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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

21
Q
A
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
Q

excipeints used in non water washable bases

(greasy thigns you add)

A
  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
Q

base (vehicles) for non water washable bases

A

*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
Q

Plastibase

A

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
Q

what are properties of asorption bases

A
  • non water washable
  • hydrophobic, greasy
  • anhydrous; hydrophilic components provide water adsorbing properties
  • upon water addition form W/O emulsions
29
Q

examples of absoroption bases

A
  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
Q

W/O emulsions as non water wahsable bases

A

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
Q

pastes as non water washable bases

A

*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
Q

silicon bases as non water washable bases

A
  • 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
Q

O/W emulsions as water washable abses

A
  • 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
Q

hydrophilic ointment

A

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
Q

vanishing cream

A

water washable base

  • steric acid + KOH = in situ emulsifyer
  • smooth easy to apply -> leaves no residue
36
Q

cleansing cream

A

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
Q

Gels as water washable bases

A
  • 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
Q

ex of gel forming materials

A

Natural gums: tragacanth, agar, pectin, alginates

Semi-synthetic or synthetic polymers: methylcellulose, hydroxymethylcellulose, hydroxypropylcellulose,

Synthetic polymers: carbopol

Clays: bentonite

39
Q

water washabe gel bases examples

A
  • Hydroxypropylcellulose (HPC) gel
    • HPC + water =-> prepare by hot or cold method
  • Zinc oxide gel
    • carbomer 934P
    • sodium hydroxide (10% solution)
    • zinc oxide
    • water
40
Q

what are hydrophilic bases? What are their properties

A
  • 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
Q

advantages and inompatabilities of hydrophilic bases

A
  • 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
Q

ex of hydrophilic bases

A
  • Polyethylene glycol ointment USP
    • low an dhigh MW polyethylene glycols
      • if 200-700 0> liquid
      • if MW > 1000 increasingly solid (flaky)
43
Q

emulsifying bases (ointment) as water washable bases

A
  • anhydrous bases containing O/W emulsifying agents
  • cream like
  • miscible with water
  • self emulsifying
    types: anionic, cationic or non ionic agetns
44
Q

ex of emulsifying bases

A
  • emulsifying pointment BP
  • liq paraffin, emulsifying wax and white petrolatum

pharmaceutics (19 decks)

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