Experimentally Validated QSAR Model for Surface pK a Prediction of Heterolipids Having Potential as Delivery Materials for Nucleic Acid Therapeutics.

The application of lipid-based drug delivery technologies for bioavailability enhancement of drugs has led to many successful products in the market for clinical use. Recent studies on amine-containing heterolipid-based synthetic vectors for delivery of siRNA have witnessed the United States Food and Drug Administration (USFDA) approval of the first siRNA drug in the year 2018. The studies on various synthetic lipids investigated for delivery of such nucleic acid therapeutics have revealed that the surface pK a of the constructed nanoparticles plays an important role. The nanoparticles showing pK a values within the range of 6-7 have performed very well. The development of high-performing lipid vectors with structural diversity and falling within the desired surface pK a is by no means trivial and requires tedious trial and error efforts; therefore, a practical solution is called for. Herein, an attempt to is made provide a solution by predicting the statistically significant pK a through a predictive quantitative structure-activity relationship (QSAR) model. The QSAR model has been constructed using a series of 56 amine-containing heterolipids having measured pK a values as a data set and employing a partial least-squares regression coupled with stepwise (SW-PLSR) forward algorithm technique. The model was tested using statistical parameters such as r 2, q 2, and pred_r 2, and the model equation explains 97.2% (r 2 = 0.972) of the total variance in the training set and it has an internal (q 2) and an external (pred_r 2) predictive ability of ∼83 and ∼63%, respectively. The model was validated by synthesizing a series of designed heterolipids and comparing measured surface pK a values of their nanoparticle assembly using a 2-(p-toluidino)-6-napthalenesulfonic acid (TNS) assay. Predicted and measured surface pK a values of the synthesized heterolipids were in good agreement with a correlation coefficient of 93.3%, demonstrating the effectiveness of this QSAR model. Therefore, we foresee that our developed model would be useful as a tool to cut short tedious trial and error processes in designing new amine-containing heterolipid vectors for delivery of nucleic acid therapeutics, especially siRNA.

Pharmaceutical analysis combined with in-silico therapeutic and toxicological profiling on zileuton and its impurities to assist in modern drug discovery.

The obligatory testing of drug molecules and their impurities to protect users against toxic compounds seems to provide interesting opportunities for new drug discovery. Impurities, which proved to be non-toxic, may be explored for their own therapeutic potential and thus be a part of future drug discovery. The essential role of pharmaceutical analysis can thus be extended to achieve this purpose. The present study examined these objectives by characterizing the major degradation products of zileuton (ZLT), a 5-lipoxygenase (5-LOX) inhibitor being prevalently used to treat asthma. The drug sample was exposed to forced degradation and found susceptible to hydrolysis and oxidative stress. The obtained Forced Degradation Products (FDP's) were resolved using an earlier developed and validated Ultra-High-Pressure Liquid Chromatography Photo-Diode-Array (UHPLC-PDA) protocol. ZLT, along with acid-and alkali-stressed samples, were subjected to Liquid-chromatography Mass-spectrometry Quadrupole Time-of-flight (LC/MS-QTOF) studies. Major degradation products were isolated using Preparative TLC and characterized using Q-TOF and/or Proton nuclear magnetic resonance (1HNMR) studies. The information obtained was assembled for structural conformation. Toxicity Prediction using Komputer Assisted Technology (TOPKAT) toxicity analyses indicated some FDP's as non-toxic when compared to ZLT. Hence, these non-toxic impurities may have bio-affinity and can be explored to interact with other therapeutic targets, to assist in drug discovery. The drug molecule and the characterized FDP's were subjected to 3-Dimensional Extra Precision (3D-XP)-molecular docking to explore changes in bio-affinity for the 5-LOX enzyme (PDB Id: 3V99). One FDP was found to have a higher binding affinity than the drug itself, indicating it may be a suitable antiasthmatic. The possibility of being active at other sites cannot be neglected and this is evaluated to a reasonable extent by Prediction of Activity Spectra for Substances (PASS). Besides being antiasthmatic, some FDP's were predicted antineoplastic, antiallergic and inhibitors of Complement Factor-D.

Self-microemulsifying drug delivery system for camptothecin using new bicephalous heterolipid with tertiary-amine as branching element.

Camptothecin (CPT) has a potent and broad-spectrum anti-tumor activity but its clinical use is limited due to its poor water solubility, stability at physiological conditions and toxicity. The aim of our study was to evaluate bicephalous heterolipid E1E for enhancing the solubility and stability of CPT through the development of a self-microemulsifying drug delivery system (SMEDDS). The solubility of CPT in heterolipid E1E was found to be 82 and 5.86 folds higher than oleic acid and ethyl oleate respectively. Molecular dynamic simulation (MDS) studies revealed that stability of hydrogen bonding between CPT with E1E contributed to solubility enhancement of CPT. SMEDDS of CPT with heterolipid E1E as an oil phase was prepared and evaluated for drug loading, droplet size, morphology, thermodynamic and long-term stability studies as per ICH guidelines. The product, CPT-SMEDDS Fc showed 1.75 mg CPT loading per 1 g of SMEDDS having a droplet size of 20.93 ±â€¯0.41 nm. CPT-SMEDDS Fc was found to be stable, equipotent as compared to doxorubicin and had low toxicity in HeLa, MCF-7, and HL-60 cell lines. These results signify that the delivery system, CPT-SMEDDS Fc could be a very good candidate to be considered for preclinical and clinical investigations.