Vivek Verma

Vivek Verma
Imperial College London | Imperial · Department of Chemical Engineering

Doctor of Philosophy

About

27
Publications
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186
Citations

Publications

Publications (27)
Article
Poor bioavailability and aqueous solubility represent a major constraint during the development of new API molecules and can influence the impact of new medicines or halt their approval to the market. Cocrystals offer a novel and competitive advantage over other conventional methods with respect towards the substantial improvement in solubility pro...
Article
Generally, pairs of polymorphs can be characterized by their ratios of equilibrium solubilities and interfacial energies (γst/γme) for a given temperature and solvent. We refer to this point as the solubility-interfacial energy characteristic point (characteristic point for short) of a polymorphic pair. The equations of the classical nucleation the...
Article
The present work investigates the solubility of the stable polymorph of celecoxib (CEL) drug in a range of pure organic solvents, including methanol, isopropanol, butanol, ethyl acetate, acetonitrile and toluene, within the temperature range 278-303 K. The solid form used has been characterized by SEM, PXRD, DSC, TGA, FTIR and Raman spectroscopy. T...
Article
Lipid cubic phase (LCP) formulations enhance the intestinal solubility and bioavailability of hydrophobic drugs by reducing precipitation and facilitating their mass transport to the intestinal surface for absorption. LCPs with an ester linkage connecting the acyl chain to the glycerol backbone (monoacylglycerols), are susceptible to chemical diges...
Article
Nanosizing of pharmaceutical drug particles is one of the most important drug delivery platforms approaches for the commercial development of poorly water-soluble drug molecules. Though nanosizing of drug particles has been proven to greatly enhance drugs dissolution rate and apparent solubility, nanosized materials have presented significant chall...
Article
Posaconazole (PSZ) is a BCS (biopharmaceutical classification system) Class II anti-fungal drug used to treat infections in immunocompromised patients. The work presented herein describes the generation of cocrystals of PSZ with 4-aminobenzoic acid (4AMB) using supercritical CO2 as an antisolvent in GAS (Gas Antisolvent) with acetonitrile, and as a...
Article
Monte Carlo (MC) and molecular dynamics (MD) computer simulations were used to investigate the role of adsorption during seeded and heterogeneous crystallization. The simulations characterized the range of adsorption energies and configurations encountered during adsorption of individual molecules of active pharmaceutical ingredients (APIs), with v...
Article
The emergence of COVID-19 pandemic has severely affected human health and world economies. According to WHO guidelines, continuous use of face mask is mandatory for personal protection for restricting the spread of bacteria and virus. Here, we report a 3-ply cotton-PLA-cotton layered biodegradable face-mask containing encapsulated phytochemicals in...
Article
Traditionally, the enhancement of nucleation rates in the presence of heterogeneous surfaces in crystallisation processes has been attributed to the modification of the interfacial energy of the system according to the classical nucleation theory. However, recent developments have shown that heterogeneous surfaces instead alter the pre-exponential...
Article
The crystal growth kinetics of piracetam, fenofibrate, phenylbutazone, acetaminophen, carbamazepine, and risperidone in methanol have been studied by two different methods; the isothermal seeded desupersaturation experiment (ISD) and the rotating disk technique (RD). Data has been collected in the range of temperature 288–303 K and at different sup...
Article
Full-text available
Poor solubility of new chemical entities (NCEs) is a major bottleneck in the pharmaceutical industry which typically leads to poor drug bioavailability and efficacy. Nanotechnologies offer an interesting route to improve the apparent solubility and dissolution rate of pharmaceutical drugs, and processes such as nano-spray drying and supercritical C...
Article
Full-text available
Multidrug products enable more effective therapies and simpler administration regimens, provided that a stable formulation is prepared, with the desired composition. In this view, solid solutions have the advantage of combining the stability of a single crystalline phase with the potential of stoichiometry variation of a mixture. Here a drug–prodru...
Article
The solubility of the racemic solid phase of ketoprofen (KTP) in methanol, ethanol, isopropanol, butanol, acetonitrile, ethyl acetate, 1,4-dioxane and toluene has been determined between 273 and 303 K by a gravimetric method. FTIR and Raman spectroscopy, SEM and PXRD, have been used to characterise the solid phase. The melting data and heat capacit...
Article
The crystal growth of tolbutamide (Form IL) in different solvents has been investigated by isothermal seeded desupersaturation experiments at different temperatures (268-283 K). Experimental data has been evaluated using empirical power law equations and the mechanistic based models: Burton-Cabrera-Frank (BCF) and Birth and Spread (B+S). The estima...
Article
Full-text available
Ratios of equilibrium solubilities rarely exceed two-fold for polymorph pairs. A model has been developed based on two intrinsic properties of polymorph pairs, namely the ratio of equilibrium solubilities of the individual pairs (C*me/C*st) and the ratio of interfacial energies (γst/γme) and one applied experimental condition, namely the supersatur...
Article
The effect of solvent on salicylamide’s crystal habit was investigated. Crystals grown experimentally in acetone, acetonitrile and methanol matched the attachment energy predicted rectangle plate vacuum habit. However, in ethyl acetate irregular hexagonal plate crystals form. This change in habit was found to be caused by the stunted growth of spec...
Article
Full-text available
Bile salts, phospholipids, and digestive proteins are amphipathic compounds found naturally in the human gastrointestinal system. Therefore, it is important to consider their effects on the crystallization kinetics and solution behaviour of drugs intended for oral delivery. Supersaturating drug delivery systems that employ high energy solid forms a...
Article
Full-text available
The crystallization of seven active pharmaceutical ingredients (APIs) (acetaminophen (AAP), carbamazepine (CBMZ), caffeine (CAF), phenylbutazone (PBZ), risperidone (RIS), clozapine base (CPB) and fenofibrate (FF)) was studied in the absence and presence of microcrystalline cellulose (MCC) which acted as a heterosurface. Two of the APIs, namely AAP...
Article
The equations of the classical nucleation theory were used to calculate the critical nucleation free energy for pairs of polymorphs. Conditions explored include supersaturation, the ratio of interfacial energies (γst/γme) and equilibrium solubility (C*me/C*st) for pairs of polymorphs, crystallization temperature and molecular volume. Analysis of th...
Article
Full-text available
A new methanol solvate of clozapine base (CPB) has been identified. It exhibits different molecular arrangements and bonding environments at low and room temperatures, while still maintaining the same PXRD pattern throughout. Slurry experiments confirmed this CPB-MeOH solvate to be the thermodynamically stable form in suspension relative to CPB. Th...
Article
This study is based on the heterogeneous nucleation of active pharmaceutical ingredients (APIs) in the presence of various excipients widely used in the pharmaceutical industry. Carbamazepine (CBMZ) was successfully crystallized in the presence of the following heterosurfaces: α/β-Lactose, β-D-Mannitol, microcrystalline cellulose and carboxymethyl...
Article
Bio-active nanomaterials, namely: Gallium oxy-hydroxide GaO(OH), also surfaceconjugated GaO(OH) with a giant sugar molecule: β-cyclodextrin (CD) have been prepared through a simple wet chemical route such that the same could be suitably used in biomedical diagnostics as well as therapeutic applications. Several physical methods were used for their...
Article
Porous composite membrane of polyacrylonitrile (PAN) and Lantana camara essential oil was synthesized by solvent casting method. Stability of oil in PAN solution was measured by XiGo nano tool indicating constant relaxation time of 1487 time/s. Pore size of few microns confirmed by electron microscopy was supported by atomic force microscopy indica...

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