are the drugs of varying
chemical nature that have the
power to excite contraction of
the uterine muscles.”
Synthetic Oxytocin (Ptocin) 5 IU/ ml amp
Syntometrine 5 U Oxytocin + 0.5 mg
Desaminooxytocin buccal tablets 50 IU
Oxytocin nasal spray 40 IU/ ml
Oxitocin is the primary mediator of myometrial
contractility during labor.
During the second half of pregnancy, uterine
smooth muscle shows an increase in the expression
of oxytocin receptors(100-200fold) and becomes
increasingly sensitive to the stimulant action of
Stimulates PG synthesis.
Physiological uterine contraction - fundal
contraction; cervical relaxation. (law of polarity
Cervical and vaginal dilatation results in an acute
release of oxytocin from the posterior pituitary in a
process known as the Ferguson reflex.
In small doses Oxytocin produces
vasodialation by direct relaxation of the
vascular smooth muscles
Transient hypotension & flushing followed by
tachycardia are observed
In high concentration Oxytocin has weak
antidiuretic & pressor activity due to
activation of vasopressin receptors
ABSORPTION, METABOLISM, AND EXCRETION
Intravenously (controlled infusion) for initiation and
augmentation of labor.
intramuscularly -control of postpartum bleeding.
Buccal & nasal spray- Limited use.
Oxytocin is not bound to plasma proteins and is
eliminated by the kidneys and liver.
Circulating half-life of max. 5 minutes. (avg 3-4min)
as plasma, utrine & placenta of pregnant women
contain enzyme oxytocinase
Circulating half life is 10 to 15 mins in non pregnant
IV controlled infusion for initiation &
augmentation of labour , abortions
IM for Post partum haemorrage
Buccal , Nasal spray for lactation
To avoid hypotension, oxytocin is
administered intravenously as
dilute solutions at a controlled
PREGNANCY LABOUR PUERPERIUM
-To stop bleeding.
To induce labour.
of 3rd stage
Contraction stress test (CST)
Oxytocin sensitivity test (OST)
For induction of labour
Start with LOW DOSE, escalate to achieve optimal
(3contraction in 10min each lasting 45sec)
Maintain the dose- oxytocin titration technique.
OBJECTIVE- Maintain normal pattern of uterine
activity till delivery and 30-60min beyond that.
Start with 4mU/min & ↑every 20min
Semi-Fowlers position - avoid venecaval
Calculation of dose delivered in milliunits(mU) &
its correlation with drop rate per minute
Units of oxytocin mixed in
500ml Ringer solution
Drops per minute
15 30 60
In terms of mU/min
2 4 8
4 8 16
10 20 40
NOTE: In majority of cases, max. response is seen with 16 mU/min
i.e 2U in 500ml RL at 60 drops per min
OBSERVATION DURING OXYTOCIN
RATE of flow – calculating drops/min
Uterine contraction - Finger tip palpation
Intra uterine pressure:-peak 50to60mmHg resting
Assessment of progress of labour - descent of
presenting part & dialatation of cervix
Indications for stopping the oxytocin
Nature of uterine contractions-
abnormal uterine contractions occurring
frequently (every 2 min or less )
lasting more than 60sec(hyperstimulation)
↑tonus in between contractions
Hyper stimulation is treated with 0.25 mg