Overview
DESCRIPTION HydrALAZINE hydrochloride, USP, is an antihypertensive, for oral administration. Its chemical name is 1-hydrazinophthalazine monohydrochloride, and its structural formula is: 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.
Mechanism of Action
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. HydrALAZINE, by altering cellular calcium metabolism, interferes with the calcium movements within the vascular smooth muscle that are responsible for initiating or maintaining the contractile state. The peripheral vasodilating effect of hydrALAZINE results in decreased arterial blood pressure (diastolic more than systolic); decreased peripheral vascular resistance; and an increased heart rate, stroke volume, and cardiac output.
Indications
- INDICATIONS AND USAGE Essential hypertension, alone or as an adjunct.
Common Doses
- 10 mg
- 25 mg
- 50 mg
- 300 mg
Dosage
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 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.
Contraindications
- CONTRAINDICATIONS Hypersensitivity to hydrALAZINE; coronary artery disease; mitral valvular rheumatic heart disease.
Side Effects
- ADVERSE REACTIONS 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.
Interactions
- No major interactions listed on the FDA label. Always consult a healthcare professional.