Single-dose pharmacokinetics and lung function of nebulized niclosamide ethanolamine in sheep.

PURPOSE: Niclosamide is approved as an oral anthelminthic, but its low oral bioavailability hinders its medical use requiring high drug exposure outside the gastrointestinal tract. An optimized solution of niclosamide for nebulization and intranasal administration using the ethanolamine salt has been developed and tested in a Phase 1 trial. In this study we investigate the pulmonary exposure of niclosamide following administration via intravenous injection, oral administration or nebulization. METHODS: We characterized the plasma and pulmonary pharmacokinetics of three ascending doses of nebulized niclosamide in sheep, compare it to intravenous niclosamide for compartmental PK modelling, and to the human equivalent approved 2 g oral dose to investigate in the pulmonary exposure of different niclosamide delivery routes. Following a single-dose administration to five sheep, niclosamide concentrations were determined in plasma and epithelial lining fluid (ELF). Non-compartmental and compartmental modeling was used to characterize pharmacokinetic profiles. Lung function tests were performed in all dose groups. RESULTS: Administration of all niclosamide doses were well tolerated with no adverse changes in lung function tests. Plasma pharmacokinetics of nebulized niclosamide behaved dose-linear and was described by a 3-compartmental model estimating an absolute bioavailability of 86%. ELF peak concentration and area under the curve was 578 times and 71 times higher with nebulization of niclosamide relative to administration of oral niclosamide. CONCLUSIONS: Single local pulmonary administration of niclosamide via nebulization was well tolerated in sheep and resulted in substantially higher peak ELF concentration compared to the human equivalent oral 2 g dose.

Aerosol Pirfenidone Pharmacokinetics after Inhaled Delivery in Sheep: a Viable Approach to Treating Idiopathic Pulmonary Fibrosis.

PURPOSE: Inhaled delivery of pirfenidone to the lungs of patients with idiopathic pulmonary fibrosis holds promise to eliminate oral-observed side effects while enhancing efficacy. This study aimed to comprehensively describe the pulmonary pharmacokinetics of inhaled aerosol pirfenidone in healthy adult sheep. METHODS: Pirfenidone concentrations were evaluated in plasma, lung-derived lymph and epithelial lining fluid (ELF) with data subjected to non-compartmental pharmacokinetic analysis. RESULTS: Compartmental pharmacokinetic evaluation indicated that a 49 mg lung-deposited dose delivered an ELF Cmax of 62 ± 23 mg/L, and plasma Cmax of 3.1 ± 1.7 mg/L. Further analysis revealed that plasma pirfenidone reached Tmax faster and at higher concentrations than in lymph. These results suggested inhaled pirfenidone was cleared from the alveolar interstitium via blood faster than the drug could equilibrate between the lung interstitial fluid and lung lymphatics. However, the data also suggested that a 'reservoir' of pirfenidone feeds into lung lymph at later time points (after it has largely been cleared from plasma), prolonging lung lymphatic exposure. CONCLUSIONS: This study indicates inhaled pirfenidone efficiently deposits in ELF and is cleared from the lungs by initial absorption into plasma, followed by later equilibrium with lung interstitial and lymph fluid.

Hydrogenated Soy Phosphatidylcholine Liposomes Stimulate Differential Expression of Chemokines And Cytokines by Rat Alveolar Macrophages In Vitro.

Liposomes are being developed as inhalable drug delivery systems, but concerns remain about their impact on the lungs. To better understand the impact of liposomes and their physicochemical properties on alveolar macrophages, the cytokine and chemokine expression profile of rat alveolar Nr8383 macrophages exposed to 0.1 and 1 mg/ml hydrogenated soy phosphatidylcholine (HSPC) liposomes was examined. Expression patterns varied considerably between liposomes in a concentration-dependent manner, with both anti- and pro-inflammatory chemokines/cytokines produced. Uncharged liposomes induce the greatest production of cytokines and chemokines, followed by PEGylated liposomes. The most significant increase in cytokine/chemokine expression was seen for IL-2 (up to 24-fold), IL-4 (up to 5-fold), IL-18 and VEGF (up to 10-fold), while liposome exposure significantly reduced MIP1 expression (5-fold). In summary, we demonstrate that liposome surface properties promote variable patterns of cytokine and chemokine secretion by alveolar macrophages. This suggests that the type of liposome employed may influence the type of immune response generated in the lung and by extension, dictate how inhaled liposomal nanomedicines affect the lungs response to inhaled toxicants and local infections.

Age-Dependent Effects of Oxytocin and Oxytocin Receptor Antagonists on Bladder Contractions: Implications for the Treatment of Overactive Bladder Syndrome.

Overactive bladder (OAB) is an age-related disorder characterised by unstable bladder contractions resulting in disruptive lower urinary tract symptoms (LUTS), thus creating a profound impact on an individual's quality of life. The development of LUTS may be linked to the overexpression of oxytocin receptors (OXTRs) within the bladder detrusor muscle, resulting in increased baseline myogenic tone. Thus, it is hypothesised that targeting OXTRs within the bladder using oxytocin antagonists may attenuate myogenic tone within the bladder, thereby providing a new therapeutic avenue for treating OAB. Organ bath contractility and immunohistochemistry techniques were conducted on bladder tissue sourced from young rats (7-8 weeks and 10-12 weeks) and older rats (4-5 months and 7-9 months). Organ bath studies revealed that oxytocin (OT) significantly increased bladder contractions, which were significantly attenuated by [ß-Mercapto-ß,ß-cyclopentamethylenepropionyl1, O-Me-Tyr2, Orn8]-Oxytocin) (1 µM) (**** p < 0.0001) and atosiban (10 µM) in both young and older rats (** p < 0.01); in contrast, cligosiban (1 µM and 10 µM) did not inhibit OT-induced contractions in both young and older rats (p ≥ 0.05). Interestingly, cligosiban (1 µM and 10 µM) significantly reduced the frequency of spontaneous contractions within the bladder of both young (*** p < 0.001) and older rats (**** p < 0.0001), while atosiban (10 µM) only demonstrated this effect in older rats (** p < 0.01). Furthermore, immunohistochemistry (IHC) analysis revealed significant colocalization of nuclear-specific oxytocin receptors (OXTRs) in the contractile (smooth muscle) cells within young (** p < 0.01) and older rats (* p < 0.05), indicating OT may be a key modulator of bladder contractility.

The Effects of Age on Prostatic Responses to Oxytocin and the Effects of Antagonists.

Benign prostatic hyperplasia (BPH) is an age-related enlargement of the prostate with urethral obstruction that predominantly affects the middle-aged and older male population, resulting in disruptive lower urinary tract symptoms (LUTS), thus creating a profound impact on an individual's quality of life. The development of LUTS may be linked to overexpression of oxytocin receptors (OXTR), resulting in increased baseline myogenic tone within the prostate. Thus, it is hypothesised that targeting OXTR using oxytocin receptor antagonists (atosiban, cligosiban, and ß-Mercapto-ß,ß-cyclopentamethylenepropionyl1, O-Me-Tyr2, Orn8]-Oxytocin (ßMßßC)), may attenuate myogenic tone within the prostate. Organ bath and immunohistochemistry techniques were conducted on prostate tissue from young and older rats. Our contractility studies demonstrated that atosiban significantly decreased the frequency of spontaneous contractions within the prostate of young rats (**** p < 0.0001), and cligosiban (* p < 0.05), and ßMßßC (**** p < 0.0001) in older rats. Additionally, immunohistochemistry findings revealed that nuclear-specific OXTR was predominantly expressed within the epithelium of the prostate of both young (*** p < 0.001) and older rats (**** p < 0.0001). In conclusion, our findings indicate that oxytocin is a key modulator of prostate contractility, and targeting OXTR is a promising avenue in the development of novel BPH drugs.

Utilization of endogenous albumin trafficking pathways in the lungs has potential to modestly increase the lung interstitial access and absorption of drug delivery systems after inhaled administration.

OBJECTIVES: Drug delivery systems typically show limited access to the lung interstitium and absorption after pulmonary delivery. The aim of this work was to undertake a proof-of-concept investigation into the potential of employing endogenous albumin and albumin absorption mechanisms in the lungs to improve lung interstitial access and absorption of inhaled drug delivery systems that bind albumin. METHODS: The permeability of human albumin (HSA) through monolayers of primary human alveolar epithelia, small airway epithelia, and microvascular endothelium were investigated. The pulmonary pharmacokinetics of bovine serum albumin (BSA) was also investigated in efferent caudal mediastinal lymph duct-cannulated sheep after inhaled aerosol administration. RESULTS: Membrane permeability coefficient values (Papp) of HSA increased in the order alveolar epithelia

Development of a hyperbranched polymer-based methotrexate nanomedicine for rheumatoid arthritis.

Methotrexate (MTX) is an effective disease modifying anti-rheumatic drug, but can cause significant hepatotoxicity and liver failure in some individuals. The goal of this work was to develop a MTX-conjugated hyperbranched polymeric nanoparticle based on oligo(ethylene glycol) methyl ether methacrylate (OEGMA) and examine its ability to selectively deliver MTX to rheumatic joints while sparing the liver. MTX was conjugated to the hyperbranched polymer via a matrix metalloproteinase-13 cleavable peptide linker. Two populations of nanoparticles were produced, with sizes averaging 20 and 200nm. Tri-peptide (FFK)-modified MTX was liberated in the presence of matrix metalloproteinase 13 (MMP-13)and showed 100 to 1000-fold lower antiproliferative capacity in monocytic THP-1 cells compared to unmodified MTX, depending on whether the gamma-carboxylate of MTX was functionalized with O-tert-butyl. Nanoparticles showed prolonged plasma exposure after intravenous injection with a terminal half-life of approximately 1 day, but incomplete (50%) absorption after subcutaneous administration. Nanoparticles selectively accumulated in inflamed joints in a rat model of rheumatoid arthritis and showed less than 5% biodistribution in the liver after 5 days. MTX-OtBu nanoparticles also showed no hepatocellular toxicity at 500 µM MTX equivalents. This work provides support for the further development of OEGMA-based hyperbranched polymers as MTX drug delivery systems for rheumatoid arthritis. STATEMENT OF SIGNIFICANCE: Nanomedicines containing covalently conjugated methotrexate offer the potential for selective accumulation of the potent hepatotoxic drug in rheumatic joints and limited liver exposure. One limitation of the high surface presentation of methotrexate on a nanoparticle surface, however, is the potential for enhanced liver uptake. We developed several OEGMA-based hyperbranched polymers containing alpha-carboxyl modified and unmodified methotrexate conjugated via an MMP-13 cleavable hexapeptide linker. The modified methotrexate polymer showed promising in vitro and in vivo behavior warranting further development and optimization as an anti-rheumatic nanomedicine. This work presents a new avenue for further research into the development of hyperbranched polymers for rheumatoid arthritis and suggests interesting approaches that may overcome some limitations associated with the translation of anti-rheumatic nanomedicines into patients.

Liposomes are Poorly Absorbed via Lung Lymph After Inhaled Administration in Sheep.

Enhancing the delivery of therapeutic agents to the lung lymph, including drugs, transfection agents, vaccine antigens and vectors, has the potential to significantly improve the treatment and prevention of a range of lung-related illnesses. One way in which lymphatic delivery can be optimized is via the use of nanomaterial-based carriers, such as liposomes. After inhaled delivery however, there is conflicting information in the literature regarding whether nanomaterials can sufficiently access the lung lymphatics to have a therapeutic benefit, in large part due to a lack of reliable quantitative pharmacokinetic data. The aim of this work was to quantitatively evaluate the pulmonary lymphatic pharmacokinetics of a model nanomaterial-based drug delivery system (HSPC liposomes) in caudal mediastinal lymph duct cannulated sheep after nebulized administration to the lungs. Liposomes were labelled with 3H-phosphatidylcholine to facilitate evaluation of pharmacokinetics and biodistribution in biological samples. While nanomaterials administered to the lungs may access the lymphatics via direct absorption from the airways or after initial uptake by alveolar macrophages, only 0.3 and 0.001% of the 3H-lipid dose was recovered in lung lymph fluid and lymph cell pellets (containing immune cells) respectively over 5 days. This suggests limited lymphatic access of liposomes, despite apparent pulmonary bioavailability of the 3H-lipid being approximately 17%, likely a result of absorption of liberated 3H-lipid after breakdown of the liposome in the presence of lung surfactant. Similarly, biodistribution of 3H in the mediastinal lymph node was insignificant after 5 days. These data suggest that liposomes, that are normally absorbed via the lymphatics after interstitial administration, do not access the lung lymphatics after inhaled administration. Alternate approaches to maximize the lung lymphatic delivery of drugs and other therapeutics need to be identified.

Pulmonary delivery of an ultra-fine oxytocin dry powder formulation: potential for treatment of postpartum haemorrhage in developing countries.

Oxytocin is recommended by the World Health Organisation as the most effective uterotonic for the prevention and treatment of postpartum haemorrhage. The requirement for parenteral administration by trained healthcare providers and the need for the drug solution to be maintained under cold-chain storage limit the use of oxytocin in the developing world. In this study, a spray-dried ultrafine formulation of oxytocin was developed with an optimal particle size diameter (1-5 µm) to facilitate aerosolised delivery via the lungs. A powder formulation of oxytocin, using mannitol, glycine and leucine as carriers, was prepared with a volume-based median particle diameter of 1.9 µm. Oxytocin content in the formulation was assayed using high-performance liquid chromatography-mass spectroscopy and was found to be unchanged after spray-drying. Ex vivo contractility studies utilising human and ovine uterine tissue indicated no difference in the bioactivity of oxytocin before and after spray-drying. Uterine electromyographic (EMG) activity in postpartum ewes following pulmonary (in vivo) administration of oxytocin closely mimicked that observed immediately postpartum (0-12 h following normal vaginal delivery of the lamb). In comparison to the intramuscular injection, pulmonary administration of an oxytocin dry powder formulation to postpartum ewes resulted in generally similar EMG responses, however a more rapid onset of uterine EMG activity was observed following pulmonary administration (129 ± 18 s) than intramuscular injection (275 ± 22 s). This is the first study to demonstrate the potential for oxytocin to elicit uterine activity after systemic absorption as an aerosolised powder from the lungs. Aerosolised oxytocin has the potential to provide a stable and easy to administer delivery system for effective prevention and treatment of postpartum haemorrhage in resource-poor settings in the developing world.