to clinic to start weekly paclitaxel. During the administration of the paclitxel test dose, the patient reported difficulty breathing, flushing, and chest tightness. Management and outcome: Both medication reactions were managed with epinephrine and other supportive medications. Fosaprepitant was taken out of the patient's antiemetic regimen for future cycles and paclitaxel was switched to nab-paclitaxel. DISCUSSION: It is well documented that paclitaxel and fosaprepitant have the potential to cause hypersensitivity reactions due to their excipients. While it is likely that each reaction was a unique event, it is difficult to ignore the possibility of cross-reactivity due to the presence of oleic acid in both excipients.

In Vitro Effects of Paclitaxel and Cremophor EL on Human Riboflavin Transporter SLC52A2.

Paclitaxel, a mitotic inhibitor with anti-cancer effects, is dissolved in Cremophor EL (CrEL). However, peripheral neuropathy is a known side effect. As one of the mechanisms of the neuropathy, mitochondrial dysfunction has been proposed, while peroxidation products are involved in the cause of CrEL-induced neurotoxicity. Riboflavin is an essential nutrient required for ATP production in mitochondria and has an antioxidant role as a coenzyme for glutathione. Therefore, riboflavin transporters might play a key role to mitigate neuropathy. However, it is unclear whether paclitaxel and CrEL affect these transporters. In this study, human riboflavin transporter SLC52A2 was used to analyze the effects of paclitaxel and CrEL. CrEL, but not paclitaxel, inhibited uptake of riboflavin in human embryonic kidney 293 cells transfected with the SLC52A2 expression vector, suggesting that altered riboflavin disposition may be involved in the pathogenesis of paclitaxel/CrEL toxicity.

Successful switch to oral tacrolimus in a patient with hypersensitivity reaction to parenteral vitamin K, cyclosporine, and tacrolimus: A case report.

INTRODUCTION: Calcineurin inhibitors are widely used for the prevention and treatment of graft versus host disease in patients undergoing allogeneic hematopoietic stem cell transplantation, and successful treatment with calcineurin inhibitors is very important for the management of these cases. CASE REPORT: A 19-year-old man with thalassemia major experienced hypersensitivity reaction to parenteral vitamin K, cyclosporine, and tacrolimus before hematopoietic stem cell transplantation. All three episodes of reaction appeared a few minutes after administration of offended drugs and cause systemic signs and symptoms of anaphylaxis, i.e. itching, flushing, difficulty in breathing, and hypotension. MANAGEMENT AND OUTCOME: Hypersensitivity reaction was fully controlled by immediately discontinuing the drug and administering hydrocortisone, chlorpheniramine, epinephrine, and intravenous fluids. During hospitalization, the patient tolerated oral tacrolimus without any complication. DISCUSSION: It appears that Cremophor EL (polyoxyethylated castor oil) which acts as a carrier, solubilizer, and emulsifier in intravenous calcineurin inhibitors is responsible for the occurrence of anaphylactic reaction (anaphylaxis); therefore, it is suggested that the administration of cremophor-containing drug should be avoided in patients with a previous history of hypersensitivity reaction to one of these drugs.

A rare case of generalized tonic-clonic seizure related to paclitaxel infusion.

WHAT IS KNOWN AND OBJECTIVE: Paclitaxel (Taxol) is an antineoplastic agent approved in the United States for the treatment of lung, breast, cervical, pancreatic cancers and Kaposi sarcoma. Paclitaxel does not cross the blood brain barrier, so central nervous system adverse effects are uncommon. CASE DESCRIPTION: We describe a 60-year-old woman with Stage IIIa squamous cell carcinoma of the left lung, who developed a generalized tonic-clonic seizure during her first infusion of paclitaxel. WHAT IS NEW AND CONCLUSION: Seizure related to a hypersensitivity reaction from paclitaxel infusion are rare but could be life-threatening and require immediate recognition, treatment and exclusion of other possible aetiologies.

Pharmacokinetic modeling of the blood-stable camptothecin analog AR-67 in two different formulations.

AR-67 is a lipophilic camptothecin analog currently under clinical investigation using a Cremophor EL based formulation. However, as potential toxicity limitations exist in the clinical use of Cremophor, an alternative cyclodextrin (SBE-ß-CD) based formulation has been proposed. Pharmacokinetic (PK) studies were conducted in mice and the SBE-ß-CD based formulation was compared with the Cremophor EL formulation. PK studies were conducted following intravenous or oral administration of AR-67 in either Cremophor or SBE-ß-CD formulation in mice. Noncompartmental analysis was used to determine the plasma and tissue drug distribution. A non-linear mixed effects (population) PK model was developed to fit both the oral and intravenous data and to estimate key PK parameters. The effect of formulation was explored as a covariate in the PK model. AR-67 in the SBE-ß-CD formulation had similar plasma PK and biodistribution to that in the Cremophor EL formulation. The proposed two-compartment model described the plasma PK of AR-67 in both formulations adequately. AR-67 in the SBE-ß-CD formulation exhibited dose linearity following both oral and intravenous administration. Our studies indicate that SBE-ß-CD is a viable alternative to Cremophor EL as a pharmaceutical excipient for formulating AR-67.

Synergistic effects of a cremophor EL drug delivery system and its U0126 cargo in an ex vivo model.

Neuroprotection has proven clinically unsuccessful in subarachnoid hemorrhage. We believe that this is because the major component in the early damage pathway, the vascular wall, has not been given the necessary focus. U0126 is a potent inhibitor of vascular phenotypical changes, exemplified by functional endothelin B (ETB) receptor upregulation. The current study aimed to determine the optimal dose of U0126 ex vivo and test the toxicology of this dose in vivo. To find the optimal dose and test a suitable in vivo delivery system, we applied an ex vivo model of blood flow cessation and investigated functional ETB receptor upregulation (using a specific agonist) as the primary endpoint. The secondary endpoint was depolarization-induced contractility assessed by 60 mM K+ stimuli. Furthermore, an in vivo toxicology study was performed on the optimal selected doses. U0126 (10 µM) had a strong effect on the prevention of functional ETB receptor contractility, combined with minimal effect on the depolarization-induced contractility. When cremophor EL was chosen for drug delivery, it had an inhibitory and additive effect (combined with U0126) on the ETB receptor contractility. Hence, 10 µM U0126 in 0.5% cremophor EL seems to be a dose that will be close to the maximal inhibition observed ex vivo on basilar arteries, without exhibiting side effects in the toxicology studies. U0126 and cremophor EL are well tolerated at doses that have effect on ETB receptor upregulation. Cremophor EL has an additional positive effect, preventing functional ETB receptor upregulation, making it suitable as a drug delivery system.