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Urolithiasis
Published in Karl H. Pang, Nadir I. Osman, James W.F. Catto, Christopher R. Chapple, Basic Urological Sciences, 2021
Metastable urine = supersaturated urine without stone formation.Concentration between solubility product and formation product.If more solute is added to metastable urine, which cannot be counteracted by inhibitors, then microcrystals will form.Increasing solute concentrations within metastable urine results in unstable urine and increased nucleation potential.
Renal Pathophysiology
Published in Manit Arya, Taimur T. Shah, Jas S. Kalsi, Herman S. Fernando, Iqbal S. Shergill, Asif Muneer, Hashim U. Ahmed, MCQs for the FRCS(Urol) and Postgraduate Urology Examinations, 2020
Herman S. Fernando, Mohamed Yehia Abdallah, Iqbal S. Shergill
The concentration product, the point at which the dissolved and crystalline components are in equilibrium for a specific set of conditions, at the point of saturation is called the thermodynamic solubility product, Ksp. Inhibitors can generally prevent the process of crystal growth or aggregation above the formation product, Kf.
Nephrolithiasis: etiology, stone composition, medical management, and prevention
Published in J Kellogg Parsons, E James Wright, The Brady Urology Manual, 2019
Crystallization: Stones are essentially salts that precipitate out of urineThe point of saturation of a salt in solution is called the solubility product (Ksp)When the product of the components of a salt (e.g. calcium and oxalate) exceeds Ksp, salt crystals will precipitate out of solutionCrystallization is based on Ksp, pH, and the presence of stone inhibitors and promotersSome stone inhibitors increase the concentration of stone components required for the crystals to precipitate out of solution (i.e. for the stone crystals to form).
Hydrogeochemical characterization, multi-exposure deterministic and probabilistic health hazard evaluation in groundwater in parts of Northern India
Published in Toxin Reviews, 2023
Herojeet Rajkumar, Pradeep K. Naik, Gagandeep Singh, Madhuri Rishi
The results of geochemical profiling (Piper plot, Gibb’s diagram, and interionic plots) and PCM clearly indicated that the aquifer chemistry of the study area is mainly influenced by interactions of aquifer materials (minerals-water phases) and cation exchange, except for some ions. Saturation index (SI) is computed to ascertain the thermodynamic equilibrium about the dissolution and precipitation state of minerals vis-à-vis the types of water–alluvial interaction (Khan et al.2021, Liu et al.2021). SI is the logarithm (base 10) of the ratio of ionic activity product (IAP) to mineral solubility product constant (Ksp) and is evaluated by using Equation (20)
Insight of the various in silico screening techniques developed for assortment of cocrystal formers and their thermodynamic characterization
Published in Drug Development and Industrial Pharmacy, 2021
Parth Sarathi, Swarupanjali Padhi
The solubility of co-crystal is highly dependent on the concentration of co-crystal components, present in the solution phase. Therefore, solubility product is employed to explain the dissociation of the co-crystal into their components and the equilibrium. Co-crystal solubility and stability can be analyzed by transition point at three-phase equilibrium (i.e. co-crystal, drug or co-former and solution phase). Solubility product (Ksp) describes the dissociation of co-crystal in the solution. Higher Ksp indicates the higher solubility of co-crystal [2,68]. A detailed discussion on solubility product have been done under the heading of phase solubility diagram. Free energy of co-crystal solubilization depend upon the free energy released from the crystal lattice of co-crystal, and the free energy related with solvation barrier, as follow [69]: solution indicates the Gibbs free energy associated with the process of solubilization, lattice indicates the Gibbs energy correlated with the crystal of a co-crystal and solvation indicates the Gibbs free energy related with the solvation barrier. Co-crystal dissolution is enhanced, when the lattice and solvation energy becomes negligible, it is because the free energy change for solubilization has decreased. For hydrophobic drug, solvation is the significant barrier on behalf of the solubilization of co-crystal.
Comparison of the relative stability of pharmaceutical cocrystals consisting of paracetamol and dicarboxylic acids
Published in Drug Development and Industrial Pharmacy, 2018
Naoto Suzuki, Masatoshi Kawahata, Kentaro Yamaguchi, Toyofumi Suzuki, Kazuo Tomono, Toshiro Fukami
Subsequently, phase-solubility diagrams of each cocrystal were prepared in acetonitrile, and the solubility products at the transition concentration reported by Good et al. [13] were calculated (Figure 8). They suggested that the solubility product is a useful index for solubility of cocrystals. The drug and ligand solution concentrations at the invariant point are referred to as the Ctr. This point separates regions where either the solid cocrystal or drug is thermodynamically stable. A solid phase of cocrystal is stable beyond the Ctr, where pure drug is stable below this concentration. Evaluating of Ctr represents the range of cocrystal thermodynamic stability in solution whereas evaluating of Ksp means the equilibrium with cocrystal. This means measurements based on Ctr will have the closest proximity and most accuracy. In this study, the solubility products of APAP–OXA and APAP–MLA were 2.3 × 10−1 and 4.6 × 10−1 mol/l, respectively, implying that APAP–OXA was formed at lower concentration than APAP–MLA. Thus, APAP–OXA APAP–OXA preferentially precipitated in the ternary system. In the case of other solvents in particular methanol, drawing the phase-solubility diagrams was difficult at ambient temperature because of an excess solubility of the solutes and/or decomposed materials. These results indicate that the stability of the cocrystals prepared by the slurry method was attributable to their solubility. Under conditions allowing two cocrystals to form, the cocrystal with low solubility formed preferentially. Good et al. [13] and Jayasankar et al. [25] reported that the solubility and stability of cocrystals differed relative to the solvent, and a similar tendency was observed in the present study. This observation is useful for selecting the solvents used to prepare cocrystals.