JNTU B.Pharmacy III PHARMACOLOGY-I Previous Question Paper (August/September-2021 - R17)

Spare receptors are a phenomenon where a maximal biological response is elicited by an agonist at a concentration that occupies only a small fraction of the total available receptors in a tissue. In such systems, the maximum effect is achieved without requiring the occupancy of all receptors because the downstream signaling mechanisms have a high amplification capacity.

The significance of spare receptors includes:

• Increased Sensitivity: The system becomes highly sensitive to low concentrations of an agonist, allowing for rapid physiological responses.
• Signal Amplification: They demonstrate that the receptor-effector coupling is efficient, where a single receptor-agonist complex can activate multiple downstream effector molecules.
• Pharmacological Reserve: They provide a functional reserve that ensures the tissue can still respond maximally even if a portion of the receptors is inactivated or blocked by irreversible antagonists.

The oral route is the most common and convenient method of drug administration. Its advantages and disadvantages are as follows:

Advantages:

• Convenience and Safety: It is the most convenient, non-invasive, and painless route, making it ideal for self-administration.
• Cost-Effectiveness: Oral dosage forms are generally cheaper to manufacture and do not require sterile conditions.
• Ease of Handling: No specialized equipment or trained personnel are required for administration.
• Systemic Action: It allows for controlled-release formulations, providing sustained therapeutic effects.

Disadvantages:

• Slow Onset: The onset of action is relatively slow compared to parenteral routes, making it unsuitable for emergencies.
• First-Pass Metabolism: Many drugs undergo significant metabolism in the liver before reaching systemic circulation, reducing bioavailability.
• Irritation and Stability: Some drugs cause gastric irritation or are destroyed by digestive enzymes and the low pH of the stomach.
• Patient Compliance: It is not suitable for unconscious patients, patients with vomiting, or drugs with unpleasant tastes or odors.