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Class III – low permeability, high solubility . Example: cimetidine; The absorption is limited by the permeation rate but the drug is solvated very fast. If the formulation does not change the permeability or gastro-intestinal duration time, then class I criteria can be applied. Class IV – low permeability, low solubility . Example: bifonazole
Esterification is also used to control solubility. For example, stearate and estolate esters of drugs have decreased solubility in gastric fluid. Later, esterases in the gastrointestinal tract (GIT) wall and blood hydrolyze these esters to release the parent drug. Coatings on a tablet or pellet may act as barriers to reducing the dissolution rate.
Where X m is the mole fraction solubility of the solute, X 1 and X 2 denote the mole fraction solubility in neat cosolvent and water. While this model is only correlative in nature, further analysis allows for the creation of a predictive element. Simplifying the above equation to: logX m = logX 2 + σ • ƒ 1
Solubility in water can be estimated from the number of hydrogen bond donors vs. alkyl sidechains in the molecule. Low water solubility translates to slow absorption and action. Too many hydrogen bond donors, on the other hand, lead to low fat solubility, so that the drug cannot penetrate the cell membrane to reach the inside of the cell.
It has the most rapid onset and offset of the volatile anesthetic drugs used for general anesthesia due to its low solubility in blood. Some drawbacks of desflurane are its low potency, its pungency and its high cost (though at low flow fresh gas rates, the cost difference between desflurane and isoflurane appears to be insignificant [2]).
Lipinski's rule of five, also known as Pfizer's rule of five or simply the rule of five (RO5), is a rule of thumb to evaluate druglikeness or determine if a chemical compound with a certain pharmacological or biological activity has chemical properties and physical properties that would likely make it an orally active drug in humans.
The drugs, while used to treat diabetes, show promise in reducing the risk of age-related diseases and kidney disease, by reducing oxidative stress and inflammation, and improving heart health and ...
This low solubility affects the bioavailability of the drug, meaning the rate at which the drug reaches the circulatory system and thus the target site. Low bioavailability is most commonly seen in oral administration, which is the preferred choice for drug administration due to its convenience, low costs, and good patient practice. [28]