Platelet activating factor (PAF) is a potent biological mediator involved in platelet aggregation, inflammation, and anaphylaxis. It is synthesized from precursor phospholipids in cell membranes by phospholipase A2 and a PAF-acetyltransferase. PAF exerts its effects by binding to specific receptors on platelets and other cells. It is degraded by PAF acetylhydrolase which hydrolyzes the acetyl group from PAF. Clinical uses of understanding PAF include treating inflammatory disorders and managing allergic reactions through modulation of its mechanisms of action and synthesis pathways.

1. ASSIGNMENT PRESENTED TO
Dr. TARIQUE MAHMOOD
ASSOCIATE PROFESSOR & HEAD
Mrs. ARSHIYA SHAMIM
ASST. PROFESSOR
PRESENTED BY
MULAYAM SINGH
DOCTOR OF PHARMACY
(2nd YEAR)
SESSION : 2018-19
PHARMACOLOGY - 1
PRY - 206
INTEGRAL UNIVERSITY , LUCKNOW
FACULTY OF PHARMACY
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Platelet activating factor:
Mechanism of action
&
Clinical uses

3. Platelet-activating factor (PAF) is
a lipid mediator that is well-known
for its ability to cause platelet
aggregation, inflammation, and
allergic response at very low
concentrations (approaching
picomolar).
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4. Platelets are tiny blood
cells that help your body
form clots to stop
bleeding. If one of your
blood vessels gets
damaged, it sends out
signals that are picked up
by platelets.
The platelets then rush
to the site of damage and
form a plug, or clot, to
repair the damage.
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In pharmacology, the
term mechanism of
action (MOA) refers to the
specific biochemical
interaction through which a
drug substance produces
its pharmacological effect. A
mechanism of
action usually includes
mention of the specific
molecular targets to which
the drug binds, such as an
enzyme or receptor.

7. relating to or based on work done
with real patients : of or relating
to the medical treatment that is
given to patients in hospitals,
clinics, etc. : requiring treatment
as a medical problem. : of or
relating to a place where medical
treatment is given : of or relating
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8. What is platelet activating factor..??
 Platelet-activating factor is a potent biological mediator that
exerts its effects in a variety of cells and tissues.
 Platelet-activating factor, also known as
PAF, PAF- acether or AGEPC (acetyl-glyceryl-ether-
phosphorylcholine), is a potent phospholipid activator and
mediator of many leukocyte functions, including
1) platelet aggregation
2) degranulation
3) inflammation, and
4) anaphylaxis.
continue….
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continue….It is also involved in changes to
vascular permeability, the oxidative burst,
chemotaxis of leukocytes, as well as
augmentation of arachidonic acid metabolism
in phagocytes.
 PAF is produced by a variety of cells, but
especially those involved in host defense,
such as
platelets, endothelial cells, neutrophils,

10. Synthesis of PAF
 PAF is synthesized from precursor phospholipids present in cell
membrane by the following reactions:
Membrane Acyl-glycero
phosphocholine
Phospholipase A2
Fatty acid
Lyso PAF
PAF-acetl
transferase
PAF
Acetyl CoA CoA
 The second step is rate limiting. Antigen-antibody reaction
and a variety of mediators stimulate PAF synthesis in a Ca2+
dependent manner on demand: there are no preformed stores of
PAF.
 In contrast to eicosanoids, the types of cells which synthesize
PAF is quite limited—mainly WBC, platelets, vascular
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11. PAF is degraded in the following
manner :
PAF Lyso PAF
Acyl glycerophosphocholin
(gets incorporated
in the membrane)
PAF acetyl-
hydrolase
Acyl-
transferase
Acetate
Fatty acid
Degradation of PAF
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PAF :- platelet activating factor
Lyso PAF :- Lysophosphatidylcholine

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audience

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