Ointments & Creams - Dr. Mirza

Definition of Semisolid Dosage Forms (SSDF)

• represent dosage forms that have properties in between solid and liquid dosage forms

• possess characteristic rheological properties to be easily applied and retained on the site of application for a prolonged time

• AKA not as rigid as solids, too thick for liquids

Advantages of SSDFs

• ability to easily incorporate a wide variety of hydrophillic/phobic drugs

• can be used both systemic and local effects

• can avoid 1st pass metabolism and mimimize unnecessary inc/dec in drug conc

Topical ROAs for SSDF

• exam question

• skin

• mucus

• eye, ear, nose, rectal

Systemic ROAs for SSDF

• exam question

• transdermal

Definition of ointment

• exam question

semisolid anhydrous preparations for external application to the skin or mucous membranes

Factors affecting drug penetration from Ointments

• exam question

• base used

• surface area covered

• amount of pressure/vigor of rubbing

• skin condition

• occlusive dressing use

What is occlusive dressing?

• exam question

Protects something from air or moisture

What is the effect of emollients?

Makes smooth and soft

What is a levigating agent?

• exam question said true or false

• used in triturating (reducing particle size)

  • using a small amount of a liquid, mixing, solvent is insoluble

In oleaginous bases, aqueous preparations may be incorporated ONLY in __________ amounts.

small

Definition of absorption bases

• exam question

permit the incorporation of aqueous solutions resulting in W/O emulsions

• Ex: hydrophilic petrolatum

Definition of emulsion bases (W/O emulsions)

• exam question

permit incorporation of additional quantities of aqueous solutions

• Ex: Lanolin

Water-removable bases are ______ in _________ emulsions.

oil in water

What is washability of water-removable bases.

• exam question

Easily removed from the skin

For sunscreens, what type of base do we want to use?

• water-removable bases

What is the drug release potential for each kind of base:

• exam question on this topic

1. oleaginous

2. absorption

3. emulsion bases

4. water-miscible/soluble

1. poor

2. poor but better than oleaginous

3. fair to good

4. good

Which base can you choose for the best drug release?

• EXAM QUESTION!!!!!!!!!!!

water-miscible/soluble

Which of the following is best if we want the best drug release potential?

a. PEG ointment

b. cold cream type

c. white petroleum

d. anhydrous lanolin

a - PEG ointment is example of water-miscible base

Definition of Creams

• emulsions that possess a fluid consistency and typically are opaque, thick liquids or soft solids that used for their emollient properties

Advantages of Creams

• O/W creams have pleasing appearance

• give a good feeling

• O/W creams are non-greasy and water-washable

• suitable for most topical application ESPECIALLY FOR OOZING WOUNDS!!!!!!!!!!!!

Are ointments or creams preferred for oozing wounds?

• exam question

creams

What is eutectic mixture?

• exam question

• A mixture of two or more substances that has a lower melting point than any of its individual components.

• Forms new drug

• Example: Drug A+ Drug B= Drug C

Compendial (aka standard) requirements for ointments and creams are:

• exam question on this topic

• minimum fill

• microbial content

Definition of Minimum Fill

• exam question on this topic

determination and comparing the net weight or volume w/ the labeled amount

Microbial Content referring to requirements for ointments and creams

• exam question on this topic

• preservatives

• ophthalmic ointment must be sterile

What is a reliable index for microbial growth?

water activity (Aw)

Why do we need water activity?

What is the equation for water activity? (just recognize)

What is the limit for water activity that provides effective control?

• exam question on this topic

1. Topical formulations contain water. Water activity is important because we don’t want microbial growth in our creams. Therefore, this is a measure of how much there is.

2. Aw = Eq RH/100

3. Aw below 0.6 provides effective control