midterm 2 Flashcards
Drug solubility In pharmaceutical solutions both the ___ and the ___ are legally required to be present in solution over the shelf-life of the formulated product.
THERAPEUTIC AGENTS
EXCIPIENTS
The dissolution of a therapeutic agent in water involves several key molecular steps:
REMOVAL OF A MOLECULE OF THE DRUG FROM THE SOLID STATE
FORMATION OF A CAVITY WITHIN THE SOLVENT
ACCOMMODATION OF THE DRUG MOLECULE
breakage of solute-solute and solvent-solvent bonds
ENDOTHERMIC PROCESSES
It occurs whenever the Gibb’s free energy of the process is NEGATIVE and involves a balance between the enthalpy of dissolution and the associated entropy at the temperature of dissolution (T).
DISSOLUTION
It is a thermodynamic potential that measures the maximum amount of reversible work that can be performed by a thermodynamic system at constant temperature and pressure.
GIBB’S FREE ENERGY
Refers to the thermodynamic capacity of API.
ENTHALPY
Refers to the m easurement of the degree of randomness or spontaneity of API.
ENTROPY
Factors affecting the solubility of therapeutic agents:
• molecular weight
• Volume
• radius of gyration Density
• number of rotatable bonds
• hydrogen bond donors and
• hydrogen bond acceptors
as the melting point of the therapeutic agent is increased, the solubility would be expected to decrease
INVERSELY RELATED TO THEIR MELTING POINTS
It is directly affected by both the type of chemical substituent groups and the substituent position.
THERAPEUTIC AGENT
thesolubilitiesoftherapeuticagentsthatareeitheracidsorbases (representing the vast majority of drug substances) are __
pH-DEPENDENT
are physiologically inert compounds.
EXCIPIENTS
It facilitates the administration of the dosage form, e.g. pourability, palatability
EXCIPIENTS
• protect the formulation from issues regarding physical and chemical stability
• enhance the solubility of the therapeutic agent.
EXCIPIENTS
It is commonly used due to the low cost and low toxicity of this ingredient.
PURIFIED WATER, USP
■ It is prepared by distillation, ion exchange methods or by reverse osmosis.
■ The solid residue (obtained after evaporation) is less than 1 mg per 100 ml of evaporated sample.
PURIFIED WATER, USP
■ It must not be used for the preparation of parenteral formulations.
PURIFIED WATER, USP
It is an odorless, sweet liquid that is miscible with water and whose co-solvency properties are due to the presence of three hydroxyl groups (termed a triol).
GLYCEROL (GLYCERIN)
It has similar co-solvency properties to ethanol.
GLYCEROL
It contains between 94.9 and 96.0% v/v ethyl alcohol (ethanol) and is commonly used as a co-solvent, both as a single co-solvent and with other co-solvents, e.g. glycerol
ALCOHOL USP
It is an odourless, colourless, viscous liquid diol that contains two hydroxyl groups. It is used in pharmaceutical preparations as a co-solvent, generally as a replacement for glycerin.
PROPYLENE GLYCOL USP
It is a polymer composed of repeating units of the monomer ethylene oxide, Lower-molecular-weight grades (PEG 200, PEG 400) are preferred as co-solvents in pharmaceutical solutions
POLY(ETHYLENE GLYCOL) PEG
These are chemicals that possess both hydrophilic (water-liking) and hydrophobic (water-disliking) regions.
SURFACE-ACTIVE AGENTS
It would prevent drug absorption across biological membranes
DRUG-POLYMER COMPLEX