COMPUTATIONAL APPROACHES RELATED TO DRUG DISPOSITION

Drug disposition connects with the movement of drug molecules inside the body after administration irrespective with the route of administration. After entering the system, drug molecule and internal body systems comes under various pharmacokinetic interactions followed by observation of suitable biological activity. In this exhaustive process, physicochemical nature of the chemical substance and physiological nature of system makes this movement competitive. In this view, pharmacokinetic and toxic properties of the molecule regulates the destination of the molecule. Various computational processes are available for in silico pharmacokinetic assessment of drug molecule after absorption through biological membrane, distributed throughout the system based on the percent ionization or partition coefficient factors followed by biologically transformed into an another entity in presence of microsomal enzymes and finally excrete out from system using various cellular transport systems as well as related cellular toxicity behavior. In this chapter, we ensemble all the possible information related with the drug movement and related computational tools to understand the possible chemical and pathophysiological changes. Here detailed knowledge on database expedition, establishment of pharmacophore model, homology modelling based on sequence similarity, molecular docking study (rigid and flexible docking) and QSAR/QSPR study (with detailed process and available softwares) are provided. These diversely united informations actually helps a researcher to understand the factual movement of a drug molecule inside the system

Identification of Novel Functional Inhibitors of Acid Sphingomyelinase

We describe a hitherto unknown feature for 27 small drug-like molecules, namely functional inhibition of acid sphingomyelinase (ASM). These entities named FIASMAs (Functional Inhibitors of Acid SphingoMyelinAse), therefore, can be potentially used to treat diseases associated with enhanced activity of ASM, such as Alzheimer's disease, major depression, radiation- and chemotherapy-induced apoptosis and endotoxic shock syndrome. Residual activity of ASM measured in the presence of 10 µM drug concentration shows a bimodal distribution; thus the tested drugs can be classified into two groups with lower and higher inhibitory activity. All FIASMAs share distinct physicochemical properties in showing lipophilic and weakly basic properties. Hierarchical clustering of Tanimoto coefficients revealed that FIASMAs occur among drugs of various chemical scaffolds. Moreover, FIASMAs more frequently violate Lipinski's Rule-of-Five than compounds without effect on ASM. Inhibition of ASM appears to be associated with good permeability across the blood-brain barrier. In the present investigation, we developed a novel structure-property-activity relationship by using a random forest-based binary classification learner. Virtual screening revealed that only six out of 768 (0.78%) compounds of natural products functionally inhibit ASM, whereas this inhibitory activity occurs in 135 out of 2028 (6.66%) drugs licensed for medical use in humans

Designing, Cytotoxic Evaluation, Molecular Docking and in Silico Pharmacokinetic Prediction of New Hydrocortisone Derivatives as Anti-Asthmatics Drugs

A series of new 20 corticosteroids were subjected to molecular property prediction. The Molecular, Physicochemical, and Biological properties were determined using Molinspiration Cheminformatics software. These compounds were further subjected to Toxicity Predictions using the Osiris Software. The calculated drug-related properties of the designed molecules were similar to those found in most marketed drugs. Amongst the proposed molecules, fourteen promising candidates can be considered as promising structures for the synthesis of new and more effective anti-asthmatic drugs. Result indicates that the derivatives are orally active molecules.  In-silico ADME and toxicity prediction was accomplished with the help of Swiss-ADMET tool provides the latest and most inclusive for diverse chemicals associated with known Absorption, Distribution, Metabolism, Excretion and Toxicity profiles. furthermore, BBB (Blood brain barrier) penetration, HIA (Human intestinal absorption), Caco-2 cell permeability and Ames test were calculated using ADMET web-based query tools incorporating a molecular build in interface enable the database to be queried by Smiles and structural similarity search. According to molecular docking results, derivatives No 4, 10 and 11 showed better docking Scores values compared to other derivatives and also dexamethasone and hydrocortisone. Keywords: Corticosteroids, Drug-likeness, Lipophilicity, Anti-asthmatic, ADME

Towards human-relevant preclinical models: fluid-dynamics and three-dimensionality as key elements

The activity of research of this thesis focuses on the relevance that appropriate in vitro fully humanized models replicating physiological microenvironments and cues (e.g., mechanical and fluidic) are essential for improving human biology knowledge and boosting new compound testing. In biomedical research, the high percentage of the low rate of successful translation from bench to bedside failure is often attributed to the inability of preclinical models in generating reliable results. Indeed, it is well known that 2D models are far from being representative of human complexity and, on the other side, although animal tests are currently required by regulatory organizations, they are commonly considered unpredictive. As a matter of fact, there is a growing awareness that 3D human tissue models and fluid-dynamic scenarios are better reproducers of the in vivo context. Therefore, during this PhD, I have worked to model and validate technologically advanced fluidic platforms, where to replicate biological processes in a systemic and dynamic environment to better assess the pharmacokinetics and the pharmacodynamics of drug candidates, by considering different case studies. First, skin absorption assays have been performed accordingly to the OECD Test Guidelines 428 comparing the standard diffusive chamber (Franz Diffusion Cell) to a novel fluidic commercially available organ on chip platform (MIVO), demonstrating the importance of emulating physiological fluid flows beneath the skin to obtain in vivo-like transdermal penetration kinetics. On the other hand, after an extensive research analysis of the currently available intestinal models, which resulted insufficient in reproducing chemicals and food absorption profiles in vivo, a mathematical model of the intestinal epithelium as a novel screening strategy has been developed. Moreover, since less than 8% of new anticancer drugs are successfully translated from preclinical to clinical trials, breast, and ovarian cancer, which are among the 5 most common causes of death in women, and neuroblastoma, which has one of the lowest survival rates of all pediatric cancers, have been considered. For each, I developed and optimized 3D ECM-like tumor models, then cultured them under fluid-dynamic conditions (previously predicted by CFD simulations) by adopting different (customized or commercially available) fluidic platforms that allowed to mimic u stimuli (fluid velocity and the fluid flow-induced shear stress) and investigate their impact on tumor cells viability and drug response. I provided evidence that such an approach is pivotal to clinically reproduce the complexity and dynamics of the cancer phenomenon (onset, progression, and metastasis) as well as to develop and validate traditional (i.e., platin-based drugs, caffein active molecule) or novel treatment strategies (i.e., hydroxyapatite nanoparticles, NK cells-based immunotherapies)

Solubility and ADMET profiles of short oligomers of lactic acid

Polylactic acid (PLA) is a polymer with an increased potential to be used in different medical applications, including tissue engineering and drug-carries. The use of PLA in medical applications implies the evaluation of the human organism\u27s response to the polymer inserting and to its degradation products. Consequently, within this study, we have investigated the solubility and ADMET profiles of the short oligomers (having the molecular weight lower than 3000 Da) resulting in degradation products of PLA. There is a linear decrease of the molar solubility of investigated oligomers with molecular weight. The results that are obtained also reveal that short oligomers of PLA have promising pharmacological profiles and limited toxicological effects on humans. These oligomers are predicted as potential inhibitors of the organic anion transporting peptides OATP1B1 and OATP1B3, they present minor probability to affect the androgen and glucocorticoid receptors, have a weak potential of hepatotoxicity, and may produce eye injuries. These outcomes may be used to guide or to supplement in vitro and/or in vivo toxicity tests such as to enhance the biodegradation properties of the biopolymer.</p

SYNTHESIS AND IN-SILICO ANTI-INFLAMMATORY INVESTIGATION OF 2, 3-DIHYDROCHROMEN-4-ONE AND 3, 4-DIHYDROBENZO[B]OXEPIN-5(2H)-ONE BASED PYRAZOLE DERIVATIVES

This study synthesized six pyrazole derivatives from the key intermediates 2,3-dihydrochromen-4-one and 3,4-dihydrobenzo[b]oxepin-5(2H)-one. We have characterized all pyrazole derivatives as well as conducted in silico anti-inflammatory studies. The DFT calculations were performed using Gaussian 09 software. The compound 9 has the lowest energy gap (∆E, 1.0698 eV), lowest hardness (0.5349 eV), highest softness (1.8695 eV), and highest electrophilicity (7.0809eV) among all pyrazole derivatives and standard Aspirin. Swiss ADME software was used to carry out the ADME analysis. The chloro-substituted pyrazole derivatives (5, 6, and 9) were non-toxic, however, the nitrogen-substituted pyrazole derivatives (10, 13 and 14) and Aspirin were toxic. The docking patterns of the pyrazole derivatives with COX-2 selective inhibitors proteins (5F19) have been studied. Compound 9 has the lower binding energy (-10.2Kcal/mol) as compared with that of other pyrazole derivatives and standard Aspirin drugs. As a result, the pyrazole derivatives compound 9 is a promising anti-inflammatory drug with selective COX-2 inhibition as compared to the Aspirin drugs physicochemical properties

Predicting skin permeability of neutral species and ionic species

The skin forms an extremely efficient barrier between internal organs and the external environ-ment, but also provides an attractive administration route. Skin permeability (as log Kp) is a critical parameter for estimating transdermal delivery of chemicals in contact with the skin in pharma-ceutics and cosmetics. Given the fact that measurement of log Kp is quite time-consuming and laborious, various mathematical models based on understanding of the fundamental mechanisms underlying skin permeation have been proposed to estimate the otherwise unavailable log Kp. However, there has been no model up to now for prediction of log Kp of ionic species. In order to solve this problem, we proposed and investigated two potential solutions in this study: one is the Potts-Guy model on the basis of partition parameters in liposome-water systems and molecular volume (MV), and the other is the extended linear free-energy relationship (LFER), which can be used to predict biological membrane permeability of ionic species. In this study, the compounds with a broad structural diversity were selected and their reten-tion factors were measured in liposome electrokinetic chromatography (LEKC), where cerasomes composed mainly of the stratum corneum (SC) lipids and liposomes (POPC80/PS20) were used as the pseudo-stationary phases, respectively. These two negatively charged membrane systems and a neutral immobilized artificial membrane (IAM) system from literature as a surrogate for neutral liposome-water partition were compared with various organic solvent-water partitioning systems using LFERs. It was observed that liposomes display a greatly different chemical environment from those of organic solvents, and no organic solvent can thus provide a general model for lipo-somes in partition processes. What is more, the correlation between the skin-water partition and organic solvent/liposome-water partitions was also investigated. The results show that cerasome exhibits a better chemical similarity with the skin as compared to phospholipid liposomes and all organic solvents. Further, the cerasome-water partition correlates better to skin permeation than other liposome-water partitions and microsomal binding. This is probably due to the unique struc-tures of ceramides that occur in SC and consequently in cerasomes. The log Kp values of nine acid anions and nine base cations were measured in this study. The data were used to construct a LFER equation for skin permeation of neutral species and ionic spe-cies, together with experimental log Kp for both species in literature. The resulting equation, with a R2 value of 0.861 and a SD value of 0.462 log units, can be used to predict log Kp for neutral species and ionic species, as well as partly ionized solutes. The predicted values for the passive permeation of the sodium ion and the tetraethylammonium ion are in good accord with the exper-imental values. It was found that neutral acids and bases are much more permeable than their ion-ized forms, and that the ratio depends on the actual structure. Using the cerasome-water partition as a substitute for the skin-water partition, the effect of ionization of solutes on skin permeation was separated to those on partition and diffusion processes. The poor permeability of ionic species is largely due to slow diffusion through the SC, especially for base cations. In addition, the Potts-Guy model based on the retention factors obtained in cerasome electro-kinetic chromatography (EKC) and MV was discussed. It was found that such a model cannot be applied to predict log Kp for ionic species because MV fails to account for their diffusion through the SC, even empirically. In conclusion, LFER is a very useful tool for predicting skin permeation, not only for neutral species but also for ionic species, whereas the Potts-Guy model may be useful for neutral species but is not applicable for ionic species.Die Haut bildet eine äußerst effiziente Barriere zwischen dem Körperinneren und der äußeren Umwelt und stellt aber auch einen attraktiven Applikationsweg dar. Die Hautpermeabilität (darge-stellt als log Kp) ist dabei auf dem Gebiet der Pharmazie und Kosmetik ein entscheidender Para-meter, um das transdermale Hautpenetrations- bzw. Hautpermeationsverhalten eines Stoffes nach dermaler Applikation abzuschätzen. Direkte Messungen des log Kp sind zeitaufwendig und müh-sam. In der vorliegenden Arbeit wurden verschiedene, auf dem Verständnis grundlegender Me-chanismen der Hautpermeation basierende, mathematische Modelle vorgeschlagen, um nicht ver-fügbare log Kp-Werte zu generieren. Bisher gab es jedoch kein Modell, um den log Kp von ioni-sierten Molekülen vorherzusagen. Um dieses Problem zu lösen, haben wir in dieser Arbeit zwei Lösungsmöglichkeiten für die Vorhersage von log Kp-Werten geladener Substanzen vorgeschlagen und im Weiteren diskutiert: Zum einen das Potts-Guy-Modell auf der Basis von Verteilungs-parametern in Liposom/Wasser-Systemen und dem Molekülvolumen (MV), zum anderen die er-weiterte lineare freie Energie-Beziehung (linear free energy relationship; LFER), die verwendet werden kann, um die Permeabilität geladener Stoffe durch biologische Membranen vorherzusagen. In dieser Arbeit wurden Verbindungen mit einer breiten strukturellen Vielfalt ausgewählt und ihre Retentionsfaktoren mit Hilfe von Liposom-Elektrokinetik-Chromatographie (liposome electrokinetic chromatography; LEKC) gemessen, wobei Cerasomen, hauptsächlich bestehend aus Lipiden des Stratum corneums (SC), bzw. Liposomen (POPC80/PS20) als pseudostationäre Phase dienten. Diese beiden negativ geladenen Membransysteme sowie ein System aus neutralen künst-lichen immobilisierten Membranen (immobilized artificial membranes; IAM) stellvertretend für eine neutrale Liposomen/Wasser-Verteilung wurden mit verschiedenen Verteilungssystemen zwi-schen organischen Lösungsmitteln und Wasser unter Anwendung der LFER verglichen. Es wurde beobachtet, dass Liposomen eine sich von organischen Lösungsmitteln stark unterscheidende chemische Umgebung besitzen. Daher stellen organische Lösungsmittel kein allgemein gültiges Modell für Liposomen in Bezug auf Verteilungsprozesse dar. Der Zusammenhang zwischen der Haut/Wasser-Verteilung und der organischen Lösungsmittel/Liposom-Wasser-Verteilung wurde ebenfalls untersucht. Die Ergebnisse zeigen, dass Cerasomen im Vergleich zu herkömmlichen Liposomen aus Phospholipiden sowie allen organischen Lösungsmitteln eine höhere chemische Ähnlichkeit mit der Haut aufweisen. Darüber hinaus konnte für die Cerasomen/Wasser-Verteilung eine bessere Korrelation mit der Hautpermeation nachgewiesen werden, als für die Liposomen-Wasser-Verteilung oder die mikrosomale Bindung. Grund hierfür ist wahrscheinlich die einzigar-tige Struktur der Ceramide, die im Stratum corneum wie auch hier in den Cerasomen vorhanden ist. Die log Kp-Werte von neun sauren, anionischen Molekülen und neun basischen, kationischen Molekülen wurden in dieser Arbeit gemessen. Aus den generierten Daten wurde in Verbindung mit log Kp Werten aus der Literatur eine LFER-Gleichung für die Hautpermeation von neutralen und ionischen Molekülen entwickelt. Die resultierende Gleichung mit einem R2 von 0,861 und einer Standardabweichung von 0,462 log Einheiten kann sowohl zur Vorhersage des log Kp-Wertes für neutrale und ionische Moleküle, als auch für Vorhersage des log Kp-Wertes teilweise ionisierter Substanzen verwendet werden. Die abgeschätzten Werte für die passive Permeation des Natrium-Ions und des Tetraethylammonium-Ions stimmen mit den experimentellen Werten gut überein. Es wurde erkannt, dass neutrale Säuren und Basen viel stärker permeieren als die dazu-gehörigen ionisierten Formen und dass das Verhältnis von der jeweiligen Struktur abhängt. Unter Verwendung der Cerasome/Wasser-Verteilung als Ersatz für die Haut-Wasser-Verteilung wurde der Effekt der Ionisierung der gelösten Substanzen auf die Hautpermeation von den Effekten auf die Verteilung und Diffusionsprozesse getrennt. Die schlechte Permeation ionischer Moleküle beruht im Wesentlichen auf der langsamen Diffusion durch das SC, vor allem für basische Kationen. Darüber hinaus wurde das Potts-Guy Modell basierend auf den Retentionsfaktoren, welche mittels Cerasome Electrokinetic Chromatography (EKC) bestimmt wurden, und MV diskutiert. Es wurde herausgefunden, dass ein solches Modell nicht für die Schätzung von log Kp-Werten ioni-scher Moleküle angewendet werden kann, da MV daran scheitert, die Diffusion durch das SC zu erfassen - auch empirisch. Zusammenfassend lässt sich sagen, dass LFER ein nützliches Hilfsmittel ist, um die Haut-permeation nicht nur für neutrale, sondern auch für ionische Moleküle vorauszusagen, wohingegen das Potts-Guy Modell gegebenenfalls für neutrale, aber nicht für ionische Moleküle anwendbar ist

Drug delivery to the brain: In situ gelling formulation enhances carbamazepine diffusion through nasal mucosa models with mucin

The objective of this work was to optimize a thermosensitive in situ gelling formulation to improve intranasal and nose-to-brain delivery of the antiepileptic drug carbamazepine (CBZ). A preliminary procedure of vehicles obtained just mixing different fractions of poloxamer 407 (P407) and poloxamer 188 (P188) revealed preparations with phase transition temperatures, times to gelation and pH values suitable for nasal delivery. Subsequently, the mucoadhesive properties of the most promising formulations were tuned by adding hydroxypropylmethylcellulose types of different viscosity grades, and the effect of the adhesive polymers was evaluated by testing in vitro time and strength of mucoadhesion on specimens of sheep nasal mucosa. The formulation that showed the greatest mucoadhesive potential in vitro, with a time and force of mucoadhesion equal to 1746,75 s and 3.66&nbsp;×&nbsp;10-4 N, respectively, was that composed of 22% P407, 5% P188 and 0.8% HPMC low-viscous and it was further investigated for its ability to increase drug solubility and to control the release of the drug. Lastly, the capability of the candidate vehicle to ensure drug permeation across the biomimetic membrane Permeapad®, an artificial phospholipid-based barrier with a stratified architecture, and the same barrier enriched with a mucin layer was verified. The final formulation was characterized by a pH value of 6.0, underwent gelation at 32.33°C in 37.85 s, thus showing all the features required by in situ gelling thermosensitive preparations designed for nasal delivery and, more notably, it conserved the ability to favor drug permeation in the presence of mucin. These findings suggest that the optimized gelling system could be a promising and easy to realize strategy to improve CBZ delivery to the brain exploiting both a direct and indirect pathway