Dermatological vehicle additives

Question 1

What are common additives to dermatological vehicles

Answer 1

1. Humectants
   
   • increase hydration of the skin at low conc
   • withdraw moisture at high conc
   • prevent prodcut from drying out
     
     • propylene glycol, glycerol, PEG
2. Levigating agents
   
   • liq to aid in incorporation and particle size reduction of powder -> oint
   • maximum 5% of final formualtoin
     
     • mineral oil, glycerol
3. Penetration enhancers
   
   • Temorarily increase the permeability of the skint o allow drug molecules to pass
     
     • ex: chemical permeation enhancers, specialized delivery systems
4. Antioxidants
5. Preservatives

Question 2

what are the properties of penetration enhancers

Answer 2

• Pharmacologically inert
• Non-toxic, non-irritating, non-allergenic
• Immediate and predictable effect
• Immediate recovery of the barrier property of the skin after removal of the agent •Should not cause loss of body fluids, electrolytes or other endogenous materials •Compatible with drugs and excipients
• Good drug solvent
• Cosmetically acceptable (good spreadability and “feel”)
• Readily formulated into the various types of topical preparations
• Odourless, tasteless, colourless and inexpensive

Question 3

ex of chemical permeation enhancers

Answer 3

Sulfoxides (DMSO)

􏰁 Azone

􏰁 Pyrrolidones

􏰁 Fatty acids (Oleic acid)

􏰁 Alcohols, glycols (ethanol, propylene glycol)

􏰁 Surfactants (SDS, Tween 80)

􏰁 Urea

􏰁 Terpenes

􏰁 Phospholipids

􏰁 Biochemical enhancers

Question 4

delivery ststems that act as peneation enhancers

Answer 4

Liposomes and other lipid-based systems

Nanoparticles

Question 5

occlusion as method to enhance percutaneous absorption

Answer 5

􏰁 Formation of an impermeable layer on the skin to prevent evaporation of water.

􏰁 Can be accomplished by plastic wrap (over applied ointment)

􏰁 Increased hydration (by preventing evaporation of water from the skin)

􏰁 Softening of the skin (emollient action)

Question 6

ex of antioxidants

Answer 6

􏰟 Butylated hydroxytoluene (BHT), 􏰟 butylated hydroxyanisole (BHA)􏰟 Ascorbic acid, ascorbyl palmitate 􏰟 Hydroquinone
􏰟 Tocopherol
􏰟 Sulfites, bisulfites

Question 7

ex of antimicrobial preservatives

Answer 7

*topical baes with aqueous phases, carbohydrates and proteins are readily attacked by bacteria and fungi

alcohols: ethanol, isopropanol
acid: benzoic acid

Mercurials; thimerosal

Phenols; phenol, cresol

p-hydroxybenzoates: methyl, propyl, butylparaben

Quaternary ammonium compounds:benzalkonium chloride, cetrimide

Question 8

treatment of acne

Answer 8

• chronic inflammation of pilsosebaceous unit, inc sebum production
• free fatty acids produced by P acnes bacteria
• Therapy
  
  • Bacteriostatics: benzoyl peroxide
  • topical antibiotics
  • exfoliants: sulfur, resorcinaol, tretinoin, salicylic acid, benzoyl perioxide
• Types of bases: liquids, gels, creams, o/w emulsions, ]NO OCCULSIVE BASES

Question 9

what type of bases to avoid for treatment of acne

Answer 9

occlusive bases

Question 10

alopecia

Answer 10

• Pathophysiology
  
  • natural or abnormal loss of hiar on scalp
    
    • family history
    • angrogenic influences
    • aging
    • systemic disorders
• Appearance
  
  • baldness, totalid (no hair) or areata (patchy hair loss
• Treatment
  
  • no satisfactory treatment (possibly Minoxidil/Rogaine®)

Question 11

types of bases used to treat alopecia

Answer 11

􏰂 water or alcohol based liquids

􏰂 gels

􏰂 creams

Question 12

eczema

Answer 12

• pathophysiology
  
  • superficial inflammation of skin
    
    • atopic dermatitis (allergic condition)
    • contact dermatitis (delaye hypersensitivity rxn)
• Appearance
  
  • intense itching, erthema, swelling edema, oozing, scaling
• Therapy
  
  • Emollients
  • Astringents
  • Antipruritics
  • Topicalcorticosteroids

Question 13

types of bases used to treat excema

Answer 13

creams

lotions

try to avoid occlusion

Question 14

psoriasis

Answer 14

• pathophysiology
  
  • chonric inflammatory skin disease
• Appearance
  
  • red patches on scalp or extremities
  • lesions covered with silver white scales will bleed if removed
• therapy
  
  • emollients (hydration)
  • keratolytics (remove scales)
  • corticosteriods (treat inflammation)

Question 15

types of abses used to treat psoriasis

Answer 15

occlusive (the more the better) -> hydrocarbons, silicon bases

• creams
• ointments with plastic wrap (INC hydration)

Question 16

Urticaria

Answer 16

• Pathophysiology
  
  • vascular reactionto insect bites, diet or drugs
• Appearance
  
  • wheals surrounded by halo accompanied by severe tiching and burning
• therapy
  
  • topical astringents
  • anti-inflammatory lotions
  • anti-histamines

Question 17

types of bases used to treat urticaria

Answer 17

􏰞 non-occlusive

􏰞 gels

􏰞 shake lotions (cool — relieve burning and itching)

􏰞 creams

Question 18

herpes simplex

Answer 18

• pathophysiology
  
  • recurrent viral infection of the skin and mucous membranes
• Appearance
  
  • vesicles appearing in clusters on erythematous base
• therapy
  
  • topcial antiviral prep
  • lotetions containing camphor and tannic acid

Question 19

types of bases used to treat herpes simplex

Answer 19

􏰞 non-occlusive

􏰞 liquid lotions

􏰞 PEG

􏰞 gels

Question 20

corns and calluses

Answer 20

• Pathophysiology
  
  • corns: raised conical hyperkaratinous lesions extending down to dermis and pressing inward on nerve endigns
    
    • causing paina nd irritation
  • calluses: circumsized thickness of skin due to pain and pressue
• Appearance
  
  • dry thickings of skin on or between toes
• Therapy
  
  • remove causative factor
  • keratolytics (salicylic acid> 10%)
  • caustics (lactic acid, tricholoroacetic acid emulsions)
  • emollients

Question 21

types of bases used to treat corns and calluses

Answer 21

• occlusive - the more the better (easier to remove by abrasion)
• collodions (liquid with organic solvents + polymer that deposits on skin)

Question 22

atheltes foot

Answer 22

• pathophysiology
  
  • superficial fungal infection of the skin
• appearance
  
  • small blisters between toes, cracks, redness, maceration, itching, burning
• Therapy
  
  • thorough dry feet after shower/bath
  • topical antifungal creams

Question 23

types of bases used to treat athletes foot

Answer 23

􏰞 non-occlusive

􏰞 o/w creams

Question 24

Define shunt route of drug permeation into/through skin?

Answer 24

Shunt route = absorption through the appendages

Question 25

Define acid mantle. Win this context, what is the significance of pH 5.5?

Answer 25

Acid mantle pH 4.2 - 5.6 → bacteriostatic and fungistatic secretions (short chain fatty acids from sebaceous and eccrine sweat glands) – formulations with pH 5.5 are said to be the most compatible with the skin

Question 26

The skin is an important heat barrier; what is the consequence of heat or cold exposure on the skin vasculature and percutaneous absorption?

Answer 26

* Heat conservation (vasoconstriction, shivering, goose bumps) * percutaneous absorption decreases * Heat loss (vasodilation, skin reddening) * percutaneous absorption increases

Question 27

Define ‘sink conditions’

Answer 27

Blood circulation in the dermis maintains sink conditions by taking up drug absorbed into skin into the systemic circulation thereby maintaining high concentration gradient between the formulation and the skin

Question 28

Define occlusion and its effects on the skin.

Answer 28

Occlusio = formation of an impermeable layer on the skin to prevent evaporation of water. \*Can be accomplished by plastic wrap over generally greasy ointments Effects: - \> Increased hydration (by preventing evaporation of water from the skin) - \> Enhanced percutaneous absorption - \> Softening of the skin (emollient action)