PSC 4215 - Exam 1 - Semisolid Dosage Forms: Creams, Ointments, and Gels

3 Semisolid dosage forms

Creams, Ointments, Gels

Ointments

Semi solid preparation used on the skin and mucous membranes

(body opening with moist lining such as the eye)

2 Main effects of oinments

Local and Systemic

Why must systemic effects of ointments be considered in pregnant or nursing patients?

Harmful drugs can enter fetal circulation and breast milk

What risk does overuse of topical drugs on large areas pose? (3)

Increased absorption → Systemic effect → Overdose

Why is retinol (a Vitamin A derivative) dangerous in pregnancy?

It is teratogenic, which means it causes fetal defects, even in small amounts

How do absorbed topical drugs reach systemic circulation? (2)

Blood and Lymphatic system

Why do weak basic drugs accumulate in breast milk?

Breast milk is acidic, so it traps weak bases such as morphine and acetaminophen

What is the purpose of topical dermatological products?

Deliver drugs into the skin to treat dermal disorders

What is the target organ of topical dermatological products?

Skin

How do transdermal products differ from topical dermatological products?

Delivers drugs thru the skin to reach system circulation

What is the target organ of transdermal products?

Systemic circulation

Why are transdermal products used instead of oral medications?

Special populations that require systemic circulation

What are the two types of dermatological products? How do they differ?

• Medicated products contain active drugs

• Unmedicated products do not contain active drugs

What are 2 functions of non-medicated dermatological products?

• Emollients → Softeners

• Anti-dehydrates → Retains moisture

What is the role of the base and vehicle in topical preparations?

• Base → Provides structure and consistency

• Vehicle → Acts as a carrier for active ingredients

What are 2 non medicated ointments that are hydrophobic? What is it used for?

• Vaseline and Aquaphor

• Physical effects

What is the function of hydrophobic ointments like Vaseline or Aquaphor?

It forms a protective barrier to enhance wound healing

What are the two types of wound healing in which hydrophobic ointments like Vaseline or Aquaphor are commonly used?

• Primary wound healing → Closed wounds such as stitches

• Secondary wound healing → Open wounds (to recover from bottom up)

What are the two main types of ointment bases?

Hydrophobic and Hydrophilic

Define the following:

Hydrophilic

Hydrophobic

Lipophilic

Lipophobic

• Hydrophilic → Attracts water

• Hydrophobic → Repels water

• Lipophilic → Attracts fat

• Lipophobic → Repels fat

4 Major types of semisolid bases

1. Oleaginous bases

2. Absorption bases

3. Water removable bases

4. Water soluble bases

T/F: Oleaginous bases are greasy and hydrophobic hydrocarbons

T

3 Reasons to use oleaginous (hydrocarbon) bases

• Emollient effect (Softener)

• Anti-dehydrate protection (Retains moisture)

• Occlusive dressing (Barrier, does not allow anything to pass thru)

Why do oleaginous bases remain on the skin for long periods?

It is immiscible with water (does not mix, forms distinct layers)

What prevents bacteria from growing in oleaginous bases?

Lipophilic nature of oleaginous bases

4 Examples of oleaginous bases

• Petrolatum

• White petrolatum

• Mineral oil

• Yellow ointment

What is Petrolatum (Vaseline), USP? Where is it produced from?

• It is a purified semi solid hydrocarbon

• It is a byproduct of petroleum

T/F: Petroleum was originally discovered thru oil drilling

T

How is white petrolatum produced?

Bleaching petrolatum

2 Components of yellow ointment

Yellow wax and Petrolatum

Mineral oil

Liquid oleaginous base

What is mineral oil used for in ointments?

Levigating agent (Helps mix dry powders into a uniform base, unmedicated)

T/F: An oleaginous base helps protect the fluidity of granulation tissue (tissue that forms during the healing of a wound)

T

What are absorption bases useful for?

It helps incorporate aqueous solutions into hydrocarbon bases to create W/O emulsions

(An emulsion is a mixture of two immiscible liquids, where one liquid is dispersed in the other in the form of tiny droplets.)

Are absorption bases easily removable by water washing?

No

2 Types of absorption bases

• Emulsifiable absorption base → Forms W/O emulsions

• Emulsified absorption base → Already in W/O emulsion form, but can incorporate more water

4 Examples of absorption bases

• Lanolin

• Anhydrous lanolin (anhydrous means without water)

• Cold creams

• Hydrophilic petrolatum

What is the dominant base in a “water in oil” emulsion?

What is the dominant base in an “oil in water” emulsion?

• Oil

• Water

What are the four components of Hydrophilic Petrolatum, and what are their functions?

1. Cholesterol → Emulsifying agent → Lipophilic component

2. Stearyl alcohol → Emulsifier → Hydrophilic component

3. White wax → Structure

4. White petrolatum → Base

What is lanolin derived from?

Purified wax like substance from sheep wool

Key function of lanolin

Retains moisture

Water removable base

Oil in water emulsion that resembles creams

T/F: Water removable bases easily wash off with water but require scrubbing

T

Can water removable bases be diluted with water? Why or why not?

Yes bc the external phase is aqueous

What is the main function of water removable bases?

Absorbs serous discharge for fasting healing

In water removable bases, indicate the components that make up the following;

1. Oil phase (2)

2. Water phase (2)

3. Emulsifier (1)

4. Preservative (2)

1. Oil phase → White petrolatum, Stearyl alcohol

2. Water phase → Purified water, Propylene glycol

3. Emulsifier → Sodium Lauryl Sulfate (SLS)

4. Preservative → Methylparaben, Propylparaben

Why do water-removable bases need preservatives?

The high water content increases risk of contamination

Do water soluble bases have any oleaginous components?

No

What kind of semi solid base is completely water washable (greaseless), and does not require scrubbing for removal

Water soluble base

What are water soluble bases used for?

Incorporating solids

What type of semi solid base provides the weakest emollient and least protective effects?

Water soluble base

T/F: The high the water content, the higher the risk of evaporation.

T

2 Examples of water soluble bases

PEG (Polyethylene Glycol Ointment, 3350 and 400) and NF (National Formulary)

Cholesterol

Nonionic, long fatty chain acid

Can cholesterol serve as an emulsifying agent?

Yes, but it must be a mixture of cholesterol and its esters

In cholesterol, what is the result of increasing OH (hydroxyl group)?

It will increase hydrophilicity

What is used to extract cholesterol?

A liquid hydrocarbon such as chloroform (CHCl3)

What semisolid base is best used for thick, dry, calloused skin (e.g., feet, elbows, knees)?

Oleaginous bases

What semi solid base is best used for wound healing, minor burns, or exuding lesions?

Absorption bases

1. _____ → Greasy, Occlusive, Emollient, Lipophilic

2. _____ → Greasy, Occlusive, Emollient, Anhydrous, Absorbs water

1. Hydrocarbon base (Oleaginous)

2. Absorption base

1. _____ → Not greasy, Not occlusive, Water washable, Can be diluted with water

2. _____ → Not greasy, Not occlusive, Water washable and soluble, Lipid free

1. Water removable base

2. Water soluble base

What are the 5 key factors influencing base selection in topical preparations?

1. Action Desired (e.g., occlusive, emollient, water-washable)

2. Physical and Chemical Properties of the Drug

3. Patient Compliance Factors (e.g., ease of washing, staining potential)

4. Bioavailability

5. Stability

Why is the "like dissolves like" principle important in base selection?

It determines release rate and duration

What happens if a lipophilic drug is in a lipophilic base?

Slow release → Long duration (Good for chronic conditions)

What happens if a hydrophilic drug is in a hydrophilic base?

Fast release → Short duration (Good for acute conditions)

Used for dry, scaly skin.

Ointments (Oleaginous)

Applied to weeping or oozing surfaces.

Creams

Applied to intertriginous areas (e.g., skin folds) or where friction occurs.

Lotions

2 Methods for ointment preparation

• Levigation → Mix components until uniform

• Fusion → Melt components together, it will cool as you mix, stop when congealed

What is a key limitation of the fusion method?

The active ingredient must be stable at high temperature

Why might preservatives or emulsifiers degrade in the fusion method?

Heat labile (lose stability)

Semi-solid dosage form that contain one or more drugs mixed or dissolved in a base. The base can be water-in-oil (W/O), oil-in-water (O/W), or water-washable (WWB) formulations.

Creams

What are creams used for?

Treat skin disorders such as dermatitis or psoriasis

What application is preferred by patients due to ease of application and removal? (Hint: Less staining than ointments)

Creams

2 Applications for creams

Rectal and Vaginal

Vanishing cream

Oil in water emulsion

Since vanishing creams have a high water content, wha does it form after evaporation?

A thin film

What is added to vanishing creams to retain moisture? Give 3 examples.

Humectants such as glycerin, propylene glycol, sorbitol

_____ Formula:

• Stearic Acid: 18g

• Mineral Oil (Light): 2g

• Lanolin: 0.5g

• Span 80: 2g

• Potassium Hydroxide: 0.7g

• Sorbitol Solution 70%: 3.7g

• Purified Water: qs ad 100g

Vanishing cream

_____ Formula:

• Cetyl Esters Wax: 125g

• White Wax: 120g

• Mineral Oil: 560g

• Sodium Borate: 5g

• Purified Water: 190ml

• Total: 1000ml

Cream

_____ Formula:

• Cetyl esters wax

• White wax 

• Almond oil 

• Sodium borate 

• Stronger rose water 

• Purified water 

• Rose oil (enhances patient compliance)

Rose water ointment

List 3 W/O emulsion bases that have aqueous mixtures

Eucerin, Nivea, Polysorb hydrate

Semisolid systems consisting of suspensions of small inorganic particles or large organic molecules interpenetrated by a liquid.

Gels

2 Types of gels

• Single phase system → Macromolecules are evenly distributed

• Two phase system = Magma → Contains floccules of small distinct particles

Example of magma (two phase system gel)

Milk of magnesium, used for heartburn, coats the stomach lining but does not neutralize hydrochloric acid

Thixotropy

Gels thickens when standing, requires shaking before use

9 Examples of penetration enhancers of transdermal preparations

DMSO, EtOH, PG, Glycerin, PEG, Urea, SDS, Poloxamers, Terpenes.

2 Examples of transdermal preparations

Nicotine patches, Hormone patches

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

Paste

What are paste used for? Provide an example

• Protective barrier

• Zinc oxide (diaper rash, wounds, eczema)

T/F: Pastes may not contain active drugs but help stabilize medication on the skin.

T

What are the 2 methods to prepare pastes?

Levigation and Fusion

Pastes are used for their stiffness, they remain in place after application and are effectively employed to _____

Absorb serous secretions

Are pastes compatible with hairy parts of the body?

No

Solid/semi-solid adhesive applied to the skin for prolonged contact using backing of paper, fabric, moleskin or plastic

Plasters

What are plasters used for? Provide an example

• Dead squamous skin (callous)

• Salicylic acid (for corn removal)

What does it mean if you feel a burning feeling when using a plaster?

It has gone too far into viable skin

What is the surface effect of ointments on the skin?

Forms protective layer

How do ointments affect the stratum corneum?

Influences hydration and absorption