Injection and Infusion are two common methods used to administer medications or fluids directly into the body, typically via the bloodstream. They differ mainly in how the substance is delivered and over what period of time. An injection is the act of delivering a substance into the body using a syringe and needle. 

💉 Examples : 

• Vaccines (IM or SC)

• Insulin (SC)

• Pain medications (IM or IV)

Types of Injections available:- 

(a) Intravenous (IV) – Into a vein (fastest effect). (b) Intramuscular (IM) – Into a muscle. (c) Subcutaneous (SC) – Into the layer under the skin. (d) Intradermal (ID) – Into the skin layer.

⚡ Injection Characteristics:- 

• Rapid administration (usually seconds to a few minutes).
• Used for small volumes (typically less than 10 mL).
• Immediate or quick onset of action.
• Often a one-time dose.

Syrups and Suspensions, two common liquid oral dosage forms used especially in pediatric and elderly care. A syrup is a concentrated aqueous (water-based) solution of sugar (usually sucrose) containing dissolved medications. 

💧 Examples:

• Paracetamol syrup

• Cough syrups (e.g., dextromethorphan)

• Antihistamines (e.g., cetirizine)

✅ Characteristics:

• Clear, homogeneous liquid (no particles).

• Sweet taste – masks bitter medication.

• Drug is completely dissolved in the liquid.

• No need to shake before use.

• Stable if stored properly.

• May contain preservatives, flavoring, and coloring agents.

📌 Advantages:

• Pleasant taste → good for children.

• Uniform dose in each spoonful.

• Easy to swallow.