Prostaglandins, Leukotrienes, Thromboxanes & PAF Platelet Activating Factor Notes in Hindi for Pharmacy Exams | Important Notes, One-Liners, Mnemonics, Drug Tricks, MCQs, FAQs & Previous Year Questions with Answers
✦ Prostaglandins, Leukotrienes, Thromboxanes और Platelet Activating Factor (PAF) —
🔷 परिचय
Prostaglandins, Leukotrienes, Thromboxanes और PAF body के local chemical mediators (Autacoids) हैं। ये hormones की तरह पूरे शरीर में नहीं घूमते, बल्कि जहाँ बनते हैं उसी के आसपास अधिक काम करते हैं।
🎯 इनका मुख्य काम
🔥 Inflammation करना
⚡ Pain उत्पन्न करना
🌡️ Fever उत्पन्न करना
🩸 Blood clot बनाना या रोकना
🫁 Bronchial tone को नियंत्रित करना
🤰 Uterus contraction कराना
🛡️ Gastric mucosa की रक्षा करना
🔍 ऐसा क्यों?
Body को injury के समय तुरंत local response चाहिए होता है। इसलिए ये mediators जल्दी बनते हैं और जल्दी टूट भी जाते हैं।
✦ पूरी कहानी कहाँ से शुरू होती है?
🏢 Cell membrane के phospholipids में Arachidonic acid stored रहता है।
जब:
🔥 Tissue injury होती है
🦠 Infection होता है
🌸 Allergy होती है
⚡ Inflammation होता है
तब enzyme activate होता है:
➡️ Phospholipase A₂
🎯 काम
Cell membrane से Arachidonic acid को बाहर निकालना।
🧠 उदाहरण
मान लो पैर में चोट लग गई।
घटना:
चोट
⬇️
Cell damage
⬇️
Phospholipase A₂ activate
⬇️
Arachidonic acid release
⬇️
अब body pain, redness, swelling, fever पैदा करने वाले mediators बनाती है।
✦ Complete Biosynthesis
Cell membrane
⬇️ (Phospholipase A₂)
Arachidonic acid
⬇️
दो रास्ते:
① ⚙️ Cyclooxygenase pathway (COX)
बनाता है:
🟢 Prostaglandins
🟢 Prostacyclin (PGI₂)
🟢 Thromboxane
② ⚙️ Lipoxygenase pathway
बनाता है:
🟢 Leukotrienes
✦ Cyclooxygenase (COX) enzyme
⚙️ COX enzyme Arachidonic acid को convert करता है:
Arachidonic acid
⬇️
PGG₂
⬇️
PGH₂
⬇️
Prostaglandins + Thromboxanes
🔍 ऐसा क्यों होता है?
PGG₂ और PGH₂ intermediate compounds हैं जिनसे अलग-अलग mediators बनते हैं।
✦ COX के प्रकार
🟢 COX-1
यह normal body function maintain करता है।
🎯 कार्य:
🛡️ Gastric mucus बनाना
🩸 Platelet function maintain करना
💧 Kidney blood flow maintain करना
🔍 उदाहरण
Stomach में acid लगातार बनता है।
अगर protection न हो:
➡️ Acid stomach को damage करेगा।
COX-1 prostaglandins बनाता है जो mucus layer बनाकर stomach को protect करते हैं।
🔴 COX-2
यह injury और inflammation के समय activate होता है।
🎯 कार्य:
⚡ Pain
🌡️ Fever
🔥 Inflammation
🔍 उदाहरण
मान लो हाथ जल गया।
तब:
COX-2 activation
⬇️
PGE₂ formation
⬇️
Pain + redness + swelling
🟡 COX-3
🧠 CNS में पाया जाता है (human role अभी स्पष्ट नहीं है)
संभावित कार्य:
⚡ Pain sensation
🌡️ Fever regulation
✦ Important Prostaglandins
🟢 PGE₂
🎯 कार्य:
⚡ Pain बढ़ाना
🌡️ Fever उत्पन्न करना
🫀 Vasodilation
🛡️ Gastric mucus secretion बढ़ाना
🤰 Uterus contraction
🔍 ऐसा क्यों?
यह pain receptors को sensitive बना देता है।
🧠 उदाहरण
Inflamed tissue को हल्का touch करने पर भी दर्द होता है।
🟢 PGF₂α
🎯 कार्य:
🤰 Uterus contraction
🫁 Bronchoconstriction
🔍 ऐसा क्यों?
Smooth muscles contract करता है।
🧠 उदाहरण
Labor pain के समय uterus contraction में भूमिका।
🟢 PGD₂
🎯 कार्य:
🌸 Allergic response
🫁 Bronchoconstriction
🟢 PGI₂ (Prostacyclin)
🎯 कार्य:
🫀 Vasodilation
🩸 Platelet aggregation रोकना
🔍 ऐसा क्यों?
अगर हर समय platelet activate होंगे तो unnecessary clot बन जाएगा।
✦ Thromboxane (TXA₂)
🩸 यह platelets बनाते हैं।
🎯 कार्य:
🩸 Platelet aggregation
🫀 Vasoconstriction
🧠 उदाहरण
उंगली कट गई:
TXA₂
⬇️
Platelets activate
⬇️
Blood clot
⬇️
Bleeding कम
✦ PGI₂ और TXA₂ याद करने की ट्रिक
🟢 PGI₂ = Platelet रोकता है
🔴 TXA₂ = Thrombus बनाता है
✦ Leukotrienes
⚙️ Lipoxygenase pathway से बनते हैं।
🟢 LTB₄
🎯 कार्य:
🚑 Neutrophils को बुलाना
🔍 ऐसा क्यों?
यह chemotactic factor है।
🟢 LTC₄, LTD₄, LTE₄
🎯 कार्य:
🫁 Bronchoconstriction
💧 Mucus secretion
🌊 Airway edema
🧠 उदाहरण
Asthma attack:
Leukotrienes ↑
⬇️
Bronchi narrow
⬇️
सांस लेने में परेशानी
✦ Platelet Activating Factor (PAF)
📌 Sources:
🩸 Platelets
⚪ Neutrophils
🧫 Macrophages
🎯 कार्य:
🩸 Platelet aggregation
🫁 Bronchoconstriction
🌊 Vascular permeability बढ़ाना
🔥 Inflammation बढ़ाना
✦ Drugs of Prostaglandins and Leukotrienes
💊 Misoprostol (PGE₁ analogue)
Mechanism
🟢 Gastric acid कम करता है
🟢 Gastric mucus बढ़ाता है
🟢 Uterus contraction करता है
Uses
🛡️ NSAID-induced ulcer prevention
🤰 Medical abortion
👶 Labor induction
Side effects
⚠️ Diarrhea
⚠️ Uterine cramps
💊 Dinoprostone (PGE₂)
Mechanism
🟢 Uterus smooth muscle contraction
Uses
👶 Labor induction
🤰 Cervical ripening
Side effects
⚠️ Uterine hyperstimulation
⚠️ Nausea
💊 Carboprost (PGF₂α analogue)
Mechanism
🟢 Strong uterine contraction
Uses
🩸 Postpartum hemorrhage
🤰 Abortion
Side effects
⚠️ Vomiting
⚠️ Diarrhea
⚠️ Bronchospasm
💊 Alprostadil (PGE₁)
Mechanism
🟢 Vasodilation
Uses
🫀 Maintain patent ductus arteriosus
🩺 Erectile dysfunction
Side effects
⚠️ Hypotension
⚠️ Flushing
💊 Latanoprost
Mechanism
🟢 Aqueous humor outflow बढ़ाता है
Uses
👁️ Open angle glaucoma
Side effects
⚠️ Iris pigmentation
⚠️ Eyelash growth
💊 Travoprost
Uses
👁️ Glaucoma
💊 Bimatoprost
Uses
👁️ Glaucoma
💇 Eyelash growth
💊 Epoprostenol (PGI₂ analogue)
Mechanism
🟢 Vasodilation
🟢 Platelet aggregation inhibition
Uses
🫀 Pulmonary hypertension
✦ Leukotriene Drugs
💊 Montelukast
Mechanism
🟢 LTD₄ receptor block करता है
Uses
🫁 Asthma
🌸 Allergic rhinitis
Side effects
⚠️ Headache
⚠️ GI upset
💊 Zafirlukast
Mechanism
🟢 Leukotriene receptor blocker
Uses
🫁 Asthma
💊 Zileuton
Mechanism
🟢 5-Lipoxygenase inhibitor
Uses
🫁 Asthma
Side effects
⚠️ Liver toxicity
✦ High Yield One Line Revision
📌 Injury → Phospholipase A₂ → Arachidonic acid → COX → Prostaglandins + Thromboxane
📌 Arachidonic acid → Lipoxygenase → Leukotrienes
🧠 Exam Trick
PGE₂ = Pain + Fever
PGI₂ = Platelet inhibition
TXA₂ = Thrombus formation
LTB₄ = Bring neutrophils
LTC₄/LTD₄/LTE₄ = Lungs tight
✦ Prostaglandins, Leukotrienes, Thromboxanes aur PAF —
✦ Table 1 : Basic Introduction
🔖 Point | 📖 Description | 🎯 Exam Importance |
Full group name | Eicosanoids | Frequently asked |
Nature | Local chemical mediators (Autacoids) | Act near site of synthesis |
Main precursor | Arachidonic acid | Starting molecule |
Source | Cell membrane phospholipids | Stored form |
Released by | Phospholipase A₂ | Rate-limiting initiating step |
Main functions | Pain, fever, inflammation, platelet function, gastric protection | High-yield |
✦ Table 2 : Complete Biosynthesis Pathway
🧪 Step | ⚙️ Enzyme | 📦 Product formed | 🎯 Importance |
Cell membrane phospholipid | Phospholipase A₂ | Arachidonic acid | Initial release step |
Arachidonic acid | Cyclooxygenase (COX) | PGG₂ | Intermediate |
PGG₂ | Peroxidase activity of COX | PGH₂ | Common precursor |
PGH₂ | Tissue enzymes | PGE₂ | Pain, fever |
PGH₂ | Tissue enzymes | PGF₂α | Uterine contraction |
PGH₂ | Tissue enzymes | PGD₂ | Allergy |
PGH₂ | Tissue enzymes | PGI₂ | Anti-platelet |
PGH₂ | Tissue enzymes | TXA₂ | Platelet aggregation |
Arachidonic acid | 5-Lipoxygenase | LTA₄ | Leukotriene precursor |
LTA₄ | Various enzymes | LTB₄/LTC₄/LTD₄/LTE₄ | Asthma/inflammation |
✦ Table 3 : COX Enzyme Types
⚙️ Enzyme | 📍 Location | 🎯 Function | 🧠 Reason |
COX-1 | Most tissues | Gastric protection | Housekeeping enzyme |
COX-1 | Platelets | TXA₂ synthesis | Clot formation |
COX-1 | Kidney | Renal blood flow | Normal physiology |
COX-2 | Inflammatory tissues | Pain | Induced during inflammation |
COX-2 | Hypothalamus | Fever | PGE₂ production |
COX-2 | Injury site | Inflammation | Cytokine activated |
COX-3 | CNS (proposed) | Pain regulation | Less clear in humans |
✦ Table 4 : Major Prostaglandins and Functions
🧪 Mediator | 🎯 Main actions | 🔍 Why it happens | 🩺 Clinical importance |
PGE₂ | Pain | Sensitizes pain receptors | Inflammation |
PGE₂ | Fever | Acts on hypothalamus | Pyrexia |
PGE₂ | Vasodilation | Smooth muscle relaxation | Redness |
PGE₂ | Gastric mucus ↑ | Mucosal protection | Anti-ulcer role |
PGF₂α | Uterine contraction | Smooth muscle stimulation | Labor |
PGF₂α | Bronchoconstriction | Airway smooth muscle contraction | Asthma |
PGD₂ | Bronchoconstriction | Allergy mediator | Hypersensitivity |
PGI₂ | Vasodilation | Vessel relaxation | Improves flow |
PGI₂ | Platelet inhibition | cAMP increase | Prevents thrombosis |
✦ Table 5 : Thromboxane (TXA₂)
🔖 Feature | 📖 Description |
Main source | Platelets |
Main enzyme pathway | COX pathway |
Major action | Platelet aggregation |
Vascular effect | Vasoconstriction |
Importance | Stops bleeding |
Excess effect | Thrombosis risk |
✦ Table 6 : PGI₂ vs TXA₂ (Very Important)
🟢 PGI₂ | 🔴 TXA₂ |
Produced by vascular endothelium | Produced by platelets |
Vasodilation | Vasoconstriction |
Inhibits platelets | Activates platelets |
Prevents clot formation | Promotes clot formation |
Maintains blood flow | Stops bleeding |
🧠 Exam Trick:
PGI₂ = Good flow
TXA₂ = Thrombus
✦ Table 7 : Leukotrienes
🧪 Leukotriene | 🎯 Action | 🔍 Reason | 🩺 Clinical importance |
LTB₄ | Neutrophil recruitment | Chemotaxis | Inflammation |
LTC₄ | Bronchoconstriction | Smooth muscle contraction | Asthma |
LTD₄ | Mucus secretion ↑ | Airway effect | Asthma |
LTE₄ | Vascular permeability ↑ | Inflammatory action | Allergy |
🧠 Trick:
LTB₄ = Bring neutrophils
LTC₄/LTD₄/LTE₄ = Lungs Tight
✦ Table 8 : Platelet Activating Factor (PAF)
🔖 Point | 📖 Description |
Source | Platelets, neutrophils, macrophages |
Main action | Platelet aggregation |
Respiratory effect | Bronchoconstriction |
Vascular effect | Permeability increase |
Inflammation | Increased |
Clinical role | Allergy and inflammatory reactions |
✦ Table 9 : Natural Prostaglandin Drugs and Analogues
💊 Drug. | 🧪 Type. | ⚙️ Mechanism. | 🎯 Uses | ⚠️ Side effects |
Misoprostol | PGE₁ analogue | Acid ↓, mucus ↑, uterine contraction ↑ | NSAID ulcer prevention, abortion | Diarrhea, cramps |
Dinoprostone | PGE₂ | Uterine contraction | Labor induction | Hyperstimulation |
Carboprost | PGF₂α analogue | Strong uterine contraction | Postpartum hemorrhage | Bronchospasm |
Alprostadil | PGE₁ | Vasodilation | Patent ductus arteriosus, erectile dysfunction | Hypotension |
Epoprostenol | PGI₂ analogue | Vasodilation + platelet inhibition | Pulmonary hypertension | Flushing |
Latanoprost | PGF₂α analogue | Aqueous outflow ↑ | Glaucoma | Iris pigmentation |
Travoprost | PGF₂α analogue | Aqueous outflow ↑ | Glaucoma | Eye irritation |
Bimatoprost | PGF₂α analogue | Aqueous outflow ↑ | Glaucoma, eyelash growth | Pigmentation |
✦ Table 10 : Leukotriene Drugs
💊 Drug | ⚙️ Mechanism | 🎯 Uses | ⚠️ Side effects |
Montelukast | LTD₄ receptor blocker | Asthma, allergic rhinitis | Headache |
Zafirlukast | Leukotriene receptor blocker | Asthma | GI upset |
Zileuton | 5-Lipoxygenase inhibitor | Asthma | Liver toxicity |
✦ Table 11 : COX Inhibitors (Very Important)
💊 Drug | Type | Action | Main use | Important adverse effect |
Aspirin | Non-selective | COX-1 + COX-2 inhibition | Pain, anti-platelet | Gastric ulcer |
Ibuprofen | Non-selective | COX inhibition | Pain, fever | GI irritation |
Diclofenac | Non-selective | COX inhibition | Inflammation | Gastric toxicity |
Indomethacin | Non-selective | COX inhibition | Arthritis | GI effects |
Celecoxib | Selective COX-2 | COX-2 inhibition | Arthritis | Cardiovascular risk |
Etoricoxib | Selective COX-2 | COX-2 inhibition | Pain, inflammation | CV risk |
✦ Ultra Short Final Revision
📌 Injury → Phospholipase A₂ → Arachidonic acid → COX → Prostaglandins + TXA₂
📌 Arachidonic acid → Lipoxygenase → Leukotrienes
📌 PGE₂ = Pain + Fever
📌 PGI₂ = Platelet inhibition
📌 TXA₂ = Platelet aggregation
📌 LTB₄ = Neutrophils
📌 LTC₄/LTD₄/LTE₄ = Asthma
📌 PAF = Platelet activation + Inflammation
📚 Textbook References
🔹 Goodman & Gilman's The Pharmacological Basis of Therapeutics https://accesspharmacy.mhmedical.com/book.aspx?bookid=2189
🔹 Katzung's Basic & Clinical Pharmacology https://accesspharmacy.mhmedical.com/book.aspx?bookid=3385
🔹 Essentials of Medical Pharmacology (K.D. Tripathi) https://jaypeebrothers.com/product/essentials-of-medical-pharmacology
🔹 Lippincott Illustrated Reviews: Pharmacology https://shop.lww.com/Lippincott-Illustrated-Reviews--Pharmacology/p/9781975170556
🌐 Scientific References
🔹 National Center for Biotechnology Information (NCBI) https://www.ncbi.nlm.nih.gov
🔹 PubMed Database https://pubmed.ncbi.nlm.nih.gov
🔹 Merck Manual Professional Edition https://www.merckmanuals.com/professional
🔹 StatPearls https://www.ncbi.nlm.nih.gov/books
References
-
Goodman & Gilman's The Pharmacological Basis of Therapeutics. McGraw-Hill Education. https://accesspharmacy.mhmedical.com/book.aspx?bookid=2189
-
Katzung BG. Basic & Clinical Pharmacology. McGraw-Hill Education. https://accesspharmacy.mhmedical.com/book.aspx?bookid=3385
-
Tripathi KD. Essentials of Medical Pharmacology. Jaypee Brothers Medical Publishers. https://jaypeebrothers.com/product/essentials-of-medical-pharmacology
-
Lippincott Illustrated Reviews: Pharmacology. Wolters Kluwer. https://shop.lww.com/Lippincott-Illustrated-Reviews--Pharmacology/p/9781975170556
-
National Center for Biotechnology Information (NCBI). https://www.ncbi.nlm.nih.gov
-
PubMed. https://pubmed.ncbi.nlm.nih.gov
-
Merck Manual Professional Edition. https://www.merckmanuals.com/professional
-
StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books