Dihydralazine

• IUPAC: (4- Hydrazinylphthalazin -1 -yl)- hydrazine
• Latin: Dihydralazinum

C02DB01

Orange needles

• Vasodilator effect on the smooth muscle
• Antihypertensive

180 ° C decomposition

300 mg · kg -1 ( LD50, mouse, i.v.)

Template: Infobox chemical / molecular formula search available

Hydralazine is a vasodilator, which is a vasodilator drug, which is therefore mainly used in pregnancy as an antihypertensive, for hypertension therapy. In Germany it is sold under the trade name Nepresol ®. Worldwide also the related hydralazine is often used.

Pharmacology

Mode of action and pharmacokinetics

Dihydralazine relaxes the smooth muscle cells of blood vessels, arteries and arterioles are so extended, resulting in a decrease in peripheral resistance. The precise molecular mechanism leading to Zellrelaxation is not known yet.

The effect after intravenous administration occurs after about 15 minutes and then holding for three to four hours. Hydralazine has a bioavailability of 30-50 % and is subject to a high first- pass effect by acetylation, where there is a difference in fast and slow acetylators. Its metabolism occurs in the liver where it is acetylated. The total clearance of hydralazine is about 8,000 ml per minute ( regardless of acetylator ), its half-life 2.2-2.6 hours (depends on acetylator ). It has a volume of distribution of 7 l / kg.

The main field of application of hydralazine is intravenous therapy for severe pre-eclampsia, there is a means of choice, because the perfusion of the uterus and placenta is not affected. However, since it is excreted in breast milk, may no longer be satisfied after administration. Use for oral long-term treatment is possible in principle, but it is due to the side effects become no longer suitable.

Side effects

In 90 % of cases, adequate blood pressure control is achieved with hydralazine. In nine randomized trials, was compared in the context of which hydralazine with other antihypertensives, it was only in a single study, an increased incidence of side effects and treatment failure in the Dihydralazingruppe. As a result of arterial aneurysm, there may be orthostatic dysregulation, pulsating headache and a so-called "flush ", an accompanying heat feelings skin redness in your face, come up to the drug-induced lupus erythematosus, which is, however, usually rapidly completely recovered after discontinuation of the drug. In addition, reflex tachycardia, and angina pectoris may occur as a sympathetic counter-regulation. Another counter-regulation by activation of the renin -angiotensin -aldosterone system can cause reduced sodium ion and water excretion, which in turn can result in edema.