pharmaceutics exam 2

solid

the most ordered state of matter

eutectic mixtures

liquid

less ordered state of matter

may or may not mix

miscible v immiscible

gas

least ordered state of matter

mixed spontaneously

evaporation/vaporization

phase transition from liquid to gas

miscible

applies to the liquid state

means liquids mix

immiscible

applies to liquid state

means liquids do not mix

eutectic point

lowest melting point (intersection of graph)

eutectic mixtures advantages

good for liquids/semisolids (no grittiness)

eutectic mixtures disadvantages

bad for dry, solid dosage forms (liquify)

eutectic mixture

solid blend of 2 or more components that melt/solidify at a single sharp temperature lower than any of its individual constituents

top of curve

liquid mixture of both drugs (reaches highest temperature)

right side of curve

liquid mixture of both drugs; solid in drug on x-axis

intersect

solid form of both drugs

comminution

reduction of solid materials from larger particle size to smaller particle size (particle size reduction)

to increase dissolution rate, increase absorption, increase formulation ease, increase extraction

why do we use communution?

trituration, pulverization by intervention, levigation, spatulation, lyophilization, spray drying

what are the methods of comminution?

trituration

reducing particle size using mortar and pestle

pulverization by intervention

reducing particle size using a solvent to dissolve a solute

levigation

reducing particle size by using an insoluble liquid (not for dry powders). smooth into paste while wet

spatulation

small-scale mixing to make a uniform mixture (blending/mixing technique)

lyophilization

freeze drying by decreasing the temperature and pressure leading to sublimation (solid to gas)

spray drying

bad for thermolabile drugs

may degrade the drug if thermobile

expensive process

what are disadvantages in spray drying?

solutions

liquid preparations that contain one or more chemical substances dissolved in a subtle solvent

transparent, form spontaneously, and particles are in their smallest size

what are the characteristics of solutions?

solute-solvent interactions must overcome solute-solute forces

(solute-solvent interactions must be stronger than the solute-solute forces in order to break them apart)

what is the formulation rule (of solutions)

“like dissolves like”

what is the dissolution theory?

polar solvents

high dielectric constant (can store more energy)

break bonds

dissolve polar drugs

nonpolar solvent

low dielectric constant

dissolves non-polar drugs

dipole interactions/Van Der Waals

dissolution rate

how fast a solute dissolves in a solvent

surface area, length of stagnant layer, solubility

what affects dissolution rate?

agitation

increases dissolution rate by decreasing stagnant layer (thin layer on surface)

.

an increase in viscosity (thickness) increases the stagnant layer

increase temp (positive heat solution)

decrease temp (negative heat solution)

what are ways to increase solubility? (in regard to temperature)

increase/decrease temperature

increase pH

add cosolvent

complexation (may degrade drug)

what are ways to increase solubility

increasing pH increase aqueous solubility in acids but decreases solubility in bases

what does increasing pH do to solubility in acids/bases?

increases aqueous solubility

what does increasing pH do to acids

decreases aqueous solubility

what does increasing pH do to bases

the presence of other compounds (drug competition); agitation

what decreases solubility? what keeps it the same?

agitation

increases dissolution rate but decreases solubility

increases dissolution rate, maintain solubility

what does particle size reduction do?

weak acid

increase in solubility when pH is increases

weak base

increase in solubility when pH is low

.

always use molarity in pH solubility equations

increase surface area

increase temperature

increase viscosity

decrease particle size

increase agitation = decrease stagnant layer

what are the dissolution rate factors?

increasing agitation decreasing stagnant layer

what does increasing agitation do to the stagnant layer

colligative properties

physical characteristics of solutions that depend solely on the number of solute particles present (not identity)

.

a change in one colligative property can be used to predict a change in the other property

decrease freezing point, increase boiling point, decrease vapor pressure, osmotic pressure

what are the types of colligative propeties

osmotic pressure

the most important physiologically (colligative property)

.

more ions = bigger effect

more concentration = more electrical flow/strength

.

van’t hoff factor (I) used for colligative properties

osmotic pressure

pressure to stop solvent movement through a semipermeable membrane

the drug must be maintained at the calculated temperature in order to increase solubility

what is the issue with increasing temp to increase solubility?

alcohol USP

contains 95% ethanol

diluted alcohol

1:1 ratio with water and alcohol USP

rubbing alcohol

70% ethanol, 70% isopropanol

distillation, ion-exchange, reverse-osmosis

water (USP methods)

distillation

type of water USP method

water is heated and steam is collected

ion-exchange

type of water USP method

water passes through column of cation/anion exchangers

reverse osmosis

type of water USP method

water as steam across filter; travels from high to low concentration

syrups

concentrated, aqueous preparations of a sugar/sugar substitute without flavoring agents and medicinal substances

contains: sucrose/sugar sub and preservative

sucrose (sugar) or sugar substitute

what is the main ingredient in syrups

viscous (dont spill easy), taste-masking

what are the advantages of syrups?

high sucrose content; sticky

disadvantages of syrups

elixirs

clear, sweetend hydroalcoholic solutions intended for oral use and usually flavored to enhance palatability (increased taste). contains alcohol (>12% = no preservative)

can have both water and alcohol soluble components

stable

ease of preparation

advantages of elixirs

alcohol content

drug interactions

less effective in taste masking

disadvantages of elixirs

0.5%

alcohol content for ages 6 and younger. <6

5%

alcohol content for ages 6-12

10%

alcohol content for ages 12 and older. >12

tinctures

alcoholic/hydroalcoholic extracts

collodions

liquid preparations composed of pyroxylin dissolved in a 3:1 mixture of ether:alcohol

highly flammable (ether)

pyroxylin + ether + alcohol

what are collodions are made of?

menstruum

extraction method; solvent used for extraction

marc

extraction method; leftover solid

percolation

Process P → solvent passed through a column of the drug

common extraction method

acid

proton donor

base

proton acceptor

strong acid/base

completely ionizes/dissociates in H2O

weak acid/base

partially ionizes/dissociates in water

buffers

resist pH change upon addition of an acid or base

buffer capacity

the measure of a solutions ability to resist pH changes upon adding strong acids or bases (strength)

drug stability, drug absorption, drug activity, patient comfort

why control pH?

a buffer forms where rate constant (k) is the lowest

when does a buffer form?

low k is slower degradation (slow breakdown of drug)

what does a low rate constant (k) do?

solubility

how much dissolves at equilibrium

dissolution rate

how fast substance dissolves

.

glycols are more polar than alcohols

water

the most common solvent

stable

solutions are physically ___