Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
34 Cards in this Set
- Front
- Back
Is a solution of a weak acid and its salt or weak base and its salt that resists drastic changes in pH when small amounts of acid or basea are added to it. |
Buffer |
|
Buffers control the pH for the ff. Reasons: |
Chemical stability Solubility of the drug Patient's comfort |
|
Factors which can produce alterations of pH are: |
Alkali in certain inexpensive containers Gases present in air such as CO2 and NH3 |
|
Pairs of related chemical compounds capable of resisting large changes in pH of a solution caused by addition of small amount of acid and base |
Buffer systems |
|
Buffer systems are composed of a _____ and the ________of its conjugate base or a weak base and the salt of its conjugate acid |
Weak acid; salt |
|
When an ______ is added in the solution, the _____ member will react. |
Acid; basic |
|
When an ____is added in the solution, the _____ member will react |
Base; acidic |
|
Each component of the buffer pair will react with either acid or base to form the other component repressing the changes in ____ ion concentration |
H |
|
A selected buffer should not: |
Participate in oxidation-reduction reaction Alter the solubility of other components Form complexes with active ingredients |
|
Two inorganic buffer systems |
Phosphate buffer system Borate buffer system |
|
Modified phosphate buffer system by the addition of NaCl to make it isotonic with _______ fluid |
Sorensen Buffer system; physiological |
|
Suitable for ophthalmic, nasal and external preparations |
Borate buffers |
|
Advantage: it can be used in solutions that contain metals that would precipitate in the presence of phosphates |
Borate Buffer system |
|
Disadvantage: _____ (when ingested) ; inefficient at physiological pH; supports _______ |
Toxic; mold growth |
|
Three Primary Borate Buffer systems : |
▪️Feldman's Buffer system ▪️Atkin's and pantin buffer system ▪️Gifford buffer system |
|
Ph of Gifford Buffer system |
pH 6-7.6 |
|
pH of Feldman's Buffer system |
pH 7.6-8.2 |
|
pH of atkins and pantin buffer system |
pH 7.6-11 |
|
Consists of an acid solution containing ____, _____) to make it isotonic), and an alkaline sokution containing ______. |
Feldman's Buffer system; boric acid, sodium chloride, sodium borate |
|
Disadvantage of fledman's buffer system |
Sodium borate is unstable |
|
Consists of an alkaline solution of _____ and an acid buffer solution of _____ and ______ |
Alkin's and pantin buffer system; sodium carbonate, boric acid and sodium chloride. |
|
Disadvantage alkin's and pantin buffer system |
Too basic for most drugs |
|
Similar to feldman buffer system but in place of ______, _____ is added to make it _____ |
Gifford buffer system; sodium chloride, potassium chloride, hypotonic |
|
Aka: Borax, sodium pyroborate, sodium tetraborate, tincal |
Sodium Borate Na2B4O7. 10H2O |
|
Properties of sodium borate: |
Odorless and effloresce in warm, dry air Soluble in water and glycerin Insoluble in alcohol |
|
________ member of the borate buffer system |
Alkaline |
|
_______ borates are insoluble in water (except for alkali metals) |
Metal |
|
Sodium borate is ____, same with _____ |
Toxic; boric acid |
|
Best eyewash when _____ enter the mucosa |
Acid |
|
Used in collyria |
1-2% |
|
Component in many mouthwashes and oral preparations |
Gifford buffer system |
|
Appliex in _____ to mouth ulcers |
Powder |
|
Weak ________ agent |
Bacteriostatic agent |
|
Forms ______ which serves as an ______ agent in cold cream and rose water ointment |
Borax soap; emulsifying agent |