Hydralazine Intravenous for Adults

Who can administer

Administration RESTRICTED - see Appendix 1

Available preparations

Hydralazine 20mg powder (ampoule)

Hydralazine 20mg per 1mL vial

Reconstitution

For ampoule containing dry powder

• Water for injection
• 1ml per 20mg ampoule
• Draw up using a 5 micron filter needle
• Dilute further prior to administration

For vials

• Dilute further prior to administration

Infusion fluids

Sodium chloride 0.9%

Methods of intravenous administration

Slow intravenous injection

• Further dilute the injection solution with Sodium chloride 0.9% (add 9ml to each 20mg = 2mg/ml solution)
• Administer required dose (see below) over 3 to 5 minutes ^{(ref 1)}

Continuous intravenous infusion

• Pre-eclampsia - add 40mg (2ml) to 38ml infusion fluid to produce a 1mg/1ml solution ^{(ref 1,2)}
• Adjust rate according to response - see under 'dose' opposite

Dose in adults

Usual dose (hypertension)

• Initial dose: 5 to 10mg as a slow intravenous injection
• If necessary, repeat after twenty to thirty minutes
• Can also be given by continuous intravenous infusion with an initial rate of 0.2 to 0.3mg/minute
• Usual dose range by continuous intravenous infusion is 0.05 to 0.15mg/minute
• Hypertensive emergency: Some sources suggest a dose of 10 to 20mg every four to six hours as needed ^{(ref 2)}
• Hypertensive emergency in pregnancy or postpartum: If systolic BP or diastolic BP remains above threshold after a total cumulative dose of 20 to 30 mg or if heart rate exceeds 100 beats per minute, another agent should be used ^{(ref 2)}

Renal or hepatic impairment

• Reduce dose if eGFR is less than 30ml/min/1.73m²- adjust dose according to clinical response
• In patients with hepatic dysfunction, the dose or interval between doses should be adjusted according to clinical response

Monitoring

• Monitor blood pressure, heart rate
• Monitor complete blood counts and ANA titre, before and periodically during prolonged hydralazine therapy, even in asymptomatic patients

Further information

• Slow acetylators, female patients and patients receiving more than 100mg per day (chronically) are at higher risk for SLE
• Incompatible with glucose solutions ^{(ref 1)}

Storage

Store below 25⁰C

References

SPC 10th March 2021

1:Injectable Medicines Administration Guide Medusa - downloaded 4th July 2023

2: Uptodate - downloaded 3rd July 2023

Therapeutic classification

Direct acting vasodilator antihypertensive