HYDRALAZINE HYDROCHLORIDE 20 mg/mL Injection, 1 mL — NDC 51662-1376-1 (Billing 51662-1376-01)

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. 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).

ADVERSE REACTIONS Adverse reactions with hydralazine hydrochloride are usually reversible when dosage is reduced. However, in some cases it may be necessary to discontinue the drug. The following adverse reactions have been observed, but there has not been enough systematic collection of data to support an estimate of their frequency.

Common: Headache, anorexia, nausea, vomiting, diarrhea, palpitations, tachycardia, angina pectoris. Less Frequent: Digestive-constipation, paralytic ileus. Cardiovascular - hypotension, paradoxical pressor response, edema.

Respiratory - dyspnea. Neurologic - peripheral neuritis, evidenced by paresthesia, numbness, and tingling; dizziness; tremors; muscle cramps, psychotic reactions characterized by depression, disorientation, or anxiety. Genitourinary - difficulty in urination.

Hematologic - blood dyscrasias, consisting of reduction in hemoglobin and red cell count, leukopenia, agranulocytosis, purpura; lymphadenopathy; splenomegaly. Hypersensitive Reactions - rash, urticaria, pruritis, fever, chills, arthralgia, eosinophilia, and, rarely, hepatitis. Other - nasal congestion, flushing, lacrimation, conjunctivitis.

PRECAUTIONS General Myocardial stimulation produced by hydralazine can cause anginal attacks and ECG changes of myocardial ischemia. 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.

The “hyperdynamic” circulation caused by hydralazine may accentuate specific cardiovascular inadequacies. For example, hydralazine may increase pulmonary artery pressure in patients with mitral valvular disease. The drug may reduce the pressor responses to epinephrine.

Postural hypotension may result from hydralazine but is less common than with ganglionic blocking agents. It should be used with caution in patients with cerebral vascular accidents. In hypertensive patients with normal kidneys who are treated with hydralazine, there is evidence of increased renal blood flow and a maintenance of glomerular filtration rate.

In some instances where control values were below normal, improved renal function has been noted after administration of hydralazine. However, as with any antihypertensive agent, hydralazine should be used with caution in patients with advanced renal damage. Peripheral neuritis, evidenced by paresthesia, numbness, and tingling, has been observed.

Publishing evidence suggests an antipyridoxine effect and that pyridoxine should be added to the regimen if symptoms develop. Laboratory Tests Complete blood counts and antinuclear antibody titer determinations are indicated before and periodically during prolonged therapy with hydralazine even though the patient is asymptomatic. These studies are also indicated if the patient develops arthralgia, fever, chest pain, continued malaise or other unexplained signs or symptoms.

A positive antinuclear antibody titer requires that the physician carefully weigh the implications of the test results against the benefits to be derived from antihypertensive therapy with hydralazine hydrochloride. Blood dyscrasias, consisting of reduction in hemoglobin and red cell count, leukopenia, agranulocytosis, and purpura, have been reported. If such abnormalities develop, therapy should be discontinued.

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 hydrochloride injection are used concomitantly.

Carcinogenesis, Mutagenesis, Impairment of Fertility In a lifetime study in Swiss albino mice, there was a statistically significant increase in the incidence of lung tumors (adenomas and adenocarcinomas) of both male and female mice given hydralazine continuously in their drinking water at a dosage of about 250 mg/kg per day (about 80 times the maximum recommended human dose). In a 2-year carcinogenicity study of rats given hydralazine by gavage at dose levels of 15, 30 and 60 mg/kg/day (approximately 5 to 20 times the recommended human daily dosage), microscopic examination of the liver revealed a small, but statistically significant increase in benign neoplastic nodules in male and female rats from the high-dose group and in female rats from the intermediate-dose group.

Benign interstitial cell tumors of the testes were also significantly increased in male rats from the high-dose group. The tumors observed are common in aged rats and a significantly increased incidence was not observed until 18 months of treatment. Hydralazine was shown to be mutagenic in bacterial systems (Gene Mutation and DNA Repair) and in one of two rats and one rabbit hepatocyte in vitro DNA repair studies.

Additional in vivo and in vitro studies using lymphoma cells, germinal cells and fibroblasts from mice, bone marrow cells from Chinese hamsters and fibroblasts from human cell lines did… [Excerpted — this section continues on DailyMed.]