Pharmaceutical Creams and Emulgels

A set of vocabulary flashcards covering key concepts and terms related to the preparation, characteristics, and formulation of pharmaceutical creams and emulgels.

What are pharmaceutical creams?

Multiphase preparations consisting of a lipophilic phase and an aqueous phase intended for external application.

Lipophilic cream (W/O) characteristics

Somewhat greasy, less miscible with skin secretions, and somewhat occlusive.

Hydrophilic cream (O/W) characteristics

Non-greasy, miscible with skin secretions, and water-washable.

Key components of a cream formulation

Drug, continuous phase, dispersed phase, and emulsifier.

Role of emulsifiers in creams

Stabilize the emulsion and ensure the formation of a homogeneous mixture.

What does HLB stand for?

Hydrophilic-Lipophilic Balance, used for selecting suitable emulsifiers for emulsions.

Bancroft’s rule significance

Helps determine whether to use high or low HLB emulsifiers for O/W or W/O emulsions.

Advantages of emulgels

Incorporation of poorly water-soluble drugs, non-greasy nature, good patient acceptability, and dual release control mechanisms.

Disadvantages of emulgels

Entrapment of air bubbles.

What is Pemulen™?

A polymeric emulsifier that produces an O/W emulsion with an external gel phase, independent of required HLB.

Formulation considerations for creams

Ensuring good solubility, stable emulsions, and suitable emulsifier choice.

Examples of common excipients in creams

Cetomacrogol, glycerol, preservatives, penetration enhancers, and antioxidants.

"Q: What is a pharmaceutical cream?"

"A: A semi-solid emulsion consisting of a lipophilic phase and an aqueous phase stabilised by an emulsifier."

"Q: What emulsion types can creams be?"

"A: Oil-in-water (O/W) or water-in-oil (W/O)."

"Q: What is the main purpose of creams?"

"A: Protective therapeutic or prophylactic application to skin or mucous membranes where occlusion is not required."

"Q: What is meant by the continuous phase of a cream?"

"A: The phase that surrounds and contains the dispersed phase."

"Q: What is a hydrophilic cream?"

"A: An O/W cream where the continuous phase is aqueous."

"Q: Key characteristics of hydrophilic (O/W) creams?"

"A: Non-greasy miscible with skin secretions water-washable non-occlusive."

"Q: What is a lipophilic cream?"

"A: A W/O cream where the continuous phase is oily."

"Q: Key characteristics of lipophilic (W/O) creams?"

"A: Somewhat greasy less water-washable less miscible with skin secretions mildly occlusive."

"Q: What are the basic components of a cream?"

"A: Drug continuous phase dispersed phase emulsifier."

"Q: Why is an emulsifier required in creams?"

"A: To stabilise the emulsion and prevent phase separation."

"Q: Role of a co-solvent in creams?"

"A: Enhances solubility of the drug."

"Q: Role of a thickener in creams?"

"A: Improves viscosity stability and drug release profile."

"Q: Role of preservatives in creams?"

"A: Prevent microbial spoilage."

"Q: Role of penetration enhancers?"

"A: Increase drug penetration through the skin."

"Q: Role of pH regulators?"

"A: Adjust formulation pH and reduce skin irritation."

"Q: Role of antioxidants?"

"A: Prevent oxidative degradation of ingredients."

"Q: Why must drug solubility be considered in cream formulation?"

"A: To ensure uniform dose distribution and stability."

"Q: How are insoluble solids incorporated into creams?"

"A: By trituration to ensure homogeneous dispersion."

"Q: What type of emulsifiers are commonly used in creams?"

"A: Amphiphilic surfactants."

"Q: What does HLB stand for?"

"A: Hydrophile–Lipophile Balance."

"Q: What does Bancroft’s rule state?"

"A: The phase in which the emulsifier is more soluble becomes the continuous phase."

"Q: What HLB range favours O/W emulsions?"

"A: High HLB (>10)."

"Q: What HLB range favours W/O emulsions?"

"A: Low HLB (

"Q: Why is HLB matching important?"

"A: Different oils require specific HLB values for stable emulsions."

"Q: Why are emulsifier blends often used?"

"A: To achieve the required HLB and improve emulsion stability."

"Q: First step in preparing a cream?"

"A: Dissolve lipophilic ingredients in the molten oily phase at minimum temperature."

"Q: How are hydrophilic ingredients prepared?"

"A: Dissolved in the aqueous phase and heated to the same temperature as the oily phase."

"Q: Why must both phases be mixed at the same temperature?"

"A: To prevent premature solidification and instability."

"Q: Why should cooling not be hastened?"

"A: Rapid cooling can destabilise the emulsion."

"Q: What is an emulgel?"

"A: An emulsion where the continuous phase is a gel."

"Q: What emulsion types can emulgels be?"

"A: O/W or W/O."

"Q: Main advantage of emulgels over creams?"

"A: Incorporation of poorly water-soluble drugs in water-based formulations."

"Q: Additional advantages of emulgels?"

"A: Non-greasy good patient acceptability dual release control enhanced stability thixotropic spreadability."

"Q: Main disadvantage of emulgels?"

"A: Entrapment of air bubbles."

"Q: What type of emulsifier is Pemulen™?"

"A: Polymeric emulsifier."

"Q: Structural components of Pemulen™?"

"A: Hydrophobic alkyl acrylate and hydrophilic acrylic acid."

"Q: How does Pemulen™ stabilise emulsions?"

"A: Hydrophobic chains embed in oil droplets while acrylic acid forms a viscous aqueous gel."

"Q: What type of emulsion does Pemulen™ form?"

"A: Oil-in-water (O/W) emulsion."

"Q: Why is Pemulen™ described as HLB-independent?"

"A: Emulsification does not depend on traditional HLB matching."

"Q: What happens to Pemulen™ on contact with skin electrolytes?"

"A: Gel de-swells causing rapid release of the oil phase."

"Q: Key difference between creams and emulgels?"

"A: Creams are semi-solid emulsions; emulgels are emulsions with a gel continuous phase providing improved stability and release control."