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semisolids (week10) Flashcards

1
Q

skin pH

A

5.5

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2
Q

main layers

A

epidermis
dermis
subcutaneous

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3
Q

layers of epidermis

A

stratum corneum
stratum lucidum
stratum spinosum
stratum germinativum/basale

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4
Q

epidermis cell types/what prod

A

keratinocytes - produce insol keratin protein and lipids
melanocytes
dendritic (langerhans) cells

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5
Q

Dermis
-matrix of CT
-

A

-matrix of CT: 75% collagen 4% elastin
- contains BVs and nerves and appendages (sweat glands, sebaceous glands, hair follicles)
-contains fibroblasts, mast cells, histocytes
-SITE OF DRUG METABOLISM
maintians “sink conditinon” due to vasculature

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6
Q

Epidermis

A

epidermis cells = viable portion of epidermis
stratum corneum dead cells
+forms impermeabble layer
+rss permeation of external cpds
SERVES AS RATE LIMITING factor in absorbtion of drugs

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7
Q

Targets for drmatologicla treatment ()

A 
skin surface
startum corneum
skin apendages
viable epidermis and dermis
systemic treatment bia percutaneous absorption
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8
Q

targets for dermatological treatment: skin surface

A
  • camoflauge or cosmetic preparations
    -protective films - barriers, sunscreans, antifungal and antibacterial preps (polysporin)
    -
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9
Q

targets for dermatological preparations: stratum corneum

A

emolients and moisurizers
+increase water content

keratolytics (remove dead cells)

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10
Q

skin appendges

A

antiperspirants (seat glands) - aluminum salts
exfoliants (in acne) - salicylic acid, tretinoin, benzoyl peroxide
depilatories - thioglycolates
antibiotics - clindamycin, tetracyclin, erythromycin
antifungals - clotrimazole, miconazole

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11
Q

targets for dermatological treatement: viable dermis and epidermis

A

topical steroidal/nonsteroidal antiinflammatory agents
local anesthetic agents
antihistamines/antipruritic
anticancer drugs

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12
Q

target regions for dermatological treatment: systemic treatment by percutaneous absorption

A

motion sickness - scopolamine
angina - nitraglycerine
hypertension - clonidine
smoking cessation - nicotine

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13
Q

selection of vehicle for optimum bioavailability

A
  • Skin disease or condition
  • Rate of the release of the drug from the vehicle (drug favors skin over vehicle)
  • Promotion of percutaneous absorption
  • Requirement for occlusion
  • Short and long term stability of the drug in the ointment base
  • Influence of the drug on the consistency of the base
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14
Q

pH above what is irritating to skin

A

above 8

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15
Q

criteria for dermatological formulations

A

1) physiochemical criteria

2) cosmetic (aesthetic) criteria

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16
Q

physiochmeical criteria Iderm form)

A
  • Stability of the active ingredient
  • Stability of adjuvants
  • Rheological properties (consistency, extrudability)
  • Prevention of loss of water or volatile compounds
  • Phase changes – homogeneity, phase separation, bleeding)
  • Particle size, particle distribution of the dispersed phase
  • Apparent pH
  • Particulate contamination
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17
Q

criteria for dermatoologic formulations: cosmetic

A
  • Pharmaceutical elegance ——> non-compliance
    • Easy transfer from container
    • Spreads readily and smoothly
    • Leaves no residue
    • Adheres to treated area without being tacky or difficult to remove
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18
Q

Dermatologic vehicles (ointments) (5)

A 
hydrocarbon bases
absorbing bases 
emulsifying bases
water soluble bases
silicone bases
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19
Q

dermatologic vehicles: creams and lotions (2)

A

O/W emulsitons

W/O emusionts

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20
Q

Dermatologic vehicles powders

A

dusting powders

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21
Q

dermatological vehicles: liquids

A

linments
soaks
tinctures

22
Q

dermatological vehicles: what are they (7)

A 
ointments
emmulsions
pastels
gels
aerosols
powders
liquids
23
Q

ointments

A

semisolid preps
hydrophillic or greasy
usually anhydrous
may contain dissolbed or dispersed medicaitons

24
Q

creams

A

semisolid preparations, both oil and water

25
non water washable bases (4)
oleaginous/hydrocarbon absorption bases W/O emulsion bases silicon bases
26
water washable vehicles (4)
O/W emulsions gels hydrophillic bases emulsifying bases
27
normal water content of stratum corneum
10-20%
28
permeability of intact vs diseased skin
``` intact = good barrier diseased = more permeable ```
29
shunt rule
durgs can permeate into the skin by absorption through the appendages
30
Acid mantle
pH 5.5 dermatological formulations with pH 5.5 are most compatible with skin bacteriocidal and fungocidal secretions from eccrine and sweat glanes (short chain FAs)
31
effects of UV light on the skin
UVB - 290-320nm - burns skin | UVA - 300-400nm - less damaging
32
effect of hot and cold exposure percutaneous abs
hot - vasodilation, red skin - more percutaneous abs cold - vasoconstriction - percutaneous abs dec
33
sink conditions
blood flow through BVs takes drugs that are percutaneously absorbed with it thus maintaining the concentration gradient needed for percutaenous absoption between the formulation and the skin
34
Pastes
- semisolid preparation - large portion of solids (20-50%) finely dispersed in a fatty vehicle for external application on the skin Very stiff - localize materials to defined regions of skin thick impermeable layer on skin - protective
35
Lotion
emulsion liquid dosage form
36
gel
semisolid -gelling agent provides stiffness -solution or colloidal dispersion for ext app gel may contain suspended particals Properties - dissolve in water - good for hairy areas - water soluble drugs easily encorporated (dissolved in aq phase or dispersed in gel)
37
occlusion
formation of impermeable layer on skin to prevent evaporation of water -may be accompagnied by plastic wrap over generally greasy ointments inc hydration by preventing evaporation of water enhance percutaneous abs soften skin (emolient action)
38
oleaginous/hydrocarbon bases
occlusive Properties - greasy - hydrophobic - non- water washable - emolient advantages - very stable - non irritating - non-sensitizing - high compatibility with drugs
39
excipients non water washable bases
1) fats and fized oils +oils tend to decomp on exposure to air light high T = become rancid 2)Waxes -esters of FA and fatty alcohols -Fatty substances with high MP (60-80) -used as stiffening agents in ointments and creams emollient properties
40
non-water washable bases: vehicles
petrolatum (yellow soft parrafin, yellow petrolatum) white petrolatum (colour bleached) yellow ointment USP white ointment USP zinc ozide ointment USP Plastibase (polyethylene and mineral oil)
41
plastibase
gelled mineral oil by addition of polyethylene unctuous base (stains, difficult to remove) consistency dosent change over wide T range useful working T 15-60 excessive heat over 90 destroys DRUGS RELEASED FASTER BY PLASTIBASE THAN PETROLACTUM
42
Absorption bases
``` types: anhydrous lanolin (wool fat) lanolin (hydrous wool fat) lanolin alcohols, liquid lanolin (lanolin oil) hydrophilic petrolatum USP aquabase ointment wool alcohols ointment BP ``` properties - hydrophobic - greasy - anhydrous (hydrophillic cpnts provide water abs properties) - add water forms W/O emulsions
43
absorption bases: anhydrous lanolin (wool fat)
- mix of sterols and lanolin alcohols which impart ability to abs water - sticky yellow unctuous mass from sheep wool - can be sensitizing - -MP 36-42 - water content 0.25% - can take up to 2x weight in water - acts as W/O emulsifier
44
unctuous
stains, difficult to remove
45
Lanolin (hydrous wool fat)
25-30% water W/O emulsion - not always used as absoption base -still take up lim amnts water
46
Absorption bases: Lanolin alcohols, liquid lanolin (lanolin oil)
purified fractions of wool fat | less tacky than wool fat
47
what part of wool fat enables the emulsifying properties
wool fat = anhydrous lanolin | its cholesterols and lanolin alcohols impart its ability to absorb water
48
W/O emulstions
more greasy than O/W good at removing oil soluble substances from surface of skin emolient and cleanisng action ex. cold creams and emolient creams
49
cold creams
use beeswax-borax in situ emulsifier OR cetyl wax of white wax`
50
Non-water washables bases: pastes
PASTES pointments containing up to 50% poweder dispersed in fatty base very stiff and locatlize materials in specific location on skin thick impermeable layer on skin - protective action
51
NON WATER WASHABLE BASES: SILICON BASES
FLUID POLYMER WITH SIMILAR PROPERTIES TO HYDROCARBON BASE HYDROPHOBIC BARRIER TO PROTECT SKIN (DIAPER RASH, BED SORES) 10-30% CONC IN OINTEMNTS

Pharm 124 (4 decks)

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