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2025-04-26

???? RRB Pharmacist Exam – Final Professional Ability Test

???? FINAL MOCK TEST ALERT! ???? FREE FOR ALL ???? RRB Pharmacist Exam – Final Professional Ability Test ????️ Date: Sunday, 27th April 2025 ⏰ Time: 11:00 AM ???? Platform: www.pharmalifeacademy.com ???? Category: RRB PHARMACIST

2025-04-25
2025-04-21

Blog 37: Imp MCQs on Pharmacodynamics for RRB & GPAT

Write the answer to the MCQ on a paper and confirm your answer with the description below. MCQs 1. An agent which activates a receptor to produce an effect similar to that of the physiological signal molecule is (a) Antagonist (b) Agonist (c) Inverse agonist (d) Enzyme 2. Study of what the drug does to the body is _____. (a) Pharmacokinetics (b) Pharmacodynamics (c) Biopharmaceutics (d) Pharmacology 3. Identify the wrong option: Pharmacodynamics is the study of _____. (a) Effects of drugs (b) Mechanism of drug action (c) Drug-drug interaction (d) Safety of drug 4. The initial combination of the drug with its receptor resulting in a conformational change in the latter is known as _____. (a) Drug action (b) Drug effect (c) Drug affinity (d) Synergism 5. Tachyphylaxis is _____. (a) Acute drug tolerance (b) Increase heart rate (c) Movement of white blood cells (d) Allergic reactions 6. The study of the relationship between drug concentration and its effects is _______. (a) Pharmacokinetics (b) Pharmacodynamics (c) Pharmacotherapeutics (d) Pharmacovigilance 7. What does the term “Potentiation” mean? (a) Cumulative ability of a drug (b) Hypersensitivity to a drug (c) Fast tolerance developing (d) Intensive increase of drug effects due to their combination 8. Rapid development of tolerance on repeated doses of a drug in quick succession, with reduction in clinical response, is termed as ________ (a) synergism (b) antagonism (c) idiosyncrasy (d) tachyphylaxis 9. In the presence of this type of antagonist, antagonism cannot be overcome by increasing agonist concentrations. (a) Competitive (b) Noncompetitive (c) Reversible (d) Nonspecific 10. When the total pharmacological effect of two or more drugs administered together is equal to the sum of their individual pharmacological actions, the effect is called (a) Synergism (b) Additive effect (c) Antagonism (d) Adverse effect 11. The ratio of median lethal dose to median effective dose is _____. (a) Bioavailability of a drug (b) Therapeutic index (c) Apparent volume of distribution of a drug (d) Therapeutic window 12. The phenomenon where interaction between two or more drugs produces an effect greater than the sum of their individual effects is _____. (a) Additive effect (b) Synergism (c) Antagonism (d) None of these 13. Identify the correct statement. (a) A drug with larger therapeutic index is safer than with one smaller therapeutic index (b) A drug with larger therapeutic index is more toxic than one with smaller therapeutic index. (c) Therapeutic index is not associated with safety of drugs. (d) Therapeutic index shows the potency of a drug 14. The opposite action of two drugs on the same physiological system is called as _____. (a) Synergism (b) Antagonism (c) Drug tolerance (d) Drug dependence 15. ED50 is the dose of a _____. (a) test substance that produces desirable effects in 50% of the animals in a dose group (b) test substance that kills 50% of the animals in a dose group (c) substance that produces maximum effect in 50% of the animals in a dose group (d) substance that produces maximum adverse effects in 50% of the animals in a dose group 16. Insulin and glucagon are considered (a) Pharmacological antagonist (b) Physiological antagonists (c) Pharmacodynamic antagonist (d) Chemical antagonist Keypoints o Pharmacodynamics is the study of biochemical and physiological effects of drugs and their mechanisms of action. o Pharmacodynamics deals with the relationship between concentration of drug at the site of action and the magnitude of the effect produced by the drug. o Pharmacodynamics deals with what a drug does to the body. o The basic types of drug action can be classified as: 1. Stimulation 2. Depression 3. Irritation 4. Replacement 5. Cytotoxic action 1. Stimulation refers to increase in the activity of specialized cells, e.g. epinephrine stimulates heart, caffeine stimulates CNS. 2. Depression means decrease in activity of specialized cells, e.g. diazepam depresses CNS, propranolol depresses heart. 3. Irritation suggests a non-selective, harmful effect and is particularly applied to less specialized cells (epithelium, connective tissue). 4. Replacement refers to the use of electrolytes, vitamins, hormones or their congeners in deficiency states e.g. iron preparations in iron deficiency anaemia, insulin in diabetes mellitus, vitamin C in Scurvy, etc. 5. Cytotoxic action refers to toxic to living cells, e.g. penicillin, chloroquine, fluorouracil, cyclophosphamide, etc. o General Mechanisms of Drug Action include 1. Physicochemical properties and drug action, e.g., (i) Due to oxidizing property, potassium permanganate acts as an antiseptic. (ii) Antacids like sodium bicarbonate neutralize gastric HCl. 2. Drug interaction with a discrete target biomolecules like enzymes, ion channels, transporters, receptors, nucleic acids, structural proteins, etc. o Ligand is any molecule which attaches selectively to a particular receptor. o Agonist is an agent which stimulates a receptor to produce an effect similar to that of the physiological signal molecule. o Inverse agonist is an agent which stimulates a receptor to produce an effect opposite to that of the agonist. o Antagonist is an agent which prevents the action of an agonist on a receptor. o Partial agonist: It is an agent which stimulates a receptor to produce submaximal effect but antagonizes the action of a full agonist. o Factors modifying action of drug are: Body size, Age, Sex, Genetics, Route of administration, Environmental factors and time of administration, Psychological factor, Pathological states (Presence of disease), Cumulation, Drug Tolerance, Drug dependence (neuroadaptation), Combined effects of drugs. o Tachyphylaxis (acute tolerance): It is the rapid development of tolerance when the drug is administered repeatedly at very short intervals of time. E.g., repeated administration of ephedrine in the treatment of asthma may produce tolerance to it. o Placebo and nocebo effects. Nocebo is negative thoughts evoked by the pessimistic attitude of the patient. Placebo is opposite of nocebo. o Drug Tolerance: It is a phenomenon where a drug becomes ineffective upon its repeated administration at the usual therapeutic dose. Progressive increase in the dose is required to produce the desired therapeutic effect. o Drug dependence (neuroadaptation): It is an altered physiological state in which the user has a strong desire to continue taking the drug either to experience its effect or to avoid the discomfort of its absence. Examples of drugs producing dependence are opioids, barbiturates, alcohol and benzodiazepines. o Combined effects of drugs: When two or more drugs are given simultaneously or in quick succession, they may not affect action of each other, or they may exhibit additive effect or synergism or antagonism. o Additive effect: The desirable therapeutic effect of the two or more drugs is in the same direction and simply adds up: Effect of drugs A + B = effect of drug A + effect of drug B. E.g. Ephedrine + Aminophylline as bronchodilator; Aspirin + Paracetamol as analgesic – antipyretic. o Synergistic effect: The desirable therapeutic effect of combination of two or more drugs is greater than the sum of their individual effects: Effect of drug A + B > effect of drug A + effect of drug B. E.g. Cotrimoxazole (sulphamethoxazole + trimethoprim) as bactericidal; Codeine and aspirin as analgesics; Procaine and adrenaline combination increases the duration of action of procaine. o Antagonism: The phenomenon where one drug decreases or stops the action of another drug then it is said to be antagonism. Effect of drugs A + B < effect of drug A + effect of drug B. o Depending on the mechanism involved, antagonism may be: 1. Chemical Antagonism: The two drugs react chemically and form a pharmacologically inactive or undesirable product. E.g. Potassium permanganate oxidizes alkaloids. It is used for gastric lavage in poisoning. Chelating agents (BAL, calcium disodium edetate) form complex with toxic metals (As, Pb). Drugs may react when mixed in the same syringe or infusion bottle and form undesirable products. E.g. Thiopentone sodium + succinylcholine chloride; Penicillin-G sodium + succinylcholine chloride 2. Physical antagonism: Antagonism due to physical property of antagonist. E.g., Activated charcoal adsorbs alkaloids and can prevent their absorption, used in alkaloidal poisonings. 3. Receptor antagonism: A receptor antagonist blocks the receptor action of the other drug which is agonist. Receptor antagonism can be competitive or non-competitive. (a) Competitive (reversible) antagonism: The antagonist competes with the agonist for the same receptors. This antagonism can be reversed by increasing concentration of the agonist at the receptor site. E.g. Acetylcholine (agonist) and atropine (antagonist) compete with each other at muscarinic receptors. (b) Non-competitive (irreversible) antagonism: The antagonist binds to an allosteric site and inactivates the receptor so that the agonist cannot be bound effectively. This antagonism cannot be reversed by increasing concentration of the agonist at the receptor site. E.g. Phenoxybenzamine binds irreversibly to α-adrenergic receptors; antagonism between diazepam – bicuculline is also non-competitive. 4. Physiological Antagonism: The two drugs act on different receptors or by different mechanisms, and have exactly opposite pharmacological effects. E.g., Bronchoconstriction produced by histamine in anaphylactic shock is antagonized by adrenaline; effect of glucagon and insulin on blood sugar level is antagonistic. o Therapeutic Index (Safety Margin): It is defined as the ratio of median lethal dose to median effective dose. A drug with larger therapeutic index is safer than one with smaller therapeutic index. Hence, drug with lesser therapeutic index should be administered cautiously. Confirm your answers below: Recommended book for the preparation of RRB Pharmacist Exam, PHARMACIST RECRUITMENT EXAM, NIRALI PRAKASHAN, PUNE To know more about the book:

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