Oxytocin

Generic Name:Oxytocin
Brand Name: Pitocin, Syntocinon
Classification: Uterine-active agents

Availability  
5 units;10 units/mL injection in 1ml ampule,vial or syringe in compatible IV solution.

Action

• As for endogenous oxytocin,but with little vasopressin activity
• Stimulates uterine contraction
• Stimulates lactating breast to eject milk

Therapeutic effects
By direct action on myofibrils, produces phasic contractions characteristic of normal delivery. Promotes milk ejection (letdown) reflex in nursing mother, thereby increasing flow (not volume) of milk; also facilitates flow of milk during period of breast engorgement. Uterine sensitivity to oxytocin increases during gestation period and peaks sharply before parturition. Not used for elective induction of labor.

Use
Induction and maintenance of labour
Controlling postpartum bleeding ang uterine hypotonicity in the third stage of labour

Dose
(Induction of labour) initially 1-4 mU/minute= 2-8 drops/minute by IV infusion,increasing at intervals of at least 20 minutes(to a maximum of 20 mU/minutes) until constractions are similar to normal labour OR
(Management of third stage of labour or postpartum haemorrhage) 5-10 IU IM or 5 IU slowly IV OR
Contraindication
Hypersensitive to drug when vaginal delivery is advised
Cephalopelvic disproportion is present
When delivery requires conversion as in tranverse lie

Adverse Effects
CV:Hypertention,increase heart rate,systemic venous returns,cardiac output
GI:Nausea and Vomiting
Repiratory:Anoxia,Asphyxia
Others:Low APGAR score at 5 mins.

Nursing implications 

Assessment & Drug Effects

• Start flow charts to record maternal BP and other vital signs, I&O ratio, weight, strength, duration, and frequency of contractions, as well as fetal heart tone and rate, before instituting treatment.
• Monitor fetal heart rate and maternal BP and pulse at least q15min during infusion period; evaluate tonus of myometrium during and between contractions and record on flow chart. Report change in rate and rhythm immediately.Stop infusion to prevent fetal anoxia, turn patient on her side, and notify physician if contractions are prolonged (occurring at less than 2-min intervals) and if monitor records contractions about 50 mm Hg or if contractions last 90 seconds or longer. Stimulation will wane rapidly within 2–3 min. Oxygen administration may be necessary.
• If local or regional (caudal, spinal) anesthesia is being given to the patient receiving oxytocin, be alert to the possibility of hypertensive crisis (sudden intense occipital headache, palpitation, marked hypertension, stiff neck, nausea, vomiting, sweating, fever, photophobia, dilated pupils, bradycardia or tachycardia, constricting chest pain).
• Monitor I&O during labor. If patient is receiving drug by prolonged IV infusion, watch for symptoms of water intoxication (drowsiness, listlessness, headache, confusion, anuria, weight gain). Report changes in alertness and orientation and changes in I&O ratio (i.e., marked decrease in output with excessive intake).
• Check fundus frequently during the first few postpartum hours and several times daily thereafter.
• Incidence of hypersensitivity or allergic reactions is higher when oxytocin is given by IM or IV injection rather than by IV infusion (diluted solution).
• Patient & Family Education.

Patient & Family Education

• Be aware of purpose and anticipated effect of oxytocin.
• Report sudden, severe headache immediately to healthcare providers.