drugs that is known to induce systemic lupus and this adverse drug event is dose dependent yet significant. Very common (>10% frequency) side effects include headache, tachycardia, and palpitations. Common (1–10% frequency) side effects include flushing, hypotension, anginal symptoms, aching or swelling joints, muscle aches, positive tests for atrial natriuretic peptide, stomach upset, diarrhea, nausea and vomiting, and swelling (sodium and water retention). Interactions It may potentiate the antihypertensive effects of: Vasodilators Calcium antagonists ACE inhibitors Diuretics Antihypertensives Tricyclic antidepressants Major tranquillisers Ethanol (alcohol) Diazoxide Drugs subject to a strong first-pass effect such as beta blockers may increase the bioavailability of hydralazine. Epinephrine (adrenaline), by its heart rate-accelerating effects as increased by hydralazine, may lead to toxicity. Mechanism of action Hydralazine is a drug that conducts the blood pressure lowering effects by vasoconstrictive repression. It is a direct-acting smooth muscle relaxant and acts as a vasodilator primarily in resistance arterioles, also known as the smooth muscle of the arterial bed. The molecular mechanism involves inhibition of inositol trisphosphate-induced Ca2+ release from the sarcoplasmic reticulum in arterial smooth muscle cells. By relaxing vascular smooth muscle, vasodilators act to decrease peripheral resistance, thereby lowering blood pressure and decreasing afterload. Chemistry Hydralazine belongs to the hydrazinophthalazine class of drugs. History The antihypertensive activity of hydralazine was discovered by scientists at Ciba, who were trying to discover drugs to treat malaria; it was initially called C-5968 and 1-hydrazinophthalazine; Ciba's patent application was filed in 1945 and issued in 1949, and the first scientific publications of its blood pressure-lowering activities appeared in 1950. It was approved by the FDA in 1953. It was one of the first antihypertensive medications that could be taken by mouth. Research Hydralazine has also been studied as a treatment for myelodysplastic syndrome in its capacity as a DNA methyltransferase inhibitor. See also Arteriolar vasodilator Cadralazine Dihydralazine Endralazine Sodium nitroprusside References External links Antihypertensive agents Hepatotoxins Hydrazines Monoamine oxidase inhibitors World Health Organization essential medicines Phthalazines Wikipedia medicine articles ready to translate