Psychological antagonist is found in: (A) Isoprenaline and sulbutamol, (B) Isoprenaline and adrenaline, (C) Isoprenaline and propranolol, (D) Adrenaline and histamine
Answer is D. (Ref Katzung 12/e p20) Physiological antagonists are those drugs that produce opposite action by acting on different receptors. Adrenaline reverses the bronchoconstrictor action of histamine (. H1 receptors) by causing bronchodilation (through beta2 receptors). Therefore,these are physiological antagonists.