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.
Symptoms and signs usually regress when the drug is discontinued but residua have been detected many years later.
Long-term treatment with steroids may be necessary.
(See PRECAUTIONS , Laboratory Tests .)
Drug Interactions MAO inhibitors should be used with caution in patients receiving hydralazine.
When other potent parenteral antihypertensive drugs, such as diazoxide, are used in combination with hydralazine, patients should be continuously observed for several hours for any excessive fall in blood pressure.
Profound hypotensive episodes may occur when diazoxide injection and hydralazine are used concomitantly.
Acute Toxicity: No deaths due to acute poisoning have been reported.
Highest known dose survived: adults, 10 g orally.
Oral LD 50 in rats: 173 and 187 mg/kg.
Signs and Symptoms: Signs and symptoms of overdosage include hypotension, tachycardia, headache, and generalized skin flushing.
Complications can include myocardial ischemia and subsequent myocardial infarction, cardiac arrhythmia, and profound shock.
Treatment: There is no specific antidote.
The gastric contents should be evacuated, taking adequate precautions against aspiration and for protection of the airway.
An activated charcoal slurry may be instilled if conditions permit.
These manipulations may have to be omitted or carried out after cardiovascular status has been stabilized, since they might precipitate cardiac arrhythmias or increase the depth of shock.
Support of the cardiovascular system is of primary importance.
Shock should be treated with plasma expanders.
If possible, vasopressors should not be given, but if a vasopressor is required, care should be taken not to precipitate or aggravate cardiac arrhythmia.
Tachycardia responds to beta blockers.
Digitalization may be necessary, and renal function should be monitored and supported as required.
No experience has been reported with extracorporeal or peritoneal dialysis.
Hydralazine hydrochloride USP, is an antihypertensive, for oral administration.
Its chemical name is 1-hydrazinophthalazine monohydrochloride, and its structural formula is: C 8 H 8 N 4 • HCl M.W.
196.64 Hydralazine hydrochloride USP is a white to off-white, odorless crystalline powder.
It is soluble in water, slightly soluble in alcohol, and very slightly soluble in ether.
It melts at about 275°C, with decomposition, and has a molecular weight of 196.64.
Hydralazine HCl Tablets are available in 10, 25, 50 and 100 mg strengths.
Each tablet contains the following inactive ingredients: lactose, magnesium stearate, microcrystalline cellulose, sodium starch glycolate and stearic acid.
In addition, the 10 mg tablet contains FD&C Red #40.
The 25 mg, 50 mg and 100 mg tablets contain FD&C Yellow #6.
this is the structure
10 mg – round, light pink colored, unscored tablets, debossed “Par 029” on one side are available in bottles of 100 (NDC #49884-029-01) and 1000 (NDC #49884-029-10).
25 mg – round, peach colored, unscored tablets, debossed “Par 027” on one side are available in bottles of 100 (NDC #49884-027-01) and 1000 (NDC #49884-027-10).
50 mg – round, peach colored, unscored tablets, debossed “Par 028” on one side are available in bottles of 100 (NDC #49884-028-01) and 1000 (NDC #49884-028-10).
100 mg – round, peach colored, unscored tablets, debossed “Par 121” on one side are available in bottles of 100 (NDC #49884-121-01) and 1000 (NDC #49884-121-10).
Store at controlled room temperature 15°-30°C (59°-86°F) [see USP].
Distributed by: Par Pharmaceutical Companies, Inc.
Spring Valley, NY 10977 Made in India by: Par Formulations Private Limited 1/58, Pudupakkam Kelambakkam-603 103 Mfg.
No.: TN00002121 Revised: 11/2014
INDICATIONS AND USAGE
Essential hypertension, alone or as an adjunct.
Pediatric Use Safety and effectiveness in children have not been established in controlled clinical trials, although there is experience with the use of hydralazine in children.
The usual recommended oral starting dosage is 0.75 mg/kg of body weight daily in four divided doses.
Dosage may be increased gradually over the next 3-4 weeks to a maximum of 7.5 mg/kg or 200 mg daily.
Nursing Mothers Hydralazine has been shown to be excreted in breast milk.
INFORMATION FOR PATIENTS
Information for Patients Patients should be informed of possible side effects and advised to take the medication regularly and continuously as directed.
DOSAGE AND ADMINISTRATION
Initiate therapy in gradually increasing dosages; adjust according to individual response.
Start with 10 mg four times daily for the first 2-4 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.