====== Eicosanoids ======

Eicosanoids are short-lived lipid mediators derived from **arachidonic acid** that regulate:
  * **Inflammation & pain**
  * **Fever**
  * **Platelet function / thrombosis**
  * **Gastric mucosal protection**
  * **Renal blood flow**
  * **Bronchial tone**

They are primarily produced via:
  * **COX pathway → prostaglandins + thromboxane**
  * **5-LOX pathway → leukotrienes**
  * (Less emphasized clinically: **lipoxins**, **CYP epoxygenase products**)

----

===== Quick Pathway Map =====

**Membrane phospholipids** → (PLA2) → **Arachidonic acid**
  * → **COX-1/COX-2** → **Prostaglandins (PGE2, PGI2, etc.) + TXA2**
  * → **5-LOX** → **Leukotrienes (LTB4, LTC4/D4/E4)**

Key clinical idea:
  * **COX inhibition** ↓ prostaglandins (pain/fever/inflammation) but can also ↓ gastric/renal protection
  * **COX-2 selectivity** lowers GI toxicity but can ↑ thrombotic risk (PGI2/TXA2 imbalance)
  * **Leukotriene blockade** helps asthma/allergic disease (especially aspirin-exacerbated respiratory disease)

----

<WRAP group>
<WRAP half column>

===== COX Inhibitors =====

==== Nonselective NSAIDs (COX-1 + COX-2) ====
  * [[eicosanoids:nsaids:ibuprofen|Ibuprofen]]
  * [[eicosanoids:nsaids:naproxen|Naproxen]]
  * [[eicosanoids:nsaids:diclofenac|Diclofenac]]
  * [[eicosanoids:nsaids:indomethacin|Indomethacin]]
  * [[eicosanoids:nsaids:ketorolac|Ketorolac]]
  * [[eicosanoids:nsaids:meloxicam|Meloxicam]]
  * [[eicosanoids:nsaids:piroxicam|Piroxicam]]
  * [[eicosanoids:nsaids:sulindac|Sulindac]]

==== Salicylates ====
  * [[eicosanoids:nsaids:aspirin|Aspirin]]

==== COX-2 Selective NSAIDs ====
  * [[eicosanoids:nsaids:celecoxib|Celecoxib]]

==== Acetaminophen (weak peripheral anti-inflammatory) ====
  * [[eicosanoids:analgesics:acetaminophen|Acetaminophen]]

</WRAP>

<WRAP half column>

===== Leukotriene Pathway Drugs =====

==== Leukotriene Receptor Antagonists (CysLT1 blockers) ====
[[respiratory:drug_classes:leukotriene_modifiers|Leukotriene Modifiers]]
  * [[respiratory:drugs:montelukast|Montelukast]]
  * [[respiratory:drugs:zafirlukast|Zafirlukast]]

==== 5-Lipoxygenase Inhibitor ====
[[respiratory:drug_classes:leukotriene_modifiers|Leukotriene Modifiers]]
  * [[respiratory:drugs:zileuton|Zileuton]]

</WRAP>
</WRAP>

----

<WRAP group>
<WRAP half column>

===== Prostaglandin Analogs =====

==== Obstetrics / Gynecology ====
  * [[eicosanoids:pg_analogs:misoprostol|Misoprostol]] (PGE1)
  * [[eicosanoids:pg_analogs:dinoprostone|Dinoprostone]] (PGE2)
  * [[eicosanoids:pg_analogs:carboprost|Carboprost]] (PGF2α)

==== Ophthalmology (glaucoma) ====
  * [[eicosanoids:pg_analogs:latanoprost|Latanoprost]]
  * [[eicosanoids:pg_analogs:travoprost|Travoprost]]
  * [[eicosanoids:pg_analogs:bimatoprost|Bimatoprost]]

</WRAP>

<WRAP half column>

===== Thromboxane / Platelet Axis =====

Aspirin is the key eicosanoid-modifying antiplatelet drug:
  * [[eicosanoids:nsaids:aspirin|Aspirin]]

(For broader antiplatelet therapy see:)
  * [[hemet:antiplatelet_agents:start|Antiplatelet Agents]]

</WRAP>
</WRAP>

----

===== High-Yield Clinical Pearls =====

  * **NSAID GI toxicity**: loss of COX-1 gastric protection → gastritis/ulcer/bleeding risk
  * **NSAID renal effects**: ↓ afferent dilation → ↓ GFR (risk ↑ in CKD, CHF, cirrhosis, dehydration)
  * **COX-2 selective**: fewer ulcers but **more thrombosis risk** in susceptible patients
  * **AERD**: COX blockade shunts AA toward leukotrienes → bronchospasm; leukotriene blockers help
  * **Misoprostol** prevents NSAID ulcers but causes diarrhea/cramping and is abortifacient

----

===== Related Physiology Pages =====
  * [[eicosanoids:physiology:arachidonic_acid_pathway|Arachidonic Acid Pathway]]
  * [[eicosanoids:physiology:cox1_vs_cox2|COX-1 vs COX-2]]
  * [[eicosanoids:physiology:leukotrienes|Leukotrienes in Asthma]]
  * [[eicosanoids:physiology:platelet_balance_pgi2_txa2|PGI2–TXA2 Balance]]