Solubility

Question 1

explain the energy in bond breaking

Answer 1

requires energy and will absorb heat

Question 2

describe the energy of bond making

Answer 2

releases energy and heat

Question 3

what is the general dissolution net effects

Answer 3

absorb heat
positive heat of solution
increase in temperature

Question 4

is solubility of substance at stated temp constant?

Answer 4

yes

Question 5

what does solubility of ionizable functional groups depend on

Answer 5

pH

Question 6

explain solubility of weak acid barbiturates

Answer 6

water soluble salts in alkaline

acidic ph causes free form to come out of solution, much less soluble

Question 7

both cation and anion monovalent

Answer 7

soluble

Question 8

one ion in a salt is monovalent

Answer 8

soluble

Question 9

both cation and anion multivalent

Answer 9

limited water solubility

Question 10

salts of alkali metals and ammonia

Answer 10

water soluble

Question 11

nitrates, sulfates, halides

Answer 11

water soluble

Question 12

hydroxides and oxides salts

Answer 12

not water soluble except for alkali metals and ammonium

Question 13

phospahtes, carbonates, silicates, borates

Answer 13

insoluble excpet for salts of alkali metals and ammonium

Question 14

molecules with polar functional group soluble up to how many carbons

Answer 14

5

Question 15

branched or straight chained molecules more soluble?

Answer 15

branched

Question 16

increased molecular weight effect on solubility

Answer 16

decreases solubility

Question 17

why is water solubility desirable in liquid dose from

Answer 17

dose of drug is in reasonable volume

Question 18

which dose forms do you want reduced solubility

Answer 18

suspensions
organoleptic reasons- mask taste
sustained release

Question 19

when is a drug considered highly soluble

Answer 19

highest dose strength soluble in <250ml water over a pH range of 1-7.5

Question 20

when is a drug considered highly permeable

Answer 20

when extent of absorption is >90% of administered dose

Question 21

class 1 drug

Answer 21

soluble and permeable

Question 22

class two drug

Answer 22

rate limiting step is solubililty

Question 23

class 3 drug

Answer 23

rate limiting step is permeability

Question 24

class 4 drug

Answer 24

no solubility or permeability

Question 25

how do you determine what dose:solubility ratio must be

Answer 25

less thn the fluid volume of where it is being administered

Question 26

eyedrop d:s

Answer 26

less than 0.02ml

Question 27

nasal d:s

Answer 27

less than 0.3ml

Question 28

how is solubility related to ionization

Answer 28

ionized- water soluble | unionized- insoluble

Question 29

what is the target ph for a formulation

Answer 29

+/- 1 ph unit from ph of max solubility

Question 30

what is a salt

Answer 30

ionizable drug with ionizable counter ion of opposite charge

Question 31

whats the most common reason for using a salt form

Answer 31

enhanced solubility leadin to improved bioavailability

Question 32

what should you consider for counter ion selection

Answer 32

pka of conjugate base should be greater than the conjugate acid common ion effects hygroscopicity

Question 33

what is hygroscopicity

Answer 33

ability to absorb moisture from the air

Question 34

what is the common ion effect

Answer 34

adding ions common to the solid will shift the equilibrium back towards the solid and reduce it solubility

Question 35

why is dissolution of salt faster than the parent drug

Answer 35

salt can act as its own buffer in the diffusion layer

Question 36

what cosolvents can be used to increase solubility of parenteral drugs and reduce water content to prevent hydrolysis

Answer 36

glycerin, alcohol, propylene glycol, polyethylene glycol

Question 37

define dielectric constant

Answer 37

ability of solvent to keep twp charges separate

Question 38

in a mixed solvent how do you determine the dielectric constant

Answer 38

multiply volume fraction of each solvent bys its dielectric constant and add them all

Question 39

what do most cosolvent cause

Answer 39

local irritation hemolysis tissue damage

Question 40

what cosolvents do opthalmic products contain

Answer 40

glycerin polyethylene glycol propylene glycol

Question 41

what is the cause of phlebitis

Answer 41

dilution of product prepared with cosolvents given as iv and drug comes out of solution

Question 42

how do cosolvents affect reaction rates

Answer 42

shifr equilibrium between reactants and transition state

Question 43

if the transistion state created by cosolvent is more ionized than reactants how does the cosolvent affect the reaction rate

Answer 43

increasing the polarity of the solvent will increase reaction rate, decreasing the polarity of the solvent will decrease the reaction rate

Question 44

what are surfactants

Answer 44

molecules with polar and non polar regions

Question 45

what is the critical micelle concentration

Answer 45

concentration of surfactant when soluble micelles form

Question 46

what surfactants are used in parenterals

Answer 46

tween and cremophor

Question 47

what do complexing agents do

Answer 47

incorporate with drug so outer hydrophilic groups of the agent interact with water and make the whole complex soluble

Question 48

what are cyclodextrans

Answer 48

molcules with 6,7,8 glucopyranoside units joined through 1-4 bonds

Question 49

what is cyclodextrin used for

Answer 49

complexes with lipid soluble drug molecule on the inside to make the whole complex soluble