OXYTOCIN

Posology Induction or enhancement of labour:

Oxytocin should not be started for 6 hours following administration of vaginal prostaglandins. ) drip infusion or, preferably, by means of a variable-speed infusion pump. 9 %). 4). To ensure even mixing, the bottle or bag must be turned upside down several times before use.

The initial infusion rate should be set at 2 to 8 drops/minute (1 to 4 milliunits/minute). It may be gradually increased at intervals not shorter than 20 minutes and increments of not more than 1 to 2 milliunits/minute, until a contraction pattern similar to that of normal labour is established.

In pregnancy near term this can often be achieved with an infusion of less than 20 drops/minute (10 milliunits/minute), and the recommended maximum rate is 40 drops/minute (20 milliunits/minute). 7 micrograms) in 500 ml. When using a motor-driven infusion pump which delivers smaller volumes than those given by drip infusion, the concentration suitable for infusion within the recommended dosage range must be calculated according to the specifications of the pump.

The frequency, strength, and duration of contractions as well as the foetal heart rate must be carefully monitored throughout the infusion. Once an adequate level of uterine activity is attained, aiming for 3 to 4 contractions every 10 minutes, the infusion rate can often be reduced.

In the event of uterine hyperactivity and/or foetal distress, the infusion must be discontinued immediately. 3). In women given oxytocin for induction or enhancement of labour, the infusion should be continued at an increased rate during the third stage of labour and for the next few hours thereafter.

v. v. v. infusion at a rate of 20 to 40 milliunits/minute. v. v. drip infusion or, preferably, by means of a variable-speed infusion pump over 5 minutes) immediately after delivery. v. v. drip infusion or, preferably, by means of a variable-speed infusion pump over 5 minutes) after delivery of the placenta.

v. v. v. 4 micrograms) of oxytocin in 500 ml of an electrolyte-containing diluent, run at the rate necessary to control uterine atony. Special populations Renal impairment No studies have been performed in renally impaired patients. Hepatic impairment No studies have been performed in hepatically impaired patients.

As there is a wide variation in uterine sensitivity, uterine spasm may be caused in some instances by what are normally considered to be low doses. v. infusion for the induction or enhancement of labour, administration at too high doses results in uterine overstimulation which may cause foetal distress, asphyxia, and death, or may lead to hypertonicity, tetanic contractions, soft tissue damage or rupture of the uterus.

v. 4). These rapid haemodynamic changes may result in myocardial ischaemia, particularly in patients with pre-existing cardiovascular disease. v. bolus injection of oxytocin at doses amounting to several IU may also lead to QTc prolongation.

4). 4). v. 4). Symptoms of water intoxication include: 1. Headache, anorexia, nausea, vomiting and abdominal pain. 2. Lethargy, drowsiness, unconsciousness and grand-mal type seizures. 3. Low blood electrolyte concentration. Undesirable effects (Tables 1 and 2) are ranked under heading of frequency, the most frequent first, using the following convention: very common (≥1/10); common (≥1/100 to <1/10); uncommon (≥1/1,000 to <1/100); rare (≥1/10,000 to <1/1,000); very rare (<1/10,000), including isolated reports; not known (cannot be estimated from the available data).

The adverse reactions (ADRs) tabulated below are based on clinical trial results as well as post-marketing reports. The adverse drug reactions derived from post-marketing experience with oxytocin are via spontaneous case reports and literature cases.

Because these reactions are reported voluntarily from a population of uncertain size, it is not possible to reliably estimate their frequency which is therefore categorised as not known. Adverse drug reactions are listed according to system organ classes in MedDRA.

Within each system organ class, ADRs are presented in order of decreasing seriousness. Table 1 Adverse drug reactions in mother System organ class Adverse drug reaction Immune system disorders Rare: Anaphylactoid reaction associated with dyspnoea, hypotension or shock Nervous system disorders Common: Headache Cardiac disorders Common: Tachycardia, bradycardia Uncommon: Arrhythmia Not known: Myocardial ischaemia, Electrocardiogram QTc prolongation Vascular disorders Not known: Hypotension, haemorrhage Gastrointestinal disorders Common: Nausea, vomiting Skin and subcutaneous tissue disorders Rare: Rash Not Known: Angioedema Pregnancy, puerperium and perinatal conditions Not known: Uterine hypertonicity, tetanic contractions, rupture of the uterus Metabolism and nutrition disorders Not known: Water intoxication, maternal hyponatraemia Respiratory, thoracic and mediastinal disorders Not known: Acute pulmonary oedema General disorders and administration site conditions Not known: Flushing Blood and lymphatic system disorders Not known: Disseminated intravascular coagulation Table 2 Adverse drug reactions in foetus/neonate System organ class Adverse drug reaction Pregnancy, puerperium and perinatal conditions Not known: Foetal distress, asphyxia and death Metabolism and nutrition disorders Not known: Neonatal hyponatraemia Reporting of suspected adverse reactions Reporting suspected adverse reactions after authorisation of the medicinal product is important.

v. v. bolus injection as it may cause an acute short-lasting hypotension accompanied with flushing and reflex tachycardia. Induction of labour The induction of labour by means of oxytocin should be attempted only when strictly indicated for medical reasons.

Administration should only be under hospital conditions and qualified medical supervision. Cardiovascular disorders Oxytocin should be used with caution in patients who have a pre-disposition to myocardial ischaemia due to pre-existing cardiovascular disease (such as hypertrophic cardiomyopathy, valvular heart disease and/or ischaemic heart disease including coronary artery vasospasm), to avoid significant changes in blood pressure and heart rate in these patients.

5).

When Oxytocin is given for induction and enhancement of labour:

Foetal distress and foetal death: Administration of oxytocin at excessive doses results in uterine overstimulation which may cause foetal distress, asphyxia and death, or may lead to hypertonicity, tetanic contractions or rupture of the uterus.

Careful monitoring of foetal heart rate and uterine motility (frequency, strength, and duration of contractions) is essential, so that the dosage may be adjusted to individual response. Particular caution is required in the presence of borderline cephalopelvic disproportion, secondary uterine inertia, mild or moderate degrees of pregnancyinduced hypertension or cardiac disease, and in patients above 35 years of age or with a history of lower-uterine-segment caesarean section.

Disseminated intravascular coagulation:

In rare circumstances, the pharmacological induction of labour using uterotonic agents, including oxytocin increases the risk of postpartum disseminated intravascular coagulation (DIC). The pharmacological induction itself and not a particular agent is linked to such risk.

1. – Hypertonic uterine contractions, mechanical obstruction to delivery, foetal distress. : – Significant cephalopelvic disproportion – Foetal malpresentation – Placenta praevia and vasa praevia – Placental abruption – Cord presentation or prolapse – Overdistension or impaired resistance of the uterus to rupture as in multiple pregnancy – Polyhydramnios – Grand multiparity – In the presence of a uterine scar resulting from major surgery including classical caesarean section.

Oxytocin should not be used for prolonged periods in patients with oxytocin-resistant uterine inertia, severe pre-eclamptic toxaemia or severe cardiovascular disorders. 5).