In clinical practice the following drugs are of importance:

1 -OXYTOCINE.2 -ERGOMETRINE.

3 -PROSTAGLANDINS .

OXYTOCIN (PITOCIN, SYNTOCINONE)It is an octapeptide hormone released from

the posterior lobe of the pituitry gland . It stimulate contraction of myometrium of pregnant uterus particularly at term. It also stimulate contraction of myoepithelial cells of breast particularly

after sucking and cause release of milk .

Clinical Uses:1 *Induction of labour.

2 *Augmentation of slow labour.3 *prevention and treatment of post partum

hemorrhage (combined with ergometrine).4 *Use as nasal spray to induce lactation.

5 *Treatment of abortion.

CONTRAINDICATION1- women of high parity(more than 5).

2 -mechanical obstruction to safe normal vaginal delivery such as contracted pelvis or abnormal fetus presentation.

3 -previous uterine scar such as caesarean section and myomectomy.

is an obstetric complication in which the placenta is inserted partially or wholly in lower uterine segment 4- (placenta previa).

ADMINSTRATION AND DOSAGE OF OXYTOCIN

It is given by i.v. infusion, but it is also given as

nasal spray but this route show irregular

absorption which lead to less contractility .

Dose of oxytocin is measured in units 500 USP (united states Pitocin) units = 1

mg So each unit = 2 µg. - Usually oxytocin preparations

(syntocinon, Pitocin) contain 10 units/ ml.

for induction of labour or to augment slow labour , the common method is to mix 2 units of oxytocin in 500 ml of 5%glucose water solution and start running this at 1 ml

(15 drop)/min.this gives approximate dose of 2-4 m unit

(milliunits) / min.

This dose is increased gradually at 15 min. interval according to strength and frequency of uterine contraction. This procedure can be done by manual control or infusion pump.

Unwanted effects of oxytocin: 1-dose –related hypotension (arising from

its vasodilator action ). 2-its antidiuretic hormone like action on

water excretion →water retention &hyponatraemia.

3-inappropriate use can lead to uterine rupture .

4-prolonged stimulation of uterus may cause fetal arrhythmias.

ERGOMETRINE (Ergonovine): It is one of ergot derivatives which act by stimulation of uterine activity. It differ from oxytocin by:

moderate dose of oxytocin cause generalized 1-

Moderate dose of oxytocin cause contractions of

uterus particularly of the fundus segment

followed by full relaxation in between

contractions . *.

While moderate doses of ergometrine cause contraction of uterus as a whole i.e. Fundus &cervix (tend to compress rather than to expel the fetus )with faster contraction (tetanic contraction ) i.e. no relaxation in between .

2*Oxytocin is given parenterally only while ergometrin is given parenteraly and orally

3* Duration of action of oxytocin is few seconds while

ergometrine reach one hour.

4* ergometrine causes vasoconstriction leading to increase blood pressure particularly in already hypertensive patient, patient with peripheral vascular disease and heart disease.

CLINICAL USES OF ERGOMETRINE

1 * Prophylaxis and treatment of post-partum hemorrhage, in normal labour and in caesarean section.

2 * Treatment of bleeding in abortion.3 * In puerperium if bleeding is heavy.

ADMINSTRATION AND DOSGE OF ERGOMETINE

1 *Orally : 0.5-1 mg, action begin after 8 min. and last for one hour.

2 *i.m. : 100-500 µg, action begins within 2-6 min. .

3 *i.v. : 250-500 µg, action begins within one min. .In the treatment of postpartum hemorrhage , 500 µg is given i.v. , if uterus is still flaccid with bleeding give another same dose (but must be the last dose). If bleeding continuous give oxytocin by i.v. infusion which give quick action but brief .

For this reason oxytocin is usually mixed with ergometrine in a preparation called syntometrine which contains :

ergometrine 500 µgoxytocin 5 i.u.

This preparation have the advantages of quik onset of action (due to oxytocin) and

prolonged effect (due to ergometrine).

Side effects of Ergometrine: 1- Vomiting 2- Vasoconstriction ,vasospasm even

of the coronary arteries resuling in angina, gangrene

3- Hypertension

Character Oxytocin Ergometrine

Contraction As

physiological

pattern

Tetanic

contraction

Uses As mentioned PPH.,mainly

Onset

&duration of

action

Rapid onset

Short duration

Moderate onset

Long duration

PROSTAGLANDINSa) PGE2

b) PGF2ά

They are modified fatty acids results from enzymatic synthesis from arachidonic acid. It has been suggested that it may play physiological rule during labour:

1- Induction of labour when there are fetal or maternal contraindication to oxytocin.

2- In case of fetal death in the uterus.

-When vaginal delivery is desired for safety of mother or child in cases such as Rh. incompatibility or maternal diabetes mellitus.

They are modified fatty acids results from enzymatic synthesis from arachidonic acid. It has been suggested that it may play physiological rule during labour:

1- Induction of labour when there are fetal or maternal contraindication to oxytocin.

2- In case of fetal death in the uterus. 3-When vaginal delivery is desired for

safety of mother or child in cases such as Rh. incompatibility or maternal diabetes mellitus.

ADMINISTRATION AND DOSAGE OF PGsPGF2 available in 5 mg /ml sterile solution called

Dinaprest. They are given i.v. , extra –amniotically, intra-amniotically, vaginal gel or vaginal pessary.

1-I.V. ROUTE.:a- 5 mg / ml of PGF2α is used for induction of

labour when PG is not contra indicated as in asthma . For I V drips, Add 1 ml from ampoule to 1000 ml or 0.5 ml to 500 ml of sterile normal saline or 5 % glucose water, start with 2.5 µg / minute, maintained at least 30 minutes, if good contraction obtained, maintain the rate. If contraction is weak increase the dose to 5 µg / min.

b- b- In therapeutic termination of pregnancy, missed abortion or vesicular mole. The dose is 50 µg / ml solution.

2- EXTRA-AMNIOTIC Take 1 ml of PGF2, add it to 19 ml

normal saline or 5% glucose water to get 20 ml diluted solution containing 250 µg/ml. Insert Foley catheter (self retaining) through cervix into space between fetal membrane and uterine wall. PGF2 solution is inserted through the catheter with initial dose 1 ml then 3 ml every 2 hour.

3 -INTRAAMNIOTIC

It is use for therapeutic termination of pregnancy in a dose of 5 mg/ml solution

used from ampule without dilution .Transabdominal tap of amniotic sac with drawn at least one ml of amniotic fluid, then 40 mg (8 ml) of PGF2 slowly injected

in the amniotic sac .