Using Salt Counterions to Modify β2-Agonist Behavior in Vivo

Oral Self-Nanoemulsifying System Containing Ionic Liquid of BX795 Is Effective against Genital HSV-2 Infection in Mice

BX795 is an emerging drug candidate that has shown a lot of promise as a next-generation non-nucleoside antiviral agent for the topical treatment of herpes simplex virus type-1 (HSV-1) and herpes simplex virus type-2 (HSV-2) infections. Our studies indicated that BX795 has limited oral bioavailability, which could be attributed to its low and pH-dependent solubility. Lipid-based formulations such as self-nanoemulsifying systems (SNESs) can improve the solubility and oral bioavailability of BX795, but the poor lipid solubility of BX795 further limits the development of SNES. To improve the loading of BX795 into SNES, we evaluated the ability of various bulky and biocompatible anions to transform BX795 into an ionic liquid (IL) with higher lipid solubility. Our studies showed that sodium lauryl sulfate and docusate sodium were able to transform BX795 into IL. Compared to pure BX795, the developed BX795 ILs showed differential in vitro cytocompatibility to HeLa cells but exhibited similar in vitro antiviral activity against HSV-2. Interestingly, BX795 docusate (BX795-Doc), an IL of BX795 with ∼135-fold higher lipid solubility than pure BX795, could be successfully incorporated into an SNES, and the developed BX795-Doc-SNES could readily form nanoemulsions of size ≤200 nm irrespective of the pH of the buffer used for dilution. Our in vitro studies showed that BX795-Doc-SNES retained the inherent antiviral activity against HSV-2 and showed similar in vitro cytocompatibility, indicating the availability of BX795 from the SNES in vitro. Finally, orally delivered SNES containing BX795-Doc showed a significant reduction in HSV-2 infection in mice compared to the untreated control. Thus, the transformation of BX795 into IL and the subsequent incorporation of the BX795 IL into the SNES are an effective strategy to improve oral therapy of genital herpes infection.

BX795-Organic Acid Coevaporates: Evaluation of Solid-State Characteristics, In Vitro Cytocompatibility and In Vitro Activity against HSV-1 and HSV-2

BX795 is a TANK binding kinase-1 inhibitor that has shown excellent therapeutic activity in murine models of genital and ocular herpes infections on topical delivery. Currently, only the BX795 free base and its hydrochloride salt are available commercially. Here, we evaluate the ability of various organic acids suitable for vaginal and/or ocular delivery to form BX795 salts/cocrystals/co-amorphous systems with the aim of facilitating pharmaceutical development of BX795. We characterized BX795-organic acid coevaporates using powder X-ray diffractometry, Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, ¹H-nuclear magnetic resonance spectroscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) to elucidate the interaction between BX795 and various organic acids such as taurine, maleic acid, fumaric acid, tartaric acid, and citric acid. Furthermore, using human corneal epithelial cells and HeLa cells, we evaluated BX795-organic acid coevaporates for in vitro cytocompatibility and in vitro antiviral activity against herpes simplex virus-type 1 (HSV-1) and type-2 (HSV-2). Our studies indicate that BX795 forms co-amorphous systems with tartaric acid and citric acid. Interestingly, the association of organic acids with BX795 improved its thermal stability. Our in vitro cytocompatibility and in vitro antiviral studies to screen suitable BX795-organic acid coevaporates for further development show that all BX795-organic acid systems, at a concentration equivalent to 10 µM BX795, retained antiviral activity against HSV-1 and HSV-2 but showed differential cytocompatibility. Further, dose-dependent in vitro cytocompatibility and antiviral activity studies on the BX795-fumaric acid system, BX795-tartaric acid co-amorphous system, and BX795-citric acid co-amorphous system show similar antiviral activity against HSV-1 and HSV-2 compared to BX795, whereas only the BX795-citric acid co-amorphous system showed higher in vitro cytocompatibility compared to BX795.

The anti-inflammatory effects of cannabidiol and cannabigerol alone, and in combination

INTRODUCTION/BACKGROUND AND PURPOSE

Studies with Cannabis Sativa plant extracts and endogenous agonists of cannabinoid receptors have demonstrated anti-inflammatory, bronchodilator, and antitussive properties in the airways of allergic and non-allergic animals. However, the potential therapeutic use of cannabis and cannabinoids for the treatment of respiratory diseases has not been widely investigated, in part because of local irritation of airways by needing to smoke the cannabis, poor bioavailability when administered orally due to the lipophilic nature of cannabinoids, and the psychoactive effects of Δ9-Tetrahydrocannabinol (Δ9-THC) found in cannabis. The primary purpose of this study was to investigate the anti-inflammatory effects of two of the non-psychotropic cannabinoids, cannabidiol (CBD) and cannabigerol (CBG) alone and in combination, in a model of pulmonary inflammation induced by bacterial lipopolysaccharide (LPS). The second purpose was to explore the effects of two different cannabinoid formulations administered orally (PO) and intraperitoneally (IP). Medium-chain triglyceride (MCT) oil was used as the sole solvent for one formulation, whereas the second formulation consisted of a Cremophor® EL (polyoxyl 35 castor oil, CrEL)-based micellar solution.

RESULTS

Exposure of guinea pigs to LPS induced a 97 ± 7% and 98 ± 3% increase in neutrophils found in bronchoalveolar lavage fluid (BAL) at 4 h and 24 h, respectively. Administration of CBD and CBG formulated with MCT oil did not show any significant effects on the LPS-induced neutrophilia measured in the BAL fluid when compared with the vehicle-treated groups. Conversely, the administration of either cannabinoid formulated with CrEL induced a significant attenuation of the LPS induced recruitment of neutrophils into the lung following both intraperitoneal (IP) and oral (PO) administration routes, with a 55-65% and 50-55% decrease in neutrophil cell recruitment with the highest doses of CBD and CBG respectively. A combination of CBD and CBG (CBD:CBG = 1:1) formulated in CrEL and administered orally was also tested to determine possible interactions between the cannabinoids. However, a mixture of CBD and CBG did not show a significant change in LPS-induced neutrophilia. Surfactants, such as CrEL, improves the dissolution of lipophilic drugs in an aqueous medium by forming micelles and entrapping the drug molecules within them, consequently increasing the drug dissolution rate. Additionally, surfactants increase permeability and absorption by disrupting the structural organisation of the cellular lipid bilayer.

CONCLUSION

In conclusion, this study has provided evidence that CBD and CBG formulated appropriately exhibit anti-inflammatory activity. Our observations suggest that these non-psychoactive cannabinoids may have beneficial effects in treating diseases characterised by airway inflammation.

A Cyclodextrin-Stabilized Spermine-Tagged Drug Triplex that Targets Theophylline to the Lungs Selectively in Respiratory Emergency

Ion-pairing a lifesaving drug such as theophylline with a targeting moiety could have a significant impact on medical emergencies such as status asthmaticus or COVID-19 induced pneumomediastinum. However, to achieve rapid drug targeting in vivo the ion-pair must be protected against breakdown before the entry into the target tissue. This study aims to investigate if inserting theophylline, when ion-paired to the polyamine transporter substrate spermine, into a cyclodextrin (CD), to form a triplex, could direct the bronchodilator to the lungs selectively after intravenous administration. NMR demonstrates that upon the formation of the triplex spermine protruded from the CD cavity and this results in energy-dependent uptake in A549 cells (1.8-fold enhancement), which persists for more than 20 min. In vivo, the triplex produces a 2.4-fold and 2.2-fold increase in theophylline in the lungs 20 min after injection in rats and mice, respectively (p < 0.05). The lung targeting is selective with no increase in uptake into the brain or the heart where the side-effects of theophylline are treatment-limiting. Selectively doubling the concentration of theophylline in the lungs could improve the benefit-risk ratio of this narrow therapeutic index medicine, which continues to be important in critical care.

An in vitro bioassay for evaluating the effect of inhaled bronchodilators on airway smooth muscle

PURPOSE

The development of inhaled drug products is expensive and involves time-consuming pharmacokinetic (PK) and pharmacodynamic (PD) studies. There are few in vitro cell-based assays to evaluate the disposition and action of orally inhaled drugs to guide early product development and minimise risk. The aim of the present study was to develop a co-culture bioassay, combining an airway epithelial cell line (Calu-3) with cultured human primary airway smooth muscle cells (ASM), integrated with apparatus to deliver pharmaceutical aerosols.

METHODS

An assay for measuring cyclic adenosine monophosphate (cAMP) in ASM derived from healthy donors was adapted to provide a biochemical surrogate for ASM relaxation. Concentration-response curves for cAMP were established for three drugs that elicit ASM relaxation: isoprenaline (ISO), forskolin (FOR) and salbutamol sulphate. The ASM bioassay was incorporated into a co-culture model in which air-interfaced Calu-3 cell layers, representing the permeability barrier of the airway epithelium, were grown on transwell inserts above ASM cells cultured in the well of the base-plate. The sensitivity of this bioassay to salbutamol delivered using different formulations and aerosol products was evaluated.

RESULTS

ASM responded with concentration dependent increases in cAMP when exposed to 10^-9 to 10^-5 M ISO, FOR or salbutamol sulphate solutions for 15 or 30 min. Salbutamol formulated with different counter ions elicited differential cAMP responses in ASM (xinafoate > base = sulphate) suggesting that this bioassay could discriminate between formulations with different potency. A similar rank order of potency was observed for the different salbutamol salts when applied as aerosols to the co-culture model.

DISCUSSION

We have developed a novel bioassay using human ASM in co-culture with human respiratory epithelial cells to better mimic various elements that contribute to the rate and extent of local drug availability in the lungs following topical administration. The bioassay offers an opportunity to investigate the factors determining the activity of inhaled bronchodilator drugs in a more biologically relevant system than that has previously been described and with further development and validation, this novel bioassay could provide a method to guide the more efficient development of inhaled bronchodilators, reducing the current reliance on in vivo studies.

Using Polar Ion-Pairs to Control Drug Delivery to the Airways of the Lungs

The rapid absorptive clearance of drugs delivered to the airways of the lungs means that many inhaled medicines have a short duration of action. The aim of this study was to investigate whether forming polar ion-pairs can modify drug absorption to slow down clearance from the airways. Salbutamol was used as a model drug and was formulated as ion-pairs in an aqueous solution with three negatively charged hydrophilic counterions: sulfate (molecular weight (MW) 142), gluconate (MW 218), and phytate (MW 736) (association constants of 1.57, 2.27, and 4.15, respectively) and one negatively charged hydrophobic counterion, octanoate (MW 166) (association constant, 2.56). All of the counterions were well tolerated by Calu-3 human bronchial epithelial cells when screened for toxicity in vitro using conditions that in silico simulations suggested maintain >80% drug-counterion association. The transport of salbutamol ion-pairs with higher polar surface area (PSA), i.e., the sulfate (PSA 52%), gluconate (PSA 50%), and phytate (PSA 79%) ion-pairs, was significantly lower compared to that of the drug alone (PSA 30%, p < 0.05). In contrast, the octanoate ion-pair (PSA 23%) did not significantly alter the salbutamol transport. The transport data for the gluconate ion-pair suggested that the pulmonary absorption half-life of the ion-paired drug would be double that of salbutamol base, and this illustrates the promise of increasing drug polarity using noncovalent complexation as an approach to control drug delivery to the airways of the lungs.