When there is urgent need, therapy in the hospitalized patient may be initiated
intramuscularly or as a rapid intravenous bolus injection directly into the
vein. Hydralazine Hydrochloride Injection should be used only when the drug
cannot be given orally. The usual dose is 20 to 40 mg, repeated as necessary.
Certain patients (especially those with marked renal damage) may require a lower
dose. Blood pressure should be checked frequently. It may begin to fall within a
few minutes after injection, with the average maximal decrease occurring in 10
to 80 minutes. In cases where there has been increased intracranial pressure,
lowering the blood pressure may increase cerebral ischemia. Most patients can be
transferred to oral hydralazine hydrochloride within 24 to 48 hours.
The product should be used immediately after the vial is opened. The product
should not be added to infusion solutions. Hydralazine Hydrochloride Injection
may discolor upon contact with metal; discolored solutions should be discarded.
Parenteral drug products should be inspected visually for particulate matter and
discoloration prior to administration, whenever solution and container permit.
Initiate therapy in gradually increasing dosages; adjust according to individual
response. Start with 10 mg four times daily for the first 2 to 4 days, increase
to 25 mg four times daily for the balance of the first week. For the second and
subsequent weeks, increase dosage to 50 mg four times daily. For maintenance,
adjust dosage to the lowest effective levels.
The incidence of toxic reactions, particularly the L.E. cell syndrome, is high
in the group of patients receiving large doses of hydralazine.
In a few resistant patients, up to 300 mg of hydralazine daily may be required
for a significant antihypertensive effect. In such cases, a lower dosage of
hydralazine combined with a thiazide and/or reserpine or a beta blocker may be
considered. However, when combining therapy, individual titration is essential
to ensure the lowest possible therapeutic dose of each drug.
HTN: Initially 10 mg qid - increase by 10-25 mg/dose q 2-5 days (maximum: 300
mg/day). Acute hypertension: Initially 10-20 mg IM/IV q 4-6 hours prn. May
increase to 40 mg/dose (change to oral therapy as soon as possible).
CHF: Initially 10 to 25mg orally 3-4 times/day. Maintenance: Typically 200 to
600 mg daily in 2-4 divided doses.
[>50 ml/min]: No changes
[10-50]: Give usual dose q8h or less.
[<10 ]: Give q8-16 hours in fast acetylators and q12-24 hours in slow
Give q8 to 16 hours in fast acetylators and q 12-24 hours in slow
National Institutes of Health, U.S. National Library of Medicine,
DailyMed Database. Provides access to the latest drug monographs submitted to the
Food and Drug Administration (FDA). Please review the latest applicable package insert for
additional information and possible updates. A local search
option of this data can be found here.
The authors make no claims of the accuracy of the information contained herein; and these suggested doses are not a substitute for clinical
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