DRUGS ACTING ON UTERUS AND TOCOLYTIC DRUGS .ppt

DRUGS ACTING ON UTERUS

2. 
Drugs acting on uterus can primarily Drugs acting on uterus can primarily
affect the endometrium or the affect the endometrium or the
myometrium.myometrium.

The most important drugs affecting The most important drugs affecting
endometrium are estrogens, endometrium are estrogens,
progestins and their antagonists. progestins and their antagonists.

Myometrium receives both sympathetic Myometrium receives both sympathetic
and parasympathetic innervation. and parasympathetic innervation.
Autonomic drugs can affect its motility. Autonomic drugs can affect its motility.

3. UTERINE STIMULANTSUTERINE STIMULANTS
These drugs increase uterine These drugs increase uterine
motility, especially at term. motility, especially at term.
Posterior pituitary hormone Posterior pituitary hormone
oxytocin, desamino oxytocin oxytocin, desamino oxytocin
Ergot alkaloids Ergometrine Ergot alkaloids Ergometrine
(Ergonovine), Methylergometrine(Ergonovine), Methylergometrine

Prostaglandins PGEProstaglandins PGE
22 , PGF , PGF
22, , 15-15-
methymethyll PGF PGF
22 ,Misoprostol ,Misoprostol

Miscellaneous Ethacridine, Quinine. Miscellaneous Ethacridine, Quinine.

4. OXYTOCINOXYTOCIN
1.1.Nonapeptide Nonapeptide
2.2.Posterior pituitary along with Posterior pituitary along with
vasopressin (ADH) vasopressin (ADH)
3.3.Pituitary extract was first used in Pituitary extract was first used in
labour in 1909. labour in 1909.
4.4.du Vigneaud in 1953 when he du Vigneaud in 1953 when he
separated Oxytocin and Vasopressinseparated Oxytocin and Vasopressin
5.5.Both are nonapeptides- 3 and 8Both are nonapeptides- 3 and 8

5. 
Both oxytocin and ADH are synthesized Both oxytocin and ADH are synthesized
within the nerve cell bodies in within the nerve cell bodies in
supraoptic and paraventricular nuclei of supraoptic and paraventricular nuclei of
hypothalamus; are transported down hypothalamus; are transported down
the axon and stored in the nerve the axon and stored in the nerve
endings within the neurohypophysis.endings within the neurohypophysis.
ACTIONSACTIONS
1.1.Uterus Uterus Oxytocin increases the force and Oxytocin increases the force and
frequency of uterine contractions.frequency of uterine contractions.
2.2.With low doses, full relaxation occurs in With low doses, full relaxation occurs in
between contractions; basal tone between contractions; basal tone
increases only with high doses.increases only with high doses.

6. 
The increased contractility is restricted to the The increased contractility is restricted to the
fundus and body; lower segment is not fundus and body; lower segment is not
contracted, may even be relaxed at term.contracted, may even be relaxed at term.

Mechanism of action Action of oxytocin on Mechanism of action Action of oxytocin on
myometrium is independent of innervation. myometrium is independent of innervation.

There are specific G-protein coupled oxytocin There are specific G-protein coupled oxytocin
receptors which mediate ate response mainly receptors which mediate ate response mainly
by depolarization of muscle fibres and influx of by depolarization of muscle fibres and influx of
CaCa
2+ 2+
ions as well as through phosphoinositide ions as well as through phosphoinositide
hydrolysis and IPhydrolysis and IP
3 3 mediated intracellular release mediated intracellular release
of Caof Ca
2+2+
ions.ions.

The number of oxytocin receptors increases The number of oxytocin receptors increases
markedly during later part of pregnancy.markedly during later part of pregnancy.

oxytocin increases PG synthesis and release by oxytocin increases PG synthesis and release by
the endometrium which may contribute to the the endometrium which may contribute to the
contractile response. contractile response.

Distinct subtypes of oxytocin receptors have Distinct subtypes of oxytocin receptors have
been shown on the myometrium and the been shown on the myometrium and the
endometriumendometrium ..

7. 
Breast Oxytocin contracts Breast Oxytocin contracts
myoepithelium of mammary alveoliand myoepithelium of mammary alveoliand
forces milk in to the bigger milk forces milk in to the bigger milk
sinusoids –’milk ejection reflex’ (milk sinusoids –’milk ejection reflex’ (milk
letdown in cattle) is initiated by suckling letdown in cattle) is initiated by suckling
so that it may be easily sucked by the so that it may be easily sucked by the
infant.infant.

CVS Conventional doses used in CVS Conventional doses used in
obstetrics have no effect on BP but obstetrics have no effect on BP but
higher doses cause vasodilatation higher doses cause vasodilatation  brief brief
fall in BP, reflex tachycardia and flushing.fall in BP, reflex tachycardia and flushing.

Kidney Oxytocin in high doses exerts an Kidney Oxytocin in high doses exerts an
ADH-like action – urine output is ADH-like action – urine output is
decreased: pulmonary edema can occur if decreased: pulmonary edema can occur if
large amounts of i.v. fluids and oxytocin large amounts of i.v. fluids and oxytocin
are infused together. Conventional doses are infused together. Conventional doses
are without any effect.are without any effect.

8. Physiological rolePhysiological role
1.1.Labour Labour
2.2.Milk ejection reflexMilk ejection reflex
3.3.Neurotransmission Neurotransmission
PHARMACOKINETICS PHARMACOKINETICS

Being a peptide, oxytocin is inactive orally Being a peptide, oxytocin is inactive orally
and is generally administered by i.m. or i.v. and is generally administered by i.m. or i.v.
routes, rarely by intranasal spray. routes, rarely by intranasal spray.

It is rapidly degraded in liver and kidney; It is rapidly degraded in liver and kidney;
Plasma t½Plasma t½
˜˜6 min, and is still shortened at 6 min, and is still shortened at
term. term.

Pregnant uterus and placenta elaborate a Pregnant uterus and placenta elaborate a
specific aminopeptidase called oxytocinase – specific aminopeptidase called oxytocinase –
which can be detected in maternal plasmawhich can be detected in maternal plasma..

9. USEUSE
1.1. Induction of labour Lobour needs to be Induction of labour Lobour needs to be
induced in case of postmaturity of prematurely induced in case of postmaturity of prematurely
in toxaemia of pregnancy, diabetic mother, in toxaemia of pregnancy, diabetic mother,
erythroblastosis, ruptured membranes or erythroblastosis, ruptured membranes or
placental insufficiency. Uterine contractions placental insufficiency. Uterine contractions
are then closely monitored; the drug is are then closely monitored; the drug is
discontinued when they are strong enough. discontinued when they are strong enough.
Usually a total of 2 – 4 IU is needed. Usually a total of 2 – 4 IU is needed.
2.2.Uterine inertia When uterine contractions are Uterine inertia When uterine contractions are
feeble and labour is not progressing feeble and labour is not progressing
satisfactorily- oxytocin can be infused i.v. (as satisfactorily- oxytocin can be infused i.v. (as
described above) to augment contractions.described above) to augment contractions.

10. Oxytocin is the drug of choice and is Oxytocin is the drug of choice and is
preferred over ergometrine/ PGs for the preferred over ergometrine/ PGs for the
above two purposes above two purposes
a)a)Because of its short t½ and slow i.v. infusion, Because of its short t½ and slow i.v. infusion,
intensity of action can be controlled and intensity of action can be controlled and
action can be quickly terminated. action can be quickly terminated.
b)b)Low concentrations allow normal relaxation Low concentrations allow normal relaxation
in between contractions – foetal oxygenation in between contractions – foetal oxygenation
does not suffer. does not suffer.
c)c)Lower segment is not contracted; foetal Lower segment is not contracted; foetal
descent is not compromised. descent is not compromised.
d)d)Uterine contractions are consistently Uterine contractions are consistently
augmented. augmented.

11. 3.3. Postpartum haemorrhage, cesarean section Postpartum haemorrhage, cesarean section
Oxytocin 5 IU may be injected i.m, or by i.v. Oxytocin 5 IU may be injected i.m, or by i.v.
infusion for an immediate response, especially infusion for an immediate response, especially
in hypertensive women in whom ergometrine in hypertensive women in whom ergometrine
is contraindicated. is contraindicated.
It acts by forcefully contracting the uterine It acts by forcefully contracting the uterine
muscle which compresses the blood vessels muscle which compresses the blood vessels
passing through it to arrest haemorrhage from passing through it to arrest haemorrhage from
the inner surface exposed by placental the inner surface exposed by placental
separation.separation.
4. Breast engorgement it way occur due to 4. Breast engorgement it way occur due to
inefficient milk ejection reflex – oxytocin is inefficient milk ejection reflex – oxytocin is
effective only in such cases; an intranasal spray effective only in such cases; an intranasal spray
may be given few minutes before sucking. It may be given few minutes before sucking. It
does not increase milk production. does not increase milk production.

12. 5.5.Oxytocin challenge test it performed determine Oxytocin challenge test it performed determine
utero – placental adequacy in high risk utero – placental adequacy in high risk
pregnancies pregnancies
Adverse effectsAdverse effects
i.i.Injudicious use of oxytocin during labour can Injudicious use of oxytocin during labour can
produce too strong uterine contractions forcing produce too strong uterine contractions forcing
the presenting part through incompletely the presenting part through incompletely
dilated birth canal causing maternal and foetal dilated birth canal causing maternal and foetal
soft tissue injury, foetal asphyxia and death.soft tissue injury, foetal asphyxia and death.
ii.ii.Water intoxication; because of ADH like action – Water intoxication; because of ADH like action –
toxaemia of pregnancy insufficiency – serious toxaemia of pregnancy insufficiency – serious
complication complication

13. Desamino – oxytocin Desamino – oxytocin
It has been developed as a buccal It has been developed as a buccal
formulation; action is similar to injected formulation; action is similar to injected
oxytocin, but less consistent. Its indications oxytocin, but less consistent. Its indications
are:are:
Induction of labour: 50IU buccal tablet Induction of labour: 50IU buccal tablet
repeated every 30 min, max 0tabs.repeated every 30 min, max 0tabs.
Uterine inertia: 25 IU every 30 min.Uterine inertia: 25 IU every 30 min.
Promotion of uterine involution 25-50 IU 5 Promotion of uterine involution 25-50 IU 5
times daily for 7 days. times daily for 7 days.
Breast engorgement 25-50 IU just before Breast engorgement 25-50 IU just before
Breast feeding. BUCTOCIN 50 IU tabBreast feeding. BUCTOCIN 50 IU tab

14. ERGOMETRINE,METHYLERGOMETRINEERGOMETRINE,METHYLERGOMETRINE
1.1. UterusUterus
2.CVS Ergometrine and methylergometrine 2.CVS Ergometrine and methylergometrine
are much weaker vasoconstrictors than are much weaker vasoconstrictors than
ergotamine and have low propensity to ergotamine and have low propensity to
cause endothelial damage.cause endothelial damage.
3. CNS High doses produce complex 3. CNS High doses produce complex
actions-partial agonistic/antagonistic actions-partial agonistic/antagonistic
interaction with adrenergic, serotonergic interaction with adrenergic, serotonergic
and dopaminergic receptors in the brain and dopaminergic receptors in the brain
have been shown.have been shown.

15. GIT high doses can increase peristalsis. GIT high doses can increase peristalsis.
Methylergometrine is 1½ times more Methylergometrine is 1½ times more
potent than ergometrine on the uterus, potent than ergometrine on the uterus,
but other action are less marked. It has but other action are less marked. It has
thus replaced ergometrine at many thus replaced ergometrine at many
obstetric units. obstetric units.
PHARMACOKINETICSPHARMACOKINETICS
The onset of uterine action is oral – 15 min The onset of uterine action is oral – 15 min
i.m. – 5 min; i.v. – almost immediate. i.m. – 5 min; i.v. – almost immediate.
They are partly metabolized in liver and They are partly metabolized in liver and
excreted in urine. Plasma t ½ is 1- 2 hours excreted in urine. Plasma t ½ is 1- 2 hours
effects of single dose last 3- 4hourseffects of single dose last 3- 4hours

16. ADVERSE EFFECTS ADVERSE EFFECTS
Nausea, vomiting and rise in BP occur Nausea, vomiting and rise in BP occur
occasionally, decrease milk secretion , occasionally, decrease milk secretion ,
inhibition of prolactin release inhibition of prolactin release
Ergometrine should be avoided in Ergometrine should be avoided in
1.1.Patients with vascular disease, Patients with vascular disease,
hypertension, toxaemia. hypertension, toxaemia.
2.2.Presence of sepsis – may cause gangrene. Presence of sepsis – may cause gangrene.
3.3.Liver and kidney disease. Liver and kidney disease.
They are contraindicated during pregnancy They are contraindicated during pregnancy
and before 3and before 3
rdrd
stage of labour. stage of labour.

17. USEUSE
1. The primary indication for ergometrine / 1. The primary indication for ergometrine /
methylergometrine is to control and methylergometrine is to control and
prevent postpartum haemorrhage (PPH) : prevent postpartum haemorrhage (PPH) :
0.2 – 0.3 mg i.m. at delivery of anterior 0.2 – 0.3 mg i.m. at delivery of anterior
shoulder reduces postpartal blood loss shoulder reduces postpartal blood loss
and prevents PPH.and prevents PPH.
However, routine use in all cases is not However, routine use in all cases is not
justified – only in those expected to bleed justified – only in those expected to bleed
more, e.g. grand multipara, uterine inertia. more, e.g. grand multipara, uterine inertia.

Multiple pregnancy should be excluded Multiple pregnancy should be excluded
before injecting.before injecting.

18. 
If PPH is occurring – 0.5 mg i.v. is If PPH is occurring – 0.5 mg i.v. is
recommended. recommended.
These drugs produce sustained tonic These drugs produce sustained tonic
uterine contraction perforating uterine contraction perforating
uterine are compressed by the uterine are compressed by the
myometrial meshwork bleeding myometrial meshwork bleeding
stops.stops.
2. After cesarean section / 2. After cesarean section /
instrumental delivery to prevent instrumental delivery to prevent
uterine atony. uterine atony.
33. . To ensure normal involution : a firm To ensure normal involution : a firm
and active uterus involutes rapidlyand active uterus involutes rapidly

19. To ensure this : 0. 125 mg of ergometrine or To ensure this : 0. 125 mg of ergometrine or
methylergometrine has been given TDS orally methylergometrine has been given TDS orally
for 7 days. for 7 days.
However, routine use in all cases is not justified However, routine use in all cases is not justified
because normal involution is not hastened. because normal involution is not hastened.
Multipara and others in whom slow involution is Multipara and others in whom slow involution is
feared – may be given prophylactically.feared – may be given prophylactically.
4. Diagnosis of variant angina A small dose 4. Diagnosis of variant angina A small dose
of ergometrine injected i.v. during coronary of ergometrine injected i.v. during coronary
angiography causes prompt constriction of angiography causes prompt constriction of
reactive segments of coronary artery that are reactive segments of coronary artery that are
responsible for variant anginaresponsible for variant angina. .

20. Chemical and Chemical and


mechanical mechanical

phospholipase A Activation stimuli phospholipase A Activation stimuli
COOHCOOH



Cyclo-oxygenase Lipoxygenase Cyclo-oxygenase Lipoxygenase


Cyclic PGGCyclic PGG
2 2 12-HPETE 5-HPETE 5-HETE 12-HPETE 5-HPETE 5-HETE

Endoperoxides Endoperoxides

PGHPGH
2 2 12-HETE LTA 12-HETE LTA
44


Isomerases Thromboxane Prostacyclin LTBIsomerases Thromboxane Prostacyclin LTB
44 LTC LTC
44
synthase synthase synthase synthase
LTDLTD
44

PGEPGE
2 2 PGDPGD
2 2 PGF PGF
2 2  TXA TXA
2 2 PGI PGI
2 2 LTE LTE
44 LTF LTF
44




TXBTXB
2 2 6Keto-PGF1 6Keto-PGF1

MEMBRANE PHOSPHOLIPID
ARACHIDONIC ACID
SRS-A

21. Prostaglandins (PGs) and Leukotrienes (LTs) Prostaglandins (PGs) and Leukotrienes (LTs)
are biologically active derivatives of 20 carbon are biologically active derivatives of 20 carbon
atom polyunsaturated essential fatty acids that atom polyunsaturated essential fatty acids that
are released from cell membrane are released from cell membrane
phospholipids. They are the major lipid derived phospholipids. They are the major lipid derived
autocoids.autocoids.

PGs may be considered to be derivatives of PGs may be considered to be derivatives of
prostanoic acid, prostanoic acid,
1.1.CVS:CVS:
PGEPGE2 and PGF2 and PGF
2 2 
cause Vasodilatation in most cause Vasodilatation in most
but not all, vascular beds. In isolated but not all, vascular beds. In isolated
preparation, they are more potent vasodilators preparation, they are more potent vasodilators
than ACh or histamine. PGFthan ACh or histamine. PGF
2 2 

22. Actions and Pathophysiological RolesActions and Pathophysiological Roles

Constricts many larger veins including pulmonary Constricts many larger veins including pulmonary
vein and artery. Fall in BP occurs when PGEvein and artery. Fall in BP occurs when PGE
2 2
is is
injected i.v., but PGFinjected i.v., but PGF
2 2 
has little effect on BP has little effect on BP

PGIPGI
22
is uniformly vasodilatory and is more potent is uniformly vasodilatory and is more potent
hypotensive than PGEhypotensive than PGE
2.2.

PG endoperoxides (GPG endoperoxides (G
22
andH andH
22
) are inherently ) are inherently
vasoconstrictor, but often produce vasodilatation vasoconstrictor, but often produce vasodilatation
or a biphasic response due to rapid conversion to or a biphasic response due to rapid conversion to
other PGs, especially PGIother PGs, especially PGI
22
in the blood vessels in the blood vessels
themselves.themselves.

PGEPGE
22
and F and F
2 2 
stimulate heart by weak direct but stimulate heart by weak direct but
most prominent reflex action due to fall in BP. most prominent reflex action due to fall in BP.
The cardiac output increases. The cardiac output increases.

23. Role :Role :
1.1. PGE is probably involved in the regulation PGE is probably involved in the regulation
of local vascular tone as a dilator. of local vascular tone as a dilator.
2.2.PGE and PGI are believed to be continuously PGE and PGI are believed to be continuously
produced locally in the ductus arteriosus produced locally in the ductus arteriosus
during foetal life-keep it patent; at birth their during foetal life-keep it patent; at birth their
synthesis is inhibited and closure occurs. synthesis is inhibited and closure occurs.
Aspirin and indomethacin induce closure Aspirin and indomethacin induce closure
when it fails to occur spontaneously. These when it fails to occur spontaneously. These
PGs may also be important in maintaining PGs may also be important in maintaining
placental blood flow.placental blood flow.
3.3.PGs, along with LTs and other autacoids may PGs, along with LTs and other autacoids may
mediate vasodilatation and exudation at the mediate vasodilatation and exudation at the
site of inflammation. site of inflammation.

24. 2. UTERUS2. UTERUS
PGEPGE
22
and PGF and PGF
22 uniformly contract human uterus, uniformly contract human uterus,
pregnant as well as nonpregnant in vivo.pregnant as well as nonpregnant in vivo.

The sensitivity is higher during pregnancy and there is The sensitivity is higher during pregnancy and there is
further modest increase with progress of pregnancy.further modest increase with progress of pregnancy.

However, even during early stages uterus is quite However, even during early stages uterus is quite
sensitive to PGs increase tone as well as amplitude of sensitive to PGs increase tone as well as amplitude of
uterine contractions.uterine contractions.
When tested in vitro, PGFWhen tested in vitro, PGF
22 consistently produces consistently produces
contraction while PGEcontraction while PGE
22
relaxes nonpregnant but relaxes nonpregnant but
contracts pregnant human uterine strips.contracts pregnant human uterine strips.

At term, PGs at low doses soften the cervix and make it At term, PGs at low doses soften the cervix and make it
more compliant.more compliant.

25. 3. Bronchial muscle 3. Bronchial muscle
PGFPGF
22 PGD PGD
22
and TXA and TXA
22
potent potent
bronchoconstrictorsbronchoconstrictors
4. GIT 4. GIT

Role PGs may be involved in mediating toxin Role PGs may be involved in mediating toxin
induced increased fluid movement in induced increased fluid movement in
secretory diarrhoeas. In certain diarrhoeas,secretory diarrhoeas. In certain diarrhoeas,
PGEPGE
22
markedly reduces acid secretion in the markedly reduces acid secretion in the
stomach.stomach.
Role PGs (especially PGIRole PGs (especially PGI
22
) appear to be involved ) appear to be involved
in the regulation of gastric mucosal blood flow. in the regulation of gastric mucosal blood flow.

26. 5. Kidney PGE5. Kidney PGE
22
and PGI and PGI
22
increase water, N increase water, N
++

and Kand K
+ +
excretion and have diuretic – Role excretion and have diuretic – Role
6. CNS – Role 6. CNS – Role
1. PGE1. PGE
22
may mediate pyrogen induced fever may mediate pyrogen induced fever
and malaise. and malaise.
2. PGs may be functioning as 2. PGs may be functioning as
neuromodulators in the brain by neuromodulators in the brain by
regulating neuronal excitability.regulating neuronal excitability.
7. ANS – Role PGs may modulate 7. ANS – Role PGs may modulate
sympathetic neurotransmission in the sympathetic neurotransmission in the
peripheryperiphery. .

27. 8.8. Peripheral nerves – Role PGs appear to serve as Peripheral nerves – Role PGs appear to serve as
algesic agents during inflammation. algesic agents during inflammation.
9. Eye – Role Locally produced PGs appear to 9. Eye – Role Locally produced PGs appear to
facilitate aqueous humor drainage, since COX – facilitate aqueous humor drainage, since COX –
2 expression in the ciliary body has been found 2 expression in the ciliary body has been found
to be deficient in wide angle glaucoma patients. to be deficient in wide angle glaucoma patients.
10. Endocrine system PGE10. Endocrine system PGE
22
facilitates the release facilitates the release
of anterior pituitary hormones – growth of anterior pituitary hormones – growth
hormone, prolactin, ACTH, FSH and LH as well as hormone, prolactin, ACTH, FSH and LH as well as
that of insulin and adrenal steroids. It has a TSH that of insulin and adrenal steroids. It has a TSH
like effect on thyroid,like effect on thyroid,
11. Metabolism PGEs are antilipolytic, exert an 11. Metabolism PGEs are antilipolytic, exert an
insulin like effect on carbohydrate metabolism insulin like effect on carbohydrate metabolism
and mobilize Caand mobilize Ca
2+2+
from bone may mediate from bone may mediate
hypercalcaemia due to bony metastasis hypercalcaemia due to bony metastasis

28. Uses :Uses :

Abortion Abortion

Induction / augmentation of labour Induction / augmentation of labour

Cervical primingCervical priming

Postpartum haemorrhage (PPH) Postpartum haemorrhage (PPH)
PGEPGE
22
(Dinoprostone) (Dinoprostone)

Peptic ulcer Peptic ulcer

Glaucoma latanoprost – isopropyl unoprostone Glaucoma latanoprost – isopropyl unoprostone
To maintain patency of ductus arteriosus PGETo maintain patency of ductus arteriosus PGE
1 1
(Alprostadil)(Alprostadil)
To avoid platelet damage PGITo avoid platelet damage PGI
22
(Epoprostenol) (Epoprostenol)
can be used to prevent platelet aggregation.can be used to prevent platelet aggregation.

29. Peripheral vascular diseases PGIPeripheral vascular diseases PGI
22

Impotence Alprostadil (PGEImpotence Alprostadil (PGE
11) injected into ) injected into
the penis causes erection lasting 1 – 2 the penis causes erection lasting 1 – 2
hours. However, oral sildenafil / tadalafil hours. However, oral sildenafil / tadalafil
is now preferred for erectile dysfunction. is now preferred for erectile dysfunction.

Side effects nausea, vomiting watery Side effects nausea, vomiting watery
diarrhoea, uterine cramps, unduly diarrhoea, uterine cramps, unduly
forceful uterine contractions, vaginal forceful uterine contractions, vaginal
bleeding, flushing, shivering, fever, bleeding, flushing, shivering, fever,
malaise, fall in BP, tachycardia, chest malaise, fall in BP, tachycardia, chest
pain.pain.

30. UTERINE RELAXANTSUTERINE RELAXANTS
Tocolytics Tocolytics
Adrenergic agonists ritodrine isoxsuprine Adrenergic agonists ritodrine isoxsuprine
oral oral
Calcium channel blockers Calcium channel blockers
Magnesium sulfate Magnesium sulfate
Oxytocin antagonist Atosiban is a peptide Oxytocin antagonist Atosiban is a peptide
analogue of oxytocin that acts as analogue of oxytocin that acts as
antagonist at the oxytocin receptors. In antagonist at the oxytocin receptors. In
clinical trials, it has been found to suppress clinical trials, it has been found to suppress
premature uterine contractions and premature uterine contractions and
postpone preterm deliverypostpone preterm delivery

31. 
Miscellaneous drugs Miscellaneous drugs

Ethyl alcohol, nitrates, progesterone, Ethyl alcohol, nitrates, progesterone,
general anaesthetics and PG synthesis general anaesthetics and PG synthesis
inhibitors are the other drugs, which can inhibitors are the other drugs, which can
depress uterine contractions. depress uterine contractions.

However, their effect is not dependable and However, their effect is not dependable and
they are rarely used clinically as tocolytics. they are rarely used clinically as tocolytics.

Progesterone has been found to prevent Progesterone has been found to prevent
miscarriage in some high risk cases.miscarriage in some high risk cases.

Halothane is an efficacious uterine relaxant Halothane is an efficacious uterine relaxant
that has been used as the anaesthetic when that has been used as the anaesthetic when
external or internal version is attempted. external or internal version is attempted.