Long Answer Question (LAQ) – 10 Marks A 45-year-old man with a prosthetic heart valve has been receiving warfarin therapy with stable anticoagulation. He develops a respiratory tract infection and is prescribed erythromycin. Three days later, he presents with gum bleeding and multiple ecchymotic patches. His INR is markedly elevated. Answer the following: a. Define drug metabolism (biotransformation) and state its objectives. (2 marks) b. Describe Phase I and Phase II drug metabolism reactions, highlighting their characteristics with suitable examples. (4 marks) c. Explain microsomal enzyme induction and microsomal enzyme inhibition, mentioning the mechanism, important examples, and clinical significance. (3 marks) d. Explain the probable mechanism responsible for the patient's bleeding after receiving erythromycin. (1 mark)