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The drugs are classified in BCS on the basis of solubility and permeability. Solubility class boundaries are based on the highest dose strength of an immediate release product. A drug is considered highly soluble when the highest dose strength is soluble in 250 ml or less of aqueous media over the pH range of 1 to 6.8.
Download as PDF; Printable version; ... drugs and biologicals with over 10,000 monographs on single substances or groups of ... solubility in solvents commonly used ...
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 forms the basis for design, manufacture, and distribution of drug products and serves as the foundation for the stable and proper use of medical drugs. [2] It covers areas such as solubility, pharmacokinetics and drug delivery. Physical pharmacy serves as principles that guide the pharmaceutical developments. [2]
The distribution of a drug between tissues is dependent on vascular permeability, regional blood flow, cardiac output and perfusion rate of the tissue and the ability of the drug to bind tissue and plasma proteins and its lipid solubility. pH partition plays a major role as well. The drug is easily distributed in highly perfused organs such as ...
The drug apparent permeability (P app) is calculated by normalizing the drug flux (j) over the initial concentration of the API in the donor compartment (c 0) as: Equation 2: = / Dimensionally, the P app represents a velocity, and it is normally expressed in cm/sec. The highest is the permeability, the highest is expected to be the ...
Formulation studies then consider such factors as particle size, polymorphism, pH, and solubility, as all of these can influence bioavailability and hence the activity of a drug. The drug must be combined with inactive ingredients by a method that ensures that the quantity of drug present is consistent in each dosage unit e.g. each tablet. The ...
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.