Questions
3 questions per university paper
Difficulty
Medium-Hard
Importance
High yield for B.Pharm and Nursing pharmacology finals
Overview
This unit covers the fundamental pharmacotherapy of the gastrointestinal and respiratory systems, focusing on maintaining acid-base balance in the gut and airway patency. It is a high-yield topic in university examinations as it tests both clinical application and mechanisms of action for common therapeutic agents. Mastering these concepts is essential for understanding how drugs modulate autonomic and inflammatory responses in chronic conditions like asthma and peptic ulcer disease.
Antiulcer and Antiemetic Drugs
Antiulcer agents work by either neutralizing gastric acid, suppressing acid secretion, or protecting the mucosal lining. Antiemetics target specific receptors in the chemoreceptor trigger zone (CTZ) and the vomiting center to prevent emesis.
- Proton Pump Inhibitors (PPIs): Omeprazole, Pantoprazole (Inhibit H+/K+ ATPase)
- H2-Receptor Antagonists: Ranitidine, Famotidine
- Antacids: Magnesium hydroxide and Aluminum hydroxide
- 5-HT3 Antagonists (Antiemetic): Ondansetron
- Dopamine Antagonists: Metoclopramide and Domperidone
Laxatives and Purgatives
These agents are classified based on their mechanism of action to relieve constipation by increasing bowel motility or stool bulk. Understanding the specific class is vital for choosing the appropriate agent for chronic vs. acute cases.
- Bulk laxatives: Psyllium husk, Methylcellulose
- Osmotic laxatives: Lactulose, Magnesium sulfate
- Stimulant purgatives: Bisacodyl, Senna
- Stool softeners: Docusate sodium
- Lubricant laxatives: Liquid paraffin
Bronchodilators and Anti-Asthma Drugs
Bronchodilators are primarily used to reverse airway obstruction in asthma and COPD by relaxing smooth muscles. They act through beta-2 adrenergic stimulation, muscarinic antagonism, or phosphodiesterase inhibition.
- SABA (Short-acting Beta Agonists): Salbutamol, Terbutaline
- LABA (Long-acting Beta Agonists): Salmeterol, Formoterol
- Methylxanthines: Theophylline, Aminophylline
- Antimuscarinics: Ipratropium bromide, Tiotropium
- Leukotriene receptor antagonists: Montelukast
- Mast cell stabilizers: Sodium cromoglycate
Formula Sheet
cAMP levels increase (Bronchodilation) via beta-2 receptor activation
H+/K+ ATPase inhibition results in decreased H+ secretion into the gastric lumen
Exam Tip
Always draw the H+/K+ ATPase pump mechanism for antiulcer questions and the beta-2/cAMP signaling pathway for bronchodilators to maximize marks.
Common Mistakes
- Confusing the mechanism of H2 antagonists (competitive inhibition) with PPIs (irreversible covalent inhibition of the proton pump).
- Failing to distinguish between maintenance therapy (corticosteroids) and rescue therapy (SABA) in asthma management.
- Misclassifying prokinetic agents like Metoclopramide purely as antiemetics without noting their dopamine-blocking activity.
More Revision Notes
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