Optimization of systemic nasal drug delivery with pharmaceutical excipients

Dermal pharmacokinetics of rivastigmine-loaded liposomes: an ex vivo-in vivo correlation study

The aim of the present study was to develop a topical liposomal formulation as a transdermal delivery of rivastigmine for the treatment of Alzheimer's disease as an alternative to the oral dosage form and to achieve smooth continuous drug delivery and maintain plasma levels within the therapeutic window. Rivastigmine-loaded liposomes were prepared by a thin layer hydration technique that was applied in ex vivo-in vivo correlation study. Permeability parameters through rat skin in ex vivo study and pharmacokinetic parameters in the in vivo study were evaluated. The ex vivo permeation study showed that liposomes provided steady-state flux 0.11 ± 0.01 mg/cm.h that were more than 2-fold the aqueous control. In the in vivo experiments, after topical application of optimized rivastigmine liposomes, the C_max 208 ng/ml and AUC_0-24 3605 (ng.h/ml) were also significantly higher than the control group (both p < 0.01). A point-to-point significant linear correlation was found between ex vivo and in vivo parameters, meaning in vivo pharmacokinetic parameters can be predicted by ex vivo permeation parameters. These data suggest that a liposomal formulation could be an effective carrier to enhance rivastigmine permeation through the skin and maintain plasma levels within the therapeutic window.

Nasal formulations for drug administration and characterization of nasal preparations in drug delivery

This special report gives an insight in the rationale of utilizing the nasal cavity for drug administration and the formulation as well as characterization of nasal preparations. As the nose is an easy-to-access, noninvasive and versatile location for absorption, this route of delivery will play an increasingly important role in future drug product development both for new and repurposed drugs. The nose can be utilized for local and systemic delivery including drug delivery to the central nervous system and the immune system. Typical formulation strategies and future developments are reviewed, which nowadays mostly comprise liquid formulations. Although they are straight forward to develop, a number of aspects from choice of solvent, osmolarity, pH, viscosity and more need to be considered, which determine formulation characteristics, not at least nasal deposition. Nasal powders offer higher stability and, along with more sophisticated nasal devices, may play a major role in the future.

Focused ultrasound enhanced intranasal delivery of brain derived neurotrophic factor produces neurorestorative effects in a Parkinson's disease mouse model

Focused ultrasound-enhanced intranasal (IN + FUS) delivery is a noninvasive approach that utilizes the olfactory pathway to administer pharmacological agents directly to the brain, allowing for a more homogenous distribution in targeted locations compared to IN delivery alone. However, whether such a strategy has therapeutic values, especially in neurodegenerative disorders such as Parkinson’s disease (PD), remains to be established. Herein, we evaluated whether the expression of tyrosine hydroxylase (TH), the rate limiting enzyme in dopamine catalysis, could be enhanced by IN + FUS delivery of brain-derived neurotrophic factor (BDNF) in a toxin-based PD mouse model. Mice were put on the subacute dosing regimen of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), producing bilateral degeneration of the nigrostriatal pathway consistent with early-stage PD. MPTP mice then received BDNF intranasally followed by multiple unilateral FUS-induced blood-brain barrier (BBB) openings in the left basal ganglia for three consecutive weeks. Subsequently, mice were survived for two months and were evaluated morphologically and behaviorally to determine the integrity of their nigrostriatal dopaminergic pathways. Mice receiving IN + FUS had significantly increased TH immunoreactivity in the treated hemisphere compared to the untreated hemisphere while mice receiving only FUS-induced BBB opening or no treatment at all did not show any differences. Additionally, behavioral changes were only observed in the IN + FUS treated mice, indicating improved motor control function in the treated hemisphere. These findings demonstrate the robustness of the method and potential of IN + FUS for the delivery of bioactive factors for treatment of neurodegenerative disorder.

Intranasal Zotepine Nanosuspension: intended for improved brain distribution in rats

BACKGROUND

Zotepine (ZTP), an antipsychotic drug is well tolerated and particularly effective for treating negative symptoms of psychosis. But is limited by low oral bioavailability caused by substantial first pass metabolism and thereby less amount of drug reaches the brain due to blood brain barrier (BBB).

OBJECTIVES

Since ZTP displays dose dependent side effects, purpose of the contemporary study is to develop zotepine loaded nanosuspension (ZTP-NS) for increased brain targeting in rats at lower doses.

METHODS

ZTP-NS is prepared by two techniques viz., sonoprecipitation (SP) and combination technique (high pressure homogenization preceded by precipitation) by employing various stabilizers. Optimized ZTP-NS was characterized for particle size, solid state, morphology and solubility. In vitro drug release of ZTP and formulations was conducted using Franz diffusion cell. Stability study was performed at different temperature conditions. Pharmacokinetic study was performed in Wistar rats to determine the bioavailability and brain distribution of ZTP after intra-nasal (IN) and intravenous (IV) administration. Histopathology of brain was done after repeated administration of IN ZTP dispersion and NS up to 14 days.

RESULTS

The optimized ZTP-NS formulated with Pluronic F-127 (0.3%w/v), Hydroxypropyl methyl cellulose E15 (0.3%w/v) and soya lecithin (0.4%w/v) showed particle size of 519.26 ± 10.44 nm & 330.2 ± 12.90 nm and zeta potential of -21.7 ± 1.39 mV and - 18.26 ± 1.64 mV with sonoprecipitation and combination technique respectively. In vitro drug release was high (81.79 ± 3.23%) for ZTP-NS prepared by combination technique. Intranasal NS resulted in high brain concentrations of 8.6 fold (sonoprecipitation) and 10.79-fold hike in AUC_0-24h in contrast to intravenous ZTP solution. Histopathology results reveal no significant changes in brain microscopic images.

CONCLUSION

ZTP-NS was successfully developed, characterized and found that nanosuspension is a favorable approach for intranasal delivery of zotepine. Graphical abstract Graphical abstract representing zotepine drawbacks, nanosuspension preparation, characterization and pharmacokinetic study in rats.

In vitro cytotoxicity and transfection efficiency of pDNA encoded p53 gene-loaded chitosan-sodium deoxycholate nanoparticles

Purpose: The objective of this work was to formulate a delivery system of pDNA encoded p53 gene-loaded chitosan-sodium deoxycholate (CS-DS) nanoparticles, and to evaluate their influence on in vitro cytotoxicity and transfection efficiency of p53 gene.

Methods: The prepared pDNA-loaded CS-DS nanoparticles were evaluated for morphology, particle size, zeta potential, entrapment efficiency %, in vitro release, in vitro cytotoxicity, and transfection efficiency.

Results: The mean particle size ranged from from 96.5 ± 11.31 to 405 ± 46.39 nm. All nanoparticles had good positive zeta potential values. Entrapment efficiency % ranged from 38.25 ± 3.25 to 94.89 ± 5.67. The agarose gel electrophoresis confirmed the strong binding between plasmid and CS. The in vitro pDNA release from nanoparticles exhibited an initial burst effect followed by a sustained drug release over a period of 6 days. In vitro cytotoxicity against human Caco-2 cells showed low cell cytotoxicity of plain CS-DS nanoparticles, while pDNA-loaded CS-DS nanoparticles showed a cytotoxic effect with increasing nanoparticles' concentration. Gene transfection, analyzed by PCR and ELISA, showed a direct correlation between gene expression and concentration of pDNA. The highest expression of the gene was achieved with pDNA concentration of 9 µg/mL with 5.7 times increase compared to naked pDNA of the same concentration.

Conclusion: The obtained results were very encouraging and offer an alternative approach to enhancing the transfection efficiency of genetic material-loaded chitosan-based delivery systems.

Evaluation of intranasal delivery route of drug administration for brain targeting

The acute or chronic drug treatments for different neurodegenerative and psychiatric disorders are challenging from several aspects. The low bioavailability and limited brain exposure of oral drugs, the rapid metabolism, elimination, the unwanted side effects and also the high dose to be added mean both inconvenience for the patients and high costs for the patients, their family and the society. The reason of low brain penetration of the compounds is that they have to overcome the blood-brain barrier which protects the brain against xenobiotics. Intranasal drug administration is one of the promising options to bypass blood-brain barrier, to reduce the systemic adverse effects of the drugs and to lower the doses to be administered. Furthermore, the drugs administered using nasal route have usually higher bioavailability, less side effects and result in higher brain exposure at similar dosage than the oral drugs. In this review the focus is on giving an overview on the anatomical and cellular structure of nasal cavity and absorption surface. It presents some possibilities to enhance the drug penetration through the nasal barrier and summarizes some in vitro, ex vivo and in vivo technologies to test the drug delivery across the nasal epithelium into the brain. Finally, the authors give a critical evaluation of the nasal route of administration showing its main advantages and limitations of this delivery route for CNS drug targeting.

Electrosteric stealth Rivastigmine loaded liposomes for brain targeting: preparation, characterization, ex vivo, bio-distribution and in vivo pharmacokinetic studies

Being one of the highly effective drugs in treatment of Alzheimer's disease, Rivastigmine brain targeting is highly demandable, therefore liposomal dispersion of Rivastigmine was prepared containing 2 mol% PEG-DSPE added to Lecithin, Didecyldimethyl ammonium bromide (DDAB), Tween 80 in 1:0.02:0.25 molar ratio. A major challenge during the preparation of liposomes is maintaining a stable formulation, therefore the aim of our study was to increase liposomal stability by addition of DDAB to give an electrostatic stability and PEG-DSPE to increase stability by steric hindrance, yielding what we called an electrosteric stealth (ESS) liposomes. A medium nano-sized liposome (478 ± 4.94 nm) with a nearly neutral zeta potential (ZP, -8 ± 0.2 mV) and an entrapment efficiency percentage of 48 ± 6.22 was prepared. Stability studies showed no major alteration after three months storage period concerning particle size, polydispersity index, ZP, entrapment efficiency and in vitro release study confirming the successful formation of a stable liposomes. No histopathological alteration was recorded for ESS liposomes of the sheep nasal mucosa. While ESS liposomes showed higher % of drug permeating through the sheep nasal mucosa (48.6%) than the drug solution (28.7%). On completing the in vivo pharmacokinetic studies of 36 rabbits showed 424.2% relative bioavailability of the mean plasma levels of the formula ESS compared to that of RHT intranasal solution and 486% relative bioavailability of the mean brain levels.

Agomelatine-based in situ gels for brain targeting via the nasal route: statistical optimization, in vitro, and in vivo evaluation

Agomelatine (AGM) is an antidepressant drug with a low absolute bioavailability due to the hepatic first pass metabolism. AGM-loaded solid lipid nanoparticles were formulated in the form of an in situ gel to prolong the intranasal retention time and subsequently to increase the absorbed amount of AGM. The optimized in situ gel formula had a sol-gel transition temperature of 31 °C ± 1.40, mucociliary transport time of 27 min ±1.41%, released after 1 and 8 h of 46.3% ± 0.85 and 70.90% ± 1.48. The pharmacokinetic study of the optimized in situ gel revealed a significant increase in the peak plasma concentration, area under plasma concentration versus time curve and absolute bioavailability compared to that of the oral suspension of Valdoxan® with the values of 247 ± 64.40 ng/mL, 6677.41 ± 1996 ng.min/mL, and 37.89%, respectively. It also gave drug targeting efficiency index of 141.42 which revealed more successful brain targeting by the intranasal route compared to the intravenous route and it had direct transport percent index of 29.29 which indicated a significant contribution of the direct nose to brain pathway in the brain drug delivery.

Intranasal agomelatine solid lipid nanoparticles to enhance brain delivery: formulation, optimization and in vivo pharmacokinetics

PURPOSE

Agomelatine is a novel antidepressant drug suffering from an extensive first-pass metabolism leading to a diminished absolute bioavailability. The aim of the study is: first to enhance its absolute bioavailability, and second to increase its brain delivery.

METHODS

To achieve these aims, the nasal route was adopted to exploit first its avoidance of the hepatic first-pass metabolism to increase the absolute bioavailability, and second the direct nose-to-brain pathway to enhance the brain drug delivery. Solid lipid nanoparticles were selected as a drug delivery system to enhance agomelatine permeability across the blood-brain barrier and therefore its brain delivery.

RESULTS

The optimum solid lipid nanoparticles have a particle size of 167.70 nm ±0.42, zeta potential of -17.90 mV ±2.70, polydispersity index of 0.12±0.10, entrapment efficiency % of 91.25%±1.70%, the percentage released after 1 h of 35.40%±1.13% and the percentage released after 8 h of 80.87%±5.16%. The pharmacokinetic study of the optimized solid lipid nanoparticles revealed a significant increase in each of the plasma peak concentration, the AUC(0-360 min) and the absolute bioavailability compared to that of the oral suspension of Valdoxan^® with the values of 759.00 ng/mL, 7,805.69 ng⋅min/mL and 44.44%, respectively. The optimized solid lipid nanoparticles gave a drug-targeting efficiency of 190.02, which revealed more successful brain targeting by the intranasal route compared with the intravenous route. The optimized solid lipid nanoparticles had a direct transport percentage of 47.37, which indicates a significant contribution of the direct nose-to-brain pathway in the brain drug delivery.

CONCLUSION

The intranasal administration of agomelatine solid lipid nanoparticles has effectively enhanced both the absolute bioavailability and the brain delivery of agomelatine.

Intranasal delivery of N-terminal modified leptin-pluronic conjugate for treatment of obesity

Leptin is an adipocyte-secreted hormone that is delivered via a specific transport system across the blood-brain barrier (BBB) to the brain where it acts on the hypothalamus receptors to control appetite and thermogenesis. Peripheral resistance to leptin due to its impaired brain delivery prevents therapeutic use of leptin in overweight and moderately obese patients. To address this problem, we modified the N-terminal amine of leptin with Pluronic P85 (LepNP85) and administered this conjugate intranasally using the nose-to-brain (INB) route to bypass the BBB. We compared this conjugate with the native leptin, the N-terminal leptin conjugate with poly(ethylene glycol) (LepNPEG5K), and two conjugates of leptin with Pluronic P85 attached randomly to the lysine amino groups of the hormone. Compared to the random conjugates of leptin with P85, LepNP85 has shown higher affinity upon binding with the leptin receptor, and similarly to native hormone activated hypothalamus receptors after direct injection into brain. After INB delivery, LepNP85 conjugate was transported to the brain and accumulated in the hypothalamus and hippocampus to a greater extent than the native leptin and LepNPEG5K and activated leptin receptors in hypothalamus at lower dose than native leptin. Our work suggests that LepNP85 can access the brain directly after INB delivery and confirms our hypothesis that the improvement in brain accumulation of this conjugate is due to its enhanced brain absorption. In conclusion, the LepNP85 with optimized conjugation chemistry is a promising candidate for treatment of obesity.

The effect of drugs and other compounds on the ciliary beat frequency of human respiratory epithelium

BACKGROUND

Cilia in the human respiratory tract play a critical role in clearing mucus and debris from the airways. Their function can be affected by a number of drugs or other substances, many of which alter ciliary beat frequency (CBF). This has implications for diseases of the respiratory tract and nasal drug delivery. This article is a systematic review of the literature that examines 229 substances and their effect on CBF.

METHODS

MEDLINE was the primary database used for data collection. Eligibility criteria based on experimental design were established, and 152 studies were ultimately selected. Each individual trial for the substances tested was noted whenever possible, including concentration, time course, specific effect on CBF, and source of tissue.

RESULTS

There was a high degree of heterogeneity between the various experiments examined in this article. Substances and their general effects (increase, no effect, decrease) were grouped into six categories: antimicrobials and antivirals, pharmacologics, human biological products, organisms and toxins, drug excipients, and natural compounds/other manipulations.

CONCLUSION

Organisms, toxins, and drug excipients tend to show a cilioinhibitory effect, whereas substances in all other categories had mixed effects. All studies examined were in vitro experiments, and application of the results in vivo is confounded by several factors. The data presented in this article should be useful in future respiratory research and examination of compounds for therapeutic and drug delivery purposes.

Feasibility Investigation of Cellulose Polymers for Mucoadhesive Nasal Drug Delivery Applications

The feasibility of various cellulose polymer derivatives, including methylcellulose (MC), hydroxypropyl methylcellulose (HPMC), sodium-carboxymethylcellulose (sodium-CMC), and cationic-hydroxyethylcellulose (cationic-HEC), for use as an excipient to enhance drug delivery in nasal spray formulations was investigated. Three main parameters for evaluating the polymers in nasal drug delivery applications include rheology, ciliary beat frequency (CBF), and permeation across nasal tissue. Reversible thermally induced viscosity enhancement was observed at near nasal physiological temperature when cellulose derivatives were combined with an additional excipient, poly(vinyl caprolactam)-poly(vinyl acetate)-poly(ethylene glycol) graft copolymer (PVCL-PVA-PEG). Cationic-HEC was shown to enhance acyclovir permeation across the nasal mucosa. None of the tested cellulosic polymers caused any adverse effects on porcine nasal tissues and cells, as assessed by alterations in CBF. Upon an increase in polymer concentration, a reduction in CBF was observed when ciliated cells were immersed in the polymer solution, and this decrease returned to baseline when the polymer was removed. While each cellulose derivative exhibited unique advantages for nasal drug delivery applications, none stood out on their own to improve more than one of the performance characteristics examined. Hence, these data may be useful for the development of new cellulose derivatives in nasal drug formulations.

Multifaceted applications of bile salts in pharmacy: an emphasis on nanomedicine

The human body has long provided pharmaceutical science with biomaterials of interesting applications. Bile salts (BSs) are biomaterials reminiscent of traditional surfactants with peculiar structure and self-assembled topologies. In the pharmaceutical field, BSs were employed on the basis of two different concepts. The first concept exploited BSs' metabolic and homeostatic functions in disease modulation, whereas the second one utilized BSs' potential to modify drug-delivery characteristics, which recently involved nanotechnology. This review is the first to gather major pharmaceutical applications of BSs from endogenous organotropism up to integration into nanomedicine, with a greater focus on the latter domain. Endogenous applications highlighted the role of BS in modulating hypercholesterolemia and cancer therapy in view of enterohepatic circulation. In addition, recent BS-integrated nanomedicines have been surveyed, chiefly size-tunable cholate nanoparticles, BS-lecithin mixed micelles, bilosomes, probilosomes, and surface-engineered bilosomes. A greater emphasis has been laid on nanosystems for vaccine and cancer therapy. The comparative advantages of BS-integrated nanomedicines over conventional nanocarriers have been noted. Paradoxical effects, current pitfalls, future perspectives, and opinions have also been outlined.

Nanotechnology for CNS delivery of bio-therapeutic agents

The current therapeutic strategies are not efficient in treating disorders related to the central nervous system (CNS) and have only shown partial alleviation of symptoms, as opposed to, disease modifying effects. With change in population demographics, the incidence of CNS disorders, especially neurodegenerative diseases, is expected to rise dramatically. Current treatment regimens are associated with severe side-effects, especially given that most of these are chronic therapies and involve elderly population. In this review, we highlight the challenges and opportunities in delivering newer and more effective bio-therapeutic agents for the treatment of CNS disorders. Bio-therapeutics like proteins, peptides, monoclonal antibodies, growth factors, and nucleic acids are thought to have a profound effect on halting the progression of neurodegenerative disorders and also provide a unique function of restoring damaged cells. We provide a review of the nano-sized formulation-based drug delivery systems and alternate modes of delivery, like the intranasal route, to carry bio-therapeutics effectively to the brain.

Effect of surface charge on the brain delivery of nanostructured lipid carriers in situ gels via the nasal route

The aim of this study was to investigate the influence of the nanocarrier surface charge on brain delivery of a model hydrophilic drug via the nasal route. Anionic and cationic nanostructured lipid carriers (NLCs) were prepared and optimized for their particle size and zeta potential. The optimum particles were incorporated in poloxamer in situ gels and their in vivo behavior was studied in the plasma and brain after administration to rats. Optimum anionic and cationic NLCs of size <200 nm and absolute zeta potential value of ≈ 34 mV were obtained. Toxicity study revealed mild to moderate reversible inflammation of the nasal epithelium in rats treated with the anionic NLCs (A7), and destruction of the lining mucosal nasal epithelium in rats treated with the cationic NLCs (C7L). The absolute bioavailability of both drug loaded anionic and cationic NLCs in situ gels was enhanced compared to that of the intranasal solution (IN) of the drug with values of 44% and 77.3%, respectively. Cationic NLCs in situ gel showed a non significant higher Cmax (maximum concentration) in the brain compared to the anionic NLCs in situ gel. Anionic NLCs in situ gel gave highest drug targeting efficiency in the brain (DTE%) with a value of 158.5 which is nearly 1.2 times that of the cationic NLCs in situ gel.

The apical junctional complex in respiratory diseases

The epithelium, including the respiratory system, acts as a selective gate between the outside environment and underlying tissue. Epithelial cells are polarized due to the formation of the apical junctional complex, which includes adherent junctions and tight junctions. Endothelial cells are one of the most important cellular constituents of blood vessels. Endothelial junctional proteins play important roles in tissue integrity as well as in vascular permeability, leukocyte extravasation, and angiogenesis. This review focuses on the apical junctional complex in respiratory diseases.

Nasal route: an alternative approach for antiemetic drug delivery

INTRODUCTION

Antiemetic drugs are used in the treatment of nausea and emesis. Development of novel delivery systems for antiemetic drugs, as an alternative to conventional preparations, is important in terms of good patient compliance and improving bioavailability. The nasal route offers unique superiorities, such as fast and high drug absorption, and high patient compliance. Therefore, a considerable amount of research has been carried out on the development of nasal delivery systems for antiemetic drugs.

AREAS COVERED

This review deals with the importance of nasal delivery of antiemetic drugs and the studies performed on this subject. The first part of this review summarizes the properties of the nasal route, its advantages and limitations, parameters affecting drug absorption through nasal mucosa, nasal passage pathways and general approaches to improve nasal transport. The second part reviews the studies conducted on the development of nasal delivery systems.

EXPERT OPINION

Due to its superiorities, the nasal route could be considered as an attractive alternative to oral and parenteral routes. To overcome the barrier properties of the nasal epithelium and to enhance transport of antiemetic drugs, several approaches, including permeation enhancers, in situ gel formulations and micro- and nanoparticulate systems, have been evaluated. The results obtained are promising and indicate that nasal formulations of some antiemetic drugs may enter the market in the near future.

Polyrotaxanes for applications in life science and biotechnology

Due to their low cytotoxicity, controllable size, and unique architecture, cyclodextrin (CD)-based polyrotaxanes and polypseudorotaxanes have inspired interesting exploitation as novel biomaterials. This review will update the recent progress in the studies on the structures of polyrotaxanes and polypseudorotaxanes based on different CDs and polymers, followed by summarizing their potential applications in life science and biotechnology, such as drug delivery, gene delivery, and tissue engineering. CD-based biodegradable polypseudorotaxane hydrogels could be used as promising injectable drug delivery systems for sustained and controlled drug release. Polyrotaxanes with drug or ligand-conjugated CDs threaded on polymer chain with biodegradable end group could be useful for controlled and multivalent targeting delivery. Cationic polyrotaxanes consisting of multiple oligoethylenimine-grafted CDs threaded on a block copolymer chain were attractive non-viral gene carries due to the strong DNA-binding ability, low cytotoxicity, and high gene transfection efficiency. Cytocleavable end caps were also introduced in the polyrotaxane systems in order to ensure efficient endosomal escape for intracellular trafficking of DNA. Finally, hydrolyzable polyrotaxane hydrogels with cross-linked α-CDs could be a desirable scaffold for cartilage and bone tissue engineering.

Nasal absorption and local tissue reaction of insulin nanocomplexes of trimethyl chitosan derivatives in rats

OBJECTIVES

The objective of this work was to explore the potential and safety of trimethyl chitosan (TMC) and PEGylated TMC for improved absorption of insulin after nasal administration.

METHODS

The nasal absorption of insulin nanocomplexes of TMC or PEGylated TMC was evaluated in anaesthetized rats. Concomitantly, the histopathological effects of these nanocomplexes on rat nasal mucosa were studied using a perfusion fixation technique.

KEY FINDINGS

All insulin nanocomplexes containing TMC or PEGylated TMC showed a 34-47% reduction in the blood glucose concentration, when the insulin absorption through the rat nasal mucosa was measured indirectly. In addition, the relative pharmacodynamic bioavailability (F(dyn)) of the formulations was found to be dependent upon the charge ratio of insulin and polymer, regardless of polymer structure. The F(dyn) apparently decreased with increasing charge ratio of insulin : polymer. Although acute alterations in nasal morphology by the formulations were affected by the charge ratio of insulin and polymer, the formulation of insulin/PEGylated TMC nanocomplexes was shown to be less toxic to the nasal epithelial membrane than insulin/TMC nanocomplexes.

CONCLUSIONS

PEGylated TMC nanocomplexes were a suitable absorption enhancer for nasal delivery of insulin.

Non-invasive systemic drug delivery: developability considerations for alternate routes of administration

Over the past few decades alternate routes of administration have gained significant momentum and attention, to complement approved drug products, or enable those that cannot be delivered by the oral or parenteral route. Intranasal, buccal/sublingual, pulmonary, and transdermal routes being the most promising non-invasive systemic delivery options. Considering alternate routes of administration early in the development process may be useful to enable new molecular entities (NME) that have deficiencies (extensive first-pass metabolism, unfavorable physicochemical properties, gastro-intestinal adverse effects) or suboptimal pharmacokinetic profiles that are identified in preclinical studies. This review article describes the various delivery considerations and extraneous factors in developing a strategy to pursue an alternate route of administration for systemic delivery. The various delivery route options are outlined with their pros and cons; key criteria and physicochemical attributes that would make a drug a suitable candidate are discussed; approaches to assess delivery feasibility, toxicity at the site of delivery, and overall developability potential are described; and lastly, product trends and their disease implications are highlighted to underscore treatment precedence that help to build scientific rationale for the pursuit of an alternate route of administration.

Formulation and evaluation of nasal mucoadhesive microspheres of sumatriptan succinate

The purpose of present research work was to develop mucoadhesive microspheres for nasal delivery with the aim to avoid hepatic first-pass metabolism, improve therapeutic efficacy and enhance residence time. For the treatment of migraine, hydroxypropyl methylcellulose (HPMC) K4M and K15M based microspheres containing sumatriptan succinate (SS) were prepared by spray-drying technique. The microspheres were evaluated with respect to the yield, particle size, incorporation efficiency, swelling property, in vitro mucoadhesion, in vitro drug release, histological study and stability. Microspheres were characterized by differential scanning calorimetry, scanning electron microscopy and X-ray diffraction study. It was found that the particle size, swelling ability and incorporation efficiency of microspheres increases with increasing drug-to-polymer ratio. HPMC-based microspheres show adequate mucoadhesion and do not have any destructive effect on nasal mucosa. On the basis of these results, SS microspheres based on HPMC may be considered as a promising nasal delivery system.

Nasal delivery of high molecular weight drugs

Nasal drug delivery may be used for either local or systemic effects. Low molecular weight drugs with are rapidly absorbed through nasal mucosa. The main reasons for this are the high permeability, fairly wide absorption area, porous and thin endothelial basement membrane of the nasal epithelium. Despite the many advantages of the nasal route, limitations such as the high molecular weight (HMW) of drugs may impede drug absorption through the nasal mucosa. Recent studies have focused particularly on the nasal application of HMW therapeutic agents such as peptide-protein drugs and vaccines intended for systemic effects. Due to their hydrophilic structure, the nasal bioavailability of peptide and protein drugs is normally less than 1%. Besides their weak mucosal membrane permeability and enzymatic degradation in nasal mucosa, these drugs are rapidly cleared from the nasal cavity after administration because of mucociliary clearance. There are many approaches for increasing the residence time of drug formulations in the nasal cavity resulting in enhanced drug absorption. In this review article, nasal route and transport mechanisms across the nasal mucosa will be briefly presented. In the second part, current studies regarding the nasal application of macromolecular drugs and vaccines with nano- and micro-particulate carrier systems will be summarised.

Cyclodextrin-based supramolecular architectures: syntheses, structures, and applications for drug and gene delivery

The supramolecular structures formed between cyclodextrins (CDs) and polymers have inspired interesting developments of novel supramolecular biomaterials. This review will update the recent progress in studies on supramolecular structures based on CDs and block copolymers, followed by the design and synthesis of CD-based supramolecular hydrogels and biodegradable polyrotaxanes for potential controlled drug delivery, and CD-containing cationic polymers and cationic polyrotaxanes for gene delivery. Supramolecular hydrogels based on the self-assembly of the inclusion complexes between CDs with biodegradable block copolymers could be used as promising injectable drug delivery systems for sustained controlled release of macromolecular drugs. Biodegradable polyrotaxanes with drug-conjugated CDs threaded on a polymer chain with degradable end-caps could be interesting supramolecular prodrugs for controlled and targeting delivery of drugs. CD-containing cationic polymers as gene carriers showed reduced cytotoxicity than non-CD-containing polymer counterparts. More importantly, the polyplexes of CD-containing cationic polymers with DNA could be pegylated through a supramolecular process using inclusion complexation between the CD moieties and a modified PEO. Finally, new cationic polyrotaxanes composed of multiple oligoethylenimine-grafted CDs threaded and end-capped on a block copolymer chain were designed and synthesized as a new class of polymeric gene delivery vectors, where the chain-interlocked cationic cyclic units formed an integrated supramolecular entity to function as a macromolecular gene vector. The development of the supramolecular biomaterials through inclusion complexation has opened up a new approach for designing novel drug and gene delivery systems, which may have many advantages over the systems based on the conventional polymeric materials.

Intranasal delivery: physicochemical and therapeutic aspects

Interest in intranasal (IN) administration as a non-invasive route for drug delivery continues to grow rapidly. The nasal mucosa offers numerous benefits as a target issue for drug delivery, such as a large surface area for delivery, rapid drug onset, potential for central nervous system delivery, and no first-pass metabolism. A wide variety of therapeutic compounds can be delivered IN, including relatively large molecules such as peptides and proteins, particularly in the presence of permeation enhancers. The current review provides an in-depth discussion of therapeutic aspects of IN delivery including consideration of the intended indication, regimen, and patient population, as well as physicochemical properties of the drug itself. Case examples are provided to illustrate the utility of IN dosing. It is anticipated that the present review will prove useful for formulation scientists considering IN delivery as a delivery route.

Transport characteristics of a beta sheet breaker peptide across excised bovine nasal mucosa

The purpose of the present study was to investigate the permeation characteristics of the beta sheet breaker peptide AS 602704 (BSB) on excised bovine nasal mucosa using an Ussing chamber model. The influence of various absorption enhancers such as sodium cholate, sodium dodecyl sulfate (SDS), cetrimidum, sodium caprate, Na(2)EDTA, polycarbophil (PCP), the thiomer conjugate polycarbophil-cysteine (PCP-Cys), and poly-l-arginine (poly-l-arg; 100 kDa) was evaluated. Additionally, the influence of temperature and pH on the transport rate as well as the stability of the peptide drug against enzymatic degradation were investigated in vitro. The effective permeability coefficient (P(eff)) of BSB in Krebs-Ringer-buffer (KRB) pH 7.4 was (1.89 +/- 0.44)* 10-5, while in the presence of sodium caprate (0.5%) a P(eff) of (9.58 +/- 1.82)*10-5 was achieved. Rank order of enhancement ratio was sodium caprate > SDS > sodium cholate > Na(2)EDTA > poly-L-arg = PCP-Cys. In case of cetrimidum and PCP even a decrease in the absorption of BSB was determined. Na2EDTA reduced the enzymatic degradation of BSB when exposed to a nasal tissue homogenate by more than the half. An increased lipophilicity of BSB because of a more acidic milieu (pH 5.5) did not lead to an increased transcellular transport. Permeation studies carried out at 4 degrees C compared to 37 degrees C demonstrated a temperature dependent permeation behaviour suggesting an additional active carrier mediated transport. The results obtained within these studies should facilitate the development of a nasal delivery system for AS 602704 for the treatment of Alzheimer's disease.

In vivo evaluation of a nasal insulin delivery system based on thiolated chitosan

The aim of this study was the preparation and in vivo evaluation of a nasal insulin delivery system based on thiolated chitosan. 2-Iminothiolane was covalently attached to chitosan. The resulting conjugate (chitosan-TBA) exhibited 304.9 +/- 63.5 micromol thiol groups per gram polymer. Microparticles were prepared via a new precipitation-micronization technique. The microparticulate delivery system comprised insulin, reduced glutathione and chitosan-TBA (Chito-TBA/Ins) or unmodified chitosan (Chito/Ins) and control microparticles were composed of insulin and mannitol (Mannitol/Ins). Due to a hydration process the size of Chito-TBA/Ins and Chito/Ins microparticles increased in phosphate buffer pH 6.8 2.6- and 2.2-fold, respectively. Fluorescent-labeled insulin-loaded chitosan-TBA microparticles showed a controlled release over 4 h. Chito-TBA/Ins administered nasally to rats led to an absolute bioavailability of 6.9 +/- 1.5%. The blood glucose level decreased for more than 2 h and the calculated absolute pharmacological efficacy was 4.9 +/- 1.4%. Chito/Ins, in comparison, displayed a bioavailability of 4.2 +/- 1.8% and a pharmacological efficacy of 0.7 +/- 0.6%. Mannitol/Ins showed a bioavailability of 1.6 +/- 0.4% and no reduction of the blood glucose level at all. According to these findings microparticles comprising chitosan-TBA seem to have substantial higher potential for nasal insulin administration than unmodified chitosan.

In vitro formulation optimization of intranasal galantamine leading to enhanced bioavailability and reduced emetic response in vivo

The purpose of the current investigation was to optimize an intranasal (IN) galantamine (an acetylcholinesterase inhibitor used for treatment of Alzheimer's disease) formulation using an in vitro tissue model, to correlate those results to in vivo bioavailability, and to compare emetic response to oral dosing. A design-of-experiments (DOE) based formulation screening employing an in vitro tissue model of human nasal epithelium was used to assess drug permeability, tight junction modulation, and cellular toxicity. In vivo studies in rats compared pharmacokinetic (PK) profiles of different formulations dosed intranasally. Finally, studies in ferrets evaluated PK and gastrointestinal (GI) related side effects of oral compared to nasal dosage forms. Galantamine permeation was enhanced without increasing cytotoxicity. Pharmacokinetic testing in rats confirmed the improved drug bioavailability and demonstrated an in vitro-in vivo correlation. Compared to oral dosing, IN galantamine resulted in a dramatically lowered incidence of GI-related side effects, e.g., retching and emesis. These findings illustrate that IN delivery represents an attractive alternative to oral dosing for this important Alzheimer's disease therapeutic. To our knowledge, the data herein represent the first direct confirmation of reducing GI-related side effects for IN galantamine compared to oral dosing.

Rapid-onset intranasal delivery of metoclopramide hydrochloride. Part I. Influence of formulation variables on drug absorption in anesthetized rats

Intranasal (IN) administration is a promising approach for rapid-onset delivery of medications and to circumvent their first-pass elimination when taken orally. Metoclopramide (MCP) is a potent antiemetic, effective even for preventing emesis induced by cancer chemotherapy. The feasibility of developing an efficacious intranasal formulation of metoclopramide has been undertaken in this study. The nasal absorption of MCP was studied in anesthetized rats over 60min using the in vivo in situ technique. The influence of several formulation variables, vis., pH and the addition of preservative, viscosity and absorption enhancing agents on the nasal MCP absorption was examined. The data obtained showed that MCP was well absorbed nasally where almost 90% of the drug was absorbed after 60min from the rat nasal cavity. The MCP absorption was pH-dependant such that the apparent first-order rate constant of absorption (K(app)) was almost tripled when the pH of the solution was increased from 5 to 8. However, deviation from the classical pH-partition theory was observed pointing to the role of aqueous pore pathway in MCP nasal absorption. The K(app) was significantly increased (P<0.05) by incorporation of 0.01% of the preservative benzalkonium chloride. Conversely, increasing the solution viscosity by the use of hydroxylpropyl methylcellulose adversely affected the rate of absorption. The use of enhancers namely sodium deoxycholate, sodium cholate, chitosan low and high molecular weight, protamine sulphate and poly-l-arginine resulted in significant increase in MCP absorption. The highest promoting effect was observed with the bile salt sodium deoxycholate where about 92% of the drug was absorbed in 25min from the rat nasal cavity and the K(app) showed more than two-fold increase as compared to control (from 0.0452 to 0.1017min(-1)).

Therapeutic utility of a novel tight junction modulating peptide for enhancing intranasal drug delivery

Previously, a novel tight junction modulating (TJM) peptide was described affording a transient, reversible lowering of transepithelial electrical resistance (TER) in an in vitro model of nasal epithelial tissue. In the current report, this peptide has been further evaluated for utility as an excipient in transepithelial drug formulations. Chemical stability was optimal at neutral to acidic pH when stored at or below room temperature, conditions relevant to therapeutic formulations. The TJM peptide was tested in the in vitro tissue model for potential to enhance permeation of a low-molecular-weight (LMW) drug, namely the acetylcholinesterase inhibitor galantamine, as well as three peptides, salmon calcitonin, parathyroid hormone 1-34 (PTH(1-34)), and peptide YY 3-36 (PYY(3-36)). In all cases, the TJM peptide afforded a dramatic improvement in drug permeation across epithelial tissue. In addition, a formulation containing PYY(3-36) and TJM peptide was dosed intranasally in rabbits, resulting in a dramatic increase in bioavailability. The TJM peptide was as or more effective in enhancing PYY(3-36) permeation in vivo at a 1000-fold lower molar concentration compared to using LMW enhancers. Based on these in vitro and in vivo data, the novel TJM peptide represents a promising advancement in intranasal formulation development.

Enhancement of nasal absorption of large molecular weight compounds by combination of mucolytic agent and nonionic surfactant

For improving the nasal absorption of poorly absorbable hydrophilic compounds, the suitability of a combination of a mucolytic agent, N-acetyl-L-cysteine (NAC), and a nonionic surfactant, polyoxyethylene (C25) lauryl ether (laureth-25), was examined. Rat studies with fluorescent isothiocyanate-labeled dextran (molecular weight ca. 4.4 kDa, FD-4) as a model hydrophilic compound revealed dramatic enhancement of nasal absorption when NAC and laureth-25 were simultaneously applied. The nasal bioavailability of FD-4 in saline solution was 8.2+/-0.6% but increased to 40.0+/-5.5% when 5% NAC and 5% laureth-25 were added. This synergistic enhancement could result from the mucolytic activity of NAC in reducing mucous viscosity by which the accessibilities of FD-4 and laureth-25 to the epithelial membrane were increased. Further rat studies proved that this formulation increased nasal absorption of salmon calcitonin. Absolute bioavailability from saline solution containing 5% NAC and 1% laureth-25 was 26.8+/-2.2%, 3.5 times that of the commercial calcitonin nasal spray Miacalcin (7.7+/-2.1%). The potential of the new formulation to cause tissue damage in terms of hemolytic activity and liberation of phospholipid from the nasal membranes was nil or slight. The combination of NAC and laureth-25 appears suitable for use in development of nasal products for poorly absorbable drugs, especially peptide and protein drugs.

Inhibition of appetite by nasal leptin administration in rats

OBJECTIVE

Leptin inhibits appetite and reduces body weight. However, subcutaneous leptin administration is not very effective on weight reduction. The present studies were undertaken to test the hypotheses that nasally administered leptin effectively accesses to the brain and inhibits appetite.

METHODS

Recombinant leptin (0.5 mg/rat) was administered into the bilateral nasal spaces of rats (i.n.). Changes in serum immunoreactive leptin (IRL) and cerebrospinal fluid (CSF)-IRL concentrations after i.n. leptin administration were compared after intraperitoneal (i.p.) administration. The influence of 0.1 or 0.5% lysophosphatidylcholine (LPC) as an optimizer of leptin absorption was examined. The anorexic effects of i.n. leptin were compared with i.p. leptin in ad libitum fed rats.

RESULTS

The i.n. leptin increased CSF-IRL concentrations, although serum IRL concentrations of rats administered leptin i.n. were lower than those administered i.p. The addition of 0.1 and 0.5% LPC dose-dependently increased serum IRL concentrations, but did not modify CSF-IRL concentrations in i.n. leptin-treated rats. The i.n. leptin inhibited dark-time food consumption at 0-1 h and 3-6 h in ad libitum fed rats. In contrast, i.p. leptin reduced food consumption only for an hour. Phosphorylated signal transducer and activator of transcription (STAT) 3 immunoreactive cells increased in the arcuate nucleus (ARC) of the hypothalamus at 3 h only following i.n. leptin.

CONCLUSION

The present study demonstrated that i.n. leptin caused longer inhibition of appetite and phosphorylation of STAT3 in ARC. It is concluded that the trans-nasal route may be useful for the selective access of leptin to the brain in obese people.

Cyclodextrins in nasal delivery of low-molecular-weight heparins: in vivo and in vitro studies

PURPOSE

To test the hypothesis that cyclodextrins reversibly enhance nasal absorption of low-molecular-weight heparins (LMWHs) and to investigate the mechanisms by which cyclodextrins enhance LMWH absorption via the nose.

METHODS

Absorption of LMWHs was studied by measuring plasma anti-factor Xa activity after nasal administration of various LMWH formulations to anesthetized rats. In vivo reversibility studies were performed to investigate if the effects of cyclodextrins are reversible and diminish with time. The absorption-enhancing mechanisms of cyclodextrins were investigated in cell culture model. The transport of enoxaparin and mannitol, changes in transepithelial electrical resistance (TEER), and distribution of tight junction protein ZO-1 were investigated.

RESULTS

Formulations containing 5% dimethyl-beta-cyclodextrin (DMbetaCD) produced the highest increase in the bioavailability of LMWH preparations tested. In vivo reversibility studies with 5% DMbetaCD showed that the effect of the absorption enhancer at the site of administration diminished with time. Transport studies using 16HBE14o(-) cells demonstrated that the increase in the permeability of enoxaparin and mannitol, reduction in TEER, and the changes in the tight junction protein ZO-1 distribution produced by 5% DMbetaCD were much greater than those produced by beta-cyclodextrin (betaCD) or hydroxyl-propyl-beta-cyclodextrin (HPbetaCD).

CONCLUSIONS

Of the cyclodextrins tested, DMbetaCD was the most efficacious in enhancing absorption of LMWHs both in vivo and in vitro. The study also suggests that cyclodextrins enhance nasal drug absorption by opening of cell-cell tight junctions.

Chain length-dependent effects of alkylmaltosides on nasal absorption of enoxaparin

The purpose of this study was to investigate whether the hydrophobic chain length of alkylmaltosides affects their efficacy as absorption promoters for nasally administered low-molecular-weight heparin and to study whether these agents enhance nasal absorption in a time-dependent manner without causing irreversible damage to the nasal epithelial membrane. For the nasal absorption studies, enoxaparin formulated with different alkylmaltosides was administered nasally to anesthetized rats and absorption of the drug was determined by measuring plasma anti-factor Xa activity. Reversibility studies were performed by administering enoxaparin at different time points after administration of alkylmaltosides. The AUC(0-360) for plasma anti-factor Xa-time curves increased with the increase in alkylmaltoside concentration in the formulations. Absolute and relative bioavailability of enoxaparin were increased by two-fold when the alkyl chain length of maltosides was increased from 8 to 14 carbons. Alkylmaltosides therefore increase nasal absorption of enoxaparin in a dose- and chain length-dependent manner. Of the alkylmaltosides tested, tetradecylmaltoside is the most potent enhancer of nasal absorption of enoxaparin. Longer chain alkylmaltosides produce a more prolonged effect on nasal mucosa compared with those with shorter alkyl chain.

Alkanoylsucroses in nasal delivery of low molecular weight heparins: in-vivo absorption and reversibility studies in rats

The efficacy of alkanoylsucroses in enhancing nasal absorption of low molecular weight heparin (LMWH) and the time span of action of these agents on the nasal membrane has been investigated. In this regard, LMWH formulated with alkanoylsucroses was administered nasally to anaesthetized male Sprague-Dawley rats and the absorption of LMWH was determined by measuring plasma antifactor Xa activity. The duration of action of these agents at the site of administration was investigated by an in-vivo reversibility study. The potency and efficacy of dodecanoylsucrose was compared with that of sodium glycocholate. Alkanoylsucroses used in this study include dodecanoylsucrose, decanoylsucrose and octanoylsucrose. These agents enhance nasal absorption of enoxaparin in a dose-dependent and chain-length-dependent manner. Of the agents tested, dodecanoylsucrose was found to be the most potent in enhancing nasal absorption of LMWH. The bioavailability of enoxaparin formulated with alkanoylsucroses was increased by several folds compared with enoxaparin formulated in saline. The reversibility study with dodecanoylsucrose showed that the effect of alkanoylsucroses faded away with time and the duration of action of this agent at the site of administration was 120-140 min. Dodecanoylsucrose was found to be twice as potent as sodium glycocholate. Overall, the nasal absorption of LMWH was effectively enhanced by co-administration of alkanoylsucroses and the effect of alkanoylsucroses on nasal epithelium was found to be reversible. The potency of these agents depends on their hydrophobic chain lengths.

Absorption enhancers for nasal drug delivery

This paper describes the basic concepts for the transmucosal delivery of drugs, and in particular the use of the nasal route for delivery of challenging drugs such as polar low-molecular-weight drugs and peptides and proteins. Strategies for the exploitation of absorption enhancers for the improvement of nasal delivery are discussed, including consideration of mechanisms of action and the correlation between toxic effect and absorption enhancement. Selected enhancer systems, such as cyclodextrins, phospholipids, bioadhesive powder systems and chitosan, are discussed in detail. Examples of the use of these enhancers in preclinical and clinical studies are given. Methods for assessing irritancy and damage to the nasal membrane from the use of absorption enhancers are also described. Finally, the mucosal use of absorption enhancers (chitosan) for the improved nasal delivery of vaccines is reported with reference to recent phase I/II clinical studies.

Intranasal delivery of PEGylated salmon calcitonins: hypocalcemic effects in rats

To evaluate the hypocalcemic effect of polyethylene gtycol-conjugated salmon calcitonins (PEG-sCT) in rats, mono-PEGylated sCTs (mono-PEG-sCTs) and unmodified sCT were administered via the intranasal route and serum calcium levels were measured by colorimetric assay using o-cresolphthalein. Mono-PEG-sCTs were prepared with different sizes of succinimidyl succinate monomethoxy PEG molecules (PEG2K), PEG5K, PEG12K) and characterized by HPLC and MALDI-TOF mass spectrometry. Nasal instillation of mono-PEG2K-sCT at a dose of 2 IU/kg resulted in sustained reduction in serum calcium levels over 8 hr, with a maximum reduction (% maxd) of 13% after 6 hr of application. Whereas unmodified sCT showed a transient decrease in serum calcium levels with the maximum reduction (5%) observed after 30 min of administration. The overall reductions in serum calcium levels expressed as the net change in AUC relative to control in 8 hr were 11.9 +/- 0.2, 4.6 +/- 0.7, and 2.6 +/- 0.7% for mono-PEG2K-, mono-PEG5K-, and mono-PEG12K-sCT, respectively, compared to 3.2 +/- 0.6% for unmodified sCT. The relative bioavailability of nasally administered 2 IU/kg of mono-PEG2K-sCT was approximately 4-fold higher than nasally administrated unmodified sCT, and the absolute bioavailability was approximately 91% of intravenously injected sCT in 8 hr. It can be concluded that the intranasal absorption of mono-PEG-sCTs was inversely related to the molecular weights of the PEG attached. Of the PEGylated sCTs examined, mono-PEG2K-sCT showed the most pronounced hypocalcemic effect. Therefore the intranasal application would probably be an alternative route of administration for mono-PEG-sCTs in achieving sustained calcium-lowering effects.

Insoluble powder formulation as an effective nasal drug delivery system

PURPOSE

To evaluate the utility of insoluble powder formulation for nasal systemic drug delivery.

METHODS

To compare the efficacy of liquid and powder formulations, the nasal absorption of drugs was examined in rats using hydrophilic compounds with various molecular weights (MW) such as phenol red, cyanocobalamin, and fluorescein isothiocyanate (FITC)-Dextrans, and several kinds of powder. Intranasal residence time was also compared among the different formulations.

RESULTS

All the drugs examined were absorbed through the nasal mucosa to varying extent; their systemic bioavailability decreased with increasing MW. Insoluble calcium carbonate (CaCO3) powder formulation provided increased absorption of drugs over the wide range of MW from 354 to 77,000 Da. In the case of phenol red, intranasal administration as a CaCO3 powder formulation resulted in a plasma concentration profile similar to that of an intravenous bolus dose due to its very rapid and complete absorption from the nasal cavity. Furthermore, improved bioavailability of FITC-Dextran (MW 4,400; FD-4) was also achieved with other insoluble powders as well as CaCO3, but not with soluble powders such as lactose, d-sorbitol, and d-mannitol. Insoluble powder formulation prolonged the residence time of FD-4 within the nasal cavity.

CONCLUSIONS

Insoluble powder formulations improve nasal bioavailability predominantly by retarding drug elimination from the absorption site and appear to be effective for nasal systemic drug delivery.

Mucoadhesive microspheres containing gentamicin sulfate for nasal administration: preparation and in vitro characterization

In this study, suitable microsphere formulations were designed in order to provide the absorption of a high polar drug through nasal mucosa. For this purpose, gentamicin sulfate (GS) was chosen as a model drug and used at different drug/polymer ratios in the microsphere formulations. The microspheres were prepared by spray drying technique. Hydroxypropyl methylcellulose was used as a mucoadhesive polymer in the formulations to increase the residence time of the microspheres on the mucosa. Sodium cholate was added into the formulations for increasing the absorption of GS through nasal mucosa. The in vitro characteristics of the microspheres were determined. The microspheres were evaluated with respect to the particle size, production yield, encapsulation efficiency, shape and surface properties, drug-polymer interaction, mucoadhesive property, in vitro drug release and suitability for nasal drug delivery.