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Prostaglandins & Leukotrienes Dr.Sangeetha Purushothaman
Prostaglandins & Leukotrienes
• Local hormones - very active,many functions..• Autacoids from 20 C PUFA Prostaglandins Prostacyclin Thromboxanes Leukotrienes
Functions
• Inflammation• Smooth muscle tone• Blood coagulation• Reproduction • GI secretion
.
.
PHOSPHOLIPIDS
ARACHIDONIC ACID
PG G2
PGH2
PG I2
LT A4
THROMBOXANE
A2
PGE2
PG D2
PG F2
LT C4
LT D4
LT B4
PHOSPHOLIPASE A2
5 LIPOOXYGENASECYCLOOXYGENASE
ISOMERASE
PROSTACYCLINE SYNTHASE
THROMBOXANE SYNTHASE
SYNTHESIS
. PHOSPHOLIPIDS
ARACHIDONIC ACID
PG G2
PGH2
PG I2
LT A4
THROMBOXANE A2
PGE2 ,PG D2 ,PG
F2
LT C4 LT D4LT B4
PHOSPHOLIPASE A2
5 LIPOOXYGENASECYCLOOXYGENASE
STEROIDS
ZILEUTONNSAIDS
BIOSYNTHESIS OF PROSTAGLANDINSEnzyme is Cyclo oxygenase(COX) COX 1-constitutive. COX 2-inducible
NSAIDS- Nonselective COX inhibitors. COXIBS - Selective COX inhibitorsAspirin- Irreversible inhibition of COX Other NSAIDS- Reversible inhibition
Actions Inflammation Most important mediators.. Synthesised as per need. NSAIDS
Actions –Smooth musclesBlood vessels
Pg E2, Prostacycline - vasodilatation
Thromboxane A2 – constriction
Actions :Smooth muscle Bronchus
• BRONCHO DILATIONPgE2
PgI2
• CONSTRICTIONPgF2α
TXA2
LT
Uterus Both uterus &cervix
Cervical ripening•PgE2
Initiation of Labour•PgE1
•PgF2
Actions • GIT
Natural ulcer protectants.. NSAIDS..
MUCUS
HCO3-
ACID
• GIT
Motility SecretionCramps
Diarrhoea
RENALPgE2,Prostacyclin -protective..
PgE2,PgI2
RENAL VASODILATATION
RBF
DIRECT ON TUBULES
DIURESISNATRIURESIS
Coagulation
TXA2PLATELETS AGGREGATION
PgI2ENDOTHELIUM
(-)AGGREGATION
PG I₂
ENDOTHELIUM
PLATELET
.
Penile erection
CNS-NeurotransmitterEYE-↓IOT
Pulmonary vessels-
vasodilatation
Preparations & Uses
Preparations
Prostaglndin Preparation PgE₁ Misoprostol ,
Alprostadil,LatanoprostPgE₂ Rioprostil , Enprostil
Dinoprostone PgF₂α Prostin15Methyl PgF₂α
Carboprost / Prostodin
Pg I ₂ Epoprostenol
Uses 1.Obstetrics Therapeutic abortion
Cervical ripening
Severe Post partum hge
PgE1/MISOPROSTOL
PgE₁/PgE2
15METHYL PgF2
im/PgE1 Rectal
2.Peptic ulcer PgE1/Misoprostol
PgE2/Enprostil,Rioprostil,Arbaprostil
3.Glaucoma : PgE1 / Latanoprost
4.Erectile dysfunction 5. PDA
6. Primary pulmonary hypertention : PgI₂
PgE1/Alprostadil
Summary of usesUse Preparation Abortion PgE1Cervical ripening PgE1 / E2Peptic ulcer PgE1Glaucoma PgE1-LatanoprostPPH PgI2PDA PgE1
ADR• Vomiting,Diarrhoea,Abdominal
cramps• Uterine cramps• Bronchospasm
LEUKOTRIENES
PHOSPHOLIPIDS
CYCLOOXYGENASE
PROSTAGLANDINS
ARACHIDONIC ACID
LEUKOTRIENES
LIPOOXYGENASE
LEUKOTRIENE RECEPTOR
MAST CELL
Zileuton
ChromoglycateNedochromil
MonteleukastZafirleukast