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Pharmaceutics > M8. Semisolids > Flashcards

M8. Semisolids Flashcards

1
Q

what dermatological treatments target the

skin surface

A
  • camouflage or cosmetic preparations
  • protective films -> barriers, sunscreens
  • antifungal and antibacterial preparations: Polysporin® (polymyxin B/gramicidin or bacitracin), Neosporin® (polymyxin B/neomycin)
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2
Q

what dermatological treatments target the

Stratum Corneum

A

emollients and moisturizers (􏰖 water content)

keratolytics (to remove dead cells)

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3
Q

what dermatological treatments target the

skin appendages

A

antiperspirants (sweat glands) -> aluminum salts

exfoliants (in acne) -> salicylic acid, tretinoin, benzoyl peroxide

depilatories -> thioglycolates

antibiotics -> clindamycin, tetracycline,

erythromycin

antifungals -> clotrimazole, miconazole

**treating hair follicles or sebacious glands

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4
Q

what dermatological treatments target the

viable epidermis and dermis

A

topical steroidal and non-steroidal anti- inflammatory agents

local anesthetic agents

antihistamines/antipruritic

anticancer drugs

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5
Q

what dermatological treatments target the

systemic treatment via percutaneous absorption

A

motion sickness -> scopolamine

angina -> nitroglycerin

hypertension -> clonidine

smoking cessation -> nicotine

*usually incorporated into transdermal patch

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6
Q

preformulation considerations for dermal delivery systems

A
  • Physicochemical properties of drug and vehicle

Dermatological and cosmetic requirements of the topical vehicle

Stability of drug into topical vehicle

Skin safety

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7
Q

what factors need to be considered for optimal bioavailability

A
  • skin disease or condition
  • rate of the release of the drug from the vehicle
  • promotion of percutaneous absorption
  • reuqirement for occulsion (if yes select a vehicle with occlusive properties)
  • short and long term stability of teh drug in the ointment base
  • influence of drug on consistency of base
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8
Q

physiochemcial criteria for dermatologic formulations

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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9
Q

cosmetic criteria for dermatologic formulations

A

Pharmaceutical elegance -> poor product may lead to 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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10
Q

vehicles for dermatolgoical preparations

A
  • Ointments: hydrocarbon, absorption, emulsifying, water soluble, silicone bases

Creams/lotions: oil in water or water in oil emulsions

  • pasts, gels, aerosoles, powders
  • liquids (liniments, soaks, tinctures)
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11
Q

how many phases are in ointments? creams?

A

ointments: single pahse behicle
creams: two phase system

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12
Q

what dermatological behicles are washable? Which are not?

A
  • Non water washable: oleaginous/hydrocarbon bases, absorption, W/O, silicone bases

Water washable: O/W emulsions, gels, hydrophilic bases, emulsifying base

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13
Q

ointemtn definition

A

A suspension or emulsion of semisolid dosage form that contains

<20% water and volatiles

>50% of hydrocarbons, waxes, or polyethylene glycols as the vehicle

for external application to the skin

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14
Q

cream definition

A
  • an emulsion semisold dosage form that contains >20% water and volatiles

<50% of hydrocarbons, waxes, or polyethylene glycols as the vehicle

for external application to the skin

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15
Q

definition of a paste

A

semisolid dosage form

contains a large proportion (i.e. 20-50%) of solids finely dispersed in a fatty vehicle for external application to the skin

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16
Q

definition of dermatological vehicle

A

An emulsion liquid dosage form for external application to the skin

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17
Q

definition of a Gel

A

A semisolid dosage form

contains a gelling agent to provide stiffness to a solution or colloidal dispersion

external application to the skin

gel may contain suspended particles

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18
Q

topical syspension

A

liquid dosage form that consists of a solid suspended in a liquid vehicle in a two- phase system for external application on the skin

19
Q

describe a topical solution

A

A clear homogeneous liquid dosage form for external application to the skin

20
Q

what are the properties of non water washable base

A

Hydrophobic

Greasy

Non-water washable

Occlusive

Emollient

22
Q

what are the advantages and disadvantages of non water washable bases

A
  • Advantages
    • very stable vehicles
    • non irritating
    • non sensitizing
    • high compatibiltiy with drugs
  • Disadvantages
    • greasiness
    • stain clothing
    • difficult to remove
    • low patient acceptance (<< emulsion bases)
23
Q

what are the effects of non water washable bases

A
  • Increased hydration (by preventing evaporation of water from the skin)
  • Enhanced percutaneous absorption
  • Softening of the skin (emollient action)
24
Q

what is occlusion and how is it accomplushed

A
  • formation of an impermeable layer on the skin to prevent evaporation of water
  • can be accomplished by plastic wrap over generally greasy ointments
25
excipeints used in non water washable bases (greasy thigns you add)
1. Fats and fixed oils * mono, di and tri glycerides * oils tend to decompose on exposure to air, light and high temp * become rancid * ex: veg oils (peanut, sesame seed, olive, cottonseed, almond, corn * ) 2. Waxes * Esters of fatty acids and fatty alcohols * fatty substances with high melting points * used as stiffening agents in ointments and creams to inc viscosity * ex: spermaceti, cetyl esters wax, white wax, yellow wax, hard paraffin
26
base (vehicles) for non water washable bases
\*petrolatum and white prteolatum) 1. Yellow ointment * yellow wax and petrolatum 2. White ointment * white wax and white petrolatum 3. Zinc oxide ointment * zinc oxide, mineral oil and white ointemnt
27
Plastibase
aka oleo gel - oleaginous/hydrocanbon base -\> non water washable - made of polyethylene and minteral oil tha tyou melt together - can be used to get drugs to be released faster
28
what are properties of asorption bases
- non water washable - hydrophobic, greasy - anhydrous; hydrophilic components provide water adsorbing properties - upon water addition form W/O emulsions
29
examples of absoroption bases
1. Anhydrous lanolin (wool fat) * mix of steriols ( cholesterol, lanosterol, dihydrocholesterol) and lanoin alcohols (give ability to absorb water) * can be sensitizing * LOW WATER CONTENT 0.25% * can take up to 2x weight in water * W/O emulsifier 2. Lanolin * 25-30% water * W/O emulsion -\> not always used as absorption base * can still take up limited amounts of water 3. other ex: wool alcohols ointment, aquabase, hydrophilic petrolatum, lanolin alc
30
W/O emulsions as non water wahsable bases
more greasy then O/W emulsions emollient cleaning action capable of absoring oil soluble compounds from skin (ex make up removers) ex: cold creams (waxes with borate form in situi emulsifiers) ex: emollient creams like rose water ointment (waxes and borate)
31
pastes as non water washable bases
\*hydrocarbon base with alrge amount of solid that is insolble in paste -\> levigation to prepare - ointments containing up to 50% powder dispersed in fatty base - very stiff consistency -\> localize amterials to defines areas of the skin - form a thick ipmermeable layer on the skin -\> protective action ex: zinc oxide paste and lassars paste (zinc oxide, starch (powders) and petrolatum
32
silicon bases as non water washable bases
- fluid polymers with porperties simialr to hydrocarbon bases - hydrophobic - used as barreir to protect the skin (diaper rash, bed sores) - concentration in ointments 10-30% ex: Dimethicones (polydimethylsiloxanes) \*water repellant properties and good lubricant
33
O/W emulsions as water washable abses
- water washable - soft - non occlusive moisturizing (inc water content -\> restores skin hydration) penetration enhancement of drug compounds ex: hydrophilic ointment, vanishing cream, cleansing cream
34
hydrophilic ointment
O/W emulsion - sodium laurylsulfate = surfactant - preservatives: methyl (hydrophilic) and propyl (lipophilic) parabens - stearyl alc and white petrolatum as oil - propylene glycol as aq phase
35
vanishing cream
water washable base - steric acid + KOH = in situ emulsifyer - smooth easy to apply -\> leaves no residue
36
cleansing cream
O/W emulsion for water washable base - stearic acid and triethanolamine -\> in situ emulsion - stearic acid, mineral oil and anhydrous lanoiln contribute to oil phase
37
Gels as water washable bases
- liquid rich, two component semi- solid colloidal systems - antural or synthetic polyers form a 3D matric through hydrophilic liq - dissolve in water and good for hairy areas - Water-soluble drugs are easily incorporated either dissolved in the aqueous phase or dispersed in gel
38
ex of gel forming materials
Natural gums: tragacanth, agar, pectin, alginates Semi-synthetic or synthetic polymers: methylcellulose, hydroxymethylcellulose, hydroxypropylcellulose, Synthetic polymers: carbopol Clays: bentonite
39
water washabe gel bases examples
* Hydroxypropylcellulose (HPC) gel * HPC + water =-\> prepare by hot or cold method * Zinc oxide gel * carbomer 934P * sodium hydroxide (10% solution) * zinc oxide * water
40
what are hydrophilic bases? What are their properties
- water soluble baess usually made by condensation of polymers of ethylene oxide - ointment like(soften or melt on skin) Non-occlusive, mix with skin exudates Do not stain clothes (greaseless) Non-irritant Chemically stable: do not hydrolyze, deteriorate, do not support mold growth Cannot take up more than 8% water (loose consistency)
41
advantages and inompatabilities of hydrophilic bases
* Advantages * anhydrous -\> useful for drugs that hydroluze * fod patient compliance -\> non staining, non occulsive * Incompatibilities * phenoles, iodine, KI, tannic acid, ailver, Mercury and bismuth salts * reudce antimicrobial activity of quaternary ammonium compounds and parabens * inactivate bacitracin and penicillin
42
ex of hydrophilic bases
* Polyethylene glycol ointment USP * low an dhigh MW polyethylene glycols * if 200-700 0\> liquid * if MW \> 1000 increasingly solid (flaky)
43
emulsifying bases (ointment) as water washable bases
- anhydrous bases containing O/W emulsifying agents - cream like - miscible with water - self emulsifying types: anionic, cationic or non ionic agetns
44
ex of emulsifying bases
- emulsifying pointment BP - liq paraffin, emulsifying wax and white petrolatum

Pharmaceutics (19 decks)

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