Prostaglandins and related compounds called eicosanoids are produced from arachidonic acid. They are classified into two main groups - prostanoids and leukotrienes/lipoxins. Prostanoids include prostaglandins, prostacyclins, and thromboxanes which are involved in platelet aggregation, vasoconstriction, smooth muscle contraction, and inhibition of platelet aggregation. Leukotrienes regulate inflammation and anaphylaxis. Prostaglandins act locally rather than distantly, are produced on demand, and are involved in processes like inflammation, fever, vomiting, and uterine contraction. They are inhibited by steroids and NSAIDs like aspirin which are used for pain

1. Dr. Ifat Ara Begum
Assistant Professor
Dept of Biochemistry
Dhaka Medical College

2. Prostaglandins and related compounds
are collectively known as eicosanoids.
They are produced from arachidonic
acid, a 20-C PUFA (5,8,11,14-
Eicosatetraenoic acid)

3. Two main groups:
1. Prostanoids: Further sub classified in to
three groups:
i. Prostaglandins (PGs)
ii.Prostacyclins (PGI2)
iii.Thromboxanes (TXs)
2. Leukotrienes & lipoxins

4. leukotrienes
Lipoxyganase
phospholipids arachidonate diacylglycerol
PGH2 Synthase
prostaglandin H2
prostacyclins thromboxanes
other prostaglandins
Prostacyclin
Synthase
Thromboxane
Synthase
Linear pathway
Cyclic pathway

7.  Are formed in almost all tissues rather than
in specialized glands
 Act locally rather than to distant sites
 Are not transported via blood
 Act on their parent cells
 Are synthesized as per need
 Are not stored in tissues

8.  TX A2 (produced mainly in platelets):
Platelet aggregation
Vasoconstriction
Smooth muscle contraction
 PG I2/Prostacyclins (produced mostly in
vascular endothelium):
Inhibition of platelet aggregation
Vasodilatation

9. PG E2 PG F2
 Vasodilatation
 Smooth muscle
relaxation (like
bronchodilatation)
 Uterine contraction
 Renal vasodilatation &
natriuresis
 Inhibition of HCl
secretion by parietal cell
 Vasoconstriction
 Smooth muscle
contraction
 Uterine contraction

10.  Leukotrienes :
Regulation of events of inflammation,
hypersensitivity & anaphylaxis
Vasoconstriction & smooth muscle
contraction
Increased vascular permeability &
chemotaxis
 Excess PGs cause pain, inflammation,
fever, nausea, vomiting, etc.

11.  Control of inflammation/BP
 Alleviation of PUD
 Relief of asthma/nasal congestion
 Prevention of thrombotic events
 Induction of labor, termination of
pregnancy & prevention of conception

12.  Steroids (inhibits phospholipase A2)
 Aspirin, NSAID (inhibit cyclooxygenase)
So, these drugs are used as pain killer &
antipyretic.