Ointments/Creams/Gels

Ointments, creams, gels and pastes are referred to as ____________________

semisolid

Ointments, creams, gels and pastes are referred to as semisolids meaning

less pourable than a liquid, and less rigid than a solid

semisolid dosage forms are applied to any ___________ body surface

external

physical properties of semisolids

1. smooth texture

2. elegant in appearance

3. non-dehydrating/gritty/greasy/staining

physiological properties of semisolids

1. non-irritating/interference

2. biocompatibility

application of semisolids

1. easy to apply (spreadability)

2. efficient drug release

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

ointments

A cream is a semisolid dosage form containing one or more drug substances dissolved or dispersed in a suitable base

creams

Ointments and creams may be differentiated by the ________ from which the semisolid is formed

base

Creams are traditionally made from ________-containing bases (more cosmetically acceptable)

water

Ointments are usually made using _________________ bases

oleaginous or anhydrous

categories of bases for ointments/creams

1. hydrocarbon bases

2. absorption bases

3. W/O emulsion bases

4. water removable bases

5. water soluble bases

hydrocarbon bases characteristics

1. water-insoluble/ not water washable

2. Oily/greasy, occlusive; Lack cosmetic appeal (WORST)

3. prevent water loss from skin

absorption bases characteristics

1. Water-insoluble, will absorb water to form W/O emulsion (BETTER absorption)

2. occlusive, lack cosmetic appeal, emollient (dry skin)

When an W/O emulsifier (emollient) is added to an oleaginous base, the mixture becomes ________________ that is capable of absorbing large amounts of water or hydro-alcoholic solutions

absorption (anhydrous) base

Remember the bases containing water are subject to microbial growth and the USP requires that these contain __________________

preservative

characteristics of W/O emulsion bases

1. Water-Insoluble, less occlusive (compared to oleaginous bases); contain water

2. More cosmetically acceptable; spread more easily on the skin; emollients

3. useful for hydrophilic drugs

characteristics of water removable bases (O/W emulsion)

1. Water-washable; can be diluted

2. Non-occlusive but cosmetically elegant; Easily removed from skin

3. ensure patient cooperation

Aqueous phase exceeds the oil phase in volume

O/W type emulsions

Usually incorporates three components of O/W type emulsions

1. oil phase

2. emulsifier (anionic, cationic, nonionic)

3. water

for water removable bases store in tight containers and add _______________ agents such as glycerin, propylene glycol to retard dehydration

auxiliary

characteristics of water-soluble bases

1. Water-soluble and washable

2. can absorb water, no oil phase

3. non-occlusive and non-greasy

additional characteristics of water soluble bases

1. preservative needed

2. no emollient properties

3. stability prone to oxidation

methods for preparing ointments

1. fusion

2. levigation

Components of the ointments are combined together and melted and cooled with constant stirring until congealed; mix ingredient in the melting state (Melting; Mixing, Cooling and Stirring)

fusion method

when preparing using the fusion method

1. add ingredients in order of decreasing mp

2. heat to fusion point

In the fusion method Ingredients with ____________ melting point are melted first. The heat is then reduced and the ingredient with the next highest melting point is added and melted. Continue the process.

highest

components of fusion

1. melting

2. mixing

3. cooling

4. stirring

when to use fusion method

Solids that can not be easily triturated

Mechanical incorporation

levigation

preparation of levigation

1. must reduce powder

2. use geometric dilution to add powder

when to use levigation

When all ingredients can be triturated

Note that a levigating agent should be physically and chemically _________________ with the phase into which the drug is dispersed

compatible

other additives to ointments

1. perfumes

2. chelating agents

3. antioxidants

4. preservatives

Most Ointments are non-sterile except ___________ ointments

Ophthalmic

Ointments must meet minimum standards for __________ contents

microbial

Ointments containing __________ are good source for microbial contamination.

water

o USP suggests tests for Staphalococcus aureus and pseudomonas aeuroginosa, because both these microbes can cause _________ infection

skin

Examples of preservatives for topical formulations

parabens

Semisolids consisting of suspensions made up of either small inorganic particles or large organic molecules interpenetrated by a liquid

gels (jellies)

classification of gels

1. single phase

2. two phase

- uniform dispersions of particles in a liquid with no apparent boundaries between dispersed particles and the medium

single phase

when the network of small discrete particles are noticeable.• Consists of small dispersed particles

two phase

homogeneous physically distinct portion of a system that is separated from other portions of the system by bounding surfaces

phases

characteristics of gel single phase

1. clear water appearance

2. translucent of polymer is not fully dissolved

characteristics of gels-two phase

1. typically inorganic

2. opaque

3. thixotropic

semisolid dosage forms that contain one or more drug substances intended for topical application.

pastes