Toxicokinetics
Frank A. Barile in Barile’s Clinical Toxicology, 2019
A solution is a chemically and physically homogeneous mixture of two or more substances in a liquid. Similarly, suspensions are pharmaceutical preparations of finely divided, insoluble solids dispersed in a liquid vehicle for oral, inhalation, or parenteral administration. The extent to which a solute dissolves in a liquid is referred to as solubility. Solubility is also described as the concentration of a compound in a solution that is in equilibrium with a solid phase at a specified temperature. For any defined solid chemical or drug, the degree of solubility is determined by the innate chemical characteristics of the solid and the temperature. Thus, solubility is constant for a solid in a particular solvent at a given temperature. In addition, different categories of solutions or suspensions are possible depending on the size of the dispersed particle.* Consequently, it is conceivable to formulate homogeneous solutions of solids, liquids, or gases (solute) in liquids (solvent). The concept can be further extended into the preparation of gases in gases and solids in solids. More detailed discussion of the chemical properties of true solutions, solute–solvent interaction, and dispersion systems can be obtained from the Suggested Readings, some of which present the reader with quantitative data on the behavior and properties of solutions). This section is concerned with basic definitions of solutes and solvents, the influence of temperature on solution stability, and the eventual movement of a dissolved substance toward absorption.
Solute Translocations
Lelio G. Colombetti in Biological Transport of Radiotracers, 2020
The simple notion that solute translocation permits entry into the cell of biochemical nutrients and exit of cellular wastes defines only a portion of the biochemical and physiological impact of transport in eukaryotic, multicellular organisms. On one hand, the complete description requires consideration of membrane-enclosed, intracellular organelles and the roles they play in the segregation of biochemical solutes and reactions. On the other hand, the description requires consideration of solute translocation from one tissue or organ to another. Over all, solute transport maintains transmembrane and interorgan communication as well as the appropriate intracellular environment. An additional consideration in solute translocation relates to transport processes involving membrane flow. Although endocytosis (as it relates to cellular uptake) and exocytosis (as it relates to cellular secretion) do not represent mechanisms of biological transport in its usual — and most correct — sense, both processes reflect important mechanisms for the translocation of large solutes across cellular membranes. In the broadest sense, the scientist who studies transport, as the scientist who studies metabolism, must ultimately be concerned with mechanism, regulation, and the continuous interplay of parallel, sequential, and opposing phenomena. I will concentrate on simple aspects of transmembrane flow in this chapter, but will try not to neglect completely these other important aspects of solute translocation in complex organisms.
Method of Extraction
Ravindra Kumar Pandey, Shiv Shankar Shukla, Amber Vyas, Vishal Jain, Parag Jain, Shailendra Saraf in Fingerprinting Analysis and Quality Control Methods of Herbal Medicines, 2018
A solution may be classified according to the states in which the solute and solvent occur, since three states of matter (gas, liquid, and crystalline solid) exist. When solids or liquids dissolve in a gas to form a gaseous solution, the molecules of the solute can be treated thermo-dynamically like a gas, similarly when gases or solids dissolve in liquids, the gases and the solids can be considered to exist in the liquid state. In the format of solid solutions, the atoms of the gas or liquid take up positions in the crystal lattice and behave like atoms or molecules of solids. The solutes (whether gases, liquids or solids) are divided into two main classes, non-electrolytes and electrolytes. Non-electrolytes are the substances that do not yield ions when dissolved in water, and therefore, do not conduct an electric current through the solution, for example, sucrose, glycerin, naphthalene, and urea. Electrolytes are substances that form some ions in solution, conduct the electric current, and show apparent “anomalous” colligative properties, that is, they produce a considerably greater freezing point depression and boiling point elevation than do non-electrolytes of the same concentration, for example, HCl, sodium sulfate, ephedrine, and phenobarbital. Electrolytes may be sublimed further into strong electrolytes and weak electrolytes which depend on whether the substance is completely or only partly ionized in water. Hydrochloric acid and sodium sulfate are strong electrolytes whereas ephedrine and phenobarbital are weak electrolytes.
Transdermal delivery via medical device technologies
Published in Expert Opinion on Drug Delivery, 2022
Shubhangi Shukla, Ryan H. Huston, Blake D. Cox, Abhay R. Satoskar, Roger J. Narayan
While drugs come in innumerable structural combinations, one way to classify them easily is using two main characteristics which provide unique advantages or challenges to their use, specifically drug permeability and drug solubility; hence, these two traits define the Biopharmaceutics Classification System taxonomy [111]. Iontophoresis has been shown to benefit many drugs with varying combinations of these traits; however, the most challenging drugs to deliver are those with low permeability and low solubility. Compared to water-soluble drugs, iontophoresis has not been thoroughly researched for use with lipophilic/hydrophobic or otherwise water-insoluble drugs. The current research has been largely focused on delivery of drugs via iontophoresis using water-based buffers and water-soluble ions; however, the principle of electroosmosis clearly supports the penetration of nonpolar or uncharged molecules as well [100]. In addition, creative drug formulations can enhance iontophoretic delivery by (a) placing drugs in liposomes or micelles; (b) mixing solutes with surfactants, cosolvents, or complexion solutes; or (c) substituting the solvent altogether [112].
Central composite rotatable design for optimization of budesonide-loaded cross-linked chitosan–dextran sulfate nanodispersion: characterization, in vitro diffusion and aerodynamic study
Published in Drug Development and Industrial Pharmacy, 2019
Divyanka Shrikant Bodas, Pradum Pundlikrao Ige
Solubility is a property of a solid, liquid, or gaseous chemical substance called solute which is to be dissolved in a solid, liquid, or gaseous solvent to form a homogenous solution of the solute in the solvent. The solubility of substance primarily depends on the solvent used as well as on temperature and pressure. The solubility of budesonide was studied in different solvents. The solubility of drug in dichloromethane, ethanol, PBS (pH 7.4 and pH 6.8) and purified water was found to be 102.66 ± 4.03 mg/mL, 92 ± 1.36 mg/mL, 0.017 ± 0.0008 mg/mL, 0.0216 ± 0.0001 mg/mL, and 0.0450 ± 0.0005 mg/mL, respectively. Solubility results showed highest solubility in dichloromethane and ethanol. The extent of solubility of a substance in a specific solvent is measured as the saturation concentration where adding more solute does not increase its concentration in the solution.
ROS-generating, pH-responsive and highly tunable reduced graphene oxide-embedded microbeads showing intrinsic anticancer properties and multi-drug co-delivery capacity for combination cancer therapy
Published in Drug Delivery, 2022
Adilakshmi Boddu, Obireddy Sreekanth Reddy, Dahong Zhang, K. S. V. Krishna Rao, Wing-Fu Lai
Emulsification followed by the gelation process was used to make curcumin-loaded microspheres. In brief, 50 mg of curcumin was dispersed in 5 mL of ethanol by magnetic stirring for 3 minutes and then transferred to 10 mL of 3% SA solution. The mixture was kept under stirring until the formation of a homogenous solution. The CUR-alginate mixture was emulsified in liquid paraffin oil at a ratio of 1:10 with 2% v/v tween 80 as a surfactant and kept under mechanical stirring at 300 rpm to produce a water/oil emulsion. Then a 10% w/v calcium chloride solution was introduced drop-wise into the emulsion for gelation while keeping the stirring speed constant for 90 minutes. After that, the formed microspheres (SA-CUR) were filtered and washed with petroleum ether before being air-dried at ambient conditions.
Related Knowledge Centers
- Chemistry
- Filtration
- Rayleigh Scattering
- Solvation
- Mixture
- Chemical Polarity
- Suspension
- Scattering
- Tyndall Effect
- Relative Density