Hydralazine Drug Information

Essential hypertension, alone or as an adjunct.

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 hydrochloride tablets. In a few resistant patients, up to 300 mg of hydrALAZINE hydrochloride tablets daily may be required for a significant antihypertensive effect.

In such cases, a lower dosage of hydrALAZINE hydrochloride tablets 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.

Adverse reactions with hydrALAZINE 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, pruritus, fever, chills, arthralgia, eosinophilia, and rarely, hepatitis. Other: nasal congestion, flushing, lacrimation, conjunctivitis.

Hypersensitivity to hydrALAZINE; coronary artery disease; mitral valvular rheumatic heart disease.

• 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.