semi solid preparation

Question 1

where do epidermal semi solids work?

Answer 1

locally at the skin’s surface

Question 2

uses of epidermal semi solids:

Answer 2

antimicrobials, astringents, lubrication, moisturising, UV protection

Question 3

where do endodermal semi solids work?

Answer 3

work locally in dermis or lower (Second layer under epidermal)

Question 4

uses of an endodermal semi solid:

Answer 4

anti-inflammatory, local anaesthetic, anti itching

Question 5

where do ttransdermal semi solids work?

Answer 5

absorb through the skin, but they work systemically (below all dermal layers)

Question 6

uses of transdermal semi solids:

Answer 6

heart medicines, hormone replacement therapy. for transdermal delivery systems, patches are more common than demi solids

Question 7

different types of semi-solid formulations?

Answer 7

creams, gels, ointments, pastes

Question 8

what is more greasy, ointments or creams?

Answer 8

ointments due to their oily vehicle (liquid paraffin, soft paraffin, paraffin wax)

Question 9

when may an ointment contain a surfactant?

Answer 9

when used as a wash

Question 10

uses of ointments:

Answer 10

emollients, local and systemic drug delivery, eyes. highly occlusive therefore good for dry skin

Question 11

how does a cream feel on the skin?

Answer 11

cool on the skin

Question 12

why does a cream require a preservative?

Answer 12

its hydrous, high water content,

Question 13

uses of a cream:

Answer 13

emollient (skin softening) and local drug delivery

Question 14

what’s more occlusive, ointments or cream? what is the benefit for each

Answer 14

ointments are more occlusive so good for dry skin.

creams are less occlusive so good for macerated skin

Question 15

what doe a paste feel like?

Answer 15

stiff

Question 16

how does a paste relate to an ointment?

Answer 16

its an ointment with up to 50% powder

Question 17

what are pastes used for:

Answer 17

lesions, skin protectants, sun block. it provides a v precise localised treatment.

Question 18

how does a paste work?

Answer 18

it forms a thick impermeable layer on the skin

Question 19

which semi solid is a 2 component semi solid?

Answer 19

gel

Question 20

which semi solids have a high water content?

Answer 20

gels, creams

Question 21

what are gels used for?

Answer 21

lubrication, delivering a drug (drug diffuses through the gel for delivery to site of action). use in the mouth (bongela)

Question 22

List excipients found in semi solids

Answer 22

oily vehicles, water miscible vehicles, gelling agents, emulsifying agents (surfactants), humectants, solids, preservatives, anti-oxidants

Question 23

list types of oily vehicles:

Answer 23

mineral oils, vegetable oils, synthetic oils. all are occlusive

Question 24

what is liquid paraffin, soft paraffin, paraffin wax

Answer 24

oily vehicles

Question 25

list some water water miscible vehicles:

Answer 25

water, alcohols and macrogols

Question 26

what part does alcohol play in excipients?

Answer 26

it is a water miscibile vehicle. it is used for cooling via evaporation

Question 27

list some aqueous gel gelling agents:

Answer 27

tragacanth, alginates, pectin, gelatine. they vary in viscosity.

Question 28

what do emulsifying agents (surfactants) do?

Answer 28

- help oil and water to form a stable uniform mix. | - will also increase the penetration of the drug

Question 29

list some emulsifying agents for water in oil:

Answer 29

lanolin, beeswax

Question 30

what is beeswax?

Answer 30

an emulsifying agents used in water in oil semi solids

Question 31

list some emulsifying agents (Surfactants):

Answer 31

polyethylene glycols, non ionic surfactants, emulsifying waxes

Question 32

what do humectants do?

Answer 32

reduce water loss from creams and gels.

Question 33

examples of humectants

Answer 33

glycerol, propylene glycol

Question 34

examples of preservatives:

Answer 34

EDTA, parabens.

Question 35

what is a disadvantage of using preservatives?

Answer 35

they can cause allergy / skin sensitisation

Question 36

what affects the stability of semi solids?

Answer 36

heat, light, microorganism growth

Question 37

what can happen to oils over time?

Answer 37

turn rancid

Question 38

What composition must a semi solid have to be most stable?

Answer 38

products low in water are most stable (ointments and pastes)

Question 39

which semi solids are the most stable?

Answer 39

ointment and pastes

Question 40

Advantages of ointments and pastes:

Answer 40

they are more stable than creams and gels, they are occlusive and protective so good for dry skin, less need for preservatives, some ointments can be used as washes.

Question 41

Disadvantages of ointments and pastes:

Answer 41

they are greasy and sticky so less appealing, they absorb slower into the kin, not to be used on macerated skin, high oil content so can be flammable

Question 42

Advantages of creams and gels:

Answer 42

Non greasy so more accepted by patients, absorb rapidly into the skin, they have a cooling effect on evaporation, can be used on macerated skin, gels have less additives

Question 43

disadvantages of creams and gels:

Answer 43

susceptible to microbial contamination so require preservative which could cause sensitiation, they are less stable and creams can crack (short expiry). short duration of action due to rapid absorption

Question 44

why must you shake the aerosol?

Answer 44

to disperse the propellant and drug

Question 45

give 3 examples of propellants

Answer 45

Hyroflouro-alkanes (HFAs) Vs Chloroflourocarbons (CFCs) | Butane

Question 46

why do you need to grind and sieve powder?

Answer 46

to increase surface area and reduce clumping

Question 47

what is trituration?

Answer 47

Method of incorporation of liquids or powders into a semi-solid base using a ceramic tile Powders – doubling up and mixed using levigation Liquids – making a small well and then mixed in gradually

Question 48

what is levigation?

Answer 48

Applying pressure to incorporate a powder into a semisolid | Avoids a gritty product

Question 49

what are some things that you need to check about the product during the final check?

Answer 49

uniformity, correct final weight, appearance, clean jar