Accelerating ionizable lipid discovery for mRNA delivery using machine learning and combinatorial chemistry

To unlock the full promise of messenger (mRNA) therapies, expanding the toolkit of lipid nanoparticles is paramount. However, a pivotal component of lipid nanoparticle development that remains a bottleneck is identifying new ionizable lipids. Here we describe an accelerated approach to discovering effective ionizable lipids for mRNA delivery that combines machine learning with advanced combinatorial chemistry tools. Starting from a simple four-component reaction platform, we create a chemically diverse library of 584 ionizable lipids. We screen the mRNA transfection potencies of lipid nanoparticles containing those lipids and use the data as a foundational dataset for training various machine learning models. We choose the best-performing model to probe an expansive virtual library of 40,000 lipids, synthesizing and experimentally evaluating the top 16 lipids flagged. We identify lipid 119-23, which outperforms established benchmark lipids in transfecting muscle and immune cells in several tissues. This approach facilitates the creation and evaluation of versatile ionizable lipid libraries, advancing the formulation of lipid nanoparticles for precise mRNA delivery.

Combinatorial development of nebulized mRNA delivery formulations for the lungs

Inhaled delivery of mRNA has the potential to treat a wide variety of diseases. However, nebulized mRNA lipid nanoparticles (LNPs) face several unique challenges including stability during nebulization and penetration through both cellular and extracellular barriers. Here we develop a combinatorial approach addressing these barriers. First, we observe that LNP formulations can be stabilized to resist nebulization-induced aggregation by altering the nebulization buffer to increase the LNP charge during nebulization, and by the addition of a branched polymeric excipient. Next, we synthesize a combinatorial library of ionizable, degradable lipids using reductive amination, and evaluate their delivery potential using fully differentiated air-liquid interface cultured primary lung epithelial cells. The final combination of ionizable lipid, charge-stabilized formulation and stability-enhancing excipient yields a significant improvement in lung mRNA delivery over current state-of-the-art LNPs and polymeric nanoparticles.

Dissolution properties and characterization of halofantrine-2-hydroxypropyl-beta-cyclodextrin binary systems

Halofantrine (HF) is a poorly water-soluble antimalarial drug with low bioavailability. Complex formation of HF.HCl and 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CD) in aqueous solution and in solid state as well as the possibility of improving the solubility and dissolution rate of the drug though complexation with the cyclodextrin were investigated. Phase-solubility profile indicated that the solubility of the drug was significantly increased in the presence of HP-beta-CD and was classified as AL-type, indicating 1:1 stoichiometric inclusion complexes and an apparent stability constant value of 2300 M(-1). Solid inclusion complexes of HF, HCl and the cyclodextrin at 1:1 molar ratios were prepared by physical mixture, kneading, co-evaporation and freeze-drying methods and characterized by X-ray diffraction and Infra-red spectroscopy. The solubility and dissolution rates of HF.HCl from the complexes were determined and found to be dependent on the preparation method of the complexes. Dissolution profile of the drug was markedly enhanced by complex formation with the cyclodextrin and the product prepared by the freeze-drying method exhibited the most superior dissolution properties compared to the other methods used in this study. The results suggest that the complexation of HF.HCl with HP-beta-CD could improve therapeutic efficacy of the drug though enhanced absorption expected from increased drug dissolution.

Clinical evaluation of Acalypha ointment in the treatment of superficial fungal skin diseases

In an open non-comparative study to evaluate the efficacy and safety of Acalypha wilkesiana ointment in superficial fungal skin diseases, 32 Nigerian patients with clinical and mycological evidence of superficial mycoses were recruited. Twelve patients defaulted and were lost to follow up, while one patient withdrew because of intolerable excoriation at the site of the lesion. Of the 19 patients that completed the trial, clinical cure was achieved in 73.3% of the patients. The ointment was very efficacious in the treatment of Tinea pedis, Pityriasis versicolor and Candida intetrigo where the cure rate was 100% in each condition. It is recommended that Acalypha ointment can be used for the treatment of these superficial mycoses.

Determination of the required HLB values of some essential oils

The required HLB values of eucalyptus, lippia and peppermint essential oils were determined using droplet size analysis and turbidimetric method on emulsions prepared with emulsifier blends of varying HLB values. The percentage increase in mean droplet diameter and the degree of dispersion of droplet sizes were determined before and after centrifugation of the emulsions. The HLB value of the emulsion with the least dispersion ratio or the least percentage increase in mean droplet diameter was taken as the required HLB of the respective essential oil. The turbidimetric method was validated by the existence of correlation (r=-0.958) between the mean droplet diameter and the turbidity of the emulsions. The turbidity curve went through a maximum at the HLB value where the mean droplet diameter was least. Based on these methods, the required HLB values of eucalyptus, lippia and peppermint oils were determined as 9.8, 12.1 and 12.3, respectively (P<0.05). Liquid paraffin was used as a reference standard and its required HLB fell within literature value.

Correlation between in vitro and in vivo parameters of commercial paracetamol tablets

Three leading and competitive commercial products of paracetamol tablets coded as brands A, B and C (A, being the innovator product) in the country were evaluated for their in vitro properties and in vivo comparative bioavailability. The studies included chemical equivalence, hardness, disintegration time, dissolution rate and systemic availability among eight healthy volunteers. The disintegration times were 2.1 min for brand A, 5.7 min for brand B and 36.2 min for brand C. The dissolution rate (T70) were 33.0 min, 74.5 min and 56.5 min for brands A, B and C, respectively. While brand A passed all the in vitro tests as specified in the official monograph, brand B failed only the dissolution rate test and brand C failed both the disintegration and dissolution tests. These significant differences observed among the products after in vitro tests were not reflected in the in vivo availability. While the absorption rate (indicated by tmax) of brand C was significantly faster (i.e. shorter) than those of Brands A and B, the extent of absorption (indicated by AUC) was comparable among the three brands. The relative bioavailabilities (with respect to brand A) were 92 and 91% for brands B and C, respectively indicating that the products were bioequivalent. Comparison of the in vitro and in vivo data suggest that the systemic absorption of paracetamol may not be dissolution--rate limited and that using in vitro dissolution rate studies alone to establish bioequivalency of paracetamol tablets should be done with caution.

Pediculocidal and scabicidal properties of Lippia multiflora essential oil

The essential oil from the leaves of Lippia multiflora Moldenke (Verbenaceae) was tested for its pediculocidal and scabicidal activites against bodylice, headlice and scabies' mites. The 'knockdown' times obtained for bodylice and headlice using lippia oil preparations were comparatively shorter than those obtained using benzyl benzoate and Delvap Super, a brand of dichlorvos. The lethal effect of the lippia oil on headlice was increased when applied in an enclosed system that prevented volatilization of the oil while allowing maximum contact of the vapour with the headlice. A 20% v/v preparation of lippia oil applied to scabietic subjects for 5 consecutive days gave 100% cure compared with 87.5% cure obtained for benzyl benzoate preparation of the same concentration. The GC-MS analysis of oil revealed, among others, the presence of terpineol, alpha- and beta-pinene which are known to be lethal to body and headlice.