Drug Delivery to the Skin - 1

?
  • Created by: LBCW0502
  • Created on: 14-12-19 17:44
What are the advantages of skin delivery? (1)
Avoids GI tract and first pass metabolism. Allows lower drug doses. Minimises S/E. Increased patient compliance. Dosing regimen can be promptly interrupted. Non-invasive dosing
1 of 38
What are the advantages of skin delivery? (1)
Possibility of controlled/sustained systemic (transdermal) or localised (dermal) drug delivery
2 of 38
Describe features of skin structure
10% of body map, 1.7 m^2, protection, stabilises BP and temperature, mediates sensitisation of temperature/touch/pain, expresses emotions, skin can be easily damaged
3 of 38
Describe features of the subcutaneous tissue (hypodermis)
Structured fatty layer over nearly whole body. Provides protection and source of energy. Thickness depends on sex, age, endocrine and nutritional status
4 of 38
Describe features of the dermis (1)
1(scalp)-5(back) mm thick, 90% of skin layer, supports epidermis. Composed of matrix connective tissue - fibrous protein (80% mainly and elastin) and glycosaminoglycan gel 20%. Comprises of connective tissue, blood, lymph vessels, nerve endings
5 of 38
Describe features of the dermis (2)
Supports skin appendages (sweat/sebaceous glands and hair follicles). Blood flows at 0.05 mL/min/mg of skin - large skin exists
6 of 38
Describe features of the eccrine sweat glands
120 per cm2 on the thigh to 620 per cm2 on the feet , 2-5 million over the whole body. Secrete a watery fluid with a pH of 4.0 - 6.8 at at ca. 1 L / day stimulated can be as high as 12 L / day
7 of 38
Describe features of the apocrine sweat glands
10 times larger than eccrine - found adult armpit, ano-genital regions. They secrete a milky fluid, proving sweat ‘odour’
8 of 38
Describe features of the sebaceous sweat glands
Forehead, face, in ear and on the middle of the back. Flask-like glands opening into hair follicle - site where acne develops. Secrete sebum - complex mixture of lipids, lubricate skin surface, maintaining pH of 5
9 of 38
Describe features of the basement membrane
500Å thick. 40KDa barrier. Connected to epidermis by hemi-desmosomes
10 of 38
Describe features of the viable epidermis
75-150 mm thick, stratified, squamous epithelium, keratinocytes are major component. 4 distinct strata responsible for keratinocyte differentiation. the basal layer (stratum basale) Contains active dividing cells - melanocytes, Langerhans, Merkel
11 of 38
Describe features of the stratum spinosum (prickle cell layer) (1)
Cells are more flattened and the nuclei are shrunk. Cells interconnect with desmosomes which can break and reform. The spaces between the desmosomes allow the passage of oxygen and nutrients
12 of 38
Describe features of the stratum spinosum (prickle cell layer) (2)
The cells also possess granules which contain lamellar subunits arranged in parallel stacks
13 of 38
Describe features of the stratum granulosum (granular cell layer)
Polypeptide building blocks of keratin aggregate to form insoluble, fibrous keratin molecules. In outermost region lamellar granules migrate to the apical cell surface cells lose their nuclei/other cytoplasmic organelles, become flattened/compacted
14 of 38
State features of the stratum lucidium
This layer is only found on the palms of the hands and the soles of the feet
15 of 38
Describe features of the stratum corneum (horny layer) - 1
10 mm thick, dead, flattened, corneocytes (40 mm in diameter and 0.5 mm thick, ca.20 layers). The outermost layers are shed at the rate of about 0.5 - 1.0 g per day, in diseases such as psoriasis this can rise to 9 -17 g
16 of 38
Describe features of the stratum corneum (horny layer) - 2
Stratum corneum cells have water content of 20% compared with of 70% in the basal layer. The stratum corneum is replaced about every 3-4 weeks
17 of 38
Describe features of the stratum corneum (horny layer) - 3
Composed mainly of insoluble bundled keratins (ca. 70%) and intercellular lipid (ca. 15%). Intercellular regions consist of lipids & some desmosomes which aid corneocyte cohesion: ceramides (50%), sterols (25%), free fatty acids (15-20%)
18 of 38
Describe features of the stratum corneum (horny layer) - 4
Sterol esters (5-10%). Lipids are organised in multi laminated sheets which are highly ordered bilayers with a rigid structure. Stratum corneum is principle barrier to skin penetration
19 of 38
Give an example of transdermal delivery (delivery to systemic circulation via the skin)
Fentanyl patch - pain relief
20 of 38
Give an example of dermal delivery (topical delivery to the skin)
Corticosteroids - dermatitis, psoriasis
21 of 38
Why is transdermal and dermal delivery difficult to achieve?
Due to barrier properties of stratum corneum. Highly lipophilic drug will remain in stratum corneum
22 of 38
Give examples of medicines and the target in the skin layers (1)
Surface (barriers, repellants, sun cream, antimicrobials, antiseptics). Local (corticosteroids, cytotoxics, antiviral, antihistamines, anaesthetics). Appendages (antimicrobials, depillatories)
23 of 38
Give examples of medicines and the target in the skin layers (2)
Systemic (nicotine, hormones, scopolamine, fentanyl, nitroglycerin, clonidine). Deeper tissues (NSAIDs?)
24 of 38
Describe features of surface treatment of the skin (1)
Protective films - sun cream, barrier creams, antibacterials, antifungals, antiseptics, deodorants, insect/parasite repellents
25 of 38
Describe features of surface treatment of the skin (2)
Sun cream – works on stratum corneum (issue – removal of sun cream, not on stratum corneum, sun burn), importance of re-applying sun cream, (waterproof or not, removal due to water/pool)
26 of 38
Describe features of surface treatment of the skin (3)
Compounds/nanoparticles – reflect physical barrier to sun. Chemicals entering the skin – if barrier protection stops (e.g. no reapplication of sun cream), anti-oxidant penetrates into the skin (UV damage – free radicals)
27 of 38
Describe features of surface treatment of the skin (4)
Anti-oxidants counteract free radicals. Actual oxidative damage can happen after exposure to the sun (at night)
28 of 38
Describe features of skin therapy - stratum corneum (1)
Therapy often complicated - antifungals, emoillients, exfolients. Moisturisers. Stratum corneum – hydrophobic barrier, regulate water release. If barrier is compromised, more drugs can enter but more water is released
29 of 38
Describe features of skin therapy - stratum corneum (2)
Skin becomes dry, moisturiser (oils – enter stratum corneum, maintain barrier). Lipids – semi-solid, changes in hydration/temperature affects drug delivery. Effects on the stratum corneum affects drug delivery.
30 of 38
What can be used to improve drug delivery to the skin?
Lidocaine patch – hydration of skin, improve drug delivery. (Benzoyl peroxide – different formulations, gel (contains alcohol, aids penetration) )
31 of 38
Give examples of appendage treatment
Antiperspirants - aluminimum salts. Exfoliants - salicylic acid/tretinoin. Depilatories - strontium sulphides, thioglycolates. Antibacterials - tetracyclines, clindamycin. Antifungals - clotrimazole, miconazole. Appendageal drug delivery - not simple
32 of 38
Describe the steps for an antiperspirant to be delivered to the skin (1)
Antiperspirant applied to skin. Perspiration mixed with antiperspirant. Antiperspirant mixes with perspiration on skin surface and in sweat duct. Chemical reaction occurs forming precipitate salt
33 of 38
Describe the steps for an antiperspirant to be delivered to the skin (2)
Inside sweat duct, antiperspirant forms a shallow plug reducing flow of percpiration
34 of 38
Give examples of types of treatment for epidermal conditions
Anti-inflammatory, anaesthetic, antipruitic, antibacterial, antihistamine, antiviral, antiparasitics, immunosuppressants, corticosteroids, cytotoxics, phototherapies, retinoids. Depots/reservoirs of drug are advantageous
35 of 38
Describe features of benzoyl peroxide
Clinical issue - blocked pores on skin (stratum corneum). Treatment - non-infected regions - face wash, infected regions - keratolytic/antibiotic creams, correct formulation required
36 of 38
State features of terbinafine
For fungal infection on surface on stratum corneum
37 of 38
State features of hydrocortisone cream
For eczema on epidermis, hydrocortisone BD for 10 days, reassure patient that cream will work/takes time for effectiveness
38 of 38

Other cards in this set

Card 2

Front

What are the advantages of skin delivery? (1)

Back

Possibility of controlled/sustained systemic (transdermal) or localised (dermal) drug delivery

Card 3

Front

Describe features of skin structure

Back

Preview of the front of card 3

Card 4

Front

Describe features of the subcutaneous tissue (hypodermis)

Back

Preview of the front of card 4

Card 5

Front

Describe features of the dermis (1)

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Pharmacy resources:

See all Pharmacy resources »See all Drug Delivery to the Skin - 1 resources »