Suspensions
Suspensions are liquid dosage forms in which solid drug particles are dispersed throughout a liquid medium. The solid particles do not dissolve in the liquid but remain suspended with the help of special agents. Suspensions are used when a drug is insoluble in water or when a liquid form is preferred for easier swallowing, especially for children and elderly patients.
Definition
A suspension is a coarse dispersion in which insoluble solid particles (the drug) are uniformly distributed throughout a liquid vehicle with the help of a suspending agent.
Composition
- Active ingredient: The insoluble drug in solid form
- Liquid vehicle: Usually water or an aqueous base
- Suspending agents: Such as tragacanth, methylcellulose, or xanthan gum, to keep particles evenly dispersed
- Sweeteners and flavoring agents: To make the suspension palatable
- Preservatives: To prevent microbial growth
- Coloring agents: To improve appearance
Advantages
- Suitable for drugs that are insoluble in water
- Improves taste and appearance, especially for pediatric use
- Easy to swallow, preferred for children and elderly
- Flexible dosing, can measure variable doses easily
- Provides better stability for some drugs compared to solutions
- Can be used for both oral and external (topical or injectable) use
Disadvantages
- Sedimentation of particles may occur on standing
- Requires shaking before use to ensure uniform dosing
- Less stable compared to solutions
- May have gritty texture or poor taste if not properly formulated
- Inaccurate dosing possible if not well mixed
Examples
- Paracetamol suspension – used as a fever and pain reliever for children
- Antacid suspensions – for acidity relief
- Amoxicillin suspension – antibiotic for bacterial infections
- Zinc oxide suspension – for skin protection and healing
Importance of Suspensions (with Examples)
- Allows administration of insoluble drugs in liquid form:
Suspensions make it possible to give drugs that do not dissolve in water by dispersing fine particles in a liquid medium.
Example: Antacid suspensions containing magnesium hydroxide or aluminum hydroxide are insoluble but effective in liquid form. - Improves patient compliance, especially in pediatric and geriatric patients:
The liquid form is easy to swallow and can be flavored, making it suitable for children and elderly patients.
Example: Paracetamol suspension is preferred for children who cannot swallow tablets. - Ensures accurate and flexible dosing:
Doses can be measured easily using spoons or droppers, and can be adjusted according to the patient's age and condition.
Example: Antibiotic suspensions like amoxicillin allow flexible dosing for children of different ages. - Useful for both oral and external use:
Suspensions can be applied externally on the skin or taken orally depending on the drug and purpose.
Example: Calamine lotion (topical suspension) is used for itching and skin irritation; oral antacids are suspensions used internally. - Provides stability and prolonged drug action:
Since the drug is in solid particles rather than dissolved, it is more stable and can release slowly, prolonging its effect.
Example: Procaine penicillin suspension (for injection) provides sustained antibiotic action. - Essential dosage form in pharmacy for drugs that cannot be made into solutions:
Some drugs lose effectiveness or chemical stability when dissolved; suspensions are the best alternative.
Example: Corticosteroid suspensions (like hydrocortisone acetate) are used when a stable solution cannot be prepared.
