Systemic delivery of parathyroid hormone (1-34) using spray freeze-dried inhalable particles.

Pulmonary delivery of peptides remains an important, noninvasive route of administration that is attractive because it offers high bioavailability and patient compliance. Optimization of particle characteristics for deposition in the deep regions of the lung after inhalation and retention of peptide stability are key challenges to their delivery to the lungs. The present study investigated the use of spray freeze-drying to produce porous inhalable parathyroid hormone (1-34)-loaded microparticles suitable for pulmonary delivery. The influence of different excipients in the medium of water or citrate buffer on microparticles characteristics, peptide stability and its systemic delivery in rats were evaluated. Using leucine at 10% (w/w) and hydroxy propyl-ß-cyclodextrin (HPßCD) at 0.04% (w/w) in water or citrate medium preserved parathyroid hormone (1-34) stability by spray freeze-drying. Aerosol performance showed that leucine was more effective than HPßCD in producing inhalable microparticles. Nevertheless, there was no statistical difference between bioavailabilities of HPßCD containing formulations and leucine-containing formulations in the presence of citrate buffer; and even in the presence of water, HPßCD resulted in higher bioavailability compared to leucine. The high absolute bioavailability (up to 47.25%) of formulations could facilitate replacement of injected form of parathyroid hormone (1-34) by dry powder inhaler form.

Inhaled sildenafil nanocomposites: lung accumulation and pulmonary pharmacokinetics.

CONTEXT: Administration of sildenafil citrate (SC) is considered as a strategy in the treatment of pulmonary hypertension. OBJECTIVE: This study reports production of the inhalable microparticles containing SC-loaded poly(lactide-co-glycolic acid)-nanoparticles. METHODS: SC-nanoparticles were prepared by the double emulsion solvent evaporation method. Next, free SC and SC-loaded nanoparticles were spray dried in the presence of appropriate excipients (lactose, maltose and trehalose). Physicochemical properties and aerodynamic behavior of prepared powders were evaluated. In addition, drug accumulation from selected formulations in the rat lung tissue was compared with oral and IV administration. RESULTS: Size and fine particle fraction of selected nanocomposites and free SC microparticles were 7 and 4.5 µm, and 60.2% and 68.2%, respectively. Following oral and IV administration, the drug was not detectable in the lung after 4 and 6 h, respectively, but in SC-loaded nanoparticles, the drug was detectable in the lung even after 12 h of inhalation. Respirable particles containing free SC provided high concentration at first that was detectable up to 6 after insufflation. CONCLUSION: In vivo study demonstrated that pulmonary administration of sildenafil and sildenafil nanoparticles produced longer half-life and higher concentration of the drug in the lung tissue as compared to oral and IV administration. So, these formulations could be more effective than oral and IV administration of this drug.

Clarithromycin dissolution enhancement by preparation of aqueous nanosuspensions using sonoprecipitation technique.

Clarithromycin (CLM) is a member of macrolide family with broad spectrum antibiotic activity. It is practically insoluble in water and its poor solubility is pH dependent. In this study, series of nanosuspensions containing CLM and stabilizer such as HPMC, NaCMC, polysorbate 80, poloxamer 188 and polyvinyl alcohol in various ratios were prepared using sonoprecipitation method. Briefly, CLM was dissolved in acid solution and the pH of solution was raised under sonication and the effects of different stabilizers on particle size of nanoparticles were evaluated. Characterization of nanoparticles in terms of size, polydispersity index, zeta potential, differential scanning calorimetery and dissolution studies was performed. Antimicrobial activity of CLM nanosuspension was compared with coarse powder by using an agar well diffusion method. The results showed that HPMC was more efficient in size reduction of particles and presence of HPMC E5 with ratio of 3:5 to CLM in formulation led to develop the stable nanosuspension with particle size of 340 nm. The obtained nanosuspension successfully showed enhanced dissolution rate and antimicrobial activity.

Formulation of inhalable lipid-based salbutamol sulfate microparticles by spray drying technique.

BACKGROUND: The aim of this work was to develop dry powder inhaler (DPI) formulations of salbutamol sulfate (SS) by the aid of solid lipid microparticles (SLmPs), composed of biocompatible phospholipids or cholesterol. METHODS: The SLmPs were prepared by using two different solvent systems (ethanol and water-ethanol) and lipid carriers (dipalmitoylphosphatidylcholine (DPPC) and cholesterol) with/without L-leucine in the spray drying process. The spray-dried microparticles were physically-mixed with coarse lactose monohydrate in order to make our final DPI formulations and were investigated in terms of physical characteristics as well as in vitro drug release profile and aerosolization behavior. RESULTS: We observed significant differences in the sizes, morphologies, and in vitro pulmonary depositions between the formulations. In particular, the SS-containing SLmPs prepared with water-ethanol (30:70 v/v) solution of DPPC and L-leucine which had then been blended with coarse lactose (1:9 w/w) exhibited the highest emitted dose (87.9%) and fine particle fraction (42.7%) among the formulations. In vitro drug release study indicated that despite of having a significant initial burst release for both cholesterol and DPPC-based microparticles, the remained drug released more slowly than the pure drug. CONCLUSION: This study demonstrated the potential of using lipid carriers as well as L-leucine in DPI formulations of SS to improve its aerosolization behavior and retard the release profile of the drug.

Preparation, characterization and optimization of sildenafil citrate loaded PLGA nanoparticles by statistical factorial design.

BACKGROUND AND THE AIM OF THE STUDY: The objective of the present study was to formulate and optimize nanoparticles (NPs) of sildenafil-loaded poly (lactic-co-glycolic acid) (PLGA) by double emulsion solvent evaporation (DESE) method. The relationship between design factors and experimental data was evaluated using response surface methodology. METHOD: A Box-Behnken design was made considering the mass ratio of drug to polymer (D/P), the volumetric proportion of the water to oil phase (W/O) and the concentration of polyvinyl alcohol (PVA) as the independent agents. PLGA-NPs were successfully prepared and the size (nm), entrapment efficiency (EE), drug loading (DL) and cumulative release of drug from NPs post 1 and 8 hrs were assessed as the responses. RESULTS: The NPs were prepared in a spherical shape and the sizes range of 240 to 316 nm. The polydispersity index of size was lower than 0.5 and the EE (%) and DL (%) varied between 14-62% and 2-6%, respectively. The optimized formulation with a desirability factor of 0.9 was selected and characterized. This formulation demonstrated the particle size of 270 nm, EE of 55%, DL of 3.9% and cumulative drug release of 79% after 12 hrs. In vitro release studies showed a burst release at the initial stage followed by a sustained release of sildenafil from NPs up to 12 hrs. The release kinetic of the optimized formulation was fitted to Higuchi model. CONCLUSIONS: Sildenafil citrate NPs with small particle size, lipophilic feature, high entrapment efficiency and good loading capacity is produced by this method. Characterization of optimum formulation, provided by an evaluation of experimental data, showed no significant difference between calculated and measured data.

Effects of processing parameters on particle size of ultrasound prepared chitosan nanoparticles: an Artificial Neural Networks Study.

The pharmacokinetic properties of chitosan nanoparticles have been shown to mainly depend on its particle size. The aim of this study was to concurrently evaluate and model the effective parameters, namely, chitosan concentration, buffer pH, amplitude and time of sonication, on the particle size of chitosan nanoparticles. Chitosan solutions were prepared and sonicated with different values for the above mentioned parameters. The data were then modeled using artificial neural networks (ANNs). The results illustrated that all four input parameters affect the size of prepared chitosan nanoparticles. While a reverse effect was observed between the size and the buffer pH as well as time and amplitude of sonication, the concentration was found to directly influence the particle size. The optimum condition to obtain the minimum size of nanoparticles in the range of 50-200 nm was found to be high values of pH and sonication time (i.e. approximately 4.9 and 500 s, respectively) and amplitude values of more than ~55.

C-terminal domain deletion enhances the protective activity of cpa/cpb loaded solid lipid nanoparticles against Leishmania major in BALB/c mice.

BACKGROUND: We have demonstrated that vaccination with pDNA encoding cysteine proteinase Type II (CPA) and Type I (CPB) with its unusual C-terminal extension (CTE) can partially protect BALB/c mice against cutaneous leishmanial infection. Unfortunately, this protection is insufficient to completely control infection without booster injection. Furthermore, in developing vaccines for leishmaniasis, it is necessary to consider a proper adjuvant and/or delivery system to promote an antigen specific immune response. Solid lipid nanoparticles have found their way in drug delivery system development against intracellular infections and cancer, but not Leishmania DNA vaccination. Therefore, undefined effect of cationic solid lipid nanoparticles (cSLN) as an adjuvant in enhancing the immune response toward leishmanial antigens led us to refocus our vaccine development projects. METHODOLOGY/PRINCIPAL FINDINGS: Three pDNAs encoding L. major cysteine proteinase type I and II (with or without CTE) were formulated by cSLN. BALB/c mice were immunized twice by 3-week interval, with cSLN-pcDNA-cpa/b, pcDNA-cpa/b, cSLN-pcDNA-cpa/b(-CTE), pcDNA-cpa/b(-CTE), cSLN, cSLN-pcDNA and PBS. Mice vaccinated with cSLN-pcDNA-cpa/b(-CTE) showed significantly higher levels of parasite inhibition related to protection with specific Th1 immune response development, compared to other groups. Parasite inhibition was determined by different techniques currently available in exploration vacciation efficacy, i.e., flowcytometry on footpad and lymph node, footpad caliper based measurements and imaging as well as lymph node microtitration assay. Among these techniques, lymph node flowcytometry was found to be the most rapid, sensitive and easily reproducible method for discrimination between the efficacy of vaccination strategies. CONCLUSIONS/SIGNIFICANCE: This report demonstrates cSLN's ability to boost immune response magnitude of cpa/cpb(-CTE) cocktail vaccination against leishmaniasis so that the average parasite inhibition percent could be increased significantly. Hence, cSLNs can be considered as suitable adjuvant and/or delivery systems for designing third generation cocktail vaccines.

Cationic solid lipid nanoparticles loaded by cysteine proteinase genes as a novel anti-leishmaniasis DNA vaccine delivery system: characterization and in vitro evaluations.

PURPOSE: Leishmaniasis is a major health problem in many tropical and sub-tropical countries and development of a safe and easily-available vaccine has high priority. Although several antigens potentially capable of inducing protective immunity have been studied, in the absence of pharmaceutical industry interest they have remained as fine publications only. Amongst them, Cathepsin L-like cysteine proteinases (CPs) have received considerable attention and type I and II CPs have been used in a heterologous prime-boost vaccination regime for experimental visceral leishmaniasis in dogs. Due to the promising results of the mentioned vaccination regime, we aimed to evaluate cationic solid lipid nanoparticles (cSLNs) for in vitro delivery of cpa, cpb and cpb(CTE) intended to be used as a cocktail DNA vaccine in our forthcoming studies. METHODS: cSLNs were formulated of cetyl palmitate, cholesterol, DOTAP and Tween 80 via melt emulsification method followed by high shear homogenization. Different formulations were prepared by anchoring pDNAs on the surface of cSLNs via charge interaction. The formulations were characterized according to their size and zeta potential as well as pDNA integrity and stability against DNase I treatment. Lipoplexes' cytotoxicity was investigated on COS-7 cells by MTT test. The effect of the DOTAP:pDNA ratio on protection ability and cytotoxicity was also studied. In vitro transfection efficiency was qualified by fluorescent microscopy and quantified using flow cytometry technique. RESULTS: cSLN-pDNA complexes were formulated with suitable size and zeta potential. Efficiency/cytotoxicity ratio of cSLN-pDNAs formulations was comparable to linear PEI-25KD-pDNAs polyplexes while exhibiting significantly lower cytotoxicity. CONCLUSION: Tested formulations were able to deliver immunogenic CP genes efficiently. This data proves the ability of this system as a promising DNA vaccine carrier for leishmaniasis to cover the main drawback of naked pDNA delivery that is rapid elimination from the circulation.