Solutions Flashcards
What is a solution?
A chemically and physically homogeneous mixture of two or more substances
What is the stability of solutions?
Poor
What is solubility?
Amount of solute dissolved in a given quantity of liquid at a given temperature
How do you increase solubility?
- Select a different solubilizing agent or solvent/co-solvent
- Select different chemical salt form
- Change pH of the solution
What is the relation between polar groups and aqueous solubility?
More polar groups = better solubility
What is the relation between salts and solubility?
- Monovalent cations are generally water soluble (Na+, K+)
2. Divalent cations are less water soluble (Ca++, Hg++)
What is the relation between molecular weight and solubility?
Increased weight = decreased solubility
What is the relation between halogens and solubility?
Halogens decrease solubility
What are co-solvents used for?
- Enhances solvation ability of water
2. Contributes to product’s chemical and/or physical stability
What are some common co-solvents in oral preparations?
Ethyl alcohol, glycerin and propylene glycol
What are some common co-solvents in oral oleaginous injections?
Corn oil, cottonseed oil, peanut oil and sesame oil
What are some traits of alcohol?
- Miscible with water.
- Able to dissolve many water insoluble ingredients such as drugs, flavorants, colorants, and antimicrobial preservatives.
In higher concentration, what can ethanol be used as?
Antimicrobial
What are some traits of glycerol and propylene glycol?
- Miscible with water and alcohol – excellent co-solvent
- Has preservative properties
- Used as a stabilizer in addition to help solubilize materials
Is purified water acceptable for parenteral administration?
No
What happens to solubility when there is a net increase of heat?
Increase of dissolution rate, not increase of solubilty
What do powders in dry mixtures contain?
Contains all components of the formulation except solvent
What are oral rehydration solutions used for?
Treat rapid fluid loss
What is the most commonly employed sugar in syrups?
Sucrose
What are some common sugar substitutes?
Sorbitol, glycerin, propylene glycol, methylcellulose, hydroxyethylcellulose (HEC)
*sugar substitutes for diabetics
What kind of vehicle are syrups?
Non-medicated or flavored
Why is there a high sugar count in syrups?
Ties up water therefore prevents microbial growth. Try to minimize free water.
What are some traits of elixirs?
- 10-12% alcohol
- Poorer the water solubility, the higher the proportion of alcohol
- Should be used to mask bad taste or high potency
What are some traits of tinctures?
- Plant extract
2. 15-80% alcohol
What are some traits of spirits?
- Prepared by simple solution, maceration, or distillation
- > 60% alcohol
- Forms a milky solution
- Used as a flavoring agent or medicinally
What are some common extraction methods?
- Maceration
2. Percolation
What is the maceration process?
Drug is soaked in solvent
What is the percolation process?
Drug is extracted by the slow
passage of solvent through a column of the material
What are some traits of coal tar topical solution?
- An alcoholic solution containing 20% coal tar and 5% polysorbate 80 (Tween 80)
- Prepared by the maceration of coal tar for 7 days with agitation, then filtered
- Final content is 81 – 86% alcohol
What are some traits of povidone iodine topical solution?
Chemical complex of iodine and polyvinyl pyrrolidine used as a surgical scrub
What are some traits of thimerosal topical solution?
Water soluble organic mercury antibacterial
used to disinfect skin prior to skin
What are some traits of collodions
Painted/applied to skin and allowed to dry to form a somewhat flexible cellulose film
