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Winter P1 > Pharm 734 Final > Flashcards

Pharm 734 Final Flashcards

1
Q

Topical Drug Delivery: Action, Uses

A

Local Action Only

  1. Protect injured areas of skin
  2. Hydrate skin
  3. Local therapeutic effect
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2
Q

Layers of Skin Anatomy

A

Epidermis
Dermis
Hyperdermis

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3
Q

Epidermis Features

A 
0.006 to 0.008mm thick
Stratum Corneum (outermost layer, 10-20% moisture)
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4
Q

Dermis Features

A

3-5mm thick

matrix of connective tissues, woven fibrous proteins, nerves, blood vessels

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5
Q

Hyperdermis Features

A

Subcutaneous Tissue

Mechanical cushion, thermal barrier, energy storage

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6
Q

Skin Appendages

A

Hair Follicles
Sweat Glands
Sebaceous Glands
Nails

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7
Q

Drug Travel Path from Skin (Cream, Gel, Lotion, Patch etc)

A

Skin Surface –> Stratum corneum –> Viable Epidermis –> Dermis –> Blood Circulation

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8
Q

Epidermis Layers and maturation

A

Stratum Basale (bottom, Hydrophilic)
Stratum Spinosum
Stratum Granulosum
Stratum Corneum (Top, Hydrophobic)

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9
Q

Protective Function of Skin

A
  1. Microbiological Barrier
  2. Chemical Barrier
  3. Radiation Barrier
  4. Heat/Temperature Regulation
  5. Immune response
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10
Q

Targeted Region of Topical Drug Delivery

A 
Surface Treatment (e.g. insect repellant, sunscreen)
Stratum Corneum (Emolient, Keratosis)
Skin Appendage (Acne, Antibiotics, Antiperspirant)
Viable Epidermis/Dermis (antihistamine, anesthetics)
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11
Q

Skin Problems at Different Regions of skin

A 
Stratum Corneum (Psoriasis, Dry Skin)
Viable Epidermis (Eczema)
Dermal/Epidermal interface (warts)
Dermis (scarring)
Hair Follicle/Sebaceous/Sweat gland (Hirsutism, Acne, Heatrash)
Other (Fungal/Athlete's foot)
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12
Q

Topical Dosage forms

A

Semi-Solids
Solids
Liquids

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13
Q

Semi Solid topical forms

A 
Ointments
Creams
Pastes
Gels
Jelly
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14
Q

Solid topical forms

A

Powders
Aerosol
Plaster

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15
Q

Liquid topical forms

A 
Solutions
Emulsions
Suspensions
lotions
Liniments
Aerosols
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16
Q

Advantages of Topical Drug Delivery

A

High drug concentration at site of application
Low risk of systemic side effects
Non-Invasive
Easy to Use

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17
Q

Disadvantages of Topical Drug Delivery

A 
Contact time for drug is limited
Ointments and creams are messy to use
Potential for systemic absorption
formulations can cause skin irritation
Difficult to measure exact dose
Rubbing, Heat, Exercise inc systemic absorption
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18
Q

Semi Solid Dosage Forms (applications)

A 
Intended for topical application
Medicated or non-medicated
Emolient (softens skin, no absorption)
Protective (protects skin against environment)
Vehicles
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19
Q

Antipruritics

A

Relieve Itching of Skin (menthol, Camphor, coal tar)

20
Q

Keratolytics

A

Remove/soften the thickened or scaly stratum corneum

21
Q

Antieczematous agents

A

Assist in removal and treatment of oozing and vesicular excretions.

22
Q

Antiparasitics

A

Destroy or inhibit living infestations

23
Q

Antiseptics and Antibiotics

A

Bacteriostatic, bactericidal, fungistatic, Fungicidal

24
Q

Antiseborrheics

A

Reduce discharge from sebaceous glands and remove symptoms

25
Q

Types of ointment bases

A

hydrocarbon (oleaginous)
absorption bases
emulsions (W/O and O/W)
Water-miscible bases

26
Q

Gels are:

A

3D network of inorganic molecules and large organic molecules in a liquid
Water-washable
Drug is dispersed/dissolved in water or a water/ethanol mixture in gel
Rate of drug release is usually fast
Sunscreen gels, gel for anti-fungal and anti-inflammatory

27
Q

Pastes are:

A

A large proportion of solid material than ointment, not less than 20% solid
Less greasy than ointment
Pastes are stiffer than ointments
Good for absorption of secretions
Not good for application to hairy areas due to stiffness
Not water washable

28
Q

Creams and Lotions are:

A

Homogenous semi-solid preparations consisting of opaque emulsion systems.
Consistency and rhelogical properties depend on the type of emulsion.
Creams can contain one or more medicinal agents dissolved in W/O or O/W
O/W cream and water = Lotion

29
Q

What physiological factors affect drug penetration

A

Thickness of SC

Condition of SC

30
Q

What drugs can cross skin? (how can drug diffusion be increased?)

A

Small hydrophilic polar molecules
Small hydrophobic molecules

(Decreasing MW, Occluding the skin, damage to skin)

31
Q

What is required for Drugs to penetrate SC?

A

Drug dissolved in base
Drug diffuse to surface of skin
Drug must partition into SC
Drug must diffuse to site of action in epidermis

32
Q

How can Drug penetration be increased?

A

Higher Drug Concentration
Thicker Layer of Ointment
Larger Surface Area

33
Q

What is Levigation?

A

The process of reducing the particle size of a solid by triturating it with small amount of liquid or melted base to wet the solid

34
Q

What are Humectants?

A

Ingredients that attract water (Glycerin, PEG, urea, lactic acid)
Pulls water into SC from deeper layers
Prevents drying of o/w creams/lotions

35
Q

What are Astringents?

A

Substances that control oozing, discharge or bleeding
Coagulate Protein, acts as protective coat, allows new cells to regenerate underneath
Used for “weeping” wounds
(E.g. Gallic Acid, Aluminum Sulfate)

36
Q

Topical Patches (NOT transdermal)

A

Intended for local action at skin

E.g. Diclofenac

37
Q

Nails

A

100x thicker than SC
very impermeable to topical drugs
Difficulty in retaining formulation on nail
Occlusive covering helps penetration

38
Q

Transermal Drug Delivery Systems

A

Facilitate the passage of therapeutic quantities of drug substance through skin into general circulation for systemic effect

39
Q

TDDS Advantages

A 
Bypass Hepatic "First Pass"
Bypass GI Incompatibility
Reduced Side Effects
Greater Compliance
Minimize Inter/Intra patient variation
Terminate therapy by removing patch
Etc.
40
Q

TDDS Disadvantages

A

permeation through skin limited
Skin irritation
patches uncomfortable
May not be economical

41
Q

TDDS Drug properties

A
  • Drugs w/ Short Hal-life
  • Proper lipophilicity/hydrophilicity
  • low molecular weight (~100-500 Da)
  • Potent drug (narrow therapeutic window)
  • should not bind extensively to skin
  • should not be irritating to skin
  • clinical necessity for steady state delivery
  • drugs can be subject to high 1st pass
42
Q

Layers of Epidermis

A

Stratum Corneum
Stratum Granulosum
Stratum Spinosum
Stratum Basale

43
Q

Epidermis Notable Facts

A
  • Turnover ~28 days (14 days dehydrate, 14 days shed)
  • Avascular
  • Stratum Corneum most important barrier
44
Q

Dermis notable features

A
  • Rich blood supply, lymphatic vessels and nerve endings
  • Drugs quickly diffuse
  • Collagen fibers (structural strength)
  • Elastin FIbers (Elasticity)
45
Q

Fick’s Law of diffusion in TDDS

A 
J = Pe x Co
J = Flux, movement of mass/area/time
46
Q

TDDS LogP target zone

A

1-4 (partition coeffecient)

47
Q

Construction of TDDS

A
  1. Impermeable Backing membrane (occlusive)
  2. Drug Reservoir/ Matrix
  3. Rate-controlling membrane
  4. Adhesive Layer
  5. Protective Liner

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