Exam 2 Review

Pharm Sci

Ionized forms are?

More water soluble

Less lipid soluble

Non-ionized forms are?

More lipid soluble

Less water soluble

Acids are?

Species that can donate a proton

Bases are?

Species that can accept a proton

When acid is added to water?

H3O will increase and OH will decrease to maintain equilibrium pH<7

When a base is added to water?

OH will increase and H3O will decrease to maintain equilibrium ph>7

Strong acids and strong bases do what in water?

Will completely dissociate, = large Ka

Non-electrolytes?

Have no acid or base functionality

Monoprotics?

Can either donate/accept 1 proton/molecule

Polyprotics?

Can either donate/accept 1+ proton/molecule

Ampholytes?

Have both acid and base functionality

Salts of acids are?

Are made with a strong base

like sodium or potassium hydroxide

Will act as conj. base

Salts of bases?

Are made with strong acids

will act as conj. acid

What is expected of fraction ionized of salt forms?

That it will be 100% ionized

ALSO CALCULATED IN RESPECT TO FREE FORM

Excipients?

Inactive ingredients that enable product quality and performance

What are the two classifications of stability?

Physical - molecules remaining the same

Chemical - molecules changed, no longer deal with the same molecule

How might physical instability arise?

Changes in phase, soluble components into insoluble components

What might happen when physical instability occurs?

Precipitation, changes in ph can change drug solubility leading to precipitation

Buffers?

Are a form of excipient, designed to maintain the solution at a consent pH

Why is pH selection in a formulation important?

It is selected to maintain solubility and minimize potential chemical degradation

Buffer capacity?

Is a measure of how well buffers maintain solution pH

What is beta in the Van Slyke mean?

The larger the beta, the more effective a buffer is, and the smaller the change in solution pH upon addition of a strong acid/base

Carbonates?

Biological buffers that maintain stable blood pH and renal function

Phosphates?

Biological buffers, H2PO4- and HPO4- 

Proteins?

Biological buffers, Hemoglobin and albumin

Why are strong acids and base not used in buffers?

They are used to adjust the pH of a solution, only at extreme pHs would their buffer capacity be available

What is intrinsic solubility?

So, moles/L of unionized acid/base that dissolves in solution

So???

Is the BASELINEE, not a function of a pH

Total solubility?

St, is all compound in solution=concentration of unionized compound + ionized form

Precipitation may occur when?

Increases as % unionized increases

Precipitation begins when concentration of HA=So

What determines the chance of a drug precipitating out of a solution?

So, pH of solution, pKa/pkb of acid/base

In weak acids, precipitation at risk when?

pH is below calculated pHp

In weak bases, precipitation at risk when?

pH is above calculated pHp

Rank weak acids from strongest to weakest

Sulfonic acids

Carboxylic acids

Aryl sulfonamides

Phenols

Imides

Thiols

Rank weak bases from strongest to weakest

Guanidines

Aliphatic nitrogens

Amidines

Ar-NH2

Aromatic Nitrogens

Strong Bases

LiOH Lithium hydroxide

NaOH Sodium hydroxide

KOH Potassium hydroxide

Ca(OH)2 Calcium hydroxide

Mg(OH)2 Magnesium hydroxide

Ba(OH)2 Barium Hydroxide

Strong acids

HCl Hydrochloric acid

H2SO4 Sulfuric Acid

HI Hydroiodic Acid

HClO4 Perchloric Acid

HNO3 Nitric Acid

HBr Hydrobromic acid