Written in EnglishRead online
Manchester thesis (Ph.D.), Department of Pharmacy.
|Contributions||University of Manchester. Department of Pharmacy.|
|The Physical Object|
|Number of Pages||255|
Download Studies of the mode of association of drug molecules in aqueous solution.
Equilibrium studies of aqueous solutions of amphiphilic drug molecules have indicated a dependency of the mode of association on the structure of the hydrophobic moiety. The association behaviour of drugs possessing diphenylmethane hydrophobic groups may Cited by: 3.
Attwood, D. () ‘Self-association of phenothiazine drugs in aqueous solutions of high ionic strength’, J. Chem.
Soc. Faraday 1, 79, – Google Scholar : D. Attwood, E. Boitard, J. Dubès, H. Tachoire, V. Mosquera, V. Perez Villar. Studies in aqueous cyclodextrin solutions have shown that practically insoluble drugs (solubility Author: Thorsteinn Loftsson. Self-association of surfactant molecules in aqueous medium facilitates the formation of micelles.
These micelles enhance the aqueous solubility of lipophilic poorly water-soluble drugs via hydrophobic micelle core and interaction with head groups with incorporation into the water-micelle interface. aqueous channels, as well as a variety of specialized carrier molecules.
For most tissues, passive aqueous diffusion through channels occurs only for molecules less than MW. A notable exception is the endothelial capillary lining, whose relatively large pores allow molecules ofto pass.
However, theFile Size: KB. Vesna Nikolić, Ljubiša Nikolić, in Characterization and Biology of Nanomaterials for Drug Delivery, Cyclodextrin Applications.
One of the most common pharmaceutical applications of cyclodextrins is to enhance drug stability and solubility in aqueous solutions.
Inclusion complexes are capable of enhancing solubility and bioavailability of various drugs, e.g., sulfanilamide [ Drug absorption is determined by the drug’s physicochemical properties, formulation, and route of administration.
Dosage forms (eg, tablets, capsules, solutions), consisting of the drug plus other ingredients, are formulated to be given by various routes (eg, oral, buccal, sublingual, rectal, parenteral, topical, inhalational). The mode of drug association mode with NPs is thus only estimated through comparative studies of zeta potential, release profiles, distribution of molar mass of the polymer, studies of adsorption and rate of association of the drug with nanostructures or even through the use of fluorescent probes.
In addition, 6CN was associated with βCD in aqueous solution and the solid state, which was confirmed by molecular modeling and the aforementioned characterization techniques.
Phase solubility studies indicated that βCD forms stable complexes with 6CN. During SAR studies, biological activity is typically investigated through in vitro tests.
Examples of drug-target intermolecular interactions have been described in another article. Drug molecules typically contain several functional groups which can interact with certain groups in the biological target. Solubility, the phenomenon of dissolution of solute in solvent to give a homogenous system, is one of the important parameters to achieve desired concentration of drug in systemic circulation for desired (anticipated) pharmacological response.
Low aqueous solubility is the major problem encountered with formulation development of new chemical entities as well as for the generic development. Phase solubility studies of indomethacin (INM) in aqueous solutions of P and PVP VA64 showed an increase in the kinetic solubility of INM compared with the pure drug at 37°C with a Ka value of.
The present work is in continuation of our earlier studies 2,3 on drug solutions in aqueous mixtures of alcohols. solution behavior of drugs in aqueous-alcoholic systems, as a function of the. Dissolution is an important step during preformulation studies because the rate of drug dissolution of a drug will exert a direct impact on bioavailability and drug delivery aspects (Bergstrom et al., ).Dissolution can be defined as the process through which drug particles tend to dissolve in the body fluids.
Any change in drug dissolution will significantly affect the bioavailability. Aqueous solutions of Poloxamer or Pluronic undergo sol-to-gel transition as the temperature increases (Fig.
).However, the implanted gel of Studies of the mode of association of drug molecules in aqueous solution. book is quickly eroded and does not persist for more than a few days at most.
To improve the system, end-group modified Poloxamers, and multiblock co-polymers consisting of Poloxamer and biodegradable polymers have been developed. Kinetic studies show that the adsorption equilibrium of aqueous drug solution is attained within 30 min whereas the TDZ–anionic micelles (10 mM) take 1 min to achieve equilibrium.
The pseudo-second-order kinetic studies follow nicely than the first-order model and Benesi–Hildebrand equation was employed to understand the binding affinity of. These modes were assigned to ν 1 MnO 6 of [Mn(OH 2) 6] 2+ and [Mn(OD 2) 6] 2+.
In Mn(NO 3) 2 (aq), the undisturbed mode at cm −1, representative of manganese hexahydrate, was also detected in dilute solutions up to ∼3 mol L −1 and no sign of nitrato complex formation could be obtained.
Simulations of molecular dynamics (MD) are playing an increasingly important role in structure-based drug discovery (SBDD). Here we review the use of MD for proteins in aqueous solvation, organic/aqueous mixed solvents (MDmix) and with small ligands, to the classic SBDD problems: Binding mode and binding free energy predictions.
The simulation of proteins in their condensed state reveals. Nanocapsules with the size of – nm are obtained usually by microfluidics micelle or emulsion formation. In the emulsion method, the micelle comprises an aqueous solution of the drug in the organic phase, and oil. On the surface of the micelles a monomer is deposited, and then it.
Aqueous solution inside biological cells surrounded by various types of hydrophobic molecules mostly includes various lipid molecules. We thus examined the localization behavior of AF in aqueous microdroplets that are interfaced with three different hydrophobic oils: glyceryl trioleate (triolein), olive oil.
2. Overcome problems arising during preparation of pharmaceutical solutions. Have information about the structure and intermolecular forces of the drug. Many drugs are formulated as solutions, or added as powder or solution forms to liquids.
Drugs with low aqueous solubility often present problems related to their formulation and. Molecular binding is an attractive interaction between two molecules that results in a stable association in which the molecules are in close proximity to each is formed when atoms or molecules bind together by sharing of electrons.
It often but not always involves some chemical bonding. In some cases, the associations can be quite strong—for example, the protein streptavidin and.
On the one hand, the spectrum of drugs displaying self-aggregation behavior is very broad and heterogeneous. From small molecules such as the b-adrenergic blocking agent propranolol hydrochlo-ride.
The UV-visible measurements reveal the distinct formation of a drug – surfactant complex. The detailed mechanism for the type of interactions was further studied by NMR titrations which show cation–π interactions between PMT and pyridinium gemini surfactant molecules.
The solubility of a drug is the amount of the drug that dissolves in a given solvent to produce a saturated solution at constant temperature and pressure.
Table 3 provides outline of different levels of solubility. For conversion of drug molecule into an effective oral formulation, it must have good aqueous solubility for better absorption. Aqueous or Organic Medium for Hematin Crystallization.
The parasite DV presents a complex environment. The vacuole comprises membrane interfaces (), an acidic aqueous solution with pH − (), and lipids, mostly mono- and diglycerides, resulting from the degradation of the transport vesicle membranes that carry hemoglobin into the DV (9, 16, 18 ⇓ –20).
Dissolution of cellulose in dissolving pulps using a 7% NaOH/% sodium sulfamate aqueous solution improved upon the addition of sodium sulfamate, and when the addition of sodium sulfamate was.
The main goal of this article is to study the diffusion mechanism of aqueous solutions and the swelling of cellulosic fibers in the silicone non-aqueous dyeing system via fluorescent labeling.
Due to non-polar media only adsorbing on the surface of fiber, cellulosic fiber could not swell as a result of the non-polar media.
However, because water molecules can diffuse into the non-crystalline. The lower increment on IMQ solubility in aqueous solution of citric acid pH can be ascribed to the increase in the solubility of the free drug which was higher than in the other media.
The apparent stability constant values can be evaluated considering the presence of the neutral drug and its protonated form in solution. Depending on the pKa, drug molecules change retentions, e.g., acids show an increase in retention as the pH is reduced, while the base shows a decrease.
If the pKa of the compound is high, lower pH or acidic mobile phase has to be chosen as it will stop unwanted association with the stationary phase.
For basic compounds, the use of high pH or. Abstract. The self-organization of pristine C 60 fullerene and its complexation with chemotherapy drugs (in particular, doxorubicin, cisplatin and landomycin A) in aqueous solution were reviewed as a possible key stage of the mechanism of the in vivo and in vitro biological synergy, observed when these drugs are administered along with C 60 fullerene.
The results of application of. 46 Physical Pharmacy 47 ( J mol –1 K), T is temperature in kelvins, c is the concentration in mol m–3 and x has a value of 1 for ionic surfactants in dilute solution. The area A occupied by a surfactant molecule at the solution–air interface can be calculated from A = 1/N A 23Γ 2 where N A is the Avogadro number ( × 10 molecules.
This compound was classified as BCS II (low solubility and high permeability), which has no pKa, logP of ~ and a melting point of ~°C. Its aqueous solubility is extremely low. While artemisinin is readily and stably extracted by aqueous decoction, flavonoids are best extracted by alcohol.
28 This is interesting in light of in vitro evidence that only ethanolic and not aqueous crude extracts of A. annua are antiplasmodial, and an absence of evidence of synergy in A.
annua aqueous extracts in vitro. 29, 30 It is also confusing given the human research on aqueous. Cyclodextrins (CDs), a group of oligosaccharides formed by glucose units bound together in a ring, show a promising ability to form complexes with drug molecules and improve their physicochemical properties without molecular modifications.
The stoichiometry of drug/CD complexes is most frequently However, natural CDs have a tendency to self-assemble and form aggregates in aqueous media. 4. Microreservoir type/ microsealed dissolution controlled systems. This is combination of the reservoir and matrix diffusion systems.
Drug reservoir 1. Suspension of drug in aqueous solution of water soluble liquid polymer. Homogenously dispersing of drug suspension in a lipophilic polymer (silicone elastomer). The relationship between the molar solubility of a drug in water, S w, at a temperature T (in kelvins), and the melting point T m, for a non-ideal solution may be written as where is the entropy of fusion (melting), γ is the activity coefficient and is the molar volume of the solvent.
Equation () shows an increase of solubility as the melting point decreases. Since an early report in the s, the mesoscale inhomogeneities formed in an aqueous solution of water-miscible small organic molecules have been debated for over forty years with a variety of explanations.
Although it was recently established that these inhomogeneities are supramolecular species caused by. Preformulation solubility studies focus on drug solvent system that could occur during the delivery of drug candidate. For e.g. A drug for oral administration should be examined for solubility in media having isotonic chloride ion concentration and acidic.
Briefly, Boc-Met-OH (5 mM; g) was dissolved in dry THF, chilled to −20μC, and stirred in an ice-salt bath. Equivalent moles of N-methylmorpholine and isobutyl chloroformate were added to the solution. After 10 min, a precooled aqueous solution of NH 2-Phe-OH ( mM; g) and sodium hydroxide ( mM; g) were added.
The reaction. In the current chapter, recent progress has been described in the field of computational quantum chemistry for the development of corrosion inhibitors.
The current chapter is divided into several sections and subdivisions. Recently, the development of green and sustainable technologies for corrosion prevention is highly desirable an increase in ecological awareness and strict environmental.
AFM studies showed that citric acid buffer-saturated n-octanol (CBSO) was the best solvent to promote crystal growth, indicating that both the aqueous .In the present study, the hydrophobicity of a residue α-helical peptide (peptide P) was altered to study the effects of peptide hydrophobicity on the mechanism of action of cationic anticancer peptides.
Hydrophobicity of the nonpolar face of the peptides was shown to correlate with peptide helicity. The self-association ability of peptides in aqueous environment, determined by the reversed.