Advanced Pharmacodynamics Flashcards
(14 cards)
Clinical Scenario: A patient on atenolol (a β1-blocker) reports fatigue and bradycardia.
Atenolol blocks β1-adrenergic receptors in the heart, reducing heart rate and contractility, causing fatigue and bradycardia.
Why is salbutamol preferred in asthma management?
It is a β2-agonist that causes bronchodilation by relaxing bronchial smooth muscle – high receptor selectivity reduces cardiac side effects.
Why must warfarin levels be closely monitored?
Warfarin has a narrow therapeutic index. Small changes in plasma levels can lead to bleeding (toxicity) or clotting (subtherapeutic effect).
What’s the pharmacodynamic rationale for combining levodopa with carbidopa in Parkinson’s disease?
Carbidopa inhibits peripheral breakdown of levodopa, allowing more to reach the brain and reducing peripheral side effects.
How do NSAIDs cause gastric irritation pharmacodynamically?
They inhibit COX-1, reducing protective gastric prostaglandins, leading to mucosal damage and increased risk of ulcers.
What’s the role of receptor upregulation and downregulation in prescribing?
Chronic agonist use may cause downregulation (tolerance). Chronic antagonist use may cause upregulation (hypersensitivity).
Why is naloxone used in opioid overdose?
It is a competitive opioid receptor antagonist that displaces opioids from μ-receptors, reversing respiratory depression.
How does drug selectivity affect side effect profiles?
More selective drugs (e.g., β1 vs β2 blockers) tend to have fewer off-target side effects.
What is the pharmacodynamic consequence of combining benzodiazepines with alcohol?
Both enhance GABAergic activity, leading to additive CNS depression and increased risk of respiratory failure.
Why is it important to understand receptor saturation?
Once all receptors are occupied, increasing the dose won’t increase effect but may increase side effects.
Why is aspirin contraindicated in children with viral infections?
Aspirin can trigger Reye’s syndrome due to effects on mitochondrial function during viral illness.
How do calcium channel blockers like amlodipine reduce blood pressure?
They block L-type calcium channels in vascular smooth muscle, causing vasodilation and decreased systemic vascular resistance.
How does pharmacodynamics differ from pharmacokinetics in prescribing?
Pharmacodynamics = What the drug does to the body (effects, receptors). Pharmacokinetics = What the body does to the drug (ADME).
Discuss the pharmacodynamic concerns related to prescribing propranolol in a patient with COPD.
Propranolol is a non-selective beta-blocker that blocks both β1 and β2 receptors. In patients with COPD, blocking β2 receptors can cause bronchoconstriction, worsening respiratory function. A more appropriate choice would be a cardioselective beta-blocker like bisoprolol, which primarily affects β1 receptors and is less likely to impact pulmonary function.
