This is a drug used in the treatment of cardiac failure and hypertension.
Mode of action:
- direct relaxing effect on vascular smooth muscle resulting in peripheral arteriolar dilatation
There is a fall in blood pressure and consequent reflex tachycardia as a result of the peripheral arteriolar dilatation caused by hydralazine. Thus, in the treatment of hypertension, a beta-adrenoreceptor blocker is also is used. There is little reflex tachycardia when this drug is used to treat cardiac failure because there is no significant change in blood pressure.
- t 1/2 - approximately 4 hours
- metabolised - mainly by acetylation
- palpitations, nausea, vomiting, tachycardia, postural hypotension
- with dosages over 200 mg then there may be the development of a lupus-like syndrome or an arthropathy resembling rheumatoid arthritis. The lupus-like syndrome that may occur with the use of hydralazine is more commonly seen in patients with HLA DR4.