Key Definitions

Question 1

Drug

Answer 1

The active ingredient of a medicine; any substance which interacts with a biological system and changes it

Question 2

Pharmacology

Answer 2

The study of the mechanism of drug action

Question 3

Potency

Answer 3

The dose of drug required to produce a specific effect of given intensity as compared to a standard reference.

Question 4

Agonist

Answer 4

• Bind to a receptor and produce a response

* Possess affinity and efficacy:- ACh, histamine

Question 5

Antagonist

Answer 5

• Antagonists:- Bind to a receptor but do not produce a response
• Competitive antagonists prevent agonist binding and so prevent (block)the response to an agonist
• Possess affinity but not efficacy (atrophine, mepyramine)

Question 6

Affinity

Answer 6

•The affinity of a drug for its receptors is a measure of how well it binds to the receptor. The affinity can be measured using a drug’s dissociation constant (Kd). This is equal to the concentration at which, at equilibrium, half the receptors will be bound with a drug.

Question 7

Efficacy

Answer 7

• Efficacy is a measure of the degree to which an agonist produces a response when binding a given proportion of receptors.
• For a full agonist, the efficacy is 1; for a partial agonist, the efficacy is less than 1 (but greater than 0)
• In some cases, it is possible to have a negative efficacy, in which case the drug is called an inverse agonist. Such drugs inhibit any intrinsic activity of a receptor that might exist in the absence of a ligand.

Question 8

Inverse agonist

Answer 8

In the field of pharmacology, an inverse agonist is an agent that binds to the same receptor as an agonist but induces a pharmacological response opposite to that agonist.

Question 9

Quantitative pharmacology

Answer 9

Based on the assumption that drugs act by entering into a simple chemical relation with certain receptors in cells and that there is a simple relation between the amount of drug fixed and by these receptors and the action produced.

Question 10

Positive allosteric effect

Answer 10

receptor more likely to open in response to a given concentration of GABA

Question 11

Pharmacokinetics

Answer 11

The study of the change in drug and metabolite concentrations in tissues and body fluids

Question 12

Absorption

Answer 12

Movement of a drug from the point of administration to the plasma

Question 13

Distribution

Answer 13

from plasma to tissues and organs. How drugs equilibrate within the body after entering the systemic circulation

Question 14

Bioavailability

Answer 14

Fraction of unchanged drug that reaches the systemic circulation

Question 15

Volume of distribution

Answer 15

The volume of fluid required to contain the total amount of drug in the body at the same concentration as that present in the plasma

Question 16

Local anaesthetics

Answer 16

Local anaesthetics reversibly block nerve conduction when applied to a restricted area of the body without loss of consciousness.

Question 17

Chemotherapy

Answer 17

Cancer and infectious microorganisms (‘unwanted cells’)

Category of cancer treatment that uses one or more anti-cancer drugs as part of a standardised chemotherapy routine

Question 18

Selective toxicity

Answer 18

Kill anti-microbial cells but not host cells

Question 19

Superinfection

Answer 19

Infection occurring after or on top of a previous infection especially after following treatment with broad spectrum antibiotics
HIV

Question 20

Drug resistance

Answer 20

Pathogens or cancers have acquired the resistance: reduction in the effectiveness of the drug