Partition coefficient
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V předložené studii se experimentálně stanovily dělící poměry diltiazemu v soustavě n-oktanolu a tlumivých roztoků o známém pH. Z těchto hodnot se vypočítaly rozdělovači koeficient a disociační konstanta diltiazemu. Léčivo s rozdělovacím koeficientem P = 597 a disociační konstantou Ka = 1,72 .10 (pKa = 7,76) bude mít předpoklady pro dobrou absorbci ve střevním traktu.
The present study experimentally determined the partition ratios of dilthiazem in the system of n-octanol and buffering solutions with known pH's. These values served to calculate the partition coefficient and dissociation constant of dilthiazem. The drug with the partition coefficient P = 597 and the dis association constant Ka = 1.72.10 (pKa=7.76) will have prerequisites for good absorption in the intestinal tract.
Medzi faktory, ktoré výrazne ovplyvňujú dostupnosť liečiva z liekovej formy, patria i pomocné látky, ktoré sú nevyhnutnou súčasťou pri formulácii lieku. Pri výbere pomocných látok pre novo formulovaný liek je potrebné vedieť, že liek nie je nikdy jednoduchou zmesou na sebe nezávislých zložiek, ale je to systém dynamický, v ktorom prebiehajú rôzne fyzikálne procesy i chemické pochody. Predložená práca je zameraná na štúdium vplyvu pomocných látok zo skupiny humektantov s odstupňovanou koncentráciou a konzervačnej prísady na rozdeľovací koeficient potenciálneho liečiva XIX M. Rozdeľovací koeficient (P’) bol stanovovaný v systéme n-oktanol/ vodný roztok s odstupňovanou koncentráciou polyolov. Pri týchto stanoveniach n-oktanol simuloval rohovú vrstvu, vodný roztok základ topického lieku. Z pomocných látok boli použité polyoly – glycerol, propylénglykol a sorbitol v 5; 10; 15 a 20% koncentrácii a antimikrobiálne účinný roztok Ajatinu® (Solutio benzododecinii bromati) v dvoch koncentráciach 0,01 a 0,1 % (m/m). Zo získaných výsledkov vyplýva, že na hodnoty rozdeľovacieho koeficientu potenciálneho liečiva XIX M majú veľký vplyv pomocné látky. Hodnota tohto parametra, a tým aj biologická dostupnosť, závisia nielen od druhu použitého polyolu a jeho koncentrácie, ale aj od koncentrácie použitej konzervačnej prísady, v tomto prípade Ajatinu®.
The factors which markedly influence availability of the drug from the dosage form include also auxiliary substances, which are an inevitable component in the formulation of the drug. In the selection of auxiliary substances for a newly formulated drug, it is necessary to know that the drug is never a simple mixture of mutually independent ingredients, but a dynamic system in which various physical and chemical processes take place. The present paper aims to study the effect of auxiliary substances from the group of humectants with graded concentrations and the effect of the preservative on the partition coefficient of potential drug XIX M. Partition coefficient (P’) was estimated in the system n-octanol/aqueous solution with graded concentrations of polyols. In these estimations, n-octanol simulated the horny layer, and the aqueous solution the base of the topical preparation. The auxiliary substances employed were polyols – glycerol, propylene glycol, and sorbitol in 5, 10, 15, and 20% concentrations and an antimicrobially effective solution of Ajatin® (Solution benzododecinii bromati) in two concentrations of 0.01 and 0.1 wt %. It follows from the obtained results that the values of partition coefficient of potential drug XIX M are greatly influenced by auxiliary substances. The value of this parameter, and therefore also biological availability, depend not only on the sort of the polyol used and its concentration, but also on the concentration of the preservative employed, in this case Ajatin®.
V práci sa sledoval vplyv pomocných, látok (propylénglykol, glycerol a sorbitol, ktoré ako humektanty a emolienty sú súčasťou niektorých základov topických prípravkov) na rozdeľovací koeficient (P') heptakaínu (XIX) a jeho morfollno- (XIX M), pyrolidíno- (XIX Z), 3-heptyloxy (XX Z), 2-pentyloxy(XIII) analógov a nesubstituovaného základného liečiva tejto série (IR-1). Obsah liečiv sa stanovoval v systéme n-oktanol/vodný roztok liečiva s prísadou 5; 10; 15 a 20% viacsýtnych alkoholov spektrofotometrický vo vodnej vrstve. Vplyv viacsýtnych alkoholov na P' sa nedá zovšeobecniť, pretože závisí od ich koncentrácie ako aj od druhu lokálneho anestetika, napr. F látky XIX M sa s rastúcou koncentráciou propylénglykolu znižuje a naopak s rastúcou koncentráciou sorbitolu zvyšuje. Z toho vyplýva, že k formulácii liekovej formy s uvedenými lokálnymi anestetikami treba pristupovať vždy individuálne.
The paper examined the effects of auxiliary substances (propyleneglycol, glycerol and sorbitol which as humestants and emollients are components of some bases of topical preparations) on the partition coefficient (P) of heptacaine (XIX) and its morpholino- (XIX M), pyrolidino- (XIX Z), 3-heptyloxy (XX Z), 3-pentyloxy- (XIII) analogues and the unsubstituted fundamental drug of this series (IR-1). The content of drugs was determined in the system n-octanol/aqueous solution of the drug with an addition of 5; 10; 15 and 20% of multisaturate alcohols spectrophotometrically in an aqueous layer. The effect of multisaturate alcohols on P caimot be generalized as it depends on their concentration as well as the sort of the local anaesthetic agent, e .g. P of substance XIXM is decreased with increasing concentration and, on the other hand, it is increased with increasing sorbitol concentration. The results show that formulation of a dosage form including these local anaesthetics must be always approached individually.
High-pressure phase behavior of systems containing water, carbon dioxide and organics has been important in several environment- and energy-related fields including carbon capture and storage, CO2 sequestration and CO2-assisted enhanced oil recovery. Here, partition coefficients (K-factors) of organic solutes between water and supercritical carbon dioxide have been correlated with extended linear solvation energy relationships (LSERs). In addition to the Abraham molecular descriptors of the solutes, the explanatory variables also include the logarithm of solute vapor pressure, the solubility parameters of carbon dioxide and water, and the internal pressure of water. This is the first attempt to include also the properties of water as explanatory variables in LSER correlations of K-factor data in CO2-water-organic systems. Increasing values of the solute hydrogen bond acidity, the solute hydrogen bond basicity, the solute dipolarity/polarizability, the internal pressure of water and the solubility parameter of water all tend to reduce the K-factor, that is, to favor the solute partitioning to the water-rich phase. On the contrary, increasing values of the solute characteristic volume, the solute vapor pressure and the solubility parameter of CO2 tend to raise the K-factor, that is, to favor the solute partitioning to the CO2-rich phase.
- MeSH
- oxid uhličitý * MeSH
- rozpouštědla chemie MeSH
- rozpustnost MeSH
- roztoky MeSH
- voda chemie MeSH
- vodíková vazba MeSH
- Publikační typ
- časopisecké články MeSH
- MeSH
- anestetika lokální chemie MeSH
- glycerol chemie MeSH
- karbamáty chemie MeSH
- povrchové napětí MeSH
- propylenglykoly chemie MeSH
- sorbitol chemie MeSH
- Publikační typ
- srovnávací studie MeSH
In recent years, organic ultraviolet filters (UVFs) received considerable attention as a group of emerging contaminants, including in Australia where the use of UVFs is particularly relevant. Passive sampling using polymers has become widely used for routine monitoring of chemicals in the aquatic environment. Application of passive samplers for monitoring chemicals in the water relies on calibration data such as chemical's polymer-water partition coefficient (Kpw) and diffusion coefficients in the sampling material (Dp), for understanding uptake and kinetic limitations. In the present study, Kpw and Dp for nine UVFs were estimated. Kpw values were determined in different water - polymer partition experiments where (1) a given mass of chemicals was dosed into the water and (2) into the polymer. Diffusion coefficients were determined using the stacking method. The estimated log Kpw and log Dp ranged from 2.9 to 6.4 L kg-1 and -11.1 to -10.5 m2s-1, respectively. The sufficient high Dp allows application of kinetic models that only consider water boundary-controlled uptake for converting silicone sampler uptake into an aqueous phase concentration using the presented Kpw.
- MeSH
- chemické látky znečišťující vodu analýza MeSH
- filtrace MeSH
- kalibrace * MeSH
- monitorování životního prostředí metody MeSH
- organické látky škodlivé účinky MeSH
- polymery chemie MeSH
- silikony * MeSH
- ultrafialové záření MeSH
- voda MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Austrálie MeSH
Biphasic solvent systems composed of an ionic liquid (IL) and supercritical carbon dioxide (scCO(2)) have become frequented in synthesis, extractions and electrochemistry. In the design of related applications, information on interphase partitioning of the target organics is essential, and the infinite-dilution partition coefficients of the organic solutes in IL-scCO(2) systems can conveniently be obtained by supercritical fluid chromatography. The data base of experimental partition coefficients obtained previously in this laboratory has been employed to test a generalized predictive model for the solute partition coefficients. The model is an amended version of that described before by Hiraga et al. (J. Supercrit. Fluids, in press). Because of difficulty of the problem to be modeled, the model involves several different concepts - linear solvation energy relationships, density-dependent solvent power of scCO(2), regular solution theory, and the Flory-Huggins theory of athermal solutions. The model shows a moderate success in correlating the infinite-dilution solute partition coefficients (K-factors) in individual IL-scCO(2) systems at varying temperature and pressure. However, larger K-factor data sets involving multiple IL-scCO(2) systems appear to be beyond reach of the model, especially when the ILs involved pertain to different cation classes.
