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Pharmaceutics > Dermatological vehicle additives > Flashcards

Dermatological vehicle additives Flashcards

1
Q

What are common additives to dermatological vehicles

A
  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
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2
Q

what are the properties of penetration enhancers

A
  • 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
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3
Q

ex of chemical permeation enhancers

A

Sulfoxides (DMSO)

􏰁 Azone

􏰁 Pyrrolidones

􏰁 Fatty acids (Oleic acid)

􏰁 Alcohols, glycols (ethanol, propylene glycol)

􏰁 Surfactants (SDS, Tween 80)

􏰁 Urea

􏰁 Terpenes

􏰁 Phospholipids

􏰁 Biochemical enhancers

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4
Q

delivery ststems that act as peneation enhancers

A

Liposomes and other lipid-based systems

Nanoparticles

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5
Q

occlusion as method to enhance percutaneous absorption

A

􏰁 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)

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6
Q

ex of antioxidants

A

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

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7
Q

ex of antimicrobial preservatives

A

*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

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8
Q

treatment of acne

A
  • 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
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9
Q

what type of bases to avoid for treatment of acne

A

occlusive bases

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10
Q

alopecia

A
  • 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®)
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11
Q

types of bases used to treat alopecia

A

􏰂 water or alcohol based liquids

􏰂 gels

􏰂 creams

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12
Q

eczema

A
  • 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
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13
Q

types of bases used to treat excema

A

creams

lotions

try to avoid occlusion

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14
Q

psoriasis

A
  • 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)
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15
Q

types of abses used to treat psoriasis

A

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

  • creams
  • ointments with plastic wrap (INC hydration)
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16
Q

Urticaria

A
  • 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
17
Q

types of bases used to treat urticaria

A

􏰞 non-occlusive

􏰞 gels

􏰞 shake lotions (cool — relieve burning and itching)

􏰞 creams

18
Q

herpes simplex

A
  • 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
19
Q

types of bases used to treat herpes simplex

A

􏰞 non-occlusive

􏰞 liquid lotions

􏰞 PEG

􏰞 gels

20
Q

corns and calluses

A
  • 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
21
Q

types of bases used to treat corns and calluses

A
  • occlusive - the more the better (easier to remove by abrasion)
  • collodions (liquid with organic solvents + polymer that deposits on skin)
22
Q

atheltes foot

A
  • 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
23
Q

types of bases used to treat athletes foot

A

􏰞 non-occlusive

􏰞 o/w creams

24
Q

Define shunt route of drug permeation into/through skin?

A

Shunt route = absorption through the appendages

25
Q

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

A

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

26
Q

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

A
  • Heat conservation (vasoconstriction, shivering, goose bumps)
    • percutaneous absorption decreases
  • Heat loss (vasodilation, skin reddening)
    • percutaneous absorption increases
27
Q

Define ‘sink conditions’

A

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

28
Q

Define occlusion and its effects on the skin.

A

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)

Pharmaceutics (19 decks)

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