physical stability

Question 1

3 different states of medicines and excipients

Answer 1

-crystaline solid
-liquid/solution
-gas

Question 2

whats the exception to medicines being at atmospheric pressure

Answer 2

• metered dose inhalers

Question 3

solid liquid transition

Answer 3

-in solid atoms oscillate in fixed positions this means increase temperature disrupts the ordered nature of the lattice

-however they a crystaline solids they have a super high melting point

Question 4

exception to having a melting point

Answer 4

suppository bases that melt at room temperature

Question 5

liquid to solid

Answer 5

-feezing that creates crystals of ice which interferes with the physical stability

Question 6

solid to gas

Answer 6

iodine can sublime.

-also freeze drying freeze water and sublime it

Question 7

liquid to gas

Answer 7

cytoxics high vapour pressure if they spill they go into a toxic gas

Question 8

evaporation

Answer 8

change of liquid to a vapour at a temperature below the boiling point

Question 9

sublimation

Answer 9

solid to vapour at a tempreture below the triple point in the phase diagram

Question 10

vapour pressure

Answer 10

-solid or liquid placed into a container and exerts a pressure at equilibrium its called a vapour pressure its always at constant pressure.

only eliquilbrium in closed system

Question 11

significance of vapour pressure

Answer 11

-vapour pressure in solids much lower than in liquids

-if lid left off bottle water has a higher vapour pressure than drugs so it will evaporate making the concentration of the medicine increased

Question 12

gas adsorption

Answer 12

form water layer on tablets because water vapour adsorbs on to the surface of the drug and evaporates at an equilibrium, the drug can dissolve in thus layer and can hydrolyse. also impacts flow of drug particles. depends on temp and water content in atmosphere its also reversible. can also get capillary condensation in pores.

Question 13

hygroscopic

Answer 13

solid that adsorbs water depends on SA and Senergy more polar means more water is absorbed.

Question 14

solubility changes

Answer 14

more than saturated the drug will crystallise out. cool makes more saturated the drug could precipitate out.

Question 15

crystalline drug definition

Answer 15

-a solid in which the constituent molecules are packed in a regularly odered, repeating pattern extending in all three spatial dimensions, they atoms are held together by non-covalent interactions. uniform form held by electrostatic interaction or hydrogen bonding.

crystaline is most common most stable and high melting point. Physically and chemically stable

Question 16

amorphous drug

Answer 16

no long range pattern. some amorphous material in crystaline drugs on surface. Amorphous material is less stable, this is because water lowers glass transition temperature so this makes material more plastic and more mobile which increases chemical reactivity which means chemical degradation.

Question 17

why amorphous less chemically stable

Answer 17

Amorphous material is less stable, this is because water lowers glass transition temperature so this makes material more plastic and more mobile which increases chemical reactivity which means chemical degradation.

Question 18

amorphous less physically stable

Answer 18

-can crystallise back out with moisture

Question 19

polymorphs

Answer 19

same molecules with different molecular packing. they have diff chemical properties like diff solubilities and diff bioavailability’s

Question 20

why choose most stable polymorphs

Answer 20

so there is no changes to drug in storage

Question 21

hydrates

Answer 21

are polymorphs of drugs but have water molecules as part of the crystal structural they also have diff soluabilities .

Question 22

why we need packaging

Answer 22

protect drug in transport, storage and use

Question 23

what three materials can packaging be made out of

Answer 23

glass- not permeable no molecules can pass through

plastics and rubber which is semi permeable so some molecules can diffuse through

Question 24

semi permeability depends on

Answer 24

-SA
-thickness
-time
-differences in partial vapour pressure

Question 25

permeation law

Answer 25

Ficks first law

Question 26

examples of permeations

Answer 26

-water vapour: coming in and out
-o2
-co2

Question 27

leachables

Answer 27

something coming out packaging into medicines.

Organic and inorganic chemical species that can be released from the surfaces of components used in storage of drug products (medicine) under conditions of normal use”.

What influences the accumulation of leachables in a medicine (solution)?
Initial amt of leachable in the container
Solubility limit of the leachable in solution
Partitioning of the leachable between the container and the solution
Migration of the leachable from the container into solution

Question 28

adsorption

Answer 28

Adsorption of solute (drug/excipient) to surface (packaging/container) occurs when chemical grps present that allow interaction

Factors that affect extent of adsorption:
Solute concentration

pH –extent of ionisation – unionised more likely to be adsorbed

Temperature-exothermic lower temp more adsorbed
Surface area

Question 29

weak acid ionisation

Answer 29

Weak acids (e.g., aspirin) will tend to ionize (lose a proton) more in higher pH (more basic) conditions, whereas weak bases (e.g., morphine) will ionize more in lower pH (more acidic) conditions.

Question 30

adsorption vs absorption

Answer 30

ad on surface

ab inside

Question 31

rubber

Answer 31

-old and natural high leachable some new have less

-all have adsorption and permeation

Question 32

plastics

Answer 32

-placticers and antioxidants are common leachable

-all permeation

-all adsorption

most is pic