OXYTOCIN ROLE IN PREGNANCY

1. OXYTOCIN

2. ● Oxytocin is on world health organizations list because of
it is life saving medication.
● Interestingly, amongst the general public it is known as
love harmone .

3. History:-
Dale first discovered oxytocin in 1909.
Blair Bell first showed action of posterior pituitary extract on
uterine muscle.
Watson Turnbull was the first to use it is an intravenous
Preparation.

4. Chemistry
● It is a Nonapeotide, the synthetic form is known as
Syntocinon ot Pitocin (synthetic oxytocin is a
decapeptide).

5. Site of production :-
In the Body neuropeptide oxytocin is synthesized by
supraoptic and Paraventricular nuclei of hypothalamus and
transferred to posterior Pituitary by carrier proteins by
hypothalamo hypophyseal circulation. It is a neurotransmitter,
harmone.
In endocrinology, the only example of positive feedback loop
is release of oxytocin.

6. Mechanism of action:-
Actions as a harmone:-
● Ecbolic (uterotonic)action:-
● In full term gravid uterus it causes physiological contractions I.e it
causes contractions of upper segment and retraction of the lower
uterine segment.
● It has no action on first trimester uterus and little action on Second
trimester uterus.
● Inthe last 3 weeks there is 8 fold increase in the sensitivity of Uterus
to oxytocin is increased by estrogen and decreased by
progesterone.

7. Action on:-
● Breasts:-
● It causes milk ejection by stimulating myoepithelial cells of the
mammaryglands.
● CVS:-
● Given as intravenous infusion in high concentration bolus,
it Can cause hypertension.
● ANTI DIURETIC ACTION:-
● Given in pharmacological doses it can cause water retention
( because it is closely related to antidiuretic harmone).

8. Neurotransmitter :-
The harmone of labour is also the harmone of love .
Oxytocin could increase anxiety, fear in response to future stress in
men,it creates sexual arousal, and helps them in maintaining their
elections.
Studies indicate that there may be a role for Oxytocin in treatment
of autism.
Evidences shows that Oxytocin injections have a positive influence
on wound healing.

9. Preparations available:-
● Ampoule/ vial for intravenous or intravenous intra
muscular use (pitocin:5units in 0.5 ml,partocin ,Gynotocin,
and Syntocinon:units/ml.
● Nasal spray
● Bucal tablets
● Interestingly an oxytocin -laced perfume is avail5in many
parts of the world (non-medical use)
● To preserve their potency ,synthetic oxytocin Ampoules
must be stored in refrigerator.

10. Routes of administration:-
● Orally ir is ineffective being a protein,it is rapidly destroyed by gastrointestinal tract.
● Buccal or nasal route:- Suggested by clement et al in 1962.
● Half to one tablet of buctocin (100-200units) inserted in buccal pouch. Increase by one tablet
every half an hour till uterine contractions begin or maximum 21 tablets are used.
● Nasal sprays or aerosol s are also available.
● Advantages of this route: action more predictable than intramuscular or subcutaneous route;if
there is hyperstimulation patients can spit out the drug. Patient is ambulatory during this treatment.
● Disadvantages:- erratic response.
● Intramuscular or subcutaneous route not used since the response Is erratic and
the dose cannot be titration to response.

11. Intravenous infusion:-
● It is the best and only route used. Given intravenously the
action starts in 20 - 30 seconds and half - life is only 3
minutes .
● IT CAN BE GIVEN IN VARIOUS WAYS :-
● Intra myometrial injection eg:- during cesarean delivery
has rarely been used.

12. IN OBSTERTRICS, OXYTOCIN CAN BE GIVEN
INTRAVENOUSLY IN 3 WAYS :
OXYTOCIN PHYSIOLOGICAL DOSES:-
● Theobald’s physiological drip :-
● He recommended a slow infusion in doses resembling
physiological doses I.e starting with 0.5 units in 500 ml of RL in
10 drops / min up to maximum dose of 40 Drops per minute.
● Increase the dose up to a maximum of 2 units per 500mlof RL.

13. Advantages of this regimen:No risk of over stimulation
Drawbacks:- The dose is ineffective in many women.

14. Anderson Turnbull’s titration method
The dose is titration against uterine response 3 contractions of
moderate intensity each lasting 30 - 45 sec per 10 min
Thus reducing induction delivery interval.
In modern clinical practice oxytocin is administerd low dose
regimen used in multipara
High dose regimen used primipara according to ACOG
guidelines.

15. Oxytocin pharmacological doses :-
● It is given for prophylaxis And treatment of atonic PPH .
● 10 to 20 units per 500 ml Of RL .
● OXYTOCIN IN ESCALATING DOSES :-
● It is given by escalating drp method ( Andersons logarithmic
method of titration: start with a dose of 4 units in 500 ml of 5%RL
and double the dose with every pint I.e. 8-16-32 and so on up To
a maximum of 100 units. This is not used anymore.

16. Oxytocin Low dose
protocol
High dose
protocol
INITIAL DOSE 1 to 2 mU/min 4 to 6 mU /min
INCREASE INTERVAL 30 min 15 to 30 minutes
DOSE INCREMENT 1 to 2 mU/ min 4 to 6 mU/min
USUAL DOSE FOR
GOOD LABOR
8 to 12 mU/ min 8 to 12 mU/min
MAXIMUM DOSE 30mU/min 42mU/ min

17. ● Using this knowledge and the fact that 1 ml = 15 drops one can easily
calculate the drip rate required for any particular Oxytocin dose in
mU/min as shown in this table.
● In majority of cases good response is obtained with 16mU/min I.e a
rate of 60 drops.min when 2 units of oxytocin are added to 500 ml of
RL .
● Oxytocin dosage regimens for labor induction Using infusion pump.
● There are two different dosage regimes ( recommended by ACOG)
that are used used for labor induction: a low dose regimen for
primigravida.
● The accuracy and control of the infusion can be greatly improved by
an infusion pump ( e .g .Cardiff infusion system):

18. ● The dose can be increase from 1 mu to 42 mu /min .
● It is doubled every 12.5 min .
● Once adequate response is achieved further increase is
stopped. It may be reduced.
● This is because the dose required for initiating uterine
contractions is more than that required for maintaining
them.
● Hence once cervix is > 5 cm dilated , dose can be
decreased to 7 mu /min .
● In some pumps this is done automatically if the
intrauterine pressure transducer shows hyperactivity.

19. Dosage regimens in places where infusion pump is not
available (INDIA)
In primigravida:-Take 10 units of oxytocin in 500 ml of NS or
RL and start with rate of 30 drops per min. Increase the drip
rate by 10 drops per min every 30 minutes till patient gets 3
uterine contractions every 10 min that are moderate in
intensity and lasting > 40 sec . Maintain this rate till delivery
or till side effects occure . Maximum dose that can be given is
60 drops/min .

20. In multipara:-
● Take 2.5 units of oxytocin in 500 ml of NS or RL and start with rate of 10
drops per minute (2.5 miu/min).
● Increase the drip rate by 10 drops per minute every 30 minutes till till patient
gets 3 uterine contractions every 10 min that are moderate intensity and
lasting for > 40 sec
● Maximum drip rate can be given is 60 drops per min.
● If good contraction pattern not established with infusion rate of 60 drops per
min , increase oxytocin concentration to 5 units in 500 ml of DA/NS and
start from 30 drops per min I.e 15 miu/ ml and gradually increase at the rate
of 10 dpm every 30 min. Until good contractions established or maximum
Rate of 60 dpm is reached . If labor Is still not established it should be
considered as failure of labor induction and patient maybe take up for
cesarean delivery.

21. Stop the infusion if hyperstimulation of
Uterus (contractions >60 sec or tachy
systole(>4 contractions perm10 min
..occurs.

22. Monitoring of oxytocin:-
● Oxytocin infusion is a potentially dangerous drug and requires
the following facilities for its optimal use : an adequately
equipped delivery area with trained nursing staff ,
resuscitation equipment;availability of operating room Staff and
and facilitates where caesarean section can be performed
within 30 min.
● Contionus fetal heart rate Monitoring preferably electronic.

23. Monitoring of patient during IV infusion :
● Patient must be under constant supervision
● Patient must be monitored every 5 to 10 min for uterine contractions,
● FHR and any other complications:a records of These should be maintained
on a chart.
● The accuracy and Control of infusion can be greatly controlled by infusion
pump.
● The dose can be increased from 1 mU to 32 mU.
● It is doubled every 12.5 min
● Once adequate response achieved further increase stopped.
● In some pumps it is automatically done if intrauterine pressure transducer
shows hyperactivity.

24. ● Maximum oxytocin dosage; majority of patients respond to
32mU/ml or less.
● Although there is no upper limit to permitted dose,
● It is wise to consider prostaglandin stimulation If uterus is
still inert at 100mu/min.

25. ● Administration of oxytocin in non electrolyte solutions like
dextrose should be avoided.
● Because they are more likely to be associated with water
intoxication and hyponatremia, especially when given in
large doses.
● To prevent this , most labor ward protocols use electrolyte
infusion like normal saline ,ringer lactate or apartment s
solution.
● Recent studies shown that adding 5%dextrose to normal
saline hydrating solution during an oxytocin drip produces
significant reduction in labor duration.

26. ● Beazley and colleagues (1975) suggested
that the dose required for initiating uterine
contractions is more that required for
maintaining them.
● Hence once cervix Is > 5 cm dilated,dose can
be decreased to 7 mu/min.

27. Contraindications:-
● Grand multipara (risk of rupture) .
● Vaginal delivery not feasible ( obstructed labor)
● Previously scarred uterus relative contraindication:-
● Acute intrapartum fetal distress
● Cardiac patients IV fluids contraindicated
● Previously history of Anaphylaxis shock.

28. Caution :-
● Vertex not fixed in the pelvis
● Unfavorable or unripe cervix
● Breech presentation
● Hydroponics
● Multiple Pregnancy

29. Uses :-
● Induction of labor ( given in physiological doses)
● Uterine Inertia ( given in physiological doses)
● Oxytocin challenge test (physiological doses)
● Prophylaxis of atonic postpartum hemorrhage)
● Treatment of atonic postpartum hemorrhage: given
pharmacological doses of 10 to 20 units per 500ml of RL or
DW
● Evacuation of V.mole given in escalating doses 10 to 20 units
each pint , doubling the dose up to maximum 80 units.
● Treatment of breast engorgment.

30. Side effects :-
● Side effects are hyperstimulation,
● rupture of Uterus
● Amniotic fluid embolism
● Fetal distress
● Fluid retention if used in high doses
● Neonatal jaundice may occur in babies delivered
to mothers who were given >20 units of oxytocin
throughout their labor.

31. Thank you.