Description and indication for use

Alprostadil is a synthetic prostaglandin used to relax the ductus arteriosus in early post-natal life, where a patent ductus is critical for survival, including Tetralogy of Fallot, pulmonary atresia, pulmonary stenosis, tricuspid atresia and transposition of the great arteries. 

Alprostadil can preserve ductal patency if administered before anatomical closure occurs.  Over time, the ductus arteriosus rapidly loses its responsiveness to alprostadil, and consequently it is most effective when commenced within 96 hours of birth.  Therefore, it is used as palliative therapy until surgery can be performed.

Alprostadil also causes vasodilation of all arterioles and inhibition of platelet aggregation.

Dose

To open a closed ductus arteriosus:

0.1 micrograms/kg/minute (100 nanograms/kg/min).  An effect is usually seen within 30-60 minutes. Reduce the dose once an effect is seen or as directed by a Consultant.¹

Doses > 0.1 micrograms/kg/minute are rarely more effective and may cause serious adverse effects.³

To maintain patency of ductus arteriosus:

0.01 to 0.02 micrograms/kg/minute (10-20 nanograms/kg/min).^{1, 2}

For persistent pulmonary hypertension of the newborn (PPHN):

0.01 to 0.05 micrograms/kg/minute (10-50 nanograms/kg/min).²

Note:  

Doses of up to 100 nanograms/kg/min have been used for PDA patency.

Doses between 50 and 100 nanograms/kg/min should be weaned and maintained at 5-10 nanogram/kg/min after response is achieved.

Maximum dose should be no greater than 100 nanograms/kg/min.

Reconstitution/Dilution

Ampoule = 500 microgram in 1 mL (Stored in refrigerator).

Note: (1000 nanograms = 1 microgram).

Use only sodium chloride 0.9% or glucose 5% as infusion fluids.⁴

For maintenance infusion:

Withdraw required amount of Alprostadil and make up to ordered volume with infusion fluid.

If dose ordered is not measurable at 500 micrograms/mL, a dilution can be made.

For example: a 1 in 10 dilution: take 1 mL of 500 micrograms/mL solution and add to 9 mL of sodium chloride 0.9% = 50 micrograms/mL.  Withdraw required dose and make up infusion as ordered.

Usual order will be as follows:

Ref: RWH: Continuous IV Infusion Chart

For opening a closed ductus arteriosus:

Prepare maintenance infusion as above and give 2.5 mL over 30 minutes (5 mL/hr) to give 100 nanograms/kg/min (set volume limit).

Prepare fresh infusion solutions every 24 hours.  Discard any solution more than 24 hours old.

Route and method of administration

IV Infusion: Given as a continuous infusion via an infusion syringe pump.

IV route is preferred, although infusions via a UAC placed at the ductal opening have been used.³

2 points of IV access preferred.

Side effects

Apnoea - usually occurs in neonates under 2 kg within the first hour of administration.³

Fever.

Cutaneous flushing - secondary to vasodilatation.

Bradycardia, hypotension, oedema.

Seizures.

Decreased platelet aggregation, thrombocytopenia.

Special precautions

Caution in patients with bleeding tendencies and seizure disorders.

Contraindications

On balance it is appropriate to use in sick patients with suspected but undiagnosed congenital heart disease even if total anomalous pulmonary venous return with obstruction has not been ruled out.

Incompatibilities

Decomposes rapidly in acidic solutions. As a general rule administer on its own although in an emergency it can be run with other fluids provided it is added close to the patient end of the infusion line.

Nursing responsibilities

Monitor with cardiorespiratory monitor and oxygen saturation monitor.

Monitor blood pressure, preferably with an arterial line.

Monitor temperature.

Ensure resuscitation/intubation equipment available.

Do not mix with any other medications or infusions in same line.

Do Not Bolus Other Drugs via Prostaglandin Infusion.

Observe IV site carefully.

Maintain patent IV at all times.

Change IV syringe every 24 hours.  When changing syringe, ensure line is clamped to prevent administering a bolus. Ensure line is unclamped after lines changed.

Check that rate ordered corresponds with dose required (nanograms/kg/min).

References

1.             RWH Neonatal Pharmacopoeia, 2nd ed. 2005.

2.             RCH Paediatric Pharmacopoeia, 13th ed. 2002.

3.             Prostin VR Product Information, Pfizer Australia Pty Ltd, 13/09/2005.

4.             Lawrence Trissel, Handbook on Injecable Drugs, 17th ed. 2013.