PH5.1-2 | Respiratory Pharmacology — Assignment

CLINICAL SCENARIO

Competencies addressed: PH5.1 (Devise management of various stages of bronchial asthma and COPD; pharmacokinetics, pharmacodynamics, therapeutic uses, and ADRs of drugs used in obstructive airway diseases and rhinitis) and PH5.2 (Explain types, salient pharmacology of cough management drugs; describe management of dry and productive cough).

This assignment develops your ability to apply drug knowledge to real clinical decisions — moving beyond recall to devise stepwise management plans, justify drug choices pharmacologically, and critically identify prescribing errors.

Section A — Asthma Step Therapy (40 marks)

A 24-year-old engineering student presents with wheezing, breathlessness, and nocturnal cough occurring 4-5 days per week for the past 2 months. She has used her salbutamol inhaler on 3 of the past 7 days. Spirometry: FEV1 72% predicted, FEV1/FVC 0.68, >12% post-bronchodilator reversibility.

(a) State her GINA classification (step and severity) and justify it with at least two criteria. (8 marks)
(b) Devise a pharmacological management plan with drug name, formulation, dose, frequency, and device. Justify each drug choice using its mechanism of action. (20 marks)
(c) She is prescribed ICS. Three months later she reports a white coating on her tongue and throat. Name this complication, explain its mechanism (pathophysiology linked to the drug's pharmacodynamics), and describe two preventive strategies with a pharmacological rationale for each. (12 marks)

Section B — COPD Management and Phenotype-Based Prescribing (35 marks)

A 58-year-old retired factory worker (35 pack-year smoker) presents with progressive breathlessness, productive cough, and two hospital admissions in the past year for respiratory exacerbations requiring oral steroids and antibiotics. Spirometry: post-bronchodilator FEV1 38% predicted (GOLD Stage III), FEV1/FVC 0.55. Blood eosinophil count: 340 cells/μL. He is currently on salbutamol as needed only.

(a) Classify this patient's COPD using GOLD 2023 (group, severity, exacerbation risk). (5 marks)
(b) Devise a complete pharmacological management plan. For each drug, state: class, specific agent, dose, route, and mechanism of action. Justify WHY each drug is appropriate for this patient's phenotype. (20 marks)
(c) Discuss ONE important drug-class safety issue relevant to his COPD management and explain its mechanism. (10 marks)

Section C — Cough Pharmacotherapy and Prescribing Errors (25 marks)

You are reviewing prescriptions in a busy outpatient clinic.

Case 1: A 40-year-old man with COPD has a productive cough producing 20 mL of purulent sputum daily. He has been prescribed: (i) dextromethorphan 30 mg TDS; (ii) salbutamol MDI PRN; (iii) azithromycin 500 mg OD x5 days.

Case 2: A 68-year-old woman on enalapril (ACE inhibitor) for hypertension reports a persistent dry, tickling cough for 6 weeks. She has been prescribed codeine linctus 10 mL TDS.

(a) For Case 1: Identify the prescribing error and explain WHY it is harmful using the pharmacology of cough. Correct the management plan. (10 marks)
(b) For Case 2: Explain the mechanism of enalapril-induced cough (name the mediator, its source, and the receptor it activates). Identify the error in the prescribed treatment. State the most appropriate pharmacological intervention. (15 marks)