Pharmaceutical Preparations Quiz

Dosage Form Design 2: Cream, Paste & Ointment

• Creams, pastes, and ointments are semi-solid dosage forms.
• They function as carriers for topically applied drugs.
• They deliver drugs to the skin, cornea, rectal tissue, nasal mucosa, vagina, buccal tissue, and external ear lining.
• Semisolids adhere to the application site for extended periods, enhancing drug delivery.

Learning Outcomes

• Students should be able to differentiate between creams, ointments, and pastes.
• Students should be able to prepare creams, ointments, and pastes.
• Students should be able to select appropriate containers for these dosage forms.
• Students should be able to prepare suitable labels for creams, ointments, and pastes.

Semi-Solid Dosage Form

• Semisolids are a significant portion of pharmaceutical dosage forms.
• They carry drugs for topical application.
• This includes use on skin, cornea, rectal tissue, nasal mucosa, vagina, buccal tissue, and external ear lining.
• Their prolonged contact with the application site prolongs drug release.

Semi-Solid Dosage Form

• Semi-solid dosage forms are intended for topical application to skin, wounds, and mucous membranes, or for cosmetic functions.
• They often serve as protective and emollient agents, aid drug penetration, or locally deliver medicines.
• The forms have been studied for systemic drug delivery over the last few years

Advantages of Semi-Solid Dosage Forms

• External application.
• Probability of side effects reduced.
• Local action.
• First-pass gut and hepatic metabolism avoidance.
• Enhanced patient compliance due to easier drug termination in problematic cases.

Disadvantages of Semi-Solid Dosage Forms

• Lack of dosage accuracy.
• Possible oxidation of the base.
• Bulky, difficult to handle.
• Potential for contamination from finger application.
• Compared to solid dosage forms, semi-solids may be less stable.

Ideal Properties of Semi-Solid Dosage Forms

• Physical: Smooth texture, elegant appearance, non-drying, non-gritty, non-greasy and non-staining, non-hygroscopic.
• Physiological: Non-irritating, miscible with skin secretions, low sensitization effect.
• Application: Easily applied, efficient drug release, high aqueous washability.

Cream, Paste, and Ointment Definitions

• Creams: Opaque, viscous, relatively soft, spreadable; usually contain over 20% water and volatiles, under 50% of hydrocarbons, waxes, or polyols as vehicles. Used for external application.
• Ointments: Homogeneous, translucent, viscous, semi-solid preparations; usually contain under 20% water and volatiles; mainly contain 50% or more hydrocarbons, waxes, or polyols as vehicles. Used for external application.
• Pastes: Thick, stiff, semi-solids; contain a high concentration (20-50%) of insoluble powder substances dispersed in a fatty or aqueous base. Used for external application, acting as protective coatings.

Usage and Types of Cream, Paste & Ointments

• Intended for topical application frequently used as a non-invasive delivery system
• Placed on the skin or eye surface
• Used intranasally.
• Sometimes introduced into cavities like vagina or rectum.
• Used for treating conditions such as dermatitis, eczema, eye infections, etc.

General Uses of Cream

• Topical skin products
• Rectal and vaginal applications

General Uses of Paste

• Semi-solid preparations with a stiff consistency contain 20-50% finely dispersed solids.
• Used for topical applications including skin, mucous membranes, and oral cavity.
• Function as a barrier when applied to the skin.
• Can absorb and neutralize noxious chemicals before reaching the skin.

General Uses of Ointments

• Protectants and physical barriers against the environment.
• Skin emollients, softening and making the skin pliable.
• Carriers for medicaments.

Types of Creams

• Aqueous cream (oil-in-water)
• Anionic emulsifying wax cream
• Cationic emulsifying wax cream
• Non-ionic emulsifying wax cream
• Oily cream (water-in-oil)

Creams: Water-in-Oil vs. Oil-in-Water

• Water-in-oil (O/W): Produced using emulsifying agents, resulting in a smooth, elegant appearance and easy rinsability for use on oozing wounds.
• Oil-in-water (W/O): Consist of synthetic waxes, suitable for rapid absorption and penetration of medication.

Methods of Preparation of Creams, Pastes, & Ointments

• API: Active Pharmaceutical Ingredient.
• Bases: Supports and carries other ingredients.
• Preservatives: Prevent contamination.
• Humectants: Maintain moisture.
• Antioxidants: Inhibit degradation.
• Emulsifier: Helps liquids mix.
• Gelling agents: Make the mixture thick.
• Permeation enhancer: Aids drug absorption.
• Buffer: Maintenance of pH.

Methods of Semi-Solid Preparation

• Trituration Method: Involves mechanically incorporating ingredients in a mortar or on a glass slab with a spatula, frequently using levigating agents (e.g., oils, glycerin) to disperse insoluble powders or powders and liquids.

• Fusion Method: Ingredients that can withstand heat are melted to produce a homogeneous mixture, followed by controlled cooling.

• Emulsification Method: Mixing ingredients with differing properties, particularly water and oil solutions, to produce homogeneous mixtures, requiring emulsifying agents and methods like trituration.

Types of Paste

• Fatty pastes (e.g., zinc oxide paste).
• Non-greasy pastes.

Packaging for Semisolids.

• Usually packaged in jars or tubes.
• Jars: Use a spatula for application, filling, and to prevent trapped air.
• Tubes: Pressure-filling technique is used.

Storing and Labeling Semisolids.

• Store in a cool place, protected from light.
• Use tightly closed containers that are completely filled.
• Proper packaging and storage conditions prevent crystallization of active ingredients and protect from air, light, moisture, and high temperatures or extreme changes impacting the preparation.
• Labelled with important details about the base (e.g., water-soluble or water-insoluble) and use only for external application.

Administration of Topicals

• Counsel patients to get maximum benefit.
• Cleanse affected area with soap and water (where applicable).
• Dry the area.
• Apply as a thin, even layer.
• Gentle massaging is sometimes advised.
• Wash hands with soap and water after application.
• Occlusion (e.g., with bandage) is often not necessary.