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Actions of Prostaglandins
Prostaglandins act by binding to different G-protein coupled receptors that in
return activate or inhibit adenylyl cyclase or stimulate phospholipase C. That
eventually results in an enhanced formation of diacylglycerol and inositol 1,4,5-
trisphosphate. Prostaglandin F2α (PGF2α), the leukotrienes, and thromboxane A2
(TXA2) activate phosphatidylinositol metabolism to perform certain functions.
Thus, activation of phosphatidylinositol metabolism leads to an increase in
intracellular Ca2+.
Prostaglandins, produced inside tissues, serve as local signals and the response
depends on specific cell types. The functions of prostaglandins and other
eicosanoids are diverse and depend on the tissue and enzymes present at the site
of action.
For instance, TXA2 released from platelets due to tissue injury, cause an increase
in bringing up new platelets for aggregation to the site of injury and also
contributes to local vasoconstriction. Whereas PGI2 is produced by endothelial
cells and its role is opposite to TXA2, PGI2 inhibits platelet aggregation and
produces vasodilation.
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Therapeutic use of Prostaglandins
Prostaglandins play an important role in the regulation of pain, inflammation, and
fever. They are also involved in the regulation of many physiological functions,
such as acid secretion and mucus formation in the gastrointestinal (GI) tract,
contractions of the uterus, and blood flow of the kidney. Prostaglandins also play
a role as chemical mediators that are released during allergic and inflammatory
processes.
Major drugs targeting Prostaglandins
DRUG
PROPERTIES
MECHANISM OF
ACTION
SIDE EFFECTS
Misoprostol
A PGE1 analog and
used to protect the
mucosal lining of
the stomach by
decreasing the
occurrence of
gastric and
duodenal ulcers
during chronic
NSAID treatment. It
is also used off -
label in obstetric
settings for labor
induction.
Misoprostol
interacts with
prostaglandin
receptors on parietal
cells present in the
stomach and
reduces gastric acid
secretion. It shows a
gastric intestinal
cytoprotective effect
by stimulation of
mucus and
bicarbonate
production. It
enhances uterine
contractions by
interacting with
prostaglandin
receptors in the
uterus.
It has a potential
risk of abortion,
thus,
contraindicated
during pregnancy.
Common side
effects are diarrhea
headache,
abdominal pain,
and spotting (in
women).
If used off -label
for labor induction,
for termination of
pregnancy, or for
cervical ripening,
misoprostol can
cause maternal or
fetal complications
such as death,
uterine damage,
infection, and fetal
bradycardia.
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Iloprost
A synthetic analog
of PGI2(prostacyclin)
and is a potential
agent for pulmonary
vasodilation so it
can be used as a
therapeutic drug for
pulmonary arterial
hypertension.
Iloprost is given as
pulmonary
inhalation and
causes a localized
effect of a decrease
in pulmonary
hypertension. The
administration of
drugs through
pulmonary
inhalation is
beneficial as it
provides a more
localized effect with
less systemic blood
pressure reduction.
The repeated doses
are required due to
the short half-life of
the drug.
Iloprost causes a
notable reduction in
pulmonary arterial
resistance following
by increase in
cardiac index and
oxygen delivery.
Iloprost mediates its
function by
activating the IP
receptors
(prostacyclin
receptors), elevating
the formation of
intracellular cAMP
(cyclic adenosine
monophosphate).
Iloprost also inhibits
TXA2 production.
Due to iloprost
inhalation, cough
and bronchospasm
can be the adverse
effects. Common
side effects include
headache,
dizziness, flushing,
and fainting.
Latanoprost,
travoprost,
and
bimatoprost
Latanoprost is a
PGF2α analog that is
used as a
therapeutic drug for
elevated intraocular
latanoprost and
travoprost bind to
the prostaglandin FP
receptors and cause
an increase in
uveoscleral outflow
These drugs can
cause adverse
effects like blurred
vision, ocular
irritation, iris color
change (increased
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pressure and open-
angle glaucoma.
Travoprost is a pro-
drug and become
active after
metabolized to free
acid. This drug is
given as ophthalmic
solution once per
day and as effective
as timolol(a
synthetic
compound) or even
better in decreasing
intraocular pressure.
Bimatoprost mimics
endogenous
prostanoids
(prostaglandin-
ethanolamides) and
has similar
effectiveness in
decreasing the
intraocular pressure.
Bimatoprost
enhances
prominence, length,
and darkness of
eyelash and also
used for treating
eyelash
hypotrichosis.
(any nontrabecular
outflow in a normal
eye), decreasing
intraocular pressure.
Bimatoprost causes
similar effects as
latanoprost and
travoprost.
brown
pigmentation),
increased number
and pigment of
eyelashes, and
foreign body
sensation.
Alprostadil
It is a PGE1
produced naturally
in tissues, for
The administration
of alprostadil is
localized either by
Major side effects,
when used as
therapy for erectile
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example, seminal
vesicles and
cavernous tissues, in
the ductus
arteriosus of the
fetus and in the
placenta.
Therapeutic
importance of
alprostadil is in the
treatment of erectile
dysfunction or in
keeping the ductus
arteriosus open in
those neonates that
have congenital
heart conditions
until surgery has
done. However,
usually, the ductus
closes soon after
delivery in order to
allow normal blood
circulation between
the heart and the
lungs.
suppository or by
injection. The drug
action occurs by
causing an increase
in intracellular cAMP
which subsequently
leads to the
activation of protein
kinase and
relaxation of smooth
muscle. Blood is
then entrapped by
dilation of
cavernosal arteries
and by the
relaxation of
trabecular smooth
muscles.
dysfunction, are
dizziness,
symptomatic
hypotension, and
syncope. Local
adverse reactions
include urethral,
penile, and
testicular pain;
prolonged
erections; and
priapism. When
administered
intravenously (IV)
in neonates, fever,
sepsis, apnea, and
seizures may be
the adverse
effects.
Lubiprostone
Lubiprostone is a
PGE1 derivative
used as a
therapeutic drug for
irritable bowel
syndrome with
constipation and
chronic idiopathic
constipation.
It exerts its effects
by stimulation of
chloride channels
(ClC-2) in the
luminal cells of the
intestinal epithelium,
thus cause an
increase in intestinal
fluid secretion. This
The common side
effect is nausea
that can be
decreased if drug
is taken with food.
The second most
reported adverse
effect is dose-
dependent
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results in the
softening of the
stool and increases
intestinal motility
diarrhea that is
followed by
headache and
abdominal pain.

Unformatted Attachment Preview

Actions of Prostaglandins Prostaglandins act by binding to different G-protein coupled receptors that in return activate or inhibit adenylyl cyclase or stimulate phospholipase C. That eventually results in an enhanced formation of diacylglycerol and inositol 1,4,5trisphosphate. Prostaglandin F2α (PGF2α), the leukotrienes, and thromboxane A2 (TXA2) activate phosphatidylinositol metabolism to perform certain functions. Thus, activation of phosphatidylinositol metabolism leads to an increase in intracellular Ca2+. Prostaglandins, produced inside tissues, serve as local signals and the response depends on specific cell types. The functions of prostaglandins and other eicosanoids are diverse and depend on the tissue and enzymes present at the site of action. For instance, TXA2 released from platelets due to tissue injury, cause an increase in bringing up new platelets for aggregation to the site of injury and also contributes to local vasoconstriction. Whereas PGI2 is produced by endothelial cells and its role is opposite to TXA2, PGI2 inhibits platelet aggregation and produces vasodilation. Therapeutic use of Prostaglandins Prostaglandins play an important role in the regulation of pain, inflammation, and fever. They are also involved in the regulation of many physiological functions, such as acid secretion and mucus formation in the gastrointestinal (GI) tract, contractions of the uterus, and blood flow of the kidney. Prostaglandins also play a role as chemical mediators that are released during allergic and inflammatory processes. Major drugs targeting Prostaglandins DRUG Misoprostol PROPERTIES A PGE1 analog and used to protect the mucosal lining of the stomach by decreasing the occurrence of gastric and duodenal ulcers during chronic NSAID treatment. It is also used off label in obstetric settings for labor induction. MECHANISM OF ACTION Misoprostol interacts with prostaglandin receptors on parietal cells present in the stomach and reduces gastric acid secretion. It shows a gastric intestinal cytoprotective effect by stimulation of mucus and bicarbonate production. It enhances uterine contractions by interacting with prostaglandin receptors in the uterus. SIDE EFFECTS It has a potential risk of abortion, thus, contraindicated during pregnancy. Common side effects are diarrhea headache, abdominal pain, and spotting (in women). If used off -label for labor induction, for termination of pregnancy, or for cervical ripening, misoprostol can cause maternal or fetal complications such as death, uterine damage, infection, and fetal bradycardia. Iloprost A synthetic analog of PGI2(prostacyclin) and is a potential agent for pulmonary vasodilation so it can be used as a therapeutic drug for pulmonary arterial hypertension. Iloprost is given as pulmonary inhalation and causes a localized effect of a decrease in pulmonary hypertension. The administration of drugs through pulmonary inhalation is beneficial as it provides a more localized effect with less systemic blood pressure reduction. The repeated doses are required due to the short half-life of the drug. Iloprost causes a notable reduction in pulmonary arterial resistance following by increase in cardiac index and oxygen delivery. Iloprost mediates its function by activating the IP receptors (prostacyclin receptors), elevating the formation of intracellular cAMP (cyclic adenosine monophosphate). Iloprost also inhibits TXA2 production. Due to iloprost inhalation, cough and bronchospasm can be the adverse effects. Common side effects include headache, dizziness, flushing, and fainting. Latanoprost, travoprost, and bimatoprost Latanoprost is a PGF2α analog that is used as a therapeutic drug for elevated intraocular latanoprost and travoprost bind to the prostaglandin FP receptors and cause an increase in uveoscleral outflow These drugs can cause adverse effects like blurred vision, ocular irritation, iris color change (increased pressure and openangle glaucoma. Travoprost is a prodrug and become active after metabolized to free acid. This drug is given as ophthalmic solution once per day and as effective as timolol(a synthetic compound) or even better in decreasing intraocular pressure. (any nontrabecular outflow in a normal eye), decreasing intraocular pressure. Bimatoprost causes similar effects as latanoprost and travoprost. brown pigmentation), increased number and pigment of eyelashes, and foreign body sensation. The administration of alprostadil is localized either by Major side effects, when used as therapy for erectile Bimatoprost mimics endogenous prostanoids (prostaglandinethanolamides) and has similar effectiveness in decreasing the intraocular pressure. Bimatoprost enhances prominence, length, and darkness of eyelash and also used for treating eyelash hypotrichosis. Alprostadil It is a PGE1 produced naturally in tissues, for Lubiprostone example, seminal vesicles and cavernous tissues, in the ductus arteriosus of the fetus and in the placenta. Therapeutic importance of alprostadil is in the treatment of erectile dysfunction or in keeping the ductus arteriosus open in those neonates that have congenital heart conditions until surgery has done. However, usually, the ductus closes soon after delivery in order to allow normal blood circulation between the heart and the lungs. suppository or by injection. The drug action occurs by causing an increase in intracellular cAMP which subsequently leads to the activation of protein kinase and relaxation of smooth muscle. Blood is then entrapped by dilation of cavernosal arteries and by the relaxation of trabecular smooth muscles. dysfunction, are dizziness, symptomatic hypotension, and syncope. Local adverse reactions include urethral, penile, and testicular pain; prolonged erections; and priapism. When administered intravenously (IV) in neonates, fever, sepsis, apnea, and seizures may be the adverse effects. Lubiprostone is a PGE1 derivative used as a therapeutic drug for irritable bowel syndrome with constipation and chronic idiopathic constipation. It exerts its effects by stimulation of chloride channels (ClC-2) in the luminal cells of the intestinal epithelium, thus cause an increase in intestinal fluid secretion. This The common side effect is nausea that can be decreased if drug is taken with food. The second most reported adverse effect is dosedependent results in the softening of the stool and increases intestinal motility diarrhea that is followed by headache and abdominal pain. Name: Description: ...
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