Study of Different Routes of Drug Administration in Mice and Rats

1. Oral Administration (PO)

• Description: Oral administration involves delivering the drug directly into the animal’s mouth, usually via a gavage needle or feeding tube.
• Procedure:
1. Preparation: Measure the required dose of the drug solution.
2. Restraint: Gently restrain the animal to prevent movement.
3. Administration: Insert the gavage needle into the mouth, passing it down the esophagus to the stomach, and slowly deliver the drug.
• Advantages: Mimics the natural route of drug intake in humans, suitable for long-term studies.
• Considerations: Requires skill to avoid injury to the animal; not suitable for drugs that are poorly absorbed or unstable in the gastrointestinal tract.

2. Intraperitoneal Administration (IP)

• Description: Intraperitoneal administration involves injecting the drug into the peritoneal cavity, the space within the abdomen that houses the intestines, liver, and other organs.
• Procedure:
1. Preparation: Prepare the drug solution and a sterile syringe with a fine needle.
2. Restraint: Position the animal on its back and gently restrain it.
3. Injection: Insert the needle into the lower right quadrant of the abdomen, avoiding the midline, and inject the drug.
• Advantages: Allows for rapid absorption and is suitable for drugs that are irritating to tissues.
• Considerations: Risk of injuring internal organs; proper technique is essential to avoid complications.

3. Intravenous Administration (IV)

• Description: Intravenous administration involves injecting the drug directly into a vein, providing immediate systemic circulation.
• Procedure:
1. Preparation: Prepare the drug solution and a sterile syringe with a fine needle.
2. Restraint: Gently restrain the animal and locate a suitable vein (e.g., tail vein in rats and mice).
3. Injection: Insert the needle into the vein and slowly inject the drug.
• Advantages: Provides rapid and complete bioavailability; suitable for drugs that require precise dosing.
• Considerations: Requires skill to locate and access veins; risk of phlebitis and other complications.

4. Subcutaneous Administration (SC)

• Description: Subcutaneous administration involves injecting the drug into the tissue layer between the skin and muscle.
• Procedure:
1. Preparation: Prepare the drug solution and a sterile syringe with a fine needle.
2. Restraint: Gently restrain the animal and lift a fold of skin.
3. Injection: Insert the needle into the subcutaneous tissue and inject the drug.
• Advantages: Suitable for slow-release formulations; less invasive than intraperitoneal or intravenous routes.
• Considerations: Slower absorption compared to IV or IP routes; risk of local irritation or infection.

5. Intramuscular Administration (IM)

• Description: Intramuscular administration involves injecting the drug directly into a muscle.
• Procedure:
1. Preparation: Prepare the drug solution and a sterile syringe with a fine needle.
2. Restraint: Gently restrain the animal and locate a suitable muscle (e.g., thigh muscle).
3. Injection: Insert the needle into the muscle and inject the drug.
• Advantages: Provides relatively rapid absorption; suitable for small volumes of drug.
• Considerations: Risk of muscle damage and pain; limited to small volumes.

6. Topical Administration

• Description: Topical administration involves applying the drug directly to the skin or mucous membranes.
• Procedure:
1. Preparation: Prepare the drug formulation (e.g., cream, gel).
2. Application: Apply the drug to the targeted area of the skin or mucous membrane.
• Advantages: Non-invasive; suitable for localized treatment.
• Considerations: Limited to drugs that can be effectively absorbed through the skin; risk of ingestion if the animal licks the treated area.