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Pharm 124 > semisolids (week10) > Flashcards

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
Q

non water washable bases (4)

A

oleaginous/hydrocarbon
absorption bases
W/O emulsion bases
silicon bases

26
Q

water washable vehicles (4)

A

O/W emulsions
gels
hydrophillic bases
emulsifying bases

27
Q

normal water content of stratum corneum

A

10-20%

28
Q

permeability of intact vs diseased skin

A 
intact = good barrier
diseased = more permeable
29
Q

shunt rule

A

durgs can permeate into the skin by absorption through the appendages

30
Q

Acid mantle

A

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
Q

effects of UV light on the skin

A

UVB - 290-320nm - burns skin

UVA - 300-400nm - less damaging

32
Q

effect of hot and cold exposure percutaneous abs

A

hot

  • vasodilation, red skin
  • more percutaneous abs

cold

  • vasoconstriction
  • percutaneous abs dec
33
Q

sink conditions

A

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
Q

Pastes

A
  • 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
Q

Lotion

A

emulsion liquid dosage form

36
Q

gel

A

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
Q

occlusion

A

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
Q

oleaginous/hydrocarbon bases

A

occlusive

Properties

  • greasy
  • hydrophobic
  • non- water washable
  • emolient

advantages

  • very stable
  • non irritating
  • non-sensitizing
  • high compatibility with drugs
39
Q

excipients non water washable bases

A

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
Q

non-water washable bases: vehicles

A

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
Q

plastibase

A

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
Q

Absorption bases

A 
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
Q

absorption bases: anhydrous lanolin (wool fat)

A
  • 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
Q

unctuous

A

stains, difficult to remove

45
Q

Lanolin (hydrous wool fat)

A

25-30% water
W/O emulsion - not always used as absoption base
-still take up lim amnts water

46
Q

Absorption bases: Lanolin alcohols, liquid lanolin (lanolin oil)

A

purified fractions of wool fat

less tacky than wool fat

47
Q

what part of wool fat enables the emulsifying properties

A

wool fat = anhydrous lanolin

its cholesterols and lanolin alcohols impart its ability to absorb water

48
Q

W/O emulstions

A

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
Q

cold creams

A

use beeswax-borax in situ emulsifier

OR

cetyl wax of white wax`

50
Q

Non-water washables bases: pastes

A

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
Q

NON WATER WASHABLE BASES: SILICON BASES

A

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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