Percutaneous delivery of cosmetic actives to the skin

Question 1

Types of transepidermal routes

Answer 1

transcellular

intercellular

Question 2

essentials for characterization of actives

Answer 2

Molecular weight
dissociation constant
solubility
octanol/water partition coefficient
net ionic charge

Question 3

Penetration ability based on ionic charge

Answer 3

un-ionized penetrates better than ionized

Question 4

penetration can be enhanced by keeping the pH of the formulation close to

Answer 4

pKa of active

Question 5

Optimal partition coefficient

Answer 5

intermediate (log P O/W 1-3)

• adequate solubility within lipid domains of SC to permit diffusion
• sufficient hydrophilic nature to allow partitioning into viable tissues of epidermis

Question 6

What is partition coefficient

Answer 6

ratio of concentrations of an active molecule in oil and water phases in the skin, due to the fact most compounds are soluble to some extent in both organic and aqueous phases.

Question 7

Formulation strategies to enhance skin penetration

Answer 7

• Increasing drug diffusion in the skin
• increasing drug solubility in the skin
• increasing degree of saturation of drug in formulation

Question 8

The ability of vehicles to deliver actives is based on

Answer 8

diffusion of actives through various skin compartments (epidermis and dermis)

Question 9

Partitioning of actives from dosage form is highly dependent on

Answer 9

relative solubility of active in components of delivery system and SC

Question 10

Sequence of percutaneous absorption

Answer 10

• Partitioning of molecule from applied vehicle phase –> SC
• molecular diffusion through SC
• Partitioning from SC –>viable epidermis
• diffusion through epidermis/upper dermis/capillary uptake

Question 11

Supersaturation boosts active penetration by

Answer 11

creating diffusional concentration gradient across SC

Question 12

Eutectic blends increase solubility of a material in skin lipids by

Answer 12

lowering melting point of active to around or below skin temperature

Question 13

Ultimate goal of penetration enhancement

Answer 13

target active in SC and/or epidermis without allowing for systemic absorption

Question 14

effect of alcohol on delivery

Answer 14

fluidizes SC

alters permeability of SC

Question 15

effect of propylene glycol on delivery

Answer 15

alter permeability of SC

alter vehicle SC partition coefficient

Question 16

Surfactants effect on delivery

Answer 16

reduce emulsion particle size

solubilize active

Question 17

Types of submicron delivery systems

Answer 17

Liposomes
niosomes
lipid particles
nanocapsules

Question 18

Liposomes are used for ______ actives, and the phospholipids forming these liposomes has what effect

Answer 18

hydrophilic

enhance penetration of encapsulated active ingredients

Question 19

composition of liposomes

Answer 19

heterogeneous lipid composition with several coexisting domains exhibiting different fluidity characteristics

Question 20

Niosomes are used for ________ because _______

Answer 20

active molecules with a wide range of solubilities

they consist of hydrophilic, amphiphilic, and lipophilic moieties

Question 21

Lipid particles (SLNP) can be used as penetration enhancers through the skin because of
this method protects drug against chemical degradation due to

Answer 21

occlusive and hydrating properties

little or no access for water to enter inner area core of lipid particle

Question 22

Franz cell apparatus measures _______ skin permeation by

Answer 22

in vitro
formulation added to top of cell covered with biologic membrane/skin substitute
periodic samples are taken to develop time-penetration profile

Question 23

In vivo active penetration can be measured with _______, in which penetration of the active is estimated from _______

Answer 23

tape stripping

amount recovered in SC by adhesive tape stripping

Question 24

Microdialysis is used for ______ and ________, and is based on _________

Answer 24

in vivo and ex vivo cutaneous delivery of actives

passive diffusion of compounds down concentration gradient across semi-permeable membrane

Question 25

Real time tracking of drug in skin layers can be obtained through

Answer 25

Confocal Roman Microspectroscopy, which gives information from deep layers under skin surface