Drug Delivery and Nano Pharmaceutics,Graduate School of Pharmaceutical Sciences,Nagoya City University, 3-1 Tanabe-dori,Mizuho-ku,Nagoya,Aichi 467-8603,Japan

Drug/polymer nanoparticles prepared using unique spray nozzles and recent progress of inhaled formulation

Tetsuya Ozeki＊,Tatsuaki Tagami

Drug Delivery and Nano Pharmaceutics,Graduate School of Pharmaceutical Sciences,Nagoya City University, 3-1 Tanabe-dori,Mizuho-ku,Nagoya,Aichi 467-8603,Japan

A R T I C L E I N F O

Article history:

Received 14 March 2014

Received in revised form

24 June 2014

Accepted 25 June 2014

Available online 1 July 2014

Pulmonary drug delivery

Inhalation

Lung diseases

Spray drying

One-step preparation of

nanocomposite particles

Inhaled formulations are promising for pulmonary and systemic non-pulmonary diseases. Functional engineered particles including drugs and drug-loaded nanocarriers have been anticipated because they can improve drug delivery eff i cacy against target sites in the lungs or blood.In this review,unique spray nozzles(e.g.,four-f l uid spray nozzle and twosolution mixing type nozzle)for the preparation of nanocomposite particles which mean microparticles containing drug nanoparticles are described.These nozzles can produce nanocomposite particles in one-step and their spray drying system is suitable for scalingup.Nanocomposite particles are useful in improving drug absorption and delivery eff i cacy against alveolar macrophages.In addition,recent studies on several pulmonary diseases (tuberculosis,lung cancer,cystic f i brosis,pneumonia,vaccine and others)and related inhaled formulations were also reviewed.

? 2014 Shenyang Pharmaceutical University.Production and hosting by Elsevier B.V.This is an open access article under the CC BY-NC-ND license(http://creativecommons.org/ licenses/by-nc-nd/3.0/).

1. Introduction

Pulmonary drug administration has the potential of a noninvasive and easy administration method.It has attracted much attention in the f i eld of pulmonary and non-pulmonary diseases for decades because of the specif i c structure and function of lung tissue;the lungs have large surface area,thin mucosal cell membrane,and blood vasculature.Alveoli, which are the site of oxygen and carbon dioxide exchange, contain blood capillaries at high density.In addition,drugs can easily penetrate the thin layer of alveolar endothelial cells and enter the blood.Compared with the oral administration, pulmonary administration avoids the hepatic metabolism, which is known as f i rst-pass effect.Moreover,the lungs contain lymph nodes and present immune competent cells. Therefore,various drugs and vaccine delivery systems targeting the lungs have been developed.

Currently,both liquid aerosol and dried powder formulations have been used in pulmonary administration and somedevices for inhalation have been recently reviewed[1].Additionally,the recently approved products of inhaled formulation was summarized in Table 1.Although the administration of aerosol by nebulizer has been established,dried formulation is superior to liquid aerosol from the stability perspective. However,the diameter of the dried powder should be controlled.The optimization of aerodynamic diameter is necessary to achieve delivery into deeper regions such as the alveoli[2].In addition,the change in the surface morphology can affect the aerodynamic diameter,and porous and wrinkled particles have been developed[3].

In this review,two special spray nozzles were introduced. Spray nozzles have been established to prepare drug “nanocomposite particles”,which are microparticles containing drug nanoparticles.These composites are useful for the preparation of inhaled formulations against pulmonary and systemic non-pulmonary diseases.Moreover,recent studies focusing on inhaled drug formulations with or without drug carriers were reviewed.

2. One-step preparation of nanocomposite particles by spray dryer equipped with special spray nozzles

The pulmonary administration has recently been anticipated to improve the absorption of poor water-soluble drugs. Approximately 40%of potential therapeutic compounds are water-insoluble compounds thatare classif i ed as biopharmaceutics classif i cation system(BCS)class 2 or 4.A common method for improving drug absorption is the size reduction of bulk drugs(e.g.,nanoparticles drugs),which could enhance their solubility because of the increase in their surface area.Furthermore,nanoparticle drugs could be more easily absorbed into the blood.

However,the benef i cial properties of nanoparticles are often easily lost by self-agglutination and their redispersion is very diff i cult.The prevention of self-agglutination is an important issue and some solutions have been developed, such as reducing their dimensions to the order of microns, which means the preparation of nanocomposite particles.In our group,nanocomposite particles have been prepared using a spray dryer equipped with a unique spray nozzle.

Table 1-Recent product of inhaled formulations in the market.

Four-f l uid spray nozzle is a unique spray nozzle containing two liquid passages and two air passages(Fig.1)(Fujisaki Electric Co.;http://www.fujisaki-hest.com).Compressed air is f l own from the air passages to transform solutions into mist. The solution f l own in the passages is mixed with compressed air and the solution is accelerated.The collision of the compressed air at the end of the nozzle generates a shockwave that transforms the solution into single micron mist.The single micron mist is quickly and eff i ciently dried because of its reduced size and increased surface area.For example,poor water-soluble drugs are dissolved in an organic solvent and the solution is f l own in one passage.Then,mannitol(MAN) aqueous solution is f l own into the other passage.The drugorganic mist and MAN-aqueous mist are mixed at the end of the nozzle,where the drug starts crystallizing by anti-solvent effect,which is the phenomenon in which solubility change induces the precipitation of the drug.The drug/MAN mist is immediately spray-dried until the drug crystallization has been completely progressed.Thus,relatively small drug nanoparticles are produced in MAN microparticles.Because one-step preparation and large amount of nanocomposite particles can be obtained by spray drying,the method is suitable for scaling-up.In previous studies,composites of f l urbiprofen/salicylate[4],polymer/MAN[5],rifampicin/MAN [6],and rifampicin/polymer/MAN[7]were developedusingthe spray dryer equipped with a four-f l uid spray nozzle.

Although the four-f l uid spray nozzle is useful in the onestep preparation of nanocomposite particles,optimization of spray drying conditions has been sometimes necessary, and it has been unclear if the anti-solvent effect occurred eff i ciently.Therefore,a two-solution mixing type nozzle has been developed to prepare nanocomposite particles(Fig.2) (Ohkawara KakohkiCo.;http://www.oc-sd.co.jp/english/ index.html).In this device,similar to the four-f l uid spray nozzle,the two solutions are separately f l own in different passages and are mixed in the mixing chamber in the nozzle. The drug solution dissolved in organic solvent is added into the MAN-aqueous solution in the mixing parts and the mixtureisimmediatelyspray-dried.Anti-solventeffect properly occurs in the mixing parts of the nozzle,and we speculate that the preparation of the nanocomposite particles is achieved in suitable conditions.The spray nozzle is customizable and some parts of it can adjust the mixing condition.Ethylcellulose(EC)is a poor water-soluble polymer,which was used as the model compound;EC/MAN composite was prepared using a spray dryer equipped with the two-solution mixing type spray nozzle[8].The composite particles prepared with this method exhibited relatively small diameter compared with those prepared using the four-f l uid spray nozzle.To extend our study,microparticles containing solid dispersion drug nanoparticles were prepared [9].Solid dispersion is a technique used to increase drug dissolution and absorption.Solid dispersion of nanoscale drugs showed enhanced intestinal absorption compared with composites containing drug nanoparticles and original drug powders.Although a detailed investigation about on the inner structure,crystallinity,and physical stability of microparticles is required in the study,these unique nanocomposite particles are promising formulations to enhance the absorption of poor water-soluble drugs.

Fig.1-A four-f l uid spray nozzle(simplif i ed image)and preparation of nanocomposite particles.

3. Inhaled formulations against pulmonary and non-pulmonary diseases

Various types of inhaled formulation have been recently developed.These formulations target various pulmonary diseases such as asthma,chronic obstructive pulmonary disease(COPD),cystic f i brosis,lung cancer,pneumonia derived from bacterial infection,and tuberculosis.In this review, recent studies about inhaled formulations specif i c for several pulmonary diseases were reviewed.The summary of articles in this review was shown in Table 2.

3.1. Tuberculosis

Tuberculosis is an infectious disease spread worldwide and primarily occurs in south Saharan regions.Patients with HIV are easily infected with TB and the co-infection yields complications[10].The infection mechanism has been well investigated[11-13].After the invasion in the lungs by the airway,the bacterium is digested by alveolar macrophages. Although several parts of the bacterium are sterilized by macrophages,other components escape from digestion, thereby residing for a long term in macrophages and allowing the bacteria to grow after host immunity decreases.Inhaled drug formulations have been adopted for tuberculosis and formulations targeting the alveolar macrophages have been successfully tested.

The dry powder formulation of nitroimidazopyran,which is a promising drug against TB,was prepared using spray drying[14].The prepared particles were porous with modif i ed aerodynamic diameters and contained 5%dipalmitoylphosphatidylcholine(DPPC),20%L-leucine,and 75%drug.The blood concentration prof i le showed that the concentration of the drug through pulmonary route was signif i cantly higher than that of the drug through oral route,which implies that its pulmonary bioavailability is higher than its oral bioavailability.The same research group evaluated the therapeutic effect and tissue damage in infected guinea pigs by comparison with a positive control(i.e.,drug/cyclodextrin suspension) [15].

Poly-(DL-lactide-co-glycolide)(PLGA)microspheres have been well studied because of their biodegradative properties and suitable particle size for pulmonary delivery.PLGA has the advantage of having a long half-life,which can vary from one week to one year.The Trojan approach(as shown in Fig.3),which targets alveolar macrophages containing bacteria,has been proposed because PLGA particles,which arelarge porous particles,are preferably digested by alveolar macrophages[16].Various methods to prepare homogenous PLGA particles have been investigated.In a recent study, rifampicin-loaded PLGAmicrosphereswere prepared by exploiting the supercritical anti-solvent process[17].The average particle size was less than 5 μm(＞60%)and this formulation was inhalable.

Fig.2-A two-solution mixing type spray nozzle(simplif i ed image)and preparation of nanocomposite particles.

Table 2-Inhaled formulation for various types of pulmonary diseases in recent articles.

3.2. Lung cancer

Lung cancer is one of the major types of cancers whose onset is related to various factors,including tobacco and asbestos. These continuous stimulationsagainstthe squamous epithelium,alveolar epithelium,and other types of cells in the lungs can damage genes and induce malignant alterations. Various anti-cancer drugs alone or in combination are currently used for the treatment of lung cancer.However, drug resistance is a challenging issue.Transporters such as those ofthe ATP-binding cassette transporterfamily, including multidrug resistance proteins,are expressed in the endothelial cells and other types of cells in the lung tissues and most types of lung cancer cells overexpress P-glycoproteins[18].One of the strategies to overcome the drug resistance is the use of drug carriers and lipid-based drug carriers such as liposomes.These drug-loaded carriers are endocytosed by cancer cells and the drugs are then released into the cytoplasm,thereby escaping from the pumping of P-glycoproteins at the cell membrane.

In a recent study,Tseng et al.prepared cisplatin-loaded EGF-modif i ed gelatin nanoparticles for targeting cancerous cells in the lung[19].This formulation showed higher Pt concentration on the highly EGFR-expressing A549 cells and showed lower Pt concentration on the low EGFR-expressing HFL1 cells,resulting in signif i cant cytotoxicity for A549 cells.In addition,the nanoparticles accumulated in EGFR-overexpressing cells in murine lung tissue after the administration of theaerosol formulation,indicatingthatthis formulation is useful for EGFR-expressing cancer cells.

Fig.3-Trojan approach:the smart drug delivery for persistent bacterium in alveolar macrophage.

Gemcitabine(GEM),which is a nucleoside analog,is frequently used for the treatment of lung cancer by intravenous infusion.Studies investigating the side effects of pulmonary administration of GEM have been recently reported. In a recent report,GEM was administered by aerosol[20]to four patients and no changes in hematologic toxicity were observed after the treatment with aerosolized GEM(4 mg/kg); however,one patient showed pulmonary toxicity.Plasma concentration of GEM was very low after pulmonary administration and the side effects were expected to be decreased. Animal studies on GEM administration by different pulmonary routes were also conducted[21].Intratracheal instillation by tracheotomy(i.t.t.)or orotracheal route(i.t.o.)was performed in rats.Then,pulmonary toxicity was investigated by checking lung morphology,histopathology,coeff i cient,wet/ dry weight ratio,cells related with inf l ammation,and inf l ammatory cytokines.Both i.t.t.and i.t.o.administrations showed good absolute bioavailability and similar acute lung injury compared with intravenous route.Preclinical studies on the use of GEM aerosol in osteosarcoma-bearing dogs were conducted bytranslationalresearch [22].GEM aerosol formulation induced increased apoptotic effect with enhanced Fas expression against lung metastatic foci.These studies indicated that GEM aerosol is an effective treatment for lung cancer.

Lungsurfactant-mimeticmicroparticlescomposed of DPPC and PEG-lipid conjugate of different lengths were also prepared using spray dryer[23].Phospholipid microparticles, which are the major component of lung surfactants,can have a fate similar to native lipids.Conjugation of PEG on the surface of these particles helps to prevent the recognition of immune competent cells,including alveolar macrophages, and enhance the mucus penetration of these particles.The same research group prepared similar lung surfactant-mimic particles containing paclitaxel[24].

Doxorubicin(DOX)is used as an anti-cancer drug against lung cancer.DOX-loaded nanoparticles were incorporated into inhalable effervescent powder[25].Lung cancer mouse model treated with this formulation had its survival signif icantly prolonged compared with mice treated with intravenous injection of DOX.Inhalable nanoparticles remained for longer duration in the lung tissue,and the radioactivity of the labeled drug-loaded nanoparticles was not found in the heart [26].These results indicated that the side effects of DOX released from those nanoparticles was minimal.A clinical trial employing inhaled DOX was also commenced for nonsmall cell lung cancer patients[27].A novel type of inhalation device(OncoMyst Model CDD-2a)was introduced in a previous study[28]and the combined effect of inhaled DOX with cisplatin was investigated.The authors concluded that thecombination was safe,eventhoughsmallsideeffectswere observed in several patients.As a rational approach,it is important to overcome drug resistance.Liposomal formulation containing DOX and designed antisense oligonucleotide (ASO)was used for inhalation[29].ASO can inhibit the target mRNA level by designing complementary sequences,and in that study,ASO against multidrug resistance-associated protein and Bcl-2,which plays the key role in apoptosis,were used.This formulation showed high antitumor activity with fewer side effects than the combination of DOX with cisplatin.

In the context of administration of inhaled anti-cancer drug formulations,the safety and protection of researchers and medical staff is important.Zarogoulidis et al.reviewed the protection methods used[30]and observed that several strategies including the use of HEPA f i lters,protected rooms (negative-pressure room),hoods and cages were mentioned, but uniform and global rules are required.In another report, large porous celecoxib-PLGA microparticles that were prepared using the supercritical f l uid method were assessed from the safety aspect[31].The microparticles prepared did not alter the lactate dehydrogenase(LDH),total protein,cell number in the bronchoalveolar lavage f l uid(BAL),collagen level,and histological analysis.

3.3. Cystic f i brosis

Cystic f i brosis is a disease caused by a mutation in the cystic f i brosis transmembrane conductance regulator gene and the immune response to airway infection is the most common cause of death.The viscosity of mucus derived from the dysfunction of mucus clearance enhances because of the infection.Various antibiotics and anti-inf l ammatory agents are used for the treatment.Corticosteroids have been used to reduce lung damages from inf l ammation.Inhaled corticosteroids have been used in children and adults to investigate the adverse effects[32].Tobramycin nanoparticles containing amorphous clarithromycin were prepared using spray drying [33].These nanoparticles were classif i ed as dispersible and porous agglomerates by evaluating the f i ne particle fraction of the drug deposition prof i les in the lungs.The antiinf l ammatory drug was spray-dried in combination with leucine,a dispersibility enhancer[34]and showed good in vitro aerosol performance.A study to understand the drug dissolutionpropertiesinthelungsusingartif i cialcysticf i brosismucus was investigated and the cytotoxicity was evaluated.Meloxicam/MAN composites were prepared using spray drying[35]. The microparticles contained polymers(PVP and PVA)that could prevent aggregation.The particles were spherical and the size was 3-5 μm,which was appropriate for pulmonary delivery.Prota et al.prepared leucine-based naringin particles asdispersibilityenhancer,whichexhibitedbetterf i neparticles fractionthannaringin-aloneparticles[36].Gentamicin/leucine powder was spray-dried to conduct an anti-microbial test[37] on artif i cial mucus model.Franz-type vertical diffusion cells were used and the formulation was loaded on the synthetic membrane covered by the artif i cial mucus layer.The mucus showed delayed permeation from the formulation.

3.4. Infectious diseases(pneumonia)

Pneumonia infection occurs in people whose immunity is weak.In particular,pneumonia is one of the major causes of death for elderly persons;thus,a fast therapy to treat it is important.Antibiotics-loaded PLGA nanospheres embedded in lactose powder have been prepared[38].Several hydrophilic polymers such as PVP and chitosan were used toachieve eff i cient size and surface properties,and alginate was used to entrap the drug.PVA-modif i ed PLGA nanoparticles reached deep regions of the lungs compared with chitosan-modif i ed PLGA nanoparticles.The drug formulation of PvdQ,which is an acyl-homoserine lactone acylase effective against Pseudomonas aeruginosa,was prepared using spray freeze-drying[39].Several types of sugar such as MAN, trehalose,and inulin were tested.Only trehalose and inulin stabilized PvdG for 4 weeks at 55°C because of their amorphous properties,whereas MAN did not stabilize PvdG because of its crystalline properties.

Duret et al.prepared itraconazole(ITZ)nanoparticles by using tocopherol polyethylene 1000 succinate(TPGS)as a stabilizer for the treatment of invasive pulmonary aspergillosis[40].After optimization,spray-dried ITZ/MAN microparticles exhibited good f i ne particles fraction.This group prepared ITZ/TPGS/MAN solid dispersion microparticles[41]. The formulation showed improved drug dissolution rate and saturation solubility.In a recent study,liposomal formulation was used.Liposomal formulations have been developed because of their biocompatibility and good drug half-life[42]. Liposomal carriers can add functions on their surface modif i cations.For example,PEGylation of liposomes could be used to prolong the mucosal clearance.In a recent study,liposomal vancomycin was nebulized in rats for the treatment of MRSA pneumonia[43].Liposomal vancomycin remained in the lung tissues compared with free vancomycin formulation.

3.5. Vaccines

Remarkably,inhaled vaccine also has been developing.The advantage of pulmonary formulation of vaccines is that the administration route is the same as that of the infection of MTBandpotentimmunitycanbesupplied[44-46]In addition, the presence of both bronchoalveolar lymphoid tissue(as lymph system)and antigen-presenting cells(as immunocompetent cells)in the lungs,enables the induction of the immune response.Hundreds of vaccines have been developed,such as recombinant BCG,BCG overexpressing native proteins,attenuated MTB,and DNA vaccines.However,in many studies,liquid formulations administered by nebulizer proved to be unstable from the standpoint of preservation.

To induce potent immune response,unique particles were prepared[47].Inf l uenza-like nanoparticles containing a peptide having the same sequence of the TB early secretary antigenic target 6 protein(ESAT-6)was developed.ESAT is a foreign epitope that has potent T-cell immune response. These particles exhibited high titers in serum.Spray-dried preparations of bacteriophages were also used against infectious diseases[48].One of the main issues of that study regarded the phage titer after spray drying.In fact,phages are delicate and suffer temperature increase and shear stress during the process of spray drying.The phage titer was different among phages,indicating that the optimization of the formulation was necessary.Another group prepared a unique inhaled formulation for tuberculosis[49]consisting of dried bacterial rod-like structures(1-4 μm in length and 200-400 nm in diameter)coupled with small particles of leucine(1 μm)The unique nano-microstructure showed drug eff i cacy and considerably reduced the bacterial burden in guinea pigs.A carrier-based inhaled formulation was also developed and PLGA microparticles containing recombinant antigen 85-B for TB were inhaled into guinea pigs[50].The antigen showed potent immunity and the bacterial burden in the lung and spleen was reduced.Moreover,a DNA vaccine encoding the bacterial latency antigen Rv1733c in which the DNA could bind with the PLGA-polyethyleneimine(PEI)chain by electric interaction showed enhanced T-cell immune response[51].

3.6. siRNA delivery for pulmonary diseases

Fig.4-A scheme of siRNA delivery system via pulmonary route.

Many pulmonary diseases including lung cancer are malignant,and therefore,gene therapy has been studied from new approaches.Functional nucleic acids such as small interfering RNA(siRNA)and plasmid DNA coding therapeutic genes received much attention in the f i eld of pulmonary delivery [52].In particular,the post-transcriptional gene silencing of a target gene by siRNA is potent compared with the effect induced by conventional antisense oligonucleotides.In addition,siRNA is safer than viral vectors.Therefore,siRNA is asuitable noveltherapeuticapproach.siRNA arerelativelylarge molecules(approximately 13 kDa)compared with conventional drugs and are water-soluble.However,although the penetration of siRNA into the cytoplasm of the target cells where siRNA can induce RNA interference is an important step to achieve therapeutic effects,it is diff i cult for siRNA to enter the cytoplasm by itself.Some reports indicate that inhaled siRNA alone can reach the targeted site,but its delivery into the cytoplasm is important for the treatment of the cells of lung tissues.

Cationic lipid-based and polymer-based carriers have been extensively used for the delivery of siRNA because these carriers can deliver the siRNA into the cytoplasm by the interaction with the negatively charged cell surfaces and by endocytosis(Fig.4).After endocytosis,the siRNA has to avoid theendosomesbeforeitisdegradedby lysosomes.In addition, cationic carriers can entrap large amount of siRNA by electrostatic interaction,and the entrapped siRNA is protected by degradation from nucleases.On the other hand,cationic carriers inf l uence the gene expression related with apoptosis, resulting in cytotoxicity.Additionally,it is sometimes diff i cult for cationic carrier-based inhaled formulations to reach the deepest regions of the lungs and the optimization of the conditions to avoid cytotoxicity and improve delivery eff iciency is required.

4. Conclusion

Drug delivery technology by inhalation has been progressing and novel techniques to prepare drug formulations with ease and cost effectiveness have been developed.The use of two unique spray nozzles to prepare nanocomposite particles is a benef i cial method for the preparation of water-insoluble drug nanoparticles and to enhance their preservation.Furthermore,the understanding of details of the target diseases is important to develop effective drug carriers.The recent studies reviewed here will be useful for the development of novel drug formulations.

R E F E R E N C E S

[1]Rogueda PG,Traini D.The nanoscale in pulmonary delivery. Part 2:formulation platforms.Expert Opin Drug Deliv 2007;4:607-620.

[2]Rogueda PG,Traini D.The nanoscale in pulmonary delivery. Part 1:deposition,fate,toxicology and effects.Expert Opin Drug Deliv 2007;4:595-606.

[3]Chan HK.What is the role of particle morphology in pharmaceutical powder aerosols?Expert Opin Drug Deliv 2008;5:909-914.

[4]Ozeki T,Beppu S,Mizoe T,et al.Preparation of two-drug composite microparticles to improve the dissolution of insoluble drug in water for use with a 4-f l uid nozzle spray drier.J Control Release 2005;107:387-394.

[5]Ozeki T,Beppu S,Mizoe T,et al.Preparation of polymeric submicron particle-containing microparticles using a 4-f l uid nozzle spray drier.Pharm Res 2006;23:177-183.

[6]Mizoe T,Ozeki T,Okada H.Application of a four-f l uid nozzle spray drier to prepare inhalable rifampicin-containing mannitol microparticles.AAPS Pharm Sci Tech 2008;9:755-761.

[7]Ohashi K,Kabasawa T,Ozeki T,et al.One-step preparation of rifampicin/poly(lactic-co-glycolic acid)nanoparticlecontaining mannitol microspheres using a four-f l uid nozzle spray drier for inhalation therapy of tuberculosis.J Control Release 2009;135:19-24.

[8]Ozeki T,Akiyama Y,Takahashi N,et al.Development of a novel and customizable two-solution mixing type spray nozzle for one-step preparation of nanoparticle-containing microparticles.Biol Pharm Bull 2012;35:1926-1931.

[9]Nishino Y,Kubota A,Kanazawa T,et al.Improved intestinal absorption of a poorly water-soluble oral drug using mannitol microparticles containing a nanosolid drug dispersion.J Pharm Sci 2012;101:4191-4200.

[10]World Health Organization.Global tuberculosis report 2013: addressing the co-epidemics of TB and HIV,vol.6;2013. pp.68-74.

[11]Muttil P,Wang C,Hickey AJ.Inhaled drug delivery for tuberculosis therapy.Pharm Res 2009;26:2401-2416.

[12]Hanif SN,Garcia-Contreras L.Pharmaceutical aerosols for the treatment and prevention of tuberculosis.Front Cell Infect Microbiol 2012;2:118.

[13]Misra A,Hickey AJ,Rossi C,et al.Inhaled drug therapy for treatment of tuberculosis.Tuberculosis(Edinb) 2011;91:71-81.

[14]Sung JC,Garcia-Contreras L,VerBerkmoes JL,et al.Dry powder nitroimidazopyran antibiotic PA-824 aerosol for inhalation.Antimicrobial Agents Chemother 2009;53:1338-1343.

[15]Garcia-Contreras L,Sung JC,Muttil P,et al.Dry powder PA-824 aerosols for treatment of tuberculosis in guinea pigs. Antimicrob Agents Chemother 2010;54:1436-1442.

[16]Ungaro F,d'Angelo I,Miro A,et al.Engineered PLGA nanoand micro-carriers for pulmonary delivery:challenges and promises.J Pharm Pharmacol 2012;64:1217-1235.

[17]Patomchaiviwat V,Paeratakul O,Kulvanich P.Formation of inhalable rifampicin-poly(L-lactide)microparticles by supercritical anti-solvent process.AAPS Pharm Sci Tech 2008;9:1119-1129.

[18]Scheffer GL,Pijnenborg AC,Smit EF,et al.Multidrug resistance related molecules in human and murine lung.J Clin Pathol 2002;55:332-339.

[19]Tseng CL,Su WY,Yen KC,et al.The use of biotinylated-EGF-modif i ed gelatin nanoparticle carrier to enhance cisplatin accumulation in cancerous lungs via inhalation. Biomaterials 2009;30:3476-3485.

[20]Lemarie E,Vecellio L,Hureaux J,et al.Aerosolized gemcitabine in patients with carcinoma of the lung: feasibility and safety study.J Aerosol Med Pulm Drug Deliv 2011;24:261-270.

[21]Min R,Li T,Du J,et al.Pulmonary gemcitabine delivery for treating lung cancer:pharmacokinetics and acute lung injury aspects in animals.Can J Physiol Pharmacol 2008;86:288-298.

[22]Rodriguez Jr CO,Crabbs TA,Wilson DW,et al.Aerosol gemcitabine:preclinical safety and in vivo antitumor activity in osteosarcoma-bearing dogs.J Aerosol Med Pulm Drug Deliv 2010;23:197-206.

[23]Meenach SA,Vogt FG,Anderson KW,et al.Design, physicochemical characterization,and optimization of organic solution advanced spray-dried inhalable dipalmitoylphosphatidylcholine(DPPC)and dipalmitoylphosphatidylethanolamine poly(ethylene glycol) (DPPE-PEG)microparticles and nanoparticles for targeted respiratory nanomedicine delivery as dry powder inhalation aerosols.Int J Nanomed 2013;8:275-293.

[24]Meenach SA,Anderson KW,Hilt JZ,et al.Characterization and aerosol dispersion performance of advanced spray-driedchemotherapeutic PEGylated phospholipid particles for dry powder inhalation delivery in lung cancer.Eur J Pharm Sci 2013;49:699-711.

[25]Roa WH,Azarmi S,Al-Hallak MH,et al.Inhalable nanoparticles,a non-invasive approach to treat lung cancer in a mouse model.J Control Release 2011;150:49-55.

[26]Al-Hallak MH,Sarfraz MK,Azarmi S,et al.Distribution of effervescent inhalable nanoparticles after pulmonary delivery:an in vivo study.Ther Deliv 2012;3:725-734.

[27]Otterson GA,Villalona-Calero MA,Hicks W.Phase I/II study of inhaled doxorubicin combined with platinum-based therapy for advanced non-small cell lung cancer.Clin Cancer Res 2010;16:2466-2473.

[28]Otterson GA,Villalona-Calero MA,Sharma S,et al.Phase I study of inhaled doxorubicin for patients with metastatic tumors to the lungs.Clin Cancer Res 2007;13:1246-1252.

[29]Garbuzenko OB,Saad M,Pozharov VP,et al.Inhibition of lung tumor growth by complex pulmonary delivery of drugs with oligonucleotides as suppressors of cellular resistance.Proc Natl Acad Sci U.S.a 2010;107:10737-10742.

[30]Zarogoulidis P,Chatzaki E,Porpodis K,et al.Inhaled chemotherapy in lung cancer:future concept of nanomedicine.Int J Nanomedicine 2012;7:1551-1572.

[31]Dhanda DS,Tyagi P,Mirvish SS,et al.Supercritical f l uid technology based large porous celecoxib-PLGA microparticles do not induce pulmonary f i brosis and sustain drug delivery and eff i cacy for several weeks following a single dose.J Control Release 2013;168:239-250.

[32]Balfour-Lynn IM,Welch K.Inhaled corticosteroids for cystic f i brosis.Cochrane Database Syst Rev 2012;11:CD001915.

[33]Pilcer G,Rosiere R,Traina K,et al.New co-spray-dried tobramycin nanoparticles-clarithromycin inhaled powder systems for lung infection therapy in cystic f i brosis patients. J Pharm Sci 2013;102:1836-1846.

[34]Stigliani M,Aquino RP,Del Gaudio P,et al.Non-steroidal anti-inf l ammatory drug for pulmonary administration: design and investigation of ketoprofen lysinate f i ne dry powders.Int J Pharm 2013;448:198-204.

[35]Pomazi A,Buttini F,Ambrus R,et al.Effect of polymers for aerolization properties of mannitol-based microcomposites containing meloxicam.Eur Polym J 2013;49:2518-2527.

[36]Prota L,Santoro A,Bifulco M,et al.Leucine enhances aerosol performance of naringin dry powder and its activity on cystic f i brosis airway epithelial cells.Int J Pharm 2011;412:8-19.

[37]Russo P,Stigliani M,Prota L,et al.Gentamicin and leucine inhalable powder:what about antipseudomonal activity and permeation through cystic f i brosis mucus?Int J Pharm 2013;440:250-255.

[38]Ungaro F,d'Angelo I,Coletta C,et al.Dry powders based on PLGA nanoparticles for pulmonary delivery of antibiotics: modulation of encapsulation eff i ciency,release rate and lung deposition pattern by hydrophilic polymers.J Control Release 2012;157:149-159.

[39]Wahjudi M,Murugappan S,van Merkerk R,et al. Development of a dry,stable and inhalable acyl-homoserinelactone-acylase powder formulation for the treatment of pulmonary Pseudomonas aeruginosa infections.Eur J Pharm Sci 2013;48:637-643.

[40]Duret C,Wauthoz N,Sebti T,et al.New inhalation-optimized itraconazole nanoparticle-based dry powders for the treatment of invasive pulmonary aspergillosis.Int J Nanomedicine 2012;7:5475-5489.

[41]Duret C,Wauthoz N,Sebti T,et al.Solid dispersions of itraconazole for inhalation with enhanced dissolution, solubility and dispersion properties.Int J Pharm 2012;428:103-113.

[42]Jaafar-Maalej C,Elaissari A,Fessi H.Lipid-based carriers: manufacturing and applications for pulmonary route.Expert Opin Drug Deliv 2012;9:1111-1127.

[43]de Jesus valle MJ,Garavis Gozalez J,Lopez FG,et al. Pulmonary disposition of vancomycin nebulized as lipid vesicles in rats.J Antibiot 2013:1-5.

[44]Lu D,Hickey AJ.Pulmonary vaccine delivery.Expert Rev Vaccines 2007;6:213-226.

[45]Garcia-Contreras L,Awashthi S,Hanif SNM,et al.Inhaled vaccines for the prevention of tuberculosis.J Mycobac Dis 2012.http://dx.doi.org/10.4172/2161-1068.S1-002.an open access journal(ISSN:2161-1068).

[46]Tonnis WF,Kersten GF,Frijlink HW,et al.Pulmonary vaccine delivery:a realistic approach?J Aerosol Med Pulm Drug Deliv 2012;25:249-260.

[47]Krammer F,Schinko T,Messner P,et al.Inf l uenza virus-like particles as an antigen-carrier platform for the ESAT-6 epitope of Mycobacterium tuberculosis.J Virol Methods 2010;167:17-22.

[48]Vandenheuvel D,Singh A,Vandersteegen K,et al.Feasibility of spray drying bacteriophages into respirable powders to combat pulmonary bacterial infections.Eur J Pharm Biopharm 2013;84:578-582.

[49]Garcia-Contreras L,Wong YL,Muttil P,et al.Immunization by a bacterial aerosol.Proc Natl Acad Sci U.S.a 2008;105:4656-4660.

[50]Lu D,Garcia-Contreras L,Muttil P,et al.Pulmonary immunization using antigen 85-B polymeric microparticles to boost tuberculosis immunity.Aaps J 2010;12:338-347.

[51]Bivas-Benita M,Lin MY,Bal SM,et al.Pulmonary delivery of DNA encoding Mycobacterium tuberculosis latency antigen Rv1733c associated to PLGA-PEI nanoparticles enhances T cell responses in a DNA prime/protein boost vaccination regimen in mice.Vaccine 2009;27:4010-4017.

[52]Lam JK,Liang W,Chan HK.Pulmonary delivery of therapeutic siRNA.Adv Drug Deliv Rev 2012;64:1-15.

*Corresponding author.Tel.:+81 52 836 3463;fax:+81 52 836 3464.

E-mail address:ozekit@phar.nagoya-cu.ac.jp(T.Ozeki).

Peer review under responsibility of Shenyang Pharmaceutical University.

http://dx.doi.org/10.1016/j.ajps.2014.06.005

1818-0876/? 2014 Shenyang Pharmaceutical University.Production and hosting by Elsevier B.V.This is an open access article under the CC BY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/3.0/).