Apresoline - General Information
A direct-acting vasodilator that is used as an antihypertensive agent.
Pharmacology of Apresoline
A vasodilator, hydralazine works by relaxing blood vessels (arterioles more than venules) and increasing the supply of blood and oxygen to the heart while reducing its workload. It also functions as an antioxidant. It inhibits membrane-bound enzymes that form reactive oxygen species, such as superoxides. Excessive superoxide counteracts NO-induced vasodilation. It is commonly used in the condition of pregnancy called preeclampsia.
Apresoline for patients
Patients should be informed of possible side effects and advised to take the medication regularly and continuously as directed. Report flu-like symptoms, rise slowly from sitting/lying position; take with meals.
MAO inhibitors should be used with caution in patients receiving hydralazine.
When other potent parental 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 infection and hydralazine are used concomitantly.
Beta-blockers (metoprolol, propranolol) serum concentrations and pharmacologic effects may be increased. Monitor cardiovascular status.
Propranolol increases hydralazine's serum concentrations. Acebutolol, atenolol, and nadolol (low hepatic clearance or no first-pass metabolism) are unlikely to be affected.
NSAIDs may decrease the hemodynamic effects of hydralazine; avoid use if possible or closely monitor cardiovascular status at the end of drug interactions
Hypersensitivity to hydralazine; coronary artery disease; mitral valvular rheumatic heart disease.
Additional information about Apresoline
Apresoline Indication: For the treatment of essential hypertension, alone or as an adjunct. Also for the management of moderate to severe hypertension, congestive heart failure, and hypertension secondary to pre-eclampsia/eclampsia.
Mechanism Of Action: Although the precise mechanism of action of hydralazine is not fully understood, the major effects are on the cardiovascular system. Apresoline apparently lowers blood pressure by exerting a peripheral vasodilating effect through a direct relaxation of vascular smooth muscle. Apresoline, 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.
Drug Interactions: Not Available
Food Interactions: Not Available
Generic Name: Hydralazine
Synonyms: Hydralazine hydrochloride
Drug Category: Antihypertensive Agents; Vasodilator Agents
Drug Type: Small Molecule; Approved
Other Brand Names containing Hydralazine: Apresoline;
Absorption: Hydralazine is rapidly and extensively absorbed (up to 90%) from the gastrointestinal tract and undergoes extensive first-pass metabolism by genetic polymorphic acetylation. Oral bioavailability of hydralazine is dependent upon acetylator phenotype. Bioavailability is approximately 31% in slow acetylators and 10% in fast acetylators.
Toxicity (Overdose): Oral LD50 in rats: 173 and 187 mg/kg
Protein Binding: 87%
Biotransformation: Hydralazine, when administered orally, undergoes extensive first-pass metabolism by genetic polymorphic acetylation, which is responsible for a threefold range of oral bioavailability. Intravenously administered hydralazine does not undergo first-pass metabolism and, therefore, is not affected by acetylator phenotype. After the drug reaches the systemic circulation, it is combined with endogenous aldehydes and ketones, including pyruvic acid, to form hydrazone metabolites. The active metabolites, hydralazine acetonide hydrazone and hydralazine pyruvate hydrazone, are equipotent with the parent, hydralazine.
Half Life: 3 to 7 hours
Dosage Forms of Apresoline: Powder, for solution Intravenous
Chemical IUPAC Name: phthalazin-1-ylhydrazine
Chemical Formula: C8H8N4
Hydralazine on Wikipedia: http://en.wikipedia.org/wiki/Hydralazine
Organisms Affected: Humans and other mammals