5. Semi-solids

Question 0

What is a topical dermatologic semi-solid?

Answer 0

• a cream, ointment or gel that delivers drug locally into skin
• skin is the target organ

Question 1

What are semi-solid dosage forms typically used for?

Answer 1

• for topical use (usually placed on the skin)

- creams, ointments, gels

Question 2

What is a transdermal semi-solid?

Answer 2

• a cream, ointment or gel that delivers the drug systemically through the skin into blood
• target organ not the skin

Question 3

What are non-medicated ointments used for?

Answer 3

• protective, emollient, lubricating activity

Question 4

What are the 4 classes of ointment bases?

Answer 4

• oleaginous (non-polar)
• absorption
• water-removable
• water soluble (polar)

Question 5

Describe oleaginous bases.

Answer 5

• hydrocarbon base (vaseline)
• emollient effects (stop moisture loss)
• occlusive
• stay on skin a long time
• hard to wash off
• small qtys of water and aqueous solutions can be incorporated (hard to do tho)
• mineral oil used levigating agent to incorporate solids

Question 6

Describe absorption bases.

Answer 6

• w/o emulsion
• two types
  
  • allows water mixing to form w/o emulsion
  • already a w/o emulsion
• used as emollient
• hard to wash off

Question 7

Describe water-removable bases.

Answer 7

• mostly o/w emulsions
• easily washed off
• since continuous is aqueous, can be diluted with water
• cosmetically acceptable
• can be applied to weeping areas
• consider preservation

Question 8

Describe water-soluble bases.

Answer 8

• called “greaseless”…no oleaginous component
• completely water washable
• ## usually contain polyethylene glycol (PEG)

Question 9

What are the considerations for picking a base?

Answer 9

• topical or subcutaneous
• rate of drug release
• occlusion wanted?
• drug stability
• drug solubility/skin feel
• easy/difficult removal
• site of application

Question 10

Describe incorporation for the preparation of ointments.

Answer 10

• spatulation used (sometimes triturate with mortar and pestle)
• reduce particle size before
• use levigation of the particle in vehicle in which its not soluble (makes smooth dispersion)
• levigating agent must be chemically and physically compatible with drug and base

Question 11

What kind of levigating agent is used in ointments?

Answer 11

water base - glycerin

oil base - liquid petroleum/mineral oil

Question 12

Describe fusion for the preparation of ointments?

Answer 12

• some or all components melted together and incorporated
• seldom go over 70 degrees celsius
• first melted = solvent
• if aqueous and oleaginous mixture, heat separately.
• stir while combining
• usually add aqueous phase to oleaginous phase

Question 13

Describe creams.

Answer 13

• water evaporated and leaves oleaginous film
• not greasy, easy to spread and remove
• used when drying needed and skin is weeping or has exudates (skin leakage)

Question 14

Describe the packaging of semi-solid dosage forms.

Answer 14

• usually packaged in wide-mouthed jars or tubes
• jars with no air entrapment
• contents should not touch lid (elegance)