Tissue compatibility and pharmacokinetics of three potential subcutaneous injectables for low‐pH drug solutions

Objectives The aim of the study was to investigate the tissue tolerance and bioavailability of four formulations containing 5% ricobendazole solubilised at low pH, following subcutaneous injection in sheep. Formulations were: a water‐in‐oil emulsion, a microemulsion, a hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD, 20%) drug solution, and a low‐pH drug solution (reference). Methods In‐vitro cytotoxicity of the formulations was investigated in L929 fibroblasts using MTS viability and lactate dehydrogenase leakage assays. Each formulation and respective vehicle was injected into either side of the back of a sheep to investigate the tissue tolerance and pharmacokinetics. Key findings In‐vitro studies suggested that both the emulsion and the microemulsion are unlikely to give a burst release of the low‐pH drug solution in aqueous media. The microemulsion showed the greatest in‐vitro cytotoxic effect but no significant difference was observed between the other formulations. In sheep, the three new formulations and vehicles caused little or no injection‐site reactions compared with a marked response to the reference formulation. Bioavailabilities of HP‐β‐CD formulation, emulsion and microemulsion formulations, relative to the reference formulation, were 194, 155 and 115%, respectively. Conclusions The three new subcutaneous injectables showed promise for reducing irritation of low‐pH solubilised ricobendazole. HP‐β‐CD significantly enhanced the drug absorption. Controlling the burst release of the low‐pH drug solution may improve tissue tolerance and minimise post‐injection precipitation, and hence increase drug bioavailability. The in‐vitro cytotoxicity studies did not predict the in‐vivo irritation effects.     

Development of Mucoadhesive Films for Buccal Administration of Flufenamic Acid: Effect of Cyclodextrin Complexation

A new mucoadhesive film for topical administration in the oral cavity of flufenamic acid, a poorly soluble anti-inflammatory drug, has been developed, using complexation with hydroxypropyl-β-cyclodextrin (HPβCD) to improve drug dissolution and release rate. Buccal films were prepared utilising chitosan as mucoadhesive polymer, KollicoatIR® as film-forming polymer and glycerol as plasticiser. Different combinations of these components were used and the obtained films were characterised for weight, thickness, swelling, mucoadhesive and mechanical properties. The film containing chitosan 2%, glycerol 7.5% and KollicoatIR® 1% showed the best properties for the development of the film formulation. The selected film was loaded with the plain drug and its colyophilised and coground products with HPβCD, and in vitro release studies in simulated saliva were performed. The improved drug dissolution properties, obtained by complexation with HPβCD, were critical to achieve complete release from film formulation during 4–5 h. On the contrary, film loaded with the plain drug showed incomplete release, not exceeding 70% release after 5 h. The developed film formulation containing the drug as complex with HPβCD can assure a prolonged drug release directly at the inflammation site and can be proposed as a new therapeutic tool in the treatment of oral mucosa inflammations.     

Terbinafine. A pharmacoeconomic evaluation of its use in superficial fungal infections

Terbinafine is an orally and topically active allylamine antifungal drug which is an effective and well tolerated therapy for a wide range of superficial dermatophyte infections. In contrast to most other commonly prescribed antifungal agents, terbinafine is fungicidal in vitro and possesses improved pharmacokinetic properties with respect to drug penetration into nail tissue following oral administration. These properties enable terbinafine to achieve high success rates with shortened therapy regimens in the treatment of dermatophyte skin infections and onychomycosis. Pharmacoeconomic analyses have shown that oral terbinafine, with its higher rates of clinical efficacy and lower rates of relapse/reinfection, is less costly and more cost effective than oral griseofulvin, ketoconazole and itraconazole when used as initial therapy in the treatment of onychomycosis. However, some points regarding the clinical efficacy of itraconazole relative to terbinafine and the drug treatment regimens used in these studies need further clarification. In the management of tinea pedis, a cost analysis suggested that initial therapy with terbinafine 1% cream was more costly than initial therapy with miconazole, oxiconazole or clotrimazole. However, in cost-effectiveness studies, terbinafine had a lower cost per disease-free day than ciclopirox, clotrimazole, ketoconazole and miconazole in the treatment of dermatophyte skin infections. In conclusion, available clinical and pharmacoeconomic data support the use of topical terbinafine as first-line treatment of dermatophyte skin infections unless the acquisition cost of terbinafine is markedly greater than that of alternative topical antifungal agents. Oral terbinafine can be recommended as a cost-effective first-line treatment, preferable to oral griseofulvin, ketoconazole and itraconazole, in patients with dermatophyte onychomycosis.     

Cyclodextrin-water soluble polymer ternary complexes enhance the solubility and dissolution behaviour of poorly soluble drugs. Case example: Itraconazole

The aim of the present series of experiments was to improve the solubility and dissolution/precipitation behaviour of a poorly soluble, weakly basic drug, using itraconazole as a case example. Binary inclusion complexes of itraconazole with two commonly used cyclodextrin derivatives and a recently introduced cyclodextrin derivative were prepared. Their solubility and dissolution behaviour was compared with that of the pure drug and the marketed formulation Sporanox®. Ternary complexes were prepared by addition of Soluplus®, a new highly water soluble polymer, during the formation of the itraconazole/cyclodextrin complex. A solid dispersion made of itraconazole and Soluplus® was also studied as a control. Solid state analysis was performed for all formulations and for pure itraconazole using powder X-ray diffraction (pX-RD) and differential scanning calorimetry (DSC). Solubility tests indicated that with all formulation approaches, the aqueous solubility of itraconazole formed with hydroxypropyl-β-cyclodextrin (HP-β-CD) or hydroxybutenyl-β-cyclodextrin (HBen-β-CD) and Soluplus® proved to be the most favourable formulation approaches. Whereas the marketed formulation and the pure drug showed very poor dissolution, both of these ternary inclusion complexes resulted in fast and extensive release of itraconazole in all test media. Using the results of the dissolution experiments, a newly developed physiologically based pharmacokinetic (PBPK) in silico model was applied to compare the in vivo behaviour of Sporanox® with the predicted performance of the most promising ternary complexes from the in vitro studies. The PBPK modelling predicted that the bioavailability of itraconazole is likely to be increased after oral administration of ternary complex formulations, especially when itraconazole is formulated as a ternary complex comprising HP-β-CD or HBen-β-CD and Soluplus®.     

Rheological and in vitro release behaviour of clotrimazole-containing aqueous SLN dispersions and commercial creams

Clotrimazole is a wide spectrum local imidazolic antifungal agent used in several dermatological creams, having e.g. 1% (m/m) such as Canesten and Fungizid-ratiopharm cream. In the present work, a new system based on solid lipid nanoparticles (SLN) containing the identical concentration of drug has been developed. A comparative study between the rheological properties of the referred creams and the developed aqueous SLN dispersions was carried out. The influence of incorporation of SLN in a standard hydrophilic cream on its flow curves was also assessed. In addition, the release of clotrimazole from the two commercial creams, as well as from aqueous SLN dispersions was studied. Concerning the rheological investigations, all tested commercial creams revealed very low shear rates and no yield points. Lipid nanoparticles having a mean diameter of approx. 200 nm have been incorporated into a hydrophilic cream, in a concentration of 20%, 30% or 40% (m/m). The hydrophilic cream containing 20% of SLN showed a dilatant-like character; however, increasing the percentage of incorporated lipid nanoparticles to 30% and 40% the formulation changed to a more pseudoplastic character, showing yield values of 28 Pa and 39 Pa, respectively. For in vitro release studies, Franz diffusion cells with a cellulose acetate membrane were used to measure the release of clotrimazole from two different commercial formulations in comparison to the aqueous SLN dispersion. After 6 h the amount of drug released was higher than 48% when delivered from both investigated commercial formulations and not higher than 25% when delivered from the aqueous SLN dispersion. The percentage of drug released determined after 24 h was more than 50% for Canesten cream and Fungizid-ratiopharm cream and not higher than 30% for the developed SLN formulation showing its prolonged release character.     

Econazole: a review of its antifungal activity and therapeutic efficacy.

Econazole1 is a recently introduced imidazole antifungal agent which is very closely related structurally to another imidazole derivative, miconazole. For local application the nitrate salt of econazole is used, while in preliminary investigations of systemic use in a few patients econazole base has been administered orally or intravenously. In uncontrolled studies in large numbers of patients, econazole nitrate has been administered topically in the treatment of dermatomycoses due to a wide variety of fungi, and vaginally in the treatment of vaginal candidosis; but it has not been compared with any other antifungal drug in controlled therapeutic trials in mycoses of the skin and has only been compared with nystatin in a few patients with vaginal candidosis. Until adequate comparative studies are done the relative place of econazole in the treatment of dermatomycoses and vaginal condidosis, compared with traditional antifungal agents and with other imidazole derivatives such as miconazole or clotrimazole, cannot be clearly stated. Nevertheless, econazole nitrate is an effective antifungal drug. In dermatological studies about 90% of a large number of patients were cured, often after a relatively short treatment period (2 to 6 weeks, as occurs with other imidazole antifungal agents). The cure rate was only slightly lower (about 85%) in patients with severe mycoses of many years' duration than in those whose infections were of more recent onset. In vaginal candidosis a 3-day treatment regimen using a 150mg suppository once daily was only slightly less effective (85% mycological cure rate) than a 15-day regimen using a 50mg dose (suppository or cream) once daily (90% cure rate). A 3 to 5 day 'higher' dose regimen was slightly more effective than a standard 15-day regimen of nystatin vaginal inserts in a small group of patients with vaginal candidosis. The convenience of the higher-dose shorter term regimen would likely be an important advantage to most patients. Whether other agents useful in vaginal candidosis would be as effective as econazole were they to be used in this way, has not been determined. Topical or intravaginal econazole nitrate has usually been well tolerated, side effects being limited to local irritation in about 1 to 4% of patients in most studies.     

Formulation and evaluation of itraconazole via liquid crystal for topical delivery system

Liquid crystal systems are used to tailor drug delivery from topical delivery system. Ternary polyoxyethylene [21] stearyl ether/ oil and water form liquid crystalline system cream, which has a potential as dosage form for 1% itraconazole as topical dermal drug delivery. Evaluation of the suggested formula was performed for the best physical performance, the compatibility of the components of lyotropic liquid crystal with itraconazole was conducted through polarized light microscopy, differential scanning calorimeter, thermogravimetric analysis and viscosity measurements. Fourier transform infrared spectroscopy has been studied. Furthermore, in vitro antimycotic inhibitory activity of 1% itraconazole from liquid crystal, was conducted using agar-cup method and Candida albicans as a test organism. The pH value of the cream was found to be 7.1, while when the drug was incorporated in the cream, the pH value was 6.7. The formula was examined under polarized microscope at 20x magnification and the birefringence that is characteristic of concentric lamellar liquid crystal was observed around the oil globules. Differential scanning calorimeter of itraconazole cream showed higher transition peak temperature at 120 degrees C for the hydrophilic gel phases. Fourier transform infrared spectroscopy revealed that there was no complex or any interaction between the surfactant and the drug. The microbial studies revealed that our formula had the highest zone of inhibition. The average +/- SD inhibition zone values of the test, control I and control II are 30.4+/-1.14, 19.6+/-1.14 and 14.8+/-0.83 mm, respectively. It was found that the test was significantly different from control I and control II, P=5.33x10(-6), 8.92x10(-5), respectively, so it may be concluded that incorporation of the drug in liquid crystal increased its antimicotic activity against Candida albicans.     

Systemic absorption of clindamycin after intravaginal administration of clindamycin phosphate ovule or cream.

The absolute bioavailability of clindamycin phosphate vaginal ovule with comparison to a reference treatment of clindamycin phosphate sterile solution, as well as the relative bioavailability of the ovule compared to clindamycin phosphate vaginal cream, was evaluated in 12 healthy adult female volunteers. Subjects were randomly assigned to receive either the ovule or cream formulation intravaginally for 3 consecutive days during the two-way crossover portion of the study. During a third treatment period, all subjects received 100 mg of clindamycin as a 4-minute intravenous infusion of clindamycin phosphate sterile solution (10 mg/mL). Clindamycin concentrations in serum were assayed by a high-performance liquid chromatography method with detection by mass spectrometry. Pharmacokinetic analyses of the serum data indicated low systemic absorption of clindamycin from the vaginal cream (about 4%), consistent with results of previous bioavailability studies. Following intravaginal administration of the clindamycin phosphate ovule, systemic absorption averaged 30%, which was approximately sevenfold greater than after dosing with the vaginal cream. The higher drug absorption for the ovule may be related to differences in formulation effects on the vaginal membrane. Nevertheless, systemic exposure to clindamycin from the ovule is still considerably lower than from a therapeutic oral dose.     

Miconazole: a review of its antifungal activity and therapeutic efficacy.

Miconazole2, a synthetic imidazole derivative, is a new topical antifungal agent for use in the local treatment of vaginal, and skin and nail infections due to yeasts and dermatophytes. It is particularly active against Candida spp., Trichophyton spp., Epidermophyton spp., Microsporum spp. and Pityrosporon orbiculare (Malassezia furfur), but also possesses some activity against Gram-positive bacteria. In vaginal candidiasis, miconazole vaginal cream has produced higher cure rates than conventional nystatin vaginal tablets or amphotericin B vaginal cream. There have been no published comparisons with nystatin vaginal cream or foaming vaginal tablets - the nystatin dosage form preferred by some clinicians. The vaginal cream has also achieved a cure where previous nystatin or natamycin therapy had failed. Miconazole has proved equally effective in both Candida and dermatophyte infections of the skin, but as yet there have been no published comparisons with other antifungal agents. However, it has been successfully used in chronic skin infections which had not responded satisfactorily to other agents such as natamycin and pecilocin. Preliminary experience with oral and intravenous miconazole therapy in systemic candidiasis is promising. Miconazole preparations are well accepted and tolerated.     

Use of cyclodextrins as solubilizing agents for simvastatin: effect of hydroxypropyl-β-cyclodextrin on lactone/hydroxyacid aqueous equilibrium

The chemical conversion of simvastatin from the lactone (SVL) to the hydroxyacid (SVA) form is becoming an intriguing issue associated with the pharmacological use of SVL. On this matter, recent findings suggest that SVL complexation with cyclodextrins (CDs) may be a useful strategy to affect its aqueous solubility and chemical stability. In this work, a reverse-phase high-performance liquid chromatography (RP-HPLC) method able to selectively identify and quantify SVL and SVA has been set up, validated and applied to follow SVL hydrolysis in the presence of HPβCD. The combination of stability results with simvastatin/HPβCD stability constants achieved from UV-vis measurements and solubility/dissolution studies allowed to get an insight into SVL/HPβCD, SVA/HPβCD and SVL/SVA equilibria taking place in aqueous solution. Results show that in the presence of HPβCD the aqueous SVL/SVA equilibrium is shifted versus the hydroxyacid form. UV-vis results, showing that the lactone and the open-ring form of simvastatin interact with HPβCD in a similar extent, suggest that hydrolysis occurs also on SVL/HPβCD complex, thus supporting a mode of interaction that does not involve the lactone ring. This hypothesis is strengthened by NMR analysis performed on SVA, HPβCD and their inclusion complex, which indicates that the lactone ring is not included in HPβCD hydrophobic cavity. Finally, results suggest that particular attention must be paid to SVL lactonization in aqueous solution when using CD-based formulations and in demonstrating their effective benefit for a specific therapeutic use.     

Itraconazole IV nanosuspension enhances efficacy through altered pharmacokinetics in the rat

The goal of this research was to evaluate an intravenous itraconazole nanosuspension dosage form, relative to a solution formulation, in the rat. Itraconazole was formulated as a nanosuspension by a tandem process of microcrystallization followed by homogenization. Acute toxicity, pharmacokinetics, and distribution were studied in the rat, and compared with a solution formulation of itraconazole. Efficacy was studied in an immunocompromised rat model, challenged with a lethal dose of either itraconazole-sensitive or itraconazole-resistant C. albicans. Itraconazole nanosuspension was tolerated at significantly higher doses compared with a solution formulation. Pharmacokinetics of the nanosuspension were altered relative to the solution formulation. C(max) was reduced and t(1/2) was much prolonged. This occurred due to distribution of the nanosuspension to organs of the monocyte phagocytic system (MPS), followed by sustained release from this IV depot. The higher dosing of the drug, enabled in the case of the nanosuspension, led to higher kidney drug levels and reduced colony counts. Survival was also shown to be superior relative to the solution formulation. Thus, formulation of itraconazole as a nanosuspension enhances efficacy of this antifungal agent relative to a solution formulation, because of altered pharmacokinetics, leading to increased tolerability, permitting higher dosing and resultant tissue drug levels.     

Itraconazole. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in superficial and systemic mycoses

Itraconazole is an orally active triazole antifungal drug which has demonstrated a broad spectrum of activity and a favourable pharmacokinetic profile. It is a potent inhibitor of most human fungal pathogens including Aspergillus sp. In non-comparative clinical trials itraconazole was shown to be extremely effective in a wide range of superficial and more serious 'deep' fungal infections when administered once or twice daily. Generally, greater than 80% of patients with superficial dermatophyte or yeast infections are cured by itraconazole. Similarly, good to excellent response rates (clinical cure or marked improvement) are achieved in paracoccidioidomycosis, histoplasmosis, sporotrichosis, blastomycosis, systemic candidiasis, coccidioidomycosis, chromomycosis, aspergillosis and cryptococcosis. Understandably, given the rare nature of some of these diseases, clinical experience is relatively limited and further evaluation, preferably controlled trials with amphotericin B and ketoconazole, would help clarify the ultimate role itraconazole will have in their management. Preliminary findings also indicate that itraconazole may hold promise for the prophylaxis of opportunistic fungal infections in patients at risk, for example women with chronic recurrent vaginal candidiasis, immunodeficient patients with chronic mucocutaneous candidiasis, AIDS patients and patients receiving immunosuppressant drugs. In studies to date itraconazole has been very well tolerated. Transient changes in indices of liver function occurred in 1 to 2% of patients; however, symptomatic liver dysfunction (as occurs infrequently with ketoconazole) has not been reported. Wider clinical experience is needed to permit clear conclusions as to whether liver dysfunction can result from itraconazole administration. Thus, while several aspects of the drug's profile require further investigation, itraconazole is a promising new oral treatment of fungal disease. The extent to which itraconazole will be employed in preference to ketoconazole will be clarified by wider clinical experience.     

Pharmacology of itraconazole

Itraconazole is a triazole antifungal agent that has a broad spectrum of activity and is well tolerated. Itraconazole is highly efficacious, particularly because its main metabolite, hydroxy-itraconazole, also has considerable antifungal activity. The original capsule formulation of itraconazole may lead to variability in absorption and the plasma concentration. For the treatment of superficial fungal infections, this is not problematical because itraconazole accumulates at the infection site, making consistently high plasma concentrations unnecessary -- a characteristic that has been exploited in the development of a pulse regimen. Because consistent plasma concentrations are critical for the more serious systemic fungal infections, variable absorption of itraconazole from the capsules limits their application. Moreover, underlying disease processes and medical interventions can reduce absorption from the capsules in some patients with systemic fungal infections. To widen the beneficial application of itraconazole to include such patients, an oral solution and an intravenous formulation were developed. These formulations combine lipophilic itraconazole with hydroxypropyl-beta-cyclodextrin, a ring of substituted glucose molecules, which improves the solubility of itraconazole. The enhanced absorption and bioavailability of itraconazole from these new formulations make them ideal for the treatment of systemic fungal infections in a wide range of patient populations. The additional flexibility offered by the different routes of administration also means that itraconazole can be used in patients at high risk, such as children or those requiring intensive care, for whom the capsule formulation may be impractical.     

Comparative evaluation of cyclosporine A/HPβCD-incorporated PLGA nanoparticles for development of effective ocular preparations

To improve poor water solubility of cyclosporine A (CsA), hydroxypropyl-beta-cyclodextrin (HPβCD) was incorporated into the nanoparticle formulation. Solid complexes of CsA with HPβCD in different ratios were prepared by the kneading method. CsA containing alone or in combination with HPβCD in poly-lactide-co-glycolide (P-CsA or P-CsA-HPβCD) nanoparticles were prepared by the emulsification solvent evaporation method. The mean size of CsA-loaded NPs was found to be approximately 220?nm. The solubility of CsA was significantly improved and the phase solubility diagram of CsA–HPβCD systems showed an A_L type phase. Nanoparticles showed high CsA encapsulation efficiency (88%) and production yield (89%). Release rate was increased by the presence of HPβCD and total cumulative release ranged from 75% to 96% in 24?h. In vitro cytotoxicity study assay resulted in a low toxicity for all types of nanoparticles. After 6?h incubation period, the cellular uptake was found at 33% and 32% for P–CsA and P–HPβCD–CsA nanoparticles, respectively.     

Encapsulation of plai oil/2-hydroxypropyl-β-cyclodextrin inclusion complexes in polyvinylpyrrolidone (PVP) electrospun nanofibers for topical application

Abstract

The aim of this study was to prepare electrospun polyvinylpyrrolidone (PVP)/2-hydroxypropyl-β-cyclodextrin (HPβCD) nanofiber mats and to incorporate plai oil (Zingiber Cassumunar Roxb.). The plai oil with 10, 20 and 30%?wt to polymer were incorporated in the PVP/HPβCD solution and electrospun to obtain nanofibers. The morphology and structure of the PVP and PVP/HPβCD nanofiber mats with and without the plai oil were analyzed using scanning electron microscopy (SEM). The thermal behaviors of the nanofiber mats were characterized using differential scanning calorimeter (DSC). Terpinen-4-ol was used as a marker of the plai oil. The amount of plai oil remaining in the PVP/HPβCD nanofiber mats was determined using gas chromatography-mass spectoscopy (GC-MS). The SEM images revealed that all of the fibers were smooth. The average diameter of fibers was 212–450?nm, and decreased with the increasing of plai oil content. The release characteristics of plai oil from the fiber showed the fast release followed by a sustained release over the experimental time of 24?h. The release rate ranged was in the order of 10%?>?20%?～?30% plai oil within 24?h. Electrospun fibers with 20% plai oil loading provided the controlled release and also showed the highest plai oil content. Hence, this electrospun nanofiber has a potential for use as an alternative topical application.     

In Vivo Efficacy of Enabling Formulations Based on Hydroxypropyl-β-Cyclodextrins,Micellar Preparation,and Liposomes for the Lipophilic Cannabinoid CB2 Agonist,MDA7

Enabling formulations based on hydroxypropyl-β-cyclodextrins (HPβCD), micellar preparation, and liposomes have been designed to deliver the racemic mixture of a lipophilic cannabinoid type 2 agonist, MDA7. The antiallodynic effects of MDA7 formulated in these three different systems were compared after intravenous (i.v.) administration in rats. Stoichiometry of the inclusion complex formed by MDA7 in HPβCD was determined by continuous variation plot, electrospray ionization–mass spectrometry (ESI–MS) analysis, phase solubility, and nuclear magnetic resonance studies and indicate formation of exclusively 1:1 adduct. Morphology and particle sizes determined by dynamic light scattering and transmission electron microscopy show the presence of a homogeneous population of closed round-shaped oligolamellar MDA7 containing liposomes, with an average size of 117 nm [polydispersity index (PDI) <0.1]. Monodisperse micelles exhibited an average size of 15 nm (PDI 0.1). HPβCD-based formulation administrated in vivo was composed of two discrete particles populations with a narrow size distribution of 3 nm (PDI <0.1) and 510 nm (PDI <0.1). HPβCD-based formulation dramatically improved antiallodynic effect of MDA7 in comparison with the liposomes preparation. Through inclusion complexation and possibly formation of aggregates, HPβCD can enhance the aqueous solubility of lipophilic drugs, thereby improving their bioavailability for i.v. administration.     

Comparative evaluation of cyclosporine A/HPβCD-incorporated PLGA nanoparticles for development of effective ocular preparations

To improve poor water solubility of cyclosporine A (CsA), hydroxypropyl-beta-cyclodextrin (HPβCD) was incorporated into the nanoparticle formulation. Solid complexes of CsA with HPβCD in different ratios were prepared by the kneading method. CsA containing alone or in combination with HPβCD in poly-lactide-co-glycolide (P-CsA or P-CsA-HPβCD) nanoparticles were prepared by the emulsification solvent evaporation method. The mean size of CsA-loaded NPs was found to be approximately 220?nm. The solubility of CsA was significantly improved and the phase solubility diagram of CsA-HPβCD systems showed an A(L) type phase. Nanoparticles showed high CsA encapsulation efficiency (88%) and production yield (89%). Release rate was increased by the presence of HPβCD and total cumulative release ranged from 75% to 96% in 24?h. In?vitro cytotoxicity study assay resulted in a low toxicity for all types of nanoparticles. After 6?h incubation period, the cellular uptake was found at 33% and 32% for P-CsA and P-HPβCD-CsA nanoparticles, respectively.     

Interaction of [d-Trp6, Des-Gly10] LHRH Ethylamide and Hydroxy Propyl β-Cyclodextrin (HPβCD): Thermodynamics of Interaction and Protection from Degradation by α-Chymotrypsin

Purpose: The purpose of this study is to investigate the mechanisms and thermodynamics of the interaction between hydroxypropyl β-cyclodextrin (HPβCD) and [d-Trp ⁶, des-Gly ¹⁰] LHRH ethylamide (deslorelin), a peptide drug. Methods: We used UV and Fluorescence spectroscopy to study the interaction of HPβCD and deslorelin. Circular dichroism was used to study the conformational changes induced in deslorelin upon interaction with HPβCD. The thermodynamics of the interaction of deslorelin and HPβCD was studied using isothermal titration calorimetry (ITC). We also determined the effect of HPβCD on the degradation of deslorelin by α-chymotrypsin. Results: UV and fluorescence spectroscopy indicated that HPβCD induced a change in polarity of the environment surrounding the chromophores of deslorelin. Wavelength selective fluorescence indicated an increase in the fluorescence polarization of deslorelin with an increase in excitation wavelength in the presence of HPβCD suggesting that tryptophan is present in a media of reduced mobility. Circular dichroism studies indicated that HPβCD stabilizes the conformation of deslorelin. In addition, ITC indicated an exothermic reaction between deslorelin and HPβCD with a low enthalpy of binding of ～?600 cal/mol and a binding affinity of ～1.25 × 10 ² M^{? 1}. Finally, the rate of degradation of deslorelin by α-chymotrypsin was decreased by 33% in the presence of HPβCD. Conclusions: These results indicate that there is an interaction between HPβCD and deslorelin, which involves the inclusion of aromatic amino acids of deslorelin into the hydrophobic cavity of the cyclodextrin. This inclusion, providing steric hindrance, may be one of the mechanisms by which HPβCD reduces enzymatic hydrolysis of deslorelin.     

Preparation and evaluation of aceclofenac microemulsion for transdermal delivery system

To develop novel transdermal formulation for aceclofenac, microemulsion was prepared for increasing its skin permeability. Based on solubility and phase studies, oil and surfactant was selected and composition was determined. Microemulsion was spontaneously prepared by mixing ingredients and the physicochemical properties such was investigated. The mean diameters of microemulsion were approximately 90 nm and the system was physically stable at room temperature at least for 3 months. In addition, the in vitro and in vivo performance of microemulsion formulation was evaluated. Aceclofenac was released from microemulsion in acidic aqueous medium, and dissolved amounts of aceclofenac was approximately 30% after 240 min. Skin permeation of aceclofenac from microemulsion formulation was higher than that of cream. Following transdermal application of aceclofenac preparation to delayed onset muscle soreness, serum creatine phosphokinase and lactate dehydrogenase activity was significantly reduced by aceclofenac. Aceclofenac in microemulsion was more potent than cream in the alleviation of muscle pain. Therefore, the microemulsion formulation of aceclofenac appear to be a reasonable transdermal delivery system of the drug with enhanced skin permeability and efficacy for the treatment of muscle damage.