Aerosol and intraperitoneal administration of ribavirin and ribavirin triacetate: pharmacokinetics and protection of mice against intracerebral infection with influenza A/WSN virus

Antiviral Effect of Ginsenosides rk1 against Influenza a Virus Infection by Targeting the Hemagglutinin 1-Mediated Virus Attachment

Influenza A virus (IAV) infections have been a serious hazard to public health everywhere. With the growing concern of drug-resistant IAV strains, there is an urgent need for novel anti-IAV medications, especially those with alternative mechanisms of action. Hemagglutinin (HA), an IAV glycoprotein, plays critical roles in the early stage of virus infection, including receptor binding and membrane fusion, making it a good target for developing anti-IAV drugs. Panax ginseng is a widely used herb in traditional medicine with extensive biological effects in various disease models, and its extract was reported to show protection in IAV-infected mice. However, the main effective anti-IAV constituents in panax ginseng remain unclear. Here, we report that ginsenoside rk1 (G-rk1) and G-rg5, out of the 23 screened ginsenosides, exhibit significant antiviral effects against 3 different IAV subtypes (H1N1, H5N1, and H3N2) in vitro. Mechanistically, G-rk1 blocked IAV binding to sialic acid in a hemagglutination inhibition (HAI) assay and an indirect ELISA assay; more importantly, we showed that G-rk1 interacted with HA1 in a dose-dependent manner in a surface plasmon resonance (SPR) analysis. Furthermore, G-rk1 treatment by intranasal inoculation effectively reduced the weight loss and mortality of mice challenged with a lethal dose of influenza virus A/Puerto Rico/8/34 (PR8). In conclusion, our findings reveal for the first time that G-rk1 possesses potent anti-IAV effects in vitro and in vivo. We have also identified and characterized with a direct binding assay a novel ginseng-derived IAV HA1 inhibitor for the first time, which could present potential approaches to prevent and treat IAV infections.

Preclinical efficacy of ribavirin in SHH and group 3 medulloblastoma

OBJECTIVE

Medulloblastoma, the most common pediatric brain malignancy, has Sonic Hedgehog (SHH) and group 3 (Myc driven) subtypes that are associated with the activity of eukaryotic initiation factor 4E (eIF4E), a critical mediator of translation, and enhancer of zeste homolog 2 (EZH2), a histone methyltransferase and master regulator of transcription. Recent drug repurposing efforts in multiple solid and hematologic malignancies have demonstrated that eIF4E and EZH2 are both pharmacologically inhibited by the FDA-approved antiviral drug ribavirin. Given the molecular overlap between medulloblastoma biology and known ribavirin activity, the authors investigated the preclinical efficacy of repurposing ribavirin as a targeted therapeutic in cell and animal models of medulloblastoma.

METHODS

Multiple in vitro assays were performed using human ONS-76 (a primitive SHH model) and D425 (an aggressive group 3 model) cells. The impacts of ribavirin on cellular growth, death, migration, and invasion were quantified using proliferation and Cell Counting Kit-8 (CCK-8) assays, flow cytometry with annexin V (AnnV) staining, scratch wound assays, and Matrigel invasion chambers, respectively. Survival following daily ribavirin treatment (100 mg/kg) was assessed in vivo in immunodeficient mice intracranially implanted with D425 cells.

RESULTS

Compared to controls, ribavirin treatment led to a significant reduction in medulloblastoma cell growth (ONS-76 proliferation assay, p = 0.0001; D425 CCK-8 assay, p < 0.0001) and a significant increase in cell death (flow cytometry for AnnV, ONS-76, p = 0.0010; D425, p = 0.0284). In ONS-76 cells, compared to controls, ribavirin significantly decreased cell migration and invasion (Matrigel invasion chamber assay, p = 0.0012). In vivo, ribavirin significantly extended survival in an aggressive group 3 medulloblastoma mouse model compared to vehicle-treated controls (p = 0.0004).

CONCLUSIONS

The authors demonstrate that ribavirin, a clinically used drug known to inhibit eIF4E and EZH2, has significant antitumor effects in multiple preclinical models of medulloblastoma, including an aggressive group 3 animal model. Ribavirin may represent a promising targeted therapeutic in medulloblastoma.

Critical View on the Usage of Ribavirin in Already Existing Psychostimulant-Use Disorder

Substance-use disorder represents a frequently hidden non-communicable chronic disease. Patients with intravenous drug addiction are at high risk of direct exposure to a variety of viral infections and are considered to be the largest subpopulation infected with the hepatitis C virus. Ribavirin is a synthetic nucleoside analog that has been used as an integral component of hepatitis C therapy. However, ribavirin medication is quite often associated with pronounced psychiatric adverse effects. It is not well understood to what extent ribavirin per se contributes to changes in drug-related neurobehavioral disturbances, especially in the case of psychostimulant drugs, such as amphetamine. It is now well-known that repeated amphetamine usage produces psychosis in humans and behavioral sensitization in animals. On the other hand, ribavirin has an affinity for adenosine A1 receptors that antagonistically modulate the activity of dopamine D1 receptors, which play a critical role in the development of behavioral sensitization. This review will focus on the current knowledge of neurochemical/ neurobiological changes that exist in the psychostimulant drug-addicted brain itself and the antipsychotic-like efficiency of adenosine agonists. Particular attention will be paid to the potential side effects of ribavirin therapy, and the opportunities and challenges related to its application in already existing psychostimulant-use disorder.

2'-Fluoro-2'-deoxycytidine is a broad-spectrum inhibitor of bunyaviruses in vitro and in phleboviral disease mouse models

2'-Fluoro-2'-deoxycytidine (2'-FdC) was reported to inhibit various viruses in vitro, including Borna disease, hepatitis C, Lassa fever, influenza and certain herpes viruses, and is inhibitory to influenza viruses in mice. We investigated the antiviral activity of 2'-FdC against several unrelated bunyaviruses in 50% cytopathic effect (CPE) inhibition assays and, with viruses that cause limited CPE, 90% virus yield reduction (VYR) assays. La Crosse (LACV), Maporal, Punta Toro, Rift Valley fever (RVFV), and San Angelo viruses were inhibited in CPE assays at 2.2-9.7 μM concentrations. In VYR assays, Heartland and severe fever with thrombocytopenia syndrome (SFTSV) viruses were inhibited at 0.9 and 3.7 μM, respectively. In contrast, ribavirin inhibited these viruses at an average of 47 μM. Antiviral efficacy studies were also conducted in mice infected with RVFV, SFTSV, and LACV. Against RVFV, 2'-FdC (100 and 200 mg/kg/day) and ribavirin (100 mg/kg/day) treatments each delayed mortality by approximately 6 days compared to placebo. Liver, spleen, and serum viral titers were significantly reduced by antiviral treatments. 2'-FdC (100 and 200 mg/kg/day) prevented death in SFTSV-infected mice, but was not as effective as favipiravir (100 mg/kg/day) based on body weight loss during infection. The 100 mg/kg/day doses of 2'-FdC and favipiravir significantly reduced liver, spleen, and serum viral titers. 2'-FdC and ribavirin afforded no protection against LACV infection in mice, which is encephalitic and thus inherently more difficult to treat. Taken together, our data suggest that 2'-FdC may be a viable candidate for treating certain non-encephalitic bunyavirus infections such as those caused by phleboviruses.

Low-dose ribavirin treatments attenuate neuroinflammatory activation of BV-2 Cells by interfering with inducible nitric oxide synthase

Microglia play a key role in defending central nervous system from various internal and external threats. However, their excessive and/or chronic activation is associated with deleterious effects in a variety of neurodegenerative diseases. Previously, we have shown that ribavirin when applied in clinically relevant dosage (10 μM) modulates activated microglia in complex fashion inducing both anti- and proinflammatory effects, simultaneously causing cytotoxicity. Here, we examined potential of low-dose ribavirin (0.1 and 1 μM) to modulate activated BV-2 microglia. Morphological and functional activation of BV-2 cells was achieved with lipopolysaccharide (LPS) stimulation. Our results demonstrated that low-dose ribavirin did not induce cell death, while 10 μM ribavirin promoted LPS induced apoptosis. We determined that 1 μM ribavirin was equally efficient in deactivation of LPS induced morphological changes as 10 μM ribavirin treatment. Ribavirin showed halfway success in reducing markers of functional activation of microglia. Namely, none of the doses had effect on LPS triggered production of proinflammatory cytokine tumor necrosis factor alpha. On the other hand, low-dose ribavirin proved its effectiveness in reduction of another inflammatory mediator, nitric oxide, by inhibiting inducible form of nitric oxide synthase. Our results imply that low-dose ribavirin may alleviate nitrosative stress during neuroinflammation.

Inhaled anti-infective chemotherapy for respiratory tract infections: successes, challenges and the road ahead

One of the most common causes of illnesses in humans is from respiratory tract infections caused by bacterial, viral or fungal pathogens. Inhaled anti-infective drugs are crucial for the prophylaxis and treatment of respiratory tract infections. The benefit of anti-infective drug delivery via inhalation is that it affords delivery of sufficient therapeutic dosages directly to the primary site of infection, while minimizing the risks of systemic toxicity or avoiding potential suboptimal pharmacokinetics/pharmacodynamics associated with systemic drug exposure. This review provides an up-to-date treatise of approved and novel developmental inhaled anti-infective agents, with particular attention to effective strategies for their use, pulmonary pharmacokinetic properties and safety.

Pulmonary vaccine delivery

This review will discuss developments in the field of pulmonary vaccine delivery. The possibilities of adopting aerosol-generation technology and specific pharmaceutical formulations for the purpose of pulmonary immunization are described. Aerosol-generation systems might offer advantages with respect to vaccine stability and antigenicity. Adjuvants and their inclusion in vaccine-delivery systems are described. Other formulation components, such as surfactants, particulate systems and dispersion of the aerosols are detailed in this paper. The noninvasive, relatively safe and low-cost nature of pulmonary delivery may provide great benefits to the public health vaccination campaign.

Aerosol exposure to Rift Valley fever virus causes earlier and more severe neuropathology in the murine model, which has important implications for therapeutic development

Rift Valley fever virus (RVFV) is an important mosquito-borne veterinary and human pathogen that can cause severe disease including acute-onset hepatitis, delayed-onset encephalitis, retinitis and blindness, or a hemorrhagic syndrome. Currently, no licensed vaccine or therapeutics exist to treat this potentially deadly disease. Detailed studies describing the pathogenesis of RVFV following aerosol exposure have not been completed and candidate therapeutics have not been evaluated following an aerosol exposure. These studies are important because while mosquito transmission is the primary means for human infection, it can also be transmitted by aerosol or through mucosal contact. Therefore, we directly compared the pathogenesis of RVFV following aerosol exposure to a subcutaneous (SC) exposure in the murine model by analyzing survival, clinical observations, blood chemistry, hematology, immunohistochemistry, and virus titration of tissues. Additionally, we evaluated the effectiveness of the nucleoside analog ribavirin administered prophylactically to treat mice exposed by aerosol and SC. The route of exposure did not significantly affect the survival, chemistry or hematology results of the mice. Acute hepatitis occurred despite the route of exposure. However, the development of neuropathology occurred much earlier and was more severe in mice exposed by aerosol compared to SC exposed mice. Mice treated with ribavirin and exposed SC were partially protected, whereas treated mice exposed by aerosol were not protected. Early and aggressive viral invasion of brain tissues following aerosol exposure likely played an important role in ribavirin's failure to prevent mortality among these animals. Our results highlight the need for more candidate antivirals to treat RVFV infection, especially in the case of a potential aerosol exposure. Additionally, our study provides an account of the key pathogenetic differences in RVF disease following two potential exposure routes and provides important insights into the development and evaluation of potential vaccines and therapeutics to treat RVFV infection.

Optimization of protocell of silica nanoparticles using 3² factorial designs

The purpose of the research is to carry out systemic optimization of protocells (liposomes entrapped with silica particles). Optimization was carried out using 3(2) factorial designs for the selection of the optimized protocell composition with reference to particle size distribution and zetapotential. This design was carried out to study the effect of independent variables such as molar ratio of phosphatidylcholine to cholesterol and concentration of silica nanoparticles. A total of nine formulations of protocells were prepared and analyzed using Design expert® software from Stat-Ease, Inc. (Version 8.0.4.1 trial 2010) for the selection of the optimized combination. Contour plots were constructed with independent variables like size and potential. Protocell with 7:3 ratio of phosphatidyl choline to cholesterol and 0.5 mg/ml of silica nanoparticles demonstrated better colloidal behaviors. The findings obtained from the software corresponding to independent variables demonstrated accurate means for the optimization of the pharmaceutical formulations.

Brain distribution of ribavirin after intranasal administration

Ribavirin has proved to be effective in vitro against several RNA viruses responsible for encephalitis in humans and animals. However, the in vivo efficacy towards the cerebral viral load seems to be limited by the blood-brain barrier. Since the nose-to-brain pathway has been indicated for delivering drugs to the brain, we investigated here the distribution of ribavirin in the central nervous system (CNS) after intranasal administration. We first tested in vitro ribavirin diffusion from an aqueous solution across a biological membrane, using Franz cells and rabbit nasal mucosa. About 35% of ribavirin permeated in 4 h across the mucosa, after reaching steady-state flux in less than 30 min. In the first in vivo experiment, ribavirin aqueous solution was administered intranasally to Sprague Dawley rats (10 mg/kg). Animals were sacrificed at 10, 20 or 30 min after administration to collect brain areas (cerebellum, olfactory bulb, cerebral cortex, basal ganglia and hippocampus) and biological fluids (cerebrospinal fluid and plasma). Ribavirin, quantified by LC-MS/MS spectrometry, was detected at each time point in all compartments with the highest concentration in olfactory bulb and decreasing in rostro-caudal direction. Two subsequent in vivo experiments compared the nasal route (ribavirin solution) with the intravenous one and the nasal administration of ribavirin solution with ribavirin powder (10 mg/kg). It was found that 20 min after administration, ribavirin concentration in olfactory bulb was similar after intravenous or nasal administration of the ribavirin solution, whereas the powder led to significantly higher levels. Ribavirin was also present in deeper compartments, such as basal ganglia and hippocampus. Even if the mechanisms involved in ribavirin nose-to-brain transport are not clear, these results suggest a rapid extracellular diffusive flux from the nasal epithelium to the olfactory bulb and different CNS areas.

Safety and pharmacokinetics of ribavirin for the treatment of la crosse encephalitis

BACKGROUND

La Crosse viral encephalitis (LACVE) is associated with residual epilepsy and neurocognitive deficits in survivors. This report summarizes 3 phases of clinical studies of children treated with intravenous (IV) ribavirin (RBV), each one exploring a different phase (I, IIA, IIB) of clinical trial development.

METHODS

In phase I, 7 children with life-threatening LACVE were treated with emergency use RBV using a moderate IV dose (8.33 mg/kg/dose q 8 hours day 1, 5 mg/kg/dose q 8 hours days 2-10). In phase IIA, 12 children with severe LACVE were enrolled: 8 treated with RBV (same dose as phase I) and 4 with placebo. In phase IIB an escalated dose was used (33 mg/kg dose 1, then 16 mg/kg/dose q 6 hours for 4 days, and 8 mg/kg/dose q 8 hours for 3 days).

RESULTS

In a group of 15 children treated in phase I and phase IIA, RBV appeared safe at moderate dose, but based on steady-state RBV levels of 9.3 μM, estimated cerebrospinal fluid levels were less than 20% of the EC50 of RBV for LACVE. At the escalated dose used in phase IIB, adverse events occurred, likely related to RBV, and therefore the trial was discontinued. Nevertheless, valuable pharmacokinetic (PK) and safety data were obtained at moderate dose, with potential treatment implications for other indications.

CONCLUSIONS

Although the results do not support the use of RBV for LACVE, this nevertheless is the largest study of antiviral treatment for LACVE to date and the largest pharmacokinetic analysis of IV RBV in children for any indication.

Fine-tuning of POPC liposomal leakage by the use of beta-cyclodextrin and several hydrophobic guests

The effect of entrapped beta-cyclodextrin (beta-CD) on the stability of multilamellar vesicles (MLVs) of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), prepared by the dehydration-rehydration method, was studied by monitoring the release of 5(6)-carboxyfluorescein encapsulated into the liposomes. Different hydrophobic guests, such as Fullerene C(60), have been incorporated into the POPC bilayer in order to modify the membrane composition. The kinetic results as well as ESI-MS measurements evidenced that the destabilizing activity of beta-CD is due to the formation of beta-CD inclusion complexes and the consequent removal of selected bilayer constituents from the liposomal membrane. Hence, when beta-CD was added to the liposomes in the form of a strong, water-soluble 2:1 beta-CD/C(60) inclusion complex, such a destabilizing effect was not observed. However, the same beta-CD/C(60) inclusion complex does not form as a result of C(60) extraction from the bilayer. This may be attributed either to the overwhelming concentration of POPC with respect to C(60) and/or to the fact that C(60) is largely aggregated in the bilayer. Turbidimetric and fluorimetric determinations of lamellarity and entrapped volume of the studied MLVs provided further evidence of the alteration of the liposomal bilayer as a consequence of the addition of beta-CD and/or the presence of the studied guests.

MegaRibavirin aerosol for the treatment of influenza A virus infections in mice

While newer neuraminidase inhibitors have been used recently to treat influenza A and B virus infections, emergence of drug resistance poses potential problems. Previous ribavirin aerosol treatments of influenza were effective and drug resistance was not observed. To make ribavirin aerosol treatment a quicker process and limited to once or twice daily treatments, a MegaRibavirin formulation (100 mg of ribavirin/mL) was developed that when used with the Aerotech II nebulizer was effective in preventing death in a lethal influenza A virus mouse model. Aerosol generated using the Aerotech II nebulizer flowing at 10 L of air/min produced aerosol droplets that contained 2.3 mg of ribavirin/L with a mass median aerodynamic diameter of 1.8 microm. Using this system for treatment, a single daily 30-min exposure on days 1-4 produced a survival rate of greater than 90%. Delaying the start of aerosol treatment for 48 or 72 h and treating once daily for 30 min for two days (days 2-3 and 3-4, respectively) still significantly increased the number of survivors and mean time to death. For the treatment of influenza in general and for pandemic avian influenza, the MegaRibavirin-Aerotech II method of aerosol treatment allows for short treatment periods, minimizes environmental issues and costs less.

Liposomes for drug delivery to the lungs by nebulization

Preparation of drug-loaded freeze-dried (FD) liposomes, designed for delivery to lungs after rehydration/nebulization was investigated. Rifampicin (RIF) incorporating multilamelar (MLV) and dried rehydrated vesicles (DRV); composed of phosphatidylcholine (PC), dipalmitoyloglycero-PC (DPPC) or distearoyloglycero-PC (DSPC), containing or not Cholesterol (Chol), were prepared. Vesicles were characterized for encapsulation efficiency (EE%), size distribution, zeta-potential, stability during freeze drying (FD) and nebulization (nebulization efficiency (NE%) and retention of RIF after nebulization (NER%)). Mucoadhesion and toxicity in A549 cells was measured. RIF EE% was not affected by liposome type but lipid composition was important; Synthetic lipid vesicles (DPPC and DSPC) had higher EE% compared to PC. As Chol increased EE% decreased. Freeze drying (FD) had no effect on EE%, however trehalose decreased EE% possibly due to RIF displacement. NER% was highly affected by lipid composition. Results of NE% and NER% for RIF-loaded liposomes show that DSPC/Chol (2:1) is the best composition for RIF delivery in vesicular form to lungs, by nebulization. Mucoadhesion and A549 cell toxicity studies were in line with this conclusion, however if mucoadhesion is required, improvement may be needed.

Liposomal dry powders as aerosols for pulmonary delivery of proteins

The purpose of this research was to develop liposomal dry powder aerosols for protein delivery. The delivery of stable protein formulations is essential for protein subunit vaccine delivery, which requires local delivery to macrophages in the lungs. Beta-glucuronidase (GUS) was used as a model protein to evaluate dry powder liposomes as inhaled delivery vehicles. Dimyristoyl phosphatylcholine:cholesterol (7:3) was selected as the liposome composition. The lyophilization of liposomes, micronization of the powders, aerosolization using a dry powder inhaler (DPI), and in vitro aerodynamic fine particle fraction upon collection in a twin-stage liquid impinger were evaluated. After lyophilization and jet-milling, the total amount of GUS and its activity, representing encapsulation efficiency and stability, were evaluated. The GUS amount and activity were measured and compared with freshly-prepared liposomes in the presence of mannitol, 43% of initial GUS amount, 29% of GUS activity after lyophilization and 36% of GUS amount, 22% of activity after micronization were obtained. Emitted doses from dry powder inhaler were 53%, 58%, 66%, and 73% for liposome powder:mannitol carrier ratios of 1:0, 1:4, 1:9, and 1:19. Fifteen percent of the liposome particles were less than 6.4 mum in aerodynamic diameter. The results demonstrate that milled liposome powders containing protein molecules can be aerosolized effectively at a fixed flow rate. Influences of different cryoprotectants on lyophilization of protein liposome formulations are reported. The feasibility of using liposomal dry powder aerosols for protein delivery has been demonstrated but further optimization is required in the context of specific therapeutic proteins.

The time-course of ribavirin-provoked changes of basal and AMPH-induced motor activities in rats

The time-course of changes of basal and amphetamine (AMPH)-induced locomotor and stereotypic activities in adult male Wistar rats after a single ribavirin injection was studied. In the first set of experiments, 10, 20 or 30 mg ribavirin/kg body weight (b.w.) were injected i.p. to rats and their basal motor activities were recorded every 10 min for 2 h and compared with those of saline-treated controls. In the second set of experiments, the animals were pretreated with ribavirin and 20 min later i.p. injected with AMPH (1.5 mg/kg b.w.). The controls received AMPH 20 min after the saline injection. Motor activity was recorded after the first injection and until 120 min after AMPH administration. Ribavirin did not significantly affect the time-course of either basal locomotor or stereotypic activities. Pretreatment with any of the applied ribavirin doses decreased the AMPH-induced hyperlocomotor response. However, the most pronounced effect was observed with ribavirin doses of 20 mg/kg and 30 mg/kg when administered during the first 10 min and 30 min after the AMPH injection respectively. In contrast, the stereotypic activities of these animals were only slightly changed. These results indicate a different susceptibility of regions in the basal ganglia to ribavirin.

Delivery of liposomes in dry powder form: aerodynamic dispersion properties

OBJECTIVE

In our previous study, we reported a novel approach of delivering liposomes in dry powder form that relies on spontaneous formation of liposomes upon dispersion of micronised phospholipid(s) based powders in an aqueous environment, thereby creating reservoirs for the encapsulation of drugs [J. Pharm. Sci. 91 (2002) 482]. In this paper, we demonstrate the in vitro generation of aerosols from these novel powders.

METHODOLOGY

Various formulations comprising different phospholipid(s) exhibiting different physico-chemical properties were prepared. Aerosol was generated using a deagglomeration rig wherein the powder was entrained at a flow rate of 60 l/min and high turbulence was generated using air-jets. Two antimicrobial agents (ciprofloxacin and CM3, a novel peptide) and a bronchodilator, salbutamol sulfate, were used as model drugs to examine the powder dispersion properties.

RESULTS

The deagglomeration rig used in this study was able to disperse 87-95% of the total loaded powder into the cascade impactor. Amongst the various formulations comprising different phospholipid(s), DMPG and (DMPC+DMPG) based formulations exhibited excellent aerodynamic dispersion properties. Fine particle fractions (FPF) of more than 50% were achieved for these formulations for three model drugs. Encapsulation of the model drugs in the FPF, obtained upon dispersion of these novel powders, is also discussed in this paper. An encapsulation of approximately 35, 40 and 25% was achieved in the FPF for ciprofloxacin, CM3 peptide and salbutamol sulfate, respectively.

A facile method of delivery of liposomes by nebulization

In this study, we have demonstrated a facile approach to the aerosol delivery of liposomes by nebulization. The approach involves mere dispersion of the physical mixture of phospholipid(s) and drug in saline, which results in spontaneous formation of liposomes thereby creating reservoirs for the encapsulation of drugs. Various phospholipids exhibiting different physico-chemical properties were investigated here. Two antimicrobial agents (ciprofloxacin and CM3, a novel peptide) and a bronchodilator, salbutamol sulfate, were used as model drugs to examine the nebulization properties. Nebulization properties were found to be dependent upon the nature of the phospholipids and drug. Among various phospholipids investigated, dimyristoyl phosphatidyl glycerol (DMPG), a combination of egg phosphatidylcholine (EPC) plus DMPG (i.e., EPC+DMPG) and dimyristoyl phosphatidylcholine (DMPC) plus DMPG (DMPC+DMPG) (molar ratios 1:1) showed encouraging results in terms of higher nebulization efficiency and lower leakage of drug after nebulization. The generated aerosols were characterized by an Andersen cascade impactor operated at 28.3 l/min. The mass median aerodynamic diameter (MMAD) values of the aerosol droplets obtained by nebulization of all the preparations containing DMPG reveal that these preparations are suitable for aerosol delivery by nebulization. This facile approach is expected to overcome problems associated with stability upon storage and high production costs.

Nebulization of niosomal all-trans-retinoic acid: an inexpensive alternative to conventional liposomes

In this study we have demonstrated the potential of encapsulating all-trans-retinoic acid (ATRA) in niosomes and delivering it as an inhaled aerosol. Niosomes may provide a means to reduce the toxicity of ATRA and alter the pharmacokinetics in a manner similar to liposomes. In addition, the low cost of the surfactants used for preparing niosomes and their greater stability compared with liposomes makes them an attractive alternative. Various nonionic surfactants were used to achieve optimum encapsulation and nebulization efficiencies, and the best formulations were obtained with combinations of (Span 20 + Tween 80) and (Span 60 + Tween 80) using an ATRA concentration of 1 mg/ml. The aerosol produced with the selected niosomal formulations upon nebulization in PARI LC STAR nebulizers driven by a Pulmo-Aide compressor was subsequently analyzed for the determination of size distribution and entrapment efficiencies on each stage of an Anderson cascade impactor operated in a manner that avoids spurious sizing due to droplet evaporation. Mass median aerodynamic diameters (MMADs) of 3.7+/-0.3 and 3.58+/-0.03 microm, geometric standard deviation (GSD) values of 1.59+/-0.17 and 1.51+/-0.01 and entrapment efficiencies well above 50% were obtained for the optimized formulations. The results are very encouraging and offer an alternative approach to the respiratory delivery of ATRA by aerosolization.

Prophylaxis and treatment of influenza encephalitis in an experimental mouse model

A mouse model study using mouse brain-adapted influenza A virus was performed to establish the prophylaxis and treatment of influenza encephalitis and encephalopathy. All mice died after intranasal inoculation of the brain-adapted influenza A virus (H7N3), and the pathological findings indicated the presence of significant encephalitis. Viral antigen was also detected in the brain, both pathologically and virologically. By contrast, infected mice immunized with inactivated vaccine of the same strain did not lose weight, which is an indicator of the overall condition of the mice, and all of them survived. Similarly, antiserum treatment in the early period (0-1 day post-infection) resulted in 100% survival, and no pathological findings were observed in the brain. However, mice treated with antiserum 3 days post-infection showed encephalitis with viral antigens in both glial cells and neurocytes. Although amantadine treatment for 4 days delayed weight loss, it did not prevent death from encephalitis. These results show vaccination and early antiserum treatment to be highly effective, whereas 4-day treatment of amantadine was not very effective in treating or preventing influenza encephalitis. The life-prolonging effect of amantadine, however, suggests that use of amantadine together with other treatments may inhibit the progression of encephalitis.

Pharmacokinetics of a benzodithiin (RD3-0028) following aerosol treatment in rat

1. RD3-0028, a benzodithiin compound, has potent antiviral activity against respiratory syncytial virus (RSV) in cell culture. The compound also inhibits growth of RSV and improves pathologic changes of interstitial pneumonia in the immunosuppressed mouse when delivered by small-particle aerosol. 2. In the present study, the absorption, distribution and excretion of 14C-RD3-0028 were compared in rat following either a single aerosol treatment or oral administration. 3. The plasma concentration was maintained at the same level from 5 min to 1 h, and decreased with a half-life of 2.2 +/- 0.1 h for 1-8 h. 4. The excretion of radioactivity in the urine and faeces at 24 h after aerosol treatment was 89.3 and 4.5%, respectively, indicating that almost all the radioactivity was rapidly excreted in the urine. The excretion of total radioactivity was 98.9% within 168 h. 5. The concentrations of radioactivity in the lung and trachea following aerosol treatment were higher than those in other tissues, and were detected even at 72 h. 6. These results suggest that the aerosol treatment might be useful for delivering RD3-0028 to the respiratory tract of RSV-infected patients.

Effective ribavirin concentration in hamster brains for antiviral chemotherapy for subacute sclerosing panencephalitis

The ribavirin concentration in hamster brains was measured by a high-performance liquid chromatography (HPLC) system and a bioassay system. When ribavirin was administered intracranially at a dosage of 10 mg/kg of body weight per day for 10 days, a dosage which results in 100% survival of hamsters infected with subacute sclerosing panencephalitis (SSPE) virus and which inhibits the replication of SSPE virus in hamster brains, the ribavirin concentration in the brains estimated by HPLC and bioassay was kept higher than 50 micrograms/g for 10 days. The effective concentration in vivo corresponds to the concentration at which ribavirin completely inhibits the replication of SSPE virus in vitro. The maximal tolerable ribavirin concentration for hamsters was calculated to be 150 micrograms/g. Although ribavirin shows toxicity to the animals at a relatively low concentration (250 to 400 micrograms/g), intrathecal or intraventricular administration of ribavirin should be explored for potential use in the treatment of patients with SSPE, while the ribavirin concentration in cerebrospinal fluid or brain tissue should be monitored.