Mixed Micellar Formulation Research Articles

Pluronic-phosphatidylcholine mixed polymeric nanomicellar formulation for curcumin drug bioavailability: Design, fabrication, characterization and in vitro bioinvestigations

Curcumin (CUR), obtained from turmeric, has biological advantages, but low aqueous solubility restricts its pharmaceutical applications. In the present work, a mixed polymeric nanomicellar formulation composed of bioactive Pluronic P123, Pluronic F68, and biocompatible phosphatidylcholine (PC) was designed and examined as the nanovehicles for overcoming the major barriers of poor bioavailability related to CUR. The CUR-incorporated P123/F68/PC mixed nanomicellar formulation (CUR-PFPC) was fabricated by the thin film technique and investigated in vitro. The fabrication of CUR-PFPC was optimized through D-optimal design. CUR-PFPC morphology, size distribution, zeta potential, drug encapsulating and incorporation efficiency, compatibility, and crystallinity were characterized using DLS, TEM, FTIR, XRD, and DSC analysis. Moreover, the cumulative drug release, antioxidant assays, and antimicrobial properties of formulations were also examined. The CUR-PFPC formulation exhibited a micellar size of 67.43 nm, a zeta potential of −15.1 mV, a PDI of 0.528, and a spherical shape. The mixed micellar formulation showed excellent compatibility and stability. The in vitro release profile of the CUR-PFPC reached over 60% in comparison to the 95% release of CUR, indicating a slow and sustained release. The DPPH assay showed that the CUR-PFPC had 96% antioxidant activity. Results show that the CUR-PFPC has powerful antibacterial and antifungal properties, which separates it from the free CUR. These findings suggest that the fabricated CUR-PFPC mixed polymeric nanomicellar formulation is thermodynamically and kinetically stable and may be considered a novel nanovehicle for hydrophobic antimicrobial drugs like CUR. Graphical Abstract [Formula: see text]

Loading of hydrophobic drug silymarin in pluronic and reverse pluronic mixed micelles

In the presented work, pure pluronic and mixed micelles of normal pluronics (F108, F127, P85 and P84) with reverse pluronic (10R5) have been studied to enhance the solubilization of the hydrophobic drug silymarin (SLY) at different % w/v proportions (4:1, 2.5, 1:4 and 5). Solubilization capacity of SLY in the mixed micelles was found to be higher than pure pluronic micelles. Drug solubilization parameters including drug loading efficiency (DL), partition coefficient (P) and Gibbs free energy of solubilization (ΔG◦) were calculated. SLY loaded mixed micellar formulation of P84:10R5 (4:1% w/v) showed maximum solubility and drug loading efficiency as compared to other mixed micellar formulations. The cmc of pure as well as mixed micellar systems has been evaluated using fluorescence measurements. The locus of SLY in these micelles was evaluated by micropolarity measurements. After solubilization, increase in hydrodynamic size evidenced by DLS measurements confirmed the solubilization of SLY in the mixed micelles. In vitro drug release study was also performed for mixed micellar formulations with maximum SLY solubilization, and it was found to exhibit sustained release drug behavior. Different kinetics models were also applied and the best fitted model for the optimum SLY loaded mixed micellar formulation was found to be the Korsmeyer-Peppas model. To investigate the anti-oxidative potential of SLY drug and SLY loaded mixed micellar formulation of P84:10R5 (4:1% w/v),1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH·) scavenging, ferrous ions (Fe2+) chelating activities, total reducing ability determination by Fe3+ to Fe2+ transformation method, 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging and nitric oxide assay were undertaken. The SLY loaded mixed micellar formulation of P84:10R5 (4:1% w/v) exhibited appreciably enhanced anti-oxidative activity as compared to SLY alone.

Mixed Pluronic-Cremophor Polymeric Micelles as Nanocarriers for Poorly Soluble Antibiotics-The Influence on the Antibacterial Activity.

In this work, novel polymeric mixed micelles from Pluronic F127 and Cremophor EL were investigated as drug delivery systems for Norfloxacin as model antibiotic drug. The optimal molar ratio of surfactants was determined, in order to decrease critical micellar concentration (CMC) and prepare carriers with minimal surfactant concentrations. The particle size, zeta potential, and encapsulation efficiency were determined for both pure and mixed micelles with selected composition. In vitro release kinetics of Norfloxacin from micelles show that the composition of surfactant mixture generates tunable extended release. The mixed micelles exhibit good biocompatibility against normal fibroblasts MRC-5 cells, while some cytotoxicity was found in all micellar systems at high concentrations. The influence of the surfactant components in the carrier on the antibacterial properties of Norfloxacin was investigated. The drug loaded mixed micellar formulation exhibit good activity against clinical isolated strains, compared with the CLSI recommended standard strains (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29213, Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922). P. aeruginosa 5399 clinical strain shows low sensitivity to Norfloxacin in all tested micelle systems. The results suggest that Cremophor EL-Pluronic F127 mixed micelles can be considered as novel controlled release delivery systems for hydrophobic antimicrobial drugs.

Paclitaxel and curcumin co-loaded mixed micelles: Improving in vitro efficacy and reducing toxicity against Abraxane®

Paclitaxel (PTX) is one of the most effective antineoplastic drugs employed for breast and ovarian cancer therapy. However, the neurotoxicity associated with PTX administration represents one of its main drawbacks reducing patient life quality. Recently, curcumin (CUR) has been explored as a neuroprotective agent due to its antioxidant properties. Then, the co-encapsulation of PTX and CUR in a mixed micellar formulation could promote a neuroprotective effect of the micellar system and optimize breast and ovarian cancer therapy. PTX-CUR-loaded Soluplus:TPGS mixed micelles were developed and characterized by nuclear magnetic resonance, scattering techniques and transmission electron microscopy. In vitro cytotoxicity was evaluated in MDA-MB-231 and SKOV-3 cancer cells. The in vitro antioxidant performance of CUR-loaded nanoformulations was confirmed employing lipid peroxidation inhibition and DPPH colorimetric assays. The neuroprotective effect of the micellar formulations was evaluated on zebrafish larvae. Mixed micelles demonstrated an excellent colloidal stability, before and after freeze-drying. Nanoformulations with both drugs demonstrated the best in vitro anticancer performance versus the commercially available nanoformulation Abraxane® in breast and ovarian cancer cells lines. The in vitro antioxidant properties of the mixed micelles with CUR were confirmed and their in vivo potential neuroprotective effect was assessed in the zebrafish model.

Supported lipid bilayer platform for characterizing the optimization of mixed monoglyceride nano-micelles

The development of real-time measurement strategies to quantitatively characterize dynamic morphological changes of cell membrane-mimicking biomaterial platforms is an important technological need for membrane-active drug development. One of the most promising classes of membrane-active drug candidates is medium-chain monoglycerides, which demonstrate potent antimicrobial and immunomodulatory activities. Each monoglyceride has distinct membrane-disruptive behaviors and biological activities and it would be advantageous to combine different monoglycerides into a mixed micellar formulation. Herein, we evaluate the development of nano-micellar formulations that are composed of C12-based glycerol monolaurate (GML) and C10-based glycerol monocaprate (GMC) mixtures and characterize the interactions of GML/GMC nano-micelles with two-dimensionally confined supported lipid bilayer (SLB) platforms in terms of real-time interaction kinetics, dynamic shape transformations, and resulting membrane lysis. Our findings indicate that GML/GMC molecules self-assemble into ideally mixed nano-micelles and GML/GMC nano-micelles trigger membrane budding to varying extents depending on the GML/GMC molar ratio. Membrane budding was minimized at intermediate GML/GMC molar ratios. Among the two components, the data further support that GMC is the main one contributing to membrane lysis and thus tuning the micellar composition can enable precise control over the balance between the extent of membrane budding and membrane lysis. Taken together, this work advances our understanding of how monoglyceride mixtures can be developed into nano-micellar formulations and demonstrates the broader potential of developing cell membrane-mimicking biomaterial platforms for medical and biotechnology applications.

A Mixed Micellar Formulation for the Transdermal Delivery of an Indirubin Analog.

Indirubin is an active component of Dang Gui Long Hui Wan, which has been used in traditional Chinese medicine to treat inflammatory diseases as well as for the prevention and treatment of human cancer, such as chronic myeloid leukemia. The therapeutic effects of indirubin analogs have been underestimated due to its poor water solubility and low bioavailability. To improve the solubility and bioavailability of indirubin analogs, we prepared a mixed micellar formulation with Kolliphor® EL and Tween 80 as surfactants, and PEG 400 as a co-surfactant, followed by complexation with (2-hydroxyproply)-β-cyclodextrin at appropriate ratios. Overall, improving the solubility and skin penetration of indirubin analogs can increase clinical efficacy and provide maximum flux through the skin.

Sodium deoxycholate mediated enhanced solubilization and stability of hydrophobic drug Clozapine in pluronic micelles

In this report, the solubilization behaviour of a hydrophobic drug Clozapine (CLZ) in micellar suspensions of pluronics having different hydrophilic lipophilic balance (HLB) ratios viz. P84, F127 and F108 in the absence and presence of bile salt sodium deoxycholate (SDC) has been studied. UV–Vis spectroscopy has been exploited to determine the solubilization capacity of the investigated micellar systems in terms of drug loading efficiency, average number of drug molecules solubilized per micelle (ns), partition coefficient (P) and standard free energy of solubilization (∆G°). The morphological and structural changes taking place in pluronics in different concentration regimes of SDC and with the addition of drug CLZ has been explored using dynamic light scattering (DLS) and small angle neutron scattering (SANS) measurements. The SANS results revealed that aggregation behaviour of pluronic-SDC mixed micelles gets improved in the presence of drug. The micropolarity measurements have been performed to shed light on the locus of solubilization of the drug in pure and mixed micellar systems. The compatibility between CLZ and drug carriers (pluronics and SDC) was confirmed using powder X-ray diffraction (PXRD) and Fourier transform infrared spectroscopy (FTIR) techniques. Among the investigated systems, P84-SDC mixed system was found to be highly efficient for CLZ loading. The long term stability data indicated that CLZ loaded P84-SDC mixed micellar formulation remained stable for 3months at room temperature. Further, it was revealed that the CLZ loaded P84-SDC mixed micelles are converted into CLZ loaded pure P84 micelles at 30-fold dilutions which remain stable up to 48-fold dilutions. The results from the present studies suggest that P84-SDC mixed micelles can serve as suitable delivery vehicles for hydrophobic drug CLZ.

Mixed micelles for encapsulation of doxorubicin with enhanced in vitro cytotoxicity on breast and ovarian cancer cell lines versus Doxil®

Doxorubicin (DOX) is used as a “first-line” antineoplastic drug in ovarian and metastatic breast cancer. However, serious side effects, such as cardiotoxicity have been reported after DOX intravenous administration. Hence, we investigated different micelle-former biomaterials, as Soluplus®, Pluronic F127, Tetronic T1107 and d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) to develop a potential mixed micellar nanocarrier for DOX delivery. Since DOX hydrochloride is a poor candidate to be encapsulated inside the hydrophobic core of the mixed micelles, we assayed a hydrophobic complex between DOX and sodium deoxycholate (NaDC) as an excellent candidate to be encapsulated within polymeric micelles. The combination of T1107:TPGS (1:3, weight ratio) demonstrated the best physicochemical properties together with a high DL capacity (6.43% w/v). Particularly, DOX in vitro release was higher at acidic tumour microenvironment pH value (5.5) than at physiological counterpart (7.4). The hydrodynamic diameter of the DOX/NaDC-loaded mixed micellar system was 10.7nm (PDI=0.239). The in vitro cytotoxicity of the mixed micellar formulation resulted significantly (p<0.05) higher than Doxil® against ovarian (SKOV-3) and triple-negative breast cancer cells (MDA-MB- 231). Further, the in vitro cellular uptake assays demonstrated a significant increment (p<0.05) of the DOX intracellular content for the mixed micelles versus Doxil® for both, SKOV-3 (at 2, 4 and 6h of incubation) and MDA-MB-231 (at 4h of incubation) cells. These findings suggest that T1107:TPGS (1:3) mixed micelles could be employed as a potential nanotechnological platform for drug delivery of DOX.

Corrigendum to ''A glucose-targeted mixed micellar formulation outperforms Genexol in breast cancer cells'' [Euro. J. Pharmaceut. Biopharmaceut. 114 (2017) 305-316

Corrigendum to ''A glucose-targeted mixed micellar formulation outperforms Genexol in breast cancer cells'' [Euro. J. Pharmaceut. Biopharmaceut. 114 (2017) 305-316

A glucose-targeted mixed micellar formulation outperforms Genexol in breast cancer cells

Breast cancer represents the top cancer among women, accounting 521.000 deaths per year. Development of targeted nanomedicines to breast cancer tissues represents a milestone to reduce chemotherapy side effects. Taking advantage of the over-expression of glucose (Glu) membrane transporters in breast cancer cells, we aim to expand the potential of a paclitaxel (PTX)-loaded mixed micellar formulation based on polyvinyl caprolactam-polyvinylacetate-polyethylene glycol graft copolymer (Soluplus®) and D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) by its surface decoration with Glu moieties. The glycopolymer (Soluplus(Glu)) was obtained by microwave-assisted ring opening reaction of δ-gluconolactone initiated by Soluplus®. The glycosylation was confirmed by 1H NMR and by agglutination assays employing Concanavalin A. The hydrodynamic diameter of Soluplus(Glu) micelles was characterized by dynamic light scattering (100.3±3.8nm) as well as the critical micellar concentration value (0.0151% w/v). Then, a mixed micelle formulation employing Soluplus®, Soluplus(Glu) and TPGS (3:1:1wt ratio) loaded with PTX (4mg/mL) was developed as a multifunctional nanocarrier. Its in vitro anticancer performance in MCF-7 (1.6-fold) and MDA-MB-231 (14.1-fold) was significantly enhanced (p<0.05) versus the unique commercially available micellar-based PTX-nanoformulation (Genexol®). Furthermore, the in vitro PTX cellular uptake assays revealed that the drug intracellular/cell content was significantly (p<0.05) higher for the Glu-containing mixed micelles versus Genexol® after 6h of incubation with MCF-7 (30.5-fold) and MDA-MB-231 (5-fold). Overall, results confirmed the potential of our Glu-decorated mixed colloidal formulation as an intelligent nanocarrier for PTX-targeted breast cancer chemotherapy.

Mixed Micelles Loaded with Bile Salt: An Approach to Enhance Intestinal Transport of the BCS Class III Drug Cefotaxime in Rats.

Cefotaxime is a class III drug according to the Biopharmaceutical Classification System due to low intestinal permeability based on poor oral bioavailability. Bile salt compounds have been shown to be effective additive for drug permeation through several biological membranes. The main purpose of this study was to investigate the ability of a mixed micelles made of phosphatidylcholine, sodium deoxycholate, and loaded with a cefotaxime-3α,7α-dihydroxy-12-keto-5β-cholanate complex to enhance the oral bioavailability of cefotaxime in rats. Thin-film hydration method was used to prepare cefotaxime-loaded mixed micelles using different bile salt concentrations (0.87-25mM of sodium deoxycholate). Overall, micelle sizes ranging from 86.9 to 155.6nm were produced with negative zeta potential values from -15.9 to -19.5mV and drug loading from 10.5 to 18.9%. The oral bioavailability of cefotaxime in mixed micellar formulation was assessed and the pharmacokinetic parameters were compared with cefotaxime-3α,7α-dihydroxy-12-keto-5β-cholanate complex and cefotaxime aqueous solution. 24 Male Wistar rats were randomly allocated into four groups (n=6, per group) to receive the following: (1) a single intravenous dose of cefotaxime (25mg/kg) in sterilized normal saline solution for injection; (2) a single oral dose of mixed micelles (100mg/kg of cefotaxime) in phosphate buffered saline administered by oral gavage; (3) a single oral dose of cefotaxime-3α,7α-dihydroxy-12-keto-5β-cholanate complex (100mg/kg of cefotaxime) in phosphate buffered saline administered by oral gavage; (4) a single oral dose of free cefotaxime (100mg/kg) in aqueous solution administered by oral gavage. Blood samples were collected for up to 24h and cefotaxime analyzed using a validated HPLC assay. Pharmacokinetic data showed that the oral bioavailability of cefotaxime in mixed micelles was found to be 4.91% higher compared to the cefotaxime in aqueous solution (1.30%). Maximum concentration (C max) of cefotaxime in mixed micellar formulation was higher (1.08±0.1µg/ml) compared to the cefotaxime-3α,7α-dihydroxy-12-keto-5β-cholanate complex (0.69±0.1µg/ml) and cefotaxime in aqueous solution (0.52±0.1µg/ml). Similarly, the mean values for area under the plasma concentration-time curve extrapolated to infinity (AUC0-∞) of cefotaxime in the mixed micellar formulation was higher (3.89±0.9μg·h/mL) compared to the cefotaxime-3α,7α-dihydroxy-12-keto-5β-cholanate complex (1.52±0.2μg·h/mL) and cefotaxime in aqueous solution (1.03±0.4μg·h/mL), respectively. The mixed micellar formulation was able to increase the oral bioavailability of the BCS Class III drug cefotaxime up to fourfold by enhancing drug permeation through the mucosal membrane of the small intestine.

Antioxidant and hepatoprotective effects of mixed micellar lipid formulation of phyllanthin and piperine in carbon tetrachloride-induced liver injury in rodents.

Phyllanthin, a sparingly water-soluble hepatoprotective lignin obtained from Phyllanthus amarus Schum. et Thonn. (Euphorbiaceae) possesses low bioavailability. Phyllanthin along with piperine (a nutraceutical bioenhancer) was formulated as a mixed micellar lipid formulation (MMLF) in the present study and investigated to resolve the low bioavailability and enhance hepatoprotective effects on oral administration. Hepatoprotective, antioxidant and bioavailability studies of MMLF, a complex phosphatidylcholine formulation of phyllanthin (CP-PC), phyllanthin + piperine (CP-P-PC) and its corresponding non-formulated phyllanthin have been carried out. Phyllanthin (30 mg kg(-1) p.o.), CP-PC (30 mg kg(-1) p.o.), CP-P-PC (30 mg kg(-1) p.o.) and the reference drug silymarin (100 mg kg(-1), p.o.) were administered daily to rats for 10 days, followed by liver damage by administering a 1 : 1 (v/v) mixture of CCl4 and olive oil (1 ml kg(-1), i.p.) for 7 days from day 4 to day 10. The degree of protection was evaluated by determining the level of marker enzymes (SGOT and SGPT), bilirubin (TB) and total proteins (TP). Further, the effects of MMLF on lipid peroxidation (LPO), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and glutathione reductase (GR) were estimated in liver homogenates to evaluate the antioxidant activity. Finally the concentration of phyllanthin was evaluated in plasma. EC50 values for the in vitro antioxidant assay with DPPH were found to be 19.99, 15.94 and 13.5 for phyllanthin, CP-PC and CP-P-PC, respectively. CP-P-PC (30 mg kg(-1) p.o.) showed significant (p < 0.05) hepatoprotective effect by reducing the levels of serum marker enzymes (SGOT, SGPT, and TB), whereas, elevated the levels of depleted total protein (TP), lipid peroxidation and antioxidant marker enzyme activities such as, GSH, SOD, CAT, GPX, and GR. The complex MMLF normalized adverse conditions of rat livers more efficiently than the non-formulated phyllanthin. The present findings indicate that the MMLF is helpful in solving the problem of low bioavailability of phyllanthin.

MPEG-b-PCL/TPGS mixed micelles for delivery of resveratrol in overcoming resistant breast cancer

Objective: Drug resistance remains a major challenge for effective breast cancer chemotherapy. Resveratrol (Res) is a promising candidate for overcoming cancer chemoresistance, but it has low bioavailability due to poor absorption, and ready metabolism limits its application. This study aims to develop a Res-loaded mixed micelle system to be effective on drug resistance of breast cancer cells.Methods: A mixed micelle system made of methoxy poly (ethylene glycol)-b-polycaprolactone (mPEG-PCL) and d-α-Tocopherol polyethylene glycol succinate was prepared and Res was encapsulated to form Res-loaded mixed micelles. Furthermore, the antitumor activity against doxorubicin (Dox)-resistant breast cancer MCF-7/ADR cells was studied and the possible mechanism was elucidated.Results: The mixed micellar formulation increased drug uptake efficiency of Res by Dox-resistant breast cancer MCF-7/ADR cells, and induced higher rates of apoptotic cell death, as assessed by the accumulation of Sub G1 phases of cell cycle, nucleus staining and Annexin-FITC/propidium iodide assay. Moreover, Res-loaded mixed micelles also markedly enhanced Dox-induced cytotoxicity in MCF-7/ADR cells and increased the cellular accumulation of Dox by downregulating the expression of P-glycoprotein (P-gp) and inhibiting the activity thereof.Conclusion: The cumulative evidence indicates that Res-loaded mixed micelles hold significant promise for the treatment of drug-resistant breast cancer.

Impact of Micellar Vehicles on in situ Intestinal Absorption Properties of Beta-Lapachone in Rats.

The aim of the present study was to examine the effect of micellar systems on the absorption of beta-lapachone (b-lap) through different intestinal segments using a single-pass rat intestinal perfusion technique. B-lap was solubilized in mixed micelles composed of phosphatidylcholine and sodium deoxycholate, and in sodium lauryl sulfate (SLS)-based conventional micelles. Both mixed micelles and SLS micelles improved the in situ permeability of b-lap in all intestinal segments tested although the mixed micellar formulation was more effective in increasing the intestinal absorption of b-lap. The permeability of b-lap was greatest in the large intestinal segments. Compared with SLS micelles, the effective permeability coefficient values measured with mixed micelles were 5- to 23-fold higher depending on the intestinal segment. Our data suggest that b-lap should be delivered to the large intestine using a mixed micellar system for improved absorption.

Development and validation of a fast and sensitive bioanalytical method for the quantitative determination of glucocorticoids—Quantitative measurement of dexamethasone in rabbit ocular matrices by liquid chromatography tandem mass spectrometry

A sensitive, selective, accurate and robust LC–MS/MS method was developed and validated for the quantitative determination of glucocorticoids in rabbit ocular tissues. Samples were processed by a simple liquid–liquid extraction procedure. Chromatographic separation was performed on Phenomenex reversed phase C18 gemini column (50 mm × 4.6 mm i.d.,) with an isocratic mobile phase composed of 30% of acetonitrile in water containing 0.1% of formic acid, at a flow rate 0.2 mL/min. Dexamethasone (DEX), prednisolone (PD) and hydrocortisone (HD) were detected with proton adducts at m/ z 393.20 → 355.30, 361.30 → 147.20 and 363.20 → 121.0 in multiple reaction monitoring (MRM) positive mode respectively. Finally, 50 μL of 0.1% novel DEX mixed micellar formulation was topically administered to a rabbit eye and concentrations were measured. The method was validated over a linear concentration range of 2.7–617.6 ng/mL. Lower limit of quantitation (LLOQ) of DEX and PD was measured in the concentration range of 2.7 and 11.0 ng/mL respectively. The resulting method demonstrated intra and inter-day precision within 13.3% and 11.1% and accuracy within 19.3% and 12.5% for DEX and PD, respectively. Both analytes were found to be stable throughout freeze–thaw cycles and during bench top and postoperative stability studies ( r 2 > 0.999). DEX concentrations in various ocular tissue samples i.e., aqueous humor, cornea, iris ciliary body, sclera and retina choroid were found to be 344.0, 1050.07, 529.6, 103.9 and 48.5 ng/mg protein respectively. Absorption of DEX after topical administration from a novel aqueous mixed micellar formulation achieved therapeutic concentration levels in posterior segment of the rabbit eye.

Mixed-Micellar Proliposomal Systems for Enhanced Oral Delivery of Progesterone

The objective of our study was to develop a mixed-micellar proliposomal formulation of poorly water-soluble drug progesterone and evaluate the dissolution profile and membrane transport. Several formulations of proliposomes were prepared by mixing different concentrations of lipid, progesterone, polysorbate 80, and microcrystalline cellulose. The mixed-micellar formulation of drug:dimyristoyl-phosphatidycholine:polysorbate 80 (1:20:3.3) exhibited the maximum dissolution (75.27%), while pure progesterone resulted in low dissolution. The above formulation showed a 4-fold increase in transport in Caco-2 cells and a 6-fold increase in transport across the everted rat intestinal sac experiments compared with control. Proliposomal formulations enhance the extent of dissolution and membrane transport of progesterone and serve as ideal carriers for oral delivery of drugs with low water solubility.

Assessment of tissue damaging effects of mixed micellar absorption enhancers on the intestinal mucosa of common carp (Cyprinus carpio), African catfish (Clarias gariepinus) and rainbow trout (Oncorhynchus mykiss) as a consequence of enhanced intestinal absorption of sGnRH-a

Non-ionic surfactant–polyoxyethylene sorbitan monooleate (Tween-80) and oleic acid are food and pharmaceutical ingredients for oral and parenteral delivery and generally regarded as safe (GRAS). They have the potential as an intestinal absorption enhancer for the development of oral drug delivery systems. However, their safety in terms of mucosal integrity has yet to be evaluated. Therefore, the purpose of the present work was to study the tissue damaging effects of Tween-80, oleic acid and of their mixed micellar formulation (oleic acid + Tween-80). This was investigated at 2 h and 24 h after rectal delivery and compared with the topical effect of polyoxyethylene 9 lauryl ether (Polydocanol). The same experiment was carried out on three species with distinct feeding habits: the common carp, Cyprinus carpio (L.); the African catfish, Clarias gariepinus (Burchell); and the rainbow trout, Oncorhynchus mykiss (Walb.). Based on the findings of this study it was concluded that Tween-80 (4%), or its mixed micelle with oleic acid (0.6%) can be considered as a safe formulation, inducing only a moderate alteration of the intestinal mucosa, comparable to the effect of an isotonic saline. By contrast, in the three species, the same dose of Polydocanol, or of its mixed micelle with oleic acid, induced severe tissue damage of the intestinal mucosa, still present after 24 h. Mixed micelles of oleic acid with Tween-80 were also demonstrated as increasing the intestinal absorption of the salmon gonadotropin releasing hormone analogue (sGnRH-a) in catfish, C. gariepinus, and consequently stimulating GtH II secretion. This effect was compared with the action of other drugs considered as intestinal absorption enhancers.

Anticoagulant Activity and Pharmacokinetic Properties of a Sub-cutaneously Administered Mixed Micellar Formulation of Argatroban in Experimental Animals

We have studied the anticoagulant properties of a novel mixed micellar formulation containing 14 mg/ml argatroban administered by the sub-cutaneous (s.c.) route to rats, rabbits, dogs and primates. Blood samples were taken at various times post-treatment for the determination of the thrombin time (TT), Ecarin clotting time (ECT) and the activated partial thromboplastin time (aPTT). Plasma levels of argatroban were determined in the dog and primate. Mixed micelles alone (0.15 M sodium glycocholate and 0.15 M egg lecithin) were without effect on the clotting parameters. The mixed micellar formulation of argatroban dose-dependently increased all three clotting parameters in the rat (1-4 mg/kg), the rabbit (1 and 2 mg/kg), the dog (1 and 2 mg/kg) and the primate (0.25 and 0.5 mg/kg). In each case the TT was the most sensitive parameter, followed by the ECT and the aPTT. The duration of action of argatroban in each species was dose dependent and varied from 3 h in the rat to 6 h in the dog. In the latter, the mixed micelle formulation had a significantly increased plasma half-life and mean residence time without affecting the overall area under the curve. The increases in the clotting time were strongly correlated with the plasma levels of argatroban and were linear across the range of concentrations obtained in the dog and the primate, although the aPTT plasma concentration response curve was very flat. Species differences were noted between the increase in clotting time for a given plasma concentration, with the primate being more sensitive than the dog (e.g. 4.7 times more so in terms of the ECT). Thus, a mixed micellar formulation of argatroban, which markedly enhances its solubility, could be useful as a potential anticoagulant for sub-cutaneous administration.

Activity of a Sub-cutaneously Administered Novel Mixed Micellar Formulation of Argatroban in Rat and Rabbit Models of Venous Thrombosis

We studied the antithrombotic activity of a mixed micellar formulation containing 14 mg/ml argatroban administered by the subcutaneous (s.c.) route in rat and rabbit models of venous thrombosis. The effects on bleeding time in the rat tail transection bleeding time test were also studied. In a tissue factor-dependent arterio-venous shunt model, argatroban treatment led to dose-dependent reduction in thrombus weight with an estimated ID50 of 1.8 mg/kg s.c. In the same model, heparin had an estimated ID50 of 179 IU/kg. The antithrombotic activity of argatroban was accompanied by increases in the thrombin and ecarin clotting times but not the aPTT, whereas heparin increased the thrombin time and aPTT but not the ecarin clotting times. Argatroban also inhibited thrombus formation in a rabbit model of thromboplastin + stasis induced thrombosis in the rabbit jugular vein with an estimated ID50 of 1 mg/kg s.c. When tested in the rat tail transection bleeding time test, the mixed micellar formulation of argatroban caused significant increases in the bleeding time as from 8 mg/kg s.c., while heparin significantly increased the bleeding time at 800 U/kg. Mixed micellar argatroban appears to have a superior safety margin to heparin in terms of antithrombotic efficacy and bleeding risk. Thus, a mixed micellar formulation of argatroban, which markedly enhances its solubility, could be useful as a potential antithrombotic agent for subcutaneous administration.

Adverse events associated with vitamin K1: results of a worldwide postmarketing surveillance programme.

We compared adverse events associated with a conventional vitamin K(1) preparation, Konakion, with a new mixed micellar formulation, Konakion MM. Data were obtained worldwide from spontaneous reports, clinical trials and postmarketing surveillance. During the period 1974 to July 1995, an estimated 635 million adults and 728 million children were prescribed Konakion or Konakion MM. Of the 404 adverse events in 286 subjects reported, 387 (96%) were associated with Konakion. Konakion MM accounted for 4% (n=17) of the reported adverse events, and 5% of total sales figures. Thirteen of the 17 adverse events (76%) reported for Konakion MM were minor injection site reactions. Overall, 120 of the adverse events were serious, of which 117 (98%) were associated with Konakion. Eighty-five probable anaphylactoid reactions (of which six were fatal) were reported for conventional Konakion, compared with one non-fatal anaphylactoid reaction for Konakion MM. During the last 12 months of postmarketing surveillance, there were 14 serious adverse events reported in an estimated 21 million individuals treated with Konakion, but none in the 13 million who received Konakion MM. These results suggest that the Cremophor EL-solubilized preparations of vitamin K(1) have a higher profile of adverse events, including anaphylactoid reactions, than the newer mixed micellar preparation, Konakion MM.