Overview. Hydralazine ( hye-DRAL-a-zeen) belongs to the general class of medicines called vasodilators. It is used to treat high blood pressure (hypertension). It is also used to control high blood pressure in the mother during pregnancy (pre-eclampsia or eclampsia) or in emergency situations when blood pressure is extremely high (hypertensive crisis).
High blood pressure adds to the workload of the heart and arteries. If it continues for a long time, the heart and arteries may not function properly. This can damage the blood vessels of the brain, heart, and kidneys, resulting in a stroke, heart failure, or kidney failure. High blood pressure may also increase the risk of heart attacks. These problems may be less likely to occur if blood pressure is controlled.
Hydralazine works by relaxing blood vessels and increasing the supply of blood and oxygen to the heart while reducing its workload. Hydralazine may also be used for other conditions as determined by your doctor. Hydralazine is available only with your doctor's prescription.
Minoxidil (mi-NOX-i-dill) belongs to the general class of medicines called Vasodilators. It is the most potent vasodilator used for hypertension. It is used to treat high blood pressure (hypertension). Minoxidil works by relaxing blood vessels so that blood passes through them more easily. Minoxidil is used for patients who have not responded to any other medications. It must be combined with a beta-blocker or clonidine to prevent an increase in the heart rate and with a diuretic to prevent retention of fluid (swelling). This helps to lower blood pressure. Minoxidil has other effects that could be bothersome for some patients. These include increased hair growth, weight gain, fast heartbeat, and chest pain. Before you take this medicine, be sure that you have discussed the use of it with your doctor.
Before Using This Medicine. In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For hydralazine, the following should be considered:
Allergies – Tell your doctor if you have ever had any unusual or allergic reaction to hydralazine. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.
Pregnancy – Although hydralazine often is used to reduce high blood pressure in pregnant women, extensive studies of hydralazine in pregnant women have not been done. However, blood problems and other problems have been reported in infants of mothers who took hydralazine during pregnancy. In addition, studies in mice have shown that high doses of hydralazine cause birth defects (cleft palate, defects in head and face bones). These birth defects also occurred in rabbits, but did not occur in rats. Before taking this medicine, make sure your doctor knows if you are pregnant or if you may become pregnant.
Breast-feeding – Hydralazine passes into breast milk. Although most medicines pass into breast milk in small amounts, many of them may be used safely while breast-feeding. Mothers who are taking this medicine and who wish to breast-feed should discuss this with their doctor.
Children – Although there is no specific information comparing use of hydralazine in children with use in other age groups, this medicine is not expected to cause different side effects or problems in children than it does in adults. However, the oral solution contains aspartame, which is converted to phenylalanine in the body. Children with phenylketonuria cannot process phenylalanine and high levels of this substance in body fluids may cause brain damage.
Older adults – Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults. Although there is no specific information comparing use of hydralazine in the elderly with use in other age groups, this medicine is not expected to cause different side effects or problems in older people than it does in younger adults.
Other medicines – Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking hydralazine, it is especially important that your health care professional know if you are taking the following:
Other medical problems – The presence of other medical problems may affect the use of hydralazine. Make sure you tell your doctor if you have any other medical problems, especially:
For patients taking the oral solution form of hydralazine :
This medicine works best if there is a constant amount in the blood. To help keep this amount constant, do not miss any doses and take the medicine at the same times each day.
Hydralazine may cause some people to have headaches or to feel dizzy. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert.
The oral solution contains 1.4 milligrams (mg) of phenylalanine per teaspoonful (5 mL). Patients with phenylketonuria cannot process phenylalanine and high levels of this substance in body fluids may cause brain damage.
For patients taking this medicine for high blood pressure:
Side Effects of This Medicine. Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
In general, side effects with hydralazine are rare at lower doses. However, check with your doctor as soon as possible if any of the following occur:
Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:
Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.