Basic Pharmacology

Question 1

Define Agonists

Answer 1

Agonists bind to receptors and elicit a response.

Question 2

Define Affinity

Answer 2

Affinity is the tendency of a drug to bind to a receptor.

Question 3

Define Efficacy

Answer 3

Efficacy is the ability of a drug to activate a receptor and produce an effect.

Question 4

What are partial agonists, and what distinguishes them from full agonists?

Answer 4

Partial agonists bind to receptors, but they have weak activation compared to full agonists. They typically have high affinity but low efficacy.

Question 5

Explain the concept of antagonists in pharmacology and provide examples of different types of antagonists.

Answer 5

Antagonists are drugs that bind to receptors and prevent agonists from achieving a response. Types of antagonists include competitive, non-competitive, and irreversible antagonists.

Question 6

Differentiate between selectivity and specificity of drugs in terms of receptor binding.

Answer 6

Selectivity refers to a drug’s preference for binding to one receptor over another, while specificity indicates that a drug binds to only one type of receptor.

Question 7

What is bioavailability (F) in drug absorption, and how is it calculated for oral and IV administration?

Answer 7

Bioavailability (F) measures how well a drug is absorbed and reaches its site of action. It is calculated as the amount absorbed after oral administration divided by the amount absorbed after IV administration. F values are always less than 1.0 for IV drugs.

Question 8

Explain the factors affecting drug distribution in the body.

Answer 8

Drug distribution depends on factors such as blood flow to tissues, the drug’s partition coefficient between blood and tissue, its ionization at plasma pH, molecular size, and the extent of tissue and plasma protein binding.

Question 9

Describe the significance of drug binding to plasma proteins in distribution and the difference between lipid-soluble and protein-bound drugs.

Answer 9

Drug binding to plasma proteins is crucial for distribution. Lipid-soluble drugs rapidly leave the bloodstream and distribute widely, while binding to proteins limits distribution. Many drugs bind reversibly and non-specifically to plasma proteins.

Question 10

Explain the concept of the volume of distribution (Vd) and how it relates to drug accumulation in tissues.

Answer 10

The volume of distribution (Vd) is a mathematical factor relating the amount of drug in the body to its plasma concentration. A high apparent Vd indicates that the drug is also present in tissues, particularly for lipophilic drugs, which can accumulate in adipose and neural tissue.