Makindo Medical Notes

🧾 About Leukotrienes

• 🧪 Leukotrienes are lipid mediators derived from arachidonic acid via the lipoxygenase pathway in leukocytes.
• 🌡️ They play a central role in allergic and inflammatory reactions.
• 💧 Increase vascular permeability → oedema and tissue swelling.
• 🧲 Act as chemoattractants, drawing neutrophils & eosinophils to sites of inflammation.
• 🌬️ Leukotriene D4 = “slow-reacting substance of anaphylaxis (SRS-A)” → potent bronchoconstrictor & intestinal smooth muscle contraction.
• 🤧 They also ↑ mucus production → key contributor to bronchial asthma pathophysiology.

📖 Clinical Relevance

• 🔥 In asthma, leukotrienes drive bronchospasm, mucus plugging, and airway oedema.
• 🤒 In allergic rhinitis, they mediate nasal congestion, sneezing, and mucus hypersecretion.
• 💊 Leukotriene receptor antagonists (LTRAs, e.g. montelukast, zafirlukast) block cysteinyl-leukotriene receptors → useful in asthma and allergic rhinitis.
• ⚕️ 5-lipoxygenase inhibitor (zileuton) reduces leukotriene synthesis but is less commonly used (liver monitoring required).

🧩 Pathophysiology in Asthma

🌬️ Triad of leukotriene effects in asthma: 1️⃣ Bronchoconstriction → wheeze, breathlessness 2️⃣ Mucus hypersecretion → sputum plugging 3️⃣ Vascular leak → airway oedema

🧪 Exam / OSCE Tips

• ❓ Leukotriene D4 = SRS-A (slow reacting substance of anaphylaxis).
• ❓ Unlike prostaglandins (can cause bronchodilatation), leukotrienes cause bronchoconstriction.
• 💊 LTRAs are add-on therapy in asthma (esp. exercise-induced or aspirin-sensitive asthma).
• 🧲 Remember: they recruit eosinophils (hallmark of allergic airway inflammation).

📚 References

• Kumar & Clark’s Clinical Medicine, 10th edition.
• BNF – Leukotriene receptor antagonists.
• British Thoracic Society / SIGN Asthma Guidelines.