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Dosage II > 21: Topical Transdermal > Flashcards

21: Topical Transdermal Flashcards

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1
Q
A
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2
Q

physiology of skin

A

-stratum corneum
-living epidermis
-dermis
-hair follicles and sweat glands

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3
Q

Stratum corneum

A

-main barrier to permeation
-brick (dead cells) and mortar (lipid) model
-permeation occurs by partitioning thru lipid material between dead cells
-lipid barrier
-state of hydration related to ease of permeation

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4
Q

Living epidermis

A

-living cells w/o capillaries
-get nutrition by diffusion from dermis
-source of skin color and tanning

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5
Q

Dermis

A

-contains capillaries
-drug needs to reach capillaries to achieve systemic action
-contains pain, thermal, tactile sensors
-injury must reach dermis to produce scarring

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6
Q

Hair follicles and sweat glands

A

-secondary route of drug absorption that bypasses the stratum corneum

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7
Q

Functions of the skin

A

-containment
-microbial barrier
-chemical/radiation/electrical/thermal barrier

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8
Q

skin pH

A

-5
-inhibits bacterial growth
-sebum has bacterio/fungostatic fatty acids

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9
Q

Skin as chemical barrier

A

-permeabiilty resistant

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10
Q

skin as a radiation barrier

A

-exposure to UV stimulates melanin which absorbed UV rays

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11
Q

skin as electrical barrier

A

-high impedance to flow of electrical current
-need to treat skin w salt solutions and overcome impedance to measure body potentials

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12
Q

Body temp

A

-98.6 by dilating/contracting blood vessels or sweating

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13
Q

Topical drug delivery

A

-local effects on barrier function (surface and stratum corneum effects)
-drug action on the skin’s glands
-effects in deep tissues

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14
Q

Transdermal drug delivery

A

-systemic drug delivery

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15
Q

Surface effects of topical drug delivery

A

-Zn oxide paste for diaper rash
-sunblock
-lip balms
-calamine, antibxs, deodorants, soaps

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16
Q

Stratum corneum effects

A

-emolliency: softening horny tissue
-keratolysis: chemical digestion and removal of horny tissues

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17
Q

drug action on skin glands

A

-antiperspirants
-acne
-hair removers

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18
Q

antiperspirants

A

-Al-Cl-
-irritate and close orifice of eccrine glands to impede sweat flow

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19
Q

acne meds

A

-soap, alc, antibxs
-retinoids reset the process of epidermal proliferation and differentiation = prevents formation of lesions

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20
Q

Topical drug effects in deep tissues

A

-topical steroids
-NSAIDs
-locak anesthetics
-lighten skin
-skin cancer

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21
Q

Topical Drug Delivery Platforms

A

-ointments
-pastes
-creams
-gels
-rigid foams

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22
Q

Ointment bases

A

-hydrocarbon (more hydrophobic)
-silicone
-absorption
-water soluble (less hydrophobic)

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23
Q

Hydrocarbon bases

A

-petrolatum
-polyethylene dissolved in mineral oil

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24
Q

silicone bases

A

contain ppolydimethylsiloxane oil

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25
absorption bases
-ointment containing w/o emulsifiers
26
Water soluble bases
-polyethylese glycol ointment
27
Pastes
-ointments w high concentration of insoluble solids are added
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Creams
-o/w or w/o emulsion
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Gels
-liquid phase trapped in matrix of polymer
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Rigid foams
-air or gad emulsified in a liquid phase -liquid phase may contain drug -aerosol shaving creams, medicated quick-breaking antiseptic foams
31
Transdermal drug delivery
-some drugs can penetrate skin and enter systemic circulation -good for drugs that experience high first pass metabolism
32
Transdermal drug delivery structure
-backing membrane --drug reservoir w drug molecules -rate-controlling porous membrane -skin-contact adhesive -blood capillary
33
Transdermal drug delivery permeability
-general inpenetrable -permeability correlates w drug's MW and Ko/w -useful for drugs with high skin permeability and low dose requirement
34
Permeability equation
log P ~ -2.7 + 0.71*logKo/w - 0.0061M -P= permeability coefficient -M= molecular weight -Ko/w= oil/water partition coefficient
35
Types of transdermal patches
-membrane-modulated -adhesive dispersion -matrix dispersion
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Membrane-modulated transdermal patches
-backiing membrane -drug reservoir -rate-controlling micropourous membrane -adhesive
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Adhesive dispersion transdermal patches
-backing membrane -drug reservoir -rate-controlling adhesive
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Matrix dispersion
-backing membrane -drug + adhesive
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slide 15
slide 15
40
Transdermal nitroglycerin
-half-life: 3 min -slightly soluble in water -soluble in common organic solvents
41
Transdermal nitroglycerin use
-prevent angina due to coronary heart disease -not for immediate relief of acute attacks
42
Transdermal rivastigmine use
-indicated for dementia associated w alzheimer's or parkinsons
43
transdermal rivastigmine dose
-4.6, 9.5, 13.3 mg/day
44
Transdermal rivastigmine
-soluble in water, ethanol, acetonitrile, n-octanol, ethyl acetate -log P: 2.3 -water solubility 2.04mg/mL -backing film, drug matrix, adhesive matrix, release liner
45
Transdermal contraceptive
-35mcg ee -150mcg -once a week for 3 weeks -upper arm, abdomen, buttock, back
46
Matrix-type transdermal system strucutre of xulane
-backing polymer layer -middle layer: adhesive + matrix + active ingredients -third layer: release liner
47
Drug diffusion through skin
-across cellular-intercellular regions -across lipid intercellular spaces -across thin lipid layers sandwiched between flattened protein cells
48
Factors affecting permeability
-hydration -solubility of drug in stratum corneum -excipients (solvents, surfactants) -pH affects ionization
49
Methods of penetration enhancement
-iontophoresis -electroporation -ultrasound -prodrugs -chemical
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iontophoresis
-uses low voltage electrical current to drive changed drugs through the skin
51
Electroporation`
-uses high voltage short to creat pores in skin
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ultrasound
-use low freq ultrasonic energy to disrupt the stratum corneum
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prodrugs
-make lipophilic
54
Chemical penetration enhancers
-alcohol, DMSO, surfactants, acetone, ethyl acetate
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Enhancers
-ionic surfactants -ascorbate, dithiothreitol -azone -DMSO
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ionic surfactants
-disorder the lipid layer of stratum corneum to swell and/or leach out some of the structural components, thus reducing the diffusional resistance
57
Ascorbate, dithiothreitol
-reducing agents -disrupt disulfide bonds of proteins in keratinized cells
58
Azone
-nonpolar, oily liquid -fluidize lipid lamella region of stratum corneum
59
Dimethyl sulfoxide (DMSO)
-dipolar solvent -enter aq region of stratum corneum -interact w the lipid polar heads to expand hydrophillic region between polar heads
60
slide26
slide26
61
Types of microneedles
-dissolving microneedles -hydrogel forming -seperable -hollow
62
Dissolving microneedles
-type of polymeric MN that can degrade or dissolve postinsertion into the skin -leads to delivery of excapsulated drug at site of application
63
Hydrogel forming microneedles
-have cross-linked hydrogel structure that can collect interstitial fluid upon skin application to in-situ hydrogel
64
Separable microneedles
-rapidly dissolvable backing layers -weaker connections between backing layers and MN tips, or based on hydrogel backing layer
65
Hollow microneedles
-each needle incorporates a hollow cavitiy within and a bore on the needle tips to which small volumes of drug can be injected
66
PVP
67
Patches application sites
-upper chest/back -upper arm -flanks
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Patch freq
-daily -BID -2 weekly -weekly -72h
69
Common errors in transdermal patch administration
-prep -removal -application -monitoring (displacement) -storage and disposal
70
Some patients do not realize
-patch must be applied directly to skin (do not tape) -remove protective liner -use one at a time -where to place (rotate) -when to change -TSS -do not cut patches for kids

Dosage II (20 decks)

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