hydralazine hydrochloride 50 MG Oral Tablet

INDICATIONS AND USAGE: Severe essential hypertension when the drug cannot be given orally or when there is an urgent need to lower blood pressure.

DOSAGE AND ADMINISTRATION: 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.

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 . )

CONTRAINDICATIONS: Hypersensitivity to hydralazine, coronary artery disease, mitral valvular rheumatic heart disease.

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. The preferential dilatation of arterioles, as compared to veins, minimizes postural hypotension and promotes the increase in cardiac output. HydrALAZINE usually increases renin activity in plasma, presumably as a result of increased secretion of renin by the renal juxtaglomerular cells in response to reflex sympathetic discharge. This increase in renin activity leads to the production of angiotensin II, which then causes stimulation of aldosterone and consequent sodium reabsorption. HydrALAZINE also maintains or increases renal and cerebral blood flow. HydrALAZINE hydrochloride is rapidly absorbed after oral administration, and peak plasma levels are reached at 1 to 2 hours. Plasma levels of apparent hydrALAZINE decline with a half-life of 3 to 7 hours. Binding to human plasma protein is 87%. Plasma levels of hydrALAZINE vary widely among individuals. HydrALAZINE is subject to polymorphic acetylation; slow acetylators generally have higher plasma levels of hydrALAZINE and require lower doses to maintain control of blood pressure. HydrALAZINE undergoes extensive hepatic metabolism; it is excreted mainly in the form of metabolites in the urine.