ADMINISTRATION ROUTES:
IV, PO
ALTERNATIVE NAMES:
Apresoline
ICU INDICATIONS:
- Afterload reduction by peripheral vasodilation
PRESENTATION AND ADMINISTRATION:
IV:
20 mg vial of powder
Reconstitute with 1 mL of water for injection
For direct injection, inject as either reconstituted solution or further dilute with a small volume of Normal saline. Give over 1-2 minutes
For IV infusion reconstitute 100 mg and add to 100 mL of compatible IV fluid
Compatible with the following IV fluids:
Normal saline, Hartmanns
Note: 5% dextrose should not be used as glucose rapidly causes hydralazine to be broken down.
Prepare solutions immediately before use and discard after 24 hours. Hydralazine undergoes colour changes in most infusion fluid, however, these changes generally do not indicate loss of potency
Store at room temperature
PO:
Rarely indicated in ICU
DOSAGE:
IV:
5 mg IV stat, then up to 20 mg/hr by infusion
DOSAGE IN RENAL FAILURE AND RENAL REPLACEMENT THERAPY:
Start with a small dose and adjust in accordance with response
DOSAGE IN PAEDIATRICS:
IV:
0.1 - 0.2 mg/kg stat, then 4 - 6 mcg/kg/min
CLINICAL PHARMACOLOGY:
Although the precise mechanism of action of hydralazine is not fully understood, the major effects are on the cardiovascular system. Hydralazine apparently lowers blood pressure by exerting a peripheral vasodilating effect through a direct relaxation of vascular smooth muscle
CONTRAINDICATIONS:
- Hypersensitivity to hydralazine
WARNINGS:
In a few patients hydralazine may produce a clinical picture simulating systemic lupus erythematosus including glomerulonephritis. In such patients hydralazine should be discontinued unless the benefit-to-risk determination requires continued antihypertensive therapy with this drug.
PRECAUTIONS:
General:
Myocardial stimulation produced by hydralazine can cause anginal attacks and ECG changes consistent myocardial ischaemia. The drug has been implicated in the production of myocardial infarction. It must, therefore, be used with caution in patients with suspected coronary artery disease.
Peripheral neuritis, evidenced by paraesthesia, numbness, and tingling, has been observed.
Laboratory Tests:
No tests in addition to routine ICU tests are required
Drug/Laboratory Test Interactions:
None known
IMPORTANT DRUG INTERACTIONS IN ICU:
Concomitant administration with other antihypertensives increases the risk of hypotension
ADVERSE REACTIONS:
Body as a Whole:
Rash, urticaria, pruritus, fever, chills
Cardiovascular System:
Hypotension, paradoxical pressor response, oedema, palpitations, tachycardia, angina pectoris
Respiratory System:
Dyspnoea
Gastrointestinal System:
Constipation, paralytic ileus, anorexia, vomiting, diarrhoea
Haematological System:
Blood dyscrasias (reduction in haemoglobin and red cell count, leukopaenia, agranulocytosis, purpura), lymphadenopathy, splenomegaly
Neurological System:
Headache, peripheral neuritis (paraesthesia, numbness, and tingling), dizziness, tremors, muscle cramps, psychotic reactions (characterised by depression, disorientation, or anxiety)