Scintigraphic evaluation in rabbits of nasal drug delivery systems based on carbopol 971p((R)) and carboxymethylcellulose

Chitosan Aerogel Particles as Nasal Drug Delivery Systems

The nasal drug delivery route has distinct advantages, such as high bioavailability, a rapid therapeutic effect, non-invasiveness, and ease of administration. This article presents the results of a study of the processes for obtaining chitosan aerogel particles that are promising as nasal or inhalation drug delivery systems. Obtaining chitosan aerogel particles includes the following steps: the preparation of a chitosan solution, gelation, solvent replacement, and supercritical drying. Particles of chitosan gels were obtained by spraying and homogenization. The produced chitosan aerogel particles had specific surface areas of up to 254 m²/g, pore volumes of up to 1.53 cm³/g, and porosities of up to 99%. The aerodynamic diameters of the obtained chitosan aerogel particles were calculated, the values of which ranged from 13 to 59 µm. According to the calculation results, a CS1 sample was used as a matrix for obtaining the pharmaceutical composition "chitosan aerogel-clomipramine". X-ray diffraction (XRD) analysis of the pharmaceutical composition determined the presence of clomipramine, predominantly in an amorphous form. Analysis of the high-performance liquid chromatography (HPLC) data showed that the mass loading of clomipramine was 35%. Experiments in vivo demonstrated the effectiveness of the pharmaceutical composition "chitosan aerogel-clomipramine" as carrier matrices for the targeted delivery of clomipramine by the "Nose-to-brain" mechanism of nasal administration. The maximum concentration of clomipramine in the frontal cortex and hippocampus was reached 30 min after administration.

Biobased polymer resources and essential oils: a green combination for antibacterial applications

To fight nosocomial infections, the excessive use of antibiotics has led to the emergence of multidrug-resistant microorganisms, which are now considered a relevant public health threat by the World Health Organization. To date, most antibacterial systems are based on the use of petro-sourced polymers, but the global supplies of these resources are depleting. Besides, silver NPs are widely accepted as the most active biocide against a wide range of bacterial strains but their toxicity is an issue. The growing interest in natural products has gained increasing interest in the last decade. Therefore, the design of functional antibacterial materials derived from biomass remains a significant challenge for the scientific community. Consequently, attention has shifted to naturally occurring substances such as essential oils (EOs), which are classified as Generally Recognized as Safe (GRAS). EOs can offer an alternative to the common antimicrobial agents as an inner solution or biocide agent to inhibit the resistance mechanism. Herein, this review not only aims at providing developments in the antibacterial modes of action of EOs against various bacterial strains and the recent advances in genomic and proteomic techniques for the elucidation of these mechanisms but also presents examples of biobased polymer resource-based EO materials and their antibacterial activities. Especially, we describe the antibacterial properties of biobased polymers, e.g. cellulose, starch, chitosan, PLA PHAs and proteins, associated with EOs (cinnamon (CEO), clove (CLEO), bergamot (BEO), ginger (GEO), lemongrass (LEO), caraway (CAEO), rosemary (REO), Eucalyptus globulus (EGEO), tea tree (TTEO), orange peel (OPEO) and apricot (Prunus armeniaca) kernel (AKEO) essential oils). Finally, we discuss the influence of EOs on the mechanical strength of bio-based materials.

The effect of ingredients commonly used in nasal and inhaled solutions on the secretion of mucus in vitro

Hypersecretion of mucus is associated with impaired mucociliary clearance that can influence the retention of active pharmaceutical ingredients in the airway but is also linked with recurrent airway disease. Therefore, the effect on mucin secretion of a range of ingredients used in solutions delivered to the nose and lung was studied. Mucin secretion from explants of ovine epithelium was quantified using an enzyme-linked lectin assay (ELLA) or sandwich ELLA depending on the compatibility of the ingredients with the assay. Benzalkonium chloride (0.015% w/w), Methocel™ E50 premium LV (1.0% w/w), propylene glycol (1.5% w/w), potassium sorbate + propylene glycol (0.3% w/w + 1.5% w/w) and polysorbate 80 (0.025% w/w), used at common working concentrations, all increased the secretion of mucin from the explants (P < 0.05). Ethylenediamine tetraacetic acid-disodium salt (EDTA) (0.015% w/w), Avicel® RC591 (1.5% w/w), fluticasone furoate (0.0004% w/w, concentration in solution) and dimethyl sulfoxide (DMSO) (0.2% w/w) did not affect mucin secretion. Compounds increasing mucin secretion could alter the rate of mucociliary clearance and the mucus could provide a barrier to drug absorption. This could predispose patients to disease and affect the activity of delivered drugs, decreasing or increasing their clinical efficacy.

Antipsychotic Potential and Safety Profile of TPGS-Based Mucoadhesive Aripiprazole Nanoemulsion: Development and Optimization for Nose-To-Brain Delivery

Delivering therapeutics to the brain using conventional dosage forms is always a challenge, thus the present study was aimed to formulate mucoadhesive nanoemulsion (MNE) of aripiprazole (ARP) for intranasal delivery to transport the drug directly to the brain. Therefore, a TPGS based ARP-MNE was formulated and optimized using the Box-Behnken statistical design. The improved in vitro release profile of the formulation was in agreement to enhanced ex vivo permeation through sheep mucous membranes with a maximum rate of permeation co-efficient (62.87  cm h^-1 × 10³) and flux (31.43  μg cm^-2.h^-1). The pharmacokinetic profile following single-dose administration showed the maximum concentration of drug in the brain (C_max) of 15.19 ± 2.51  μg mL^-1 and T_max of 1 h in animals with ARP-MNE as compared to 10.57 ± 1.88  μg mL^-1 and 1 h, and 2.52 ± 0.38  μg mL^-1 and 3 h upon intranasal and intravenous administration of ARP-NE, respectively. Further, higher values of % drug targeting efficiency (96.9%) and % drug targeting potential (89.73%) of ARP-MNE through intranasal administration were investigated. The studies in Wistar rats showed no existence of extrapyramidal symptoms through the catalepsy test and forelimb retraction results. No ex vivo ciliotoxicity on nasal mucosa reflects the safety of the components and delivery tool. Further, findings on locomotor activity and hind-limb retraction test in ARP-MNE treated animals established its antipsychotic efficacy. Thus, it can be inferred that the developed ARP-MNE could effectively be explored as brain delivery cargo in the effective treatment of schizophrenia without producing any toxic manifestation.

Biomaterials to Prevent Post-Operative Adhesion

Surgery is performed to treat various diseases. During the process, the surgical site is healed through self-healing after surgery. Post-operative or tissue adhesion caused by unnecessary contact with the surgical site occurs during the normal healing process. In addition, it has been frequently found in patients who have undergone surgery, and severe adhesion can cause chronic pain and various complications. Therefore, anti-adhesion barriers have been developed using multiple biomaterials to prevent post-operative adhesion. Typically, anti-adhesion barriers are manufactured and sold in numerous forms, such as gels, solutions, and films, but there are no products that can completely prevent post-operative adhesion. These products are generally applied over the surgical site to physically block adhesion to other sites (organs). Many studies have recently been conducted to increase the anti-adhesion effects through various strategies. This article reviews recent research trends in anti-adhesion barriers.

Quantification and Evaluation of Glycyrrhizic Acid-loaded Surface Decorated Nanoparticles by UHPLC-MS/MS and used in the Treatment of Cerebral Ischemia

Background:

Glycyrrhizic Acid (GRA), a potent antioxidant triterpene saponin glycoside and neuroprotective properties exhibits an important role in the treatment of neurological disorders i.e. cerebral ischemia. GRA is water soluble, therefore it’s have low bioavailability in the brain.

Objective:

To enhance brain bioavailability for intranasally administered Glycyrrhizic Acidencapsulated- chitosan-coated-PCL-Nanoparticles (CS-GRA-PCL-NPs).

Methods:

Chitosan-coated-PCL-Nanoparticles (CS-PCL-NPs) were developed through double emulsification- solvent evaporation technique and further characterized for particle size, zeta potential, size distribution, encapsulation efficiency as well as in vitro drug release. UPLC triple quadrupole Qtrap MS/MS method was developed to evaluate brain-drug uptake for optimized CS-GRA-PCL-NPs and to determine its pharmacokinetic in rat’s brain as well as plasma.

Results:

Mean particles size (231.47±7.82), polydispersity index (PDI) i.e. (0.216±0.030) and entrapment efficiency (65.69±5.68) was determined for developed NPs. UPLC triple quadrupole Qtrap MS/MS method study showed a significantly high mucoadhesive potential of CS-GRA-PCL-NPs and least for conventional and homogenized nanoformulation; elution time for GRA and internal standard (IS) Hydrocortisone as 0.37 and 1.94 min at m/z 821.49/113.41 and 363.45/121.40 were observed, respectively. Furthermore, intra and inter-assay (%CV) of 0.49-5.48, %accuracy (90.00-99.09%) as well as a linear dynamic range (10.00 ng/mL -2000.0 ng/mL), was observed. Pharmacokinetic studies in Wistar rat brain exhibited a high AUC0-24 alongwith an amplified Cmax (p** < 0.01) as compared to i.v. treated group.

Conclusion:

Intranasal administration of developed CS-coated-GRA-loaded-PCL-NPs enhanced the drug bioavailability in rat brain along with successfully UPLC-MS/MS method and thus preparation of GRA-NPs may help treat cerebral ischemia effectively. The toxicity studies performed at the end revealed safe nature of optimized nanoformulation.

Antiadhesive Effect of the Mixed Solution of Sodium Hyaluronate and Sodium Carboxymethylcellulose after Endoscopic Sinus Surgery

Background

We evaluated the clinical efficacy and safety of the mixed solution of sodium hyaluronate and sodium carboxymethylcellulose (HA-CMC) for prevention of adhesion after endoscopic sinus surgery.

Methods

Preoperative computed tomography (CT) scans were graded. At the completion of surgery, HA-CMC was applied to Merocel and repeatedly applied after the removal of Merocel. As a control, normal saline was applied. Endoscopic examination was performed postoperatively and grading was done.

Results

The rate of adhesion was the highest at 2 weeks postoperatively and was significantly lower in the HA-CMC–treated group than the control on all postoperative days. The grouping of cases by CT scores at 2 weeks postoperatively showed lower adhesion formation with the HA-CMC treatment than the control. The safety profile of the patients was normal at 4 weeks postoperatively.

Conclusion

HA-CMC is an efficacious and safe material in decreasing the incidence of adhesion after endoscopic sinus surgery.

Challenges and trends in apomorphine drug delivery systems for the treatment of Parkinson's disease

Parkinson's disease (PD) is a chronic debilitating disease affecting approximately 1% of the population over the age of 60. The severity of PD is correlated to the degree of dopaminergic neuronal loss. Apomorphine has a similar chemical structure as the neurotransmitter dopamine and has been used for the treatment of advanced PD patients. In PD patients, apomorphine is normally administered subcutaneously with frequent injections because of the compound's extensive hepatic first-pass metabolism. There is, hence, a large unmet need for alternative administrative routes for apomorphine to improve patient compliance. The present review focuses on the research and development of alternative delivery of apomorphine, aiming to highlight the potential of non-invasive apomorphine therapy in PD, such as sublingual delivery and transdermal delivery.

Nasal in-situ gels for delivery of rasagiline mesylate: improvement in bioavailability and brain localization

Intranasal thermosensitive gel for rasagiline mesylate (RM) was developed for effective treatment of Parkinson's disease. Intranasal gels were prepared by combination of poloxamer 407 and poloxamer 188 (1:1) with mucoadhesive polymers (carbopol 934 P and chitosan). The formulations were evaluated for sol-gel transition temperature, in-vitro drug release and in-vivo mucociliary transit time. Further, optimal intranasal gel formulations were tested for in-vivo pharmacokinetic behavior, nasal toxicity studies and brain uptake studies. It was found that optimal formulations had acceptable gelation temperature (28-33 °C) and adequate in-vitro drug release profile. Pharmacokinetic study in rabbits showed significant (p < 0.05) improvement in bioavailability (four- to six-folds) of the drug from intranasal gels than oral solution. Chronic exposure studies in Wistar rats showed that these intranasal gels were non-irritant and non-toxic to rat nasal mucosa. Estimation of RM in rat brain tissue showed significant (p < 0.01) improvement in uptake of RM form intranasal gel formulations than nasal solution.

Thermoreversible nasal in situ gel of venlafaxine hydrochloride: formulation, characterization, and pharmacodynamic evaluation

In order to improve the bioavailability of the antidepressant drug, venlafaxine hydrochloride, in situ mucoadhesive thermoreversible gel, was formulated using Lutrol F127 (18%) as a thermo gelling polymer. Mucoadhesion was modulated by trying carbopol 934, PVP K30, HPMC K4M, sodium alginate, tamarind seed gum, and carrageenan as mucoadhesive polymers. Results revealed that as the concentration of mucoadhesive polymer increased the mucoadhesive strength increased but gelation temperature decreased. Formulation was optimized on the basis of clarity, pH, gelation temperature, mucoadhesive strength, gel strength, viscosity, drug content, diffusion through sheep nasal mucosa, histopathological evaluation of mucosa, and pharmacodynamic study in rats. Final formulation T5 containing 18% Lutrol F127 and 0.3% PVP K30 was considered as an optimized formulation. T5 released 97.86±0.073% drug in 150 min with a flux of 0.1545 mg cm(-2) min(-1) and gelation temperature 31.17±0.30°C. Histopathological evaluation of nasal mucosa revealed that T5 formulation was safe for nasal administration as it caused no damage to nasal epithelium. From the results of pharmacodynamic study, mainly forced swim test (FST), it was concluded that venlafaxine hydrochloride was more effective as an antidepressant by nasal route as in situ gel nasal drops in comparison to oral administration of equivalent dose.

Phenylboronic acid-functionalized glycopolymeric nanoparticles for biomacromolecules delivery across nasal respiratory

The aim of this study was to explore the potential of the mucoadhesive and enzyme-inhibitory phenylboronic acid-functionalized glycopolymeric nanoparticles as carriers for the nasal delivery of biomacromolecules. The glycopolymers were prepared by the random copolymerization of 3-acrylamidophenylboronic acid and N-acetyl glucosamine. Insulin, as a model, was encapsulated within self-assembled glypolymeric nanoparticles. Nanoparticle size, insulin loading, and insulin release were characterized. In vitro cytotoxicity experiment showed the glycopolymers were cytocompatible (≥ 80% cell viability). Adhesiveness was determined from the absorption amount of mucin, reaching up to 1180 μg/mL. Moreover, the results obtained from in vivo administration of insulin-loaded p(AAPBA-r-MAGA) nanoparticles to rats evidenced that the nanoparticles enhanced insulin absorption across the nasal mucosal barrier and did not induce irritation of nasal mucosa. Thus, insulin-loaded nanoparticles were able to significantly decrease plasma glucose levels (more than 35% reduction). These results suggest that p(AAPBA-r-MAGA) nanoparticles have potential application for the nasal delivery of biomacromolecules.

Comparison of in vitro methods of measuring mucoadhesion: ellipsometry, tensile strength and rheological measurements

In this work three in vitro methods for the measurement of mucoadhesion have been compared: ellipsometry, tensile strength and rheology. The conditions used for the three methods have been as similar as possible. Six different polymers were investigated: sodium carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), chitosan, polyvinyl pyrrolidone (PVP) and two cross-linked polyacrylic acids, Noveon (hydrophobically modified) and Carbopol. The results showed that PVP did not exhibit mucoadhesion according to any of the methods used. Chitosan, Noveon, Carbopol, CMC and HEC showed good mucoadhesion in the tensile strength and the rheological measurements, but not in the ellipsometry investigation. Chitosan was the only polymer showing good mucoadhesion with the ellipsometry method. No two methods gave the same ranking of mucoadhesive strength of the polymers. The conflicting results obtained with the different methods underline the need for further improvements in existing experimental techniques and theoretical concepts for the correct assessment of mucoadhesive properties.

Characterization and in vitro evaluation of freeze-dried microparticles composed of granisetron-cyclodextrin complex and carboxymethylcellulose for intranasal delivery

The aim of this study was to prepare microparticles (MPs) of granisetron (GRN) in combination with hydroxypropyl-β-cyclodextrin (HP-β-CD) and sodium carboxymethylcellulose (CMC-Na) by the simple freeze-drying method for intranasal delivery. The composition of MPs was determined from the phase-solubility study of GRN in various CDs. Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD) analysis and differential scanning calorimetry (DSC) studies were performed to evaluate possible interactions between GRN and excipients. The results indicated the formation of inclusion complex between GRN and CD, and the conversion of drug into amorphous state. The in vitro release of GRN from MPs was determined in phosphate buffered saline (pH 6.4) at 37°C. Cytotoxicity of the MPs and in vitro permeation study were conducted by using primary human nasal epithelial (HNE) cells and their monolayer system cultured by air-liquid interface (ALI) method, respectively. The MPs showed significantly higher GRN release profile compared to pure GRN. Moreover, the prepared MPs showed significantly lower cytotoxicity and higher permeation profile than that of GRN powder (p<0.05). These results suggested that the MPs composed of GRN, HP-β-CD and CMC-Na represent a simple and new GRN intranasal delivery system as an alternative to the oral and intravenous administration of GRN.

Evaluation of ISCOM matrices clearance from rabbit nasal cavity by γ scintigraphy

Immune stimulating complexes and/or ISCOM matrices (adjuvant nanoparticles without antigen as a structural component) found potential applications as nasal vaccine adjuvant/delivery system owing to virus like particulate structure and saponin as potent Th1 adjuvant. One of important limiting factor for nasal vaccine delivery is the limited time available for absorption within the nasal cavity due to mucociliary clearance. In this report the clearance rate of ISCOM matrices from nasal cavity of rabbit was determined by gamma scintigraphy. ISCOM matrices were radiolabelled with (99m)Tc by direct labelling method using stannous chloride as a reducing agent. (99m)Tc labelled ISCOM matrices were administered into the nostril of female New Zealand rabbits and 1 min static views were repeated each 15 min until 4h. Clearance rate of ISCOM matrices from nasal cavity was calculated after applying the physical decay corrections. The mean labelling efficiency for ISCOM matrices were calculated as approximately 58.4%. ISCOM matrices showed slower clearance rate compared to sodium pertechnetate control solution (p<0.005) from nasal cavity that may be due to particulate and hydrophobic characters of ISCOM particles even though it was also cleared within 4h from nasal cavity. Mucoadhesive ISCOM formulations that retain in nasal cavity for longer duration of time may reduce the dose/frequency of vaccine for nasal immunization.

Nasal administration of metoclopramide from different dosage forms: in vitro, ex vivo, and in vivo evaluation

Nasal drug delivery is an interesting route of administration for metoclopramide hydrochloride (MTC) in preventing different kind of emesis. Currently, the routes of administration of antiemetics are oral or intravenous, although patient compliance is often impaired by the difficulties associated with acute emesis or invasiveness of parenteral administration. In this perspective, nasal dosage forms (solution, gel, and lyophilized powder) of MTC were prepared by using a mucoadhesive polymer sodium carboxymethylcellulose (NaCMC). In vitro and ex vivo drug release studies were performed in a modified horizontal diffusion chamber with cellulose membrane and excised cattle nasal mucosa as diffusion barriers. The tolerance of nasal mucosa to the formulation and its components were investigated using light microscopy. In vivo studies were carried out for the optimized formulations in sheep and the pharmacokinetics parameters were compared with oral solution and IV dosage form. The release of MTC from solution and powder formulations was found to be higher than gel formulation (p < 0.05). Histopathological examination did not detect any severe damage. Hydroxypropyl-beta-cyclodextrin (HPbetaCD) used in powder formulations was found to be effective for enhancing the release and absorption of MTC. In contrast to in vitro and ex vivo experiments nasal bioavailability of gel is higher than those of solution and powder (p < 0.05). In conclusion, the NaCMC gel formulation of MTC with mucoadhesive properties with increased permeation rate is promising for prolonging nasal residence time and thereby nasal absorption.

Gellan gum based microparticles of metoclopromide hydrochloride for intranasal delivery: development and evaluation

The purpose of this study was to develop nasal microparticles of metoclopromide employing gellan gum as a polymer by spray drying method. This method of microencapsulation is particularly less dependent on the solubility characteristics of the drug and polymer and is simple, reproducible, and easy to scale up. The microparticles were evaluated for characteristics like particle size, incorporation efficiency, swelling ability, zeta potential, mucoadhesion, thermal analysis, X-ray diffraction (XRD) study and in vitro drug release. The microparticles so prepared had irregular shape and smooth but distorted surface morphology. They were negatively charged. The particle size ranged from 9.38 to 10.67 microm. Differential scanning calorimetry (DSC) studies revealed that metoclopromide was molecularly dispersed inside the microparticles. The swelling was increased with increase in amount of polymer. The release of drug from microparticles was moderately sustained without lag time and attributed to formation of hydrogel; ionically cross linked hydrogel was hypothesized. The formulation was found to be non toxic to nasal tissue. These in vitro preliminary results show that spray dried microparticles based on gellan gum could be suitable nasal delivery system for the administration of metoclopromide.

Assessment of clotrimazole gels for in vitro stability and in vivo retention in the frontal sinus of dogs

OBJECTIVE

To evaluate the stability and retention of viscous formulations of the antifungal drug clotrimazole in vitro and to evaluate retention times, absorption, and histologic response to these compounds when placed in the frontal sinus of dogs.

ANIMALS

6 male Beagles.

PROCEDURES

1% clotrimazole gels were formulated with hydroxypropyl cellulose, poloxamer, and carboxymethylcellulose sodium bases. Commercially available 1% clotrimazole creams were also evaluated. Each compound was incubated at 37 degrees C in a funnel. Volume retained and clotrimazole stability were evaluated for 4 weeks. Six compounds were then chosen for in vivo evaluation. The frontal sinuses of 6 dogs were filled with 1 of the 6 compounds. Computed tomographic evaluation was performed weekly for up to 4 weeks to evaluate gel retention. Blood samples were collected to evaluate clotrimazole absorption. Following euthanasia, sinuses were examined histologically.

RESULTS

Commercially available clotrimazole creams were not retained in funnels in vitro. In vivo, hydroxypropyl cellulose- and carboxymethylcellulose-based gels resulted in the most severe inflammatory response and were retained the longest. Poloxamer-based gels had a shorter retention time and were associated with less inflammation. Clotrimazole was minimally absorbed. Despite a marked inflammatory response to several of the clotrimazole-containing gels, no notable adverse clinical responses were observed.

CONCLUSIONS AND CLINICAL RELEVANCE

Poloxamer gels had the most promise for improving drug contact within the frontal sinus of dogs, while limiting the inflammatory response. Poloxamer gels have the additional benefit of improved handling as a result of reverse gelation (ie, they gel when warmed to 37 degrees C).

Novel dry powder preparations of whole inactivated influenza virus for nasal vaccination

The purpose of these studies was to enhance mucosal and systemic antibody production in response to increased local residence time of a whole inactivated influenza virus administered as a dry powder nasal vaccine formulation. Spray-freeze-drying (SFD) particles suitable for nasal delivery were characterized for physico-chemical properties and stability. Mucoadhesive compounds (MA) were characterized for their effects on nasal residence time of vaccine powders in rats compared with published in vitro data and elicited immune responses. SFD particles (D(50) = 26.9 microm) were spherical with a specific surface area of 1.25 m(2)/g. Thermal analysis indicated SFD powders were amorphous and demonstrated improved stability with respect to liquid formulations under various storage conditions. In vitro physico-chemical studies and in vivo scintigraphic imaging experiments indicated sodium alginate (SA) and carboxymethylcellulose-high molecular weight (CMC-HMW) powder formulations most significantly increased residence time in Brown Norway rats. Intramuscular delivery provided equivalent serum antibody titers to intranasal (IN) powder without MA, in the presence of CMC-HMW, SA, and hydroxypropyl methylcellulose (HPMC-HMW) after initial dosing and all formulations except IN powder with chitosan after boosting. IN liquid provided equivalent serum antibody titers to all IN powders after the initial vaccination and significantly greater serum antibody titers than IN powder with chitosan after boosting. Trends were consistent between residence time studies and immune response; however, no statistically significant differences between powder and liquid formulations were observed. It was concluded that enhanced serum and mucosal antibody responses were elicited by a dry powder nasal vaccine, specifically, administered in the presence of sodium alginate.

Molecular optical imaging of therapeutic targets of cancer

Recent progress in discerning the molecular events that accompany carcinogenesis has led to development of new cancer therapies directly targeted against the molecular changes of neoplasia. Molecular-targeted therapeutics have shown significant improvements in response rates and decreased toxicity as compared to conventional cytotoxic therapies which lack specificity for tumor cells. In order to fully explore the potential of molecular-targeted therapy, a new set of tools is required to dynamically and quantitatively image and monitor the heterogeneous molecular profiles of tumors in vivo. Currently, molecular markers can only be visualized in vitro using complex immunohistochemical staining protocols. In this chapter, we discuss emerging optical tools to image in vivo a molecular profile of risk-based hallmarks of cancer for selecting and monitoring therapy. We present the combination of optically active, targeted nanoparticles for molecular imaging with advances in minimally invasive optical imaging systems, which can be used to dynamically image both a molecular and phenotypic profile of risk and to monitor changes in this profile during therapy.

Extruded and spheronized beads containing Carbopol® 974P to deliver nonelectrolytes and salts of weakly basic drugs

The purpose of the study was to explore the utilization of Carbopol 974P, NF, resin in a bead dosage form manufactured by extrusion and spheronization. It was possible to prepare beads in this study by using calcium chloride to overcome the tack problem associated with wetted Carbopol 974P. The actives included both salts of weakly basic drugs (chlorpheniramine maleate and diphenhydramine hydrochloride) and nonelectrolytes (caffeine and dyphylline) which have a broad range of solubilities. Nonelectrolytes were released faster than the salts of weakly basic drugs. This is contrary to the behavior typically seen with a matrix system where the more soluble drug is released faster than a poorly soluble one. In the results of the present study, the solubility does not determine the drug release rate. Ionic interactions between the protonated amines of the salts and the carboxylates of the Carbopol resin are suggested to be the reason for the slower release of the salts of weakly basic drugs. Data from tack measurements confirm that this ionic interaction affects the behavior of the wetted Carbopol. In addition to the drug release profiles, bead average diameter, roundness, friability, and density were also determined.

Nasal clearance in health and disease

This paper reviews the anatomical and physiological factors of importance for nasal drug delivery and discusses in particular the influence of the nasal mucociliary clearance mechanism on the nasal absorption of drugs. The effect of nasal pathological conditions on the mucociliary clearance mechanism and the possible effect of such disease states on nasal drug transport are also discussed. Strategies for the exploitation of bioadhesive drug delivery systems and especially nasal absorption enhancers for the improvement of nasal drug delivery are evaluated to include considerations of the mechanism of action and correlation between the degree of bioadhesion and absorption enhancement and transport of drugs across the nasal membrane. A range of studies involving bioadhesive/absorption enhancer systems are detailed. A selected bioadhesive material, chitosan, which has been shown to have excellent absorption enhancer properties for a variety of drugs is discussed in some detail.

Pharmaceutical applications of mucoadhesion for the non-oral routes

The adhesion of pharmaceutical formulations to the mucosal tissue offers the possibility of creating an intimate and prolonged contact at the site of administration. This prolonged residence time can result in enhanced absorption and, in combination with a controlled release of the drug, also improved patient compliance by reducing the frequency of administration. During the almost 30 years over which mucoadhesion has been studied, a considerable amount of knowledge has been gained, and much has been learned about the different mechanisms occurring at the formulation-mucus interface and the properties that affect these mechanisms. The in-vivo performance of a dosage form not only depends on the mechanisms occurring at the interface, but also on the properties of the total mucoadhesive complex: the dosage form, the mucosa and the interface between them. A wide variety of methods are used for studying mucoadhesion; some rather similar to the in-vivo situation and some mimicking the interface alone. In this review, the mucus surface, the methods used for the study of mucoadhesion, the different mechanisms involved in mucoadhesion and theories underpinning them have been described. The complexity of mucoadhesion when trying to systemize the subject will also be discussed. The last part of the review describes the buccal, nasal, ocular, vaginal and rectal routes and provides examples of what can be achieved in-vivo when using mucoadhesive formulations.

Evaluation of the clearance characteristics of various microspheres in the human nose by gamma-scintigraphy

The nasal cavity possesses many advantages as a site for drug delivery, such as; ease of administration, applicability for long-term treatments and a large surface area for absorption. One important limiting factor for nasal drug delivery is the limited time available for absorption within the nasal cavity due to mucociliary clearance. Several drug delivery systems including different kinds of microspheres have been tried for encapsulation of drugs and increasing the residence time in nasal cavity. In this study the clearance rate of three kinds of microspheres (Alginate, PLGA, and Sephadex) was determined by gamma-scintigraphy with lactose powder being used as negative control. (99m)Tc labeled microspheres were prepared using technetium pertechnetate in the presence of a potent reducing agent, stannus chloride. The labeling procedure was set in a manner that each 3-5 mg of microspheres contained 2 MBq of radioactivity. Labeling efficiency was calculated by paper chromatography using acetone as a mobile phase. Each delivery system containing 2 MBq of activity was administered into right nostril of four healthy volunteers and 1 min static views were repeated each half an hour until 4 h. Clearance rates were compared using two regions of interest (ROIs); the initial site of deposition of particles, and all of the nasopharynx region. The clearance rate of each one of microspheres was calculated after applying the physical decay corrections. The mean labeling efficiencies for Alginate, PLGA, and Sephadex microspheres were calculated as 60%, 59%, and 74%, respectively. The cleared percent of formulations from nasopharynx region after 4 h was determined as follows: PLGA microspheres 48.5 +/- 8.2%; Alginate microspheres 45.0 +/- 0.8%; Sephadex microspheres 63.1 +/- 3.4%; lactose powder 74.5 +/- 4.9%. Alginate and PLGA microspheres showed the lowest clearance rate compared to lactose powder (P < 0.0001 and P < 0.001, respectively), followed by Sephadex microspheres (P < 0.01). The clearance profiles of formulations from deposition ROI and nasopharynx ROI were identical. This study shows that Alginate and PLGA microspheres have the highest mucoadhesion properties and are suitable nasal delivery systems. Futhermore, this study proves that limiting step for the nasal clearance of nasally administered particulate systems is their dislocation from the initial site of deposition, and their following interactions with mucus layer in the rest of the nasal passage does not significantly affect the clearance time.

Mouse models of global airway allergy: what have we learned and what should we do next?

Recent epidemiological and clinical data indicate that allergic rhinitis and asthma coexist and should be considered as one airway allergy syndrome. In spite of the importance of this new concept of global airway allergy, it has not fundamentally changed our daily diagnostic and therapeutic strategies so far because of the lack of essential clues to understand the correlation between allergic inflammation in upper and lower airways. Because of the resemblance of experimentally induced allergic airway inflammation in mice to inflamed airways of allergic patients, mouse models can enhance our insight into mechanisms underlying the global airway allergy syndrome. We here review data generated in mice that are relevant for understanding the development of airway allergy and provide new options for research on the so-called 'united airway disease'.

The biopharmaceutical aspects of nasal mucoadhesive drug delivery

Nasal drug administration has frequently been proposed as the most feasible alternative to parenteral injections. This is due to the high permeability of the nasal epithelium, allowing a higher molecular mass cut-off at approximately 1000 Da, and the rapid drug absorption rate with plasma drug profiles sometimes almost identical to those from intravenous injections. Despite the potential of nasal drug delivery, it has a number of limitations. In this review, the anatomy and physiology of the nasal cavity, as well as ciliary beating and mucociliary clearance as they relate to nasal drug absorption, are introduced. The rationale for nasal drug delivery and its limitations, some factors that influence nasal drug absorption, and the experimental models used in nasal drug delivery research are also reviewed. Nasal mucoadhesion as a promising method of nasal absorption enhancement is discussed, and factors that influence mucoadhesion, as well as safety of nasal mucoadhesive drug delivery systems are reviewed in detail. Nasal drug administration is presently mostly used for local therapies within the nasal cavity. Anti-allergic drugs and nasal decongestants are the most common examples. However, nasal drug administration for systemic effects has been practised since ancient times. Nasally-administered psychotropic drugs by native Americans, the use of tobacco snuffs, and nasal administration of illicit drugs such as cocaine are all well known (Illum & Davis 1992). Nowadays, the nasal cavity is being actively explored for systemic administration of other therapeutic agents, particularly peptides and proteins (Illum 1992; Edman & Björk 1992), as well as for immunization purposes (Lemoine et al 1998). To better understand the basis for nasal drug absorption and factors that can influence it, a brief review of the anatomy and physiology of the nose is appropriate.