Hydralazine Nursing Considerations

Last updated on May 16th, 2022 at 09:16 pm

Hydralazine Nursing Implications

Hydralazine Nursing Pharmacology

Hydralazine is a medication used to treat hypertension, under the classification of vasodilators. Its function is to relax blood vessels so the blood can flow easily through them. Although it was originally developed as a treatment for malaria in the 1950s, hydralazine manifests the ability to lower high blood pressure and it was, later, utilized for a new purpose.

Indications of Hydralazine

  • Treatment for moderate to severe high blood pressure. Hydralazine is given alone or as an adjunct therapy to other antihypertensive drugs. It works directly to the blood vessels by relaxing the arteriole, reducing arterial pressure, thus, making the blood easier to flow, resulting in lowering blood pressure. It is used alone or can be combined with other medication that lowers blood pressure.
  • Post heart valve replacement. Based on research, patients given hydralazine Intravenous after heart valve replacement had stable blood pressure and heart rate. With its capacity to dilate the arterial system and improve the cardiac output by reducing arterial pressure, and vascular resistance.
  • Treatment for heart failure. Hydralazine is used as supplementary medication in combination with other long-acting nitrates among patients with moderate to severe chronic heart failure, and the optimal doses of conventional treatment were tested not sufficient. It acts as a smooth muscle relaxant and effective dilator. The major effect of hydralazine in blood flow, especially in patients with heart failure is improving the cardiac output and stroke volume, but at the same time lowering the vascular resistance without having any remarkable changes in pulmonary and systemic pressure. In patients with chronic heart failure with decreased cardiac output, hydralazine treatment results in continuous benefits in blood flow and clinical effects.
  • Preeclampsia/Eclampsia. Hydralazine is one of the first-line agents used both in acute preeclampsia and severe hypertension during pregnancy. As an arteriolar dilator, it lowers blood pressure but may cause tachycardia. It has a slow onset of action, between 10 to 20 minutes, and the peak is around 20 minutes approximately after the medication is given. Hydralazine is a safe and effective treatment in hypertensive emergencies among obstetric patients when even when given intravenously through boluses.

Mechanism of Action of Hydralazine

Hydralazine is a drug that directly dilates the arteriole, a small branch of the artery that leads to capillaries.

According to research, the exact mechanism is not entirely understood, but theories state that it is connected with intracellular calcium hemostasis.

Hydralazine prevents calcium metabolism and transport in the vascular smooth muscles that are responsible for the contraction.

The effect of hydralazine in the peripheral vessels is it relaxes the arteriolar smooth muscle, lowering the pressure in the artery, reducing vascular resistant while improving the heart rate, stroke volume, and cardiac output that resulting in a lowering of blood pressure.

Also, hydralazine improves the blood flow to the brain and kidneys.

Pharmacokinetics of Hydralazine

Hydralazine has greatly been a drug of choice in treating congestive heart failure, and hypertension, for it causes dilatation of arterioles. Its related reflex-baroreceptor moderator responses or increase heart rate and greater ejection velocity are reduced in congestive heart failure.

  • Absorption

Data describes that Hydralazine is well absorbed in the gastrointestinal tract. If oral hydralazine is taken with food, the bioavailability of the medication is increased.

Bioavailability: Slow acetylator: 30-50%; rapid acetylator: 22-30%. If given intravenously, the onset of effect is 5 to 20 minutes, with a maximum effect of 10 to 80 minutes. Meanwhile, if taken orally, it is rapidly absorbed. The blood pressure-lowering effect is effect 20 to 300 minutes.

Duration: For oral dosing, the total duration is 3 to 8 hours and for intravenous dosing, the total duration is 1 to 4 hours.

  • Distribution

Protein-bound is 85% to 90%

Vd: 0.3 to 8.2 L/kg

  • Metabolism

Hydralazine is metabolized extensively by the Liver. In total, there is 5 known metabolic pathway for hydralazine. The minor metabolic pathway for hydralazine is called Acetylation, and the major pathway is called hydroxylation. It can undergo the process and metabolize to either phthalazine or α-ketoglutarate hydrazone. It can be later on converted to or directly metabolize into phthalazinone. Hydralazine may go through a changeable conversion to the active form of hydralazine acetone hydrazone. It can be converted continuously to the active pyruvic acid hydrazone or the pyruvic acid hydrazone tricyclic dehydration product. These by-products can transform to and fro between these two forms.

  • Excretion

65% to 95% of hydralazine is excreted in the urine, and less than 10% is recovered in the feces. The half-life of hydralazine is about 2.2 to 7.8h in rapid acetylators and 2.0 to 5.8h in slow acetylators. In patients with heart failure, the half-life is 57 to 241 minutes and 105 minutes on average. For cases of patients with hypertension, the half-life is 200 minutes for rapid acetylators and 297 minutes for slow acetylators. Generally, slow acetylators have a higher level of plasma hydralazine, thus requiring a lower dose to control blood pressure. However, other components like acetylation as a minor metabolic pathway for hydralazine may put up to differences in elimination rate.

Side Effects of Hydralazine

Some side effects can be experienced when taking hydralazine. These side effects are mild and expected to subside within a couple of days. Inform the doctor immediately if these symptoms last longer and got worsen:

The following are some serious side effects that may occur. It is recommended to call for an immediate medical response if any of these happen:

  • Loss of consciousness
  • Muscle pain
  • Joint pain
  • Fever
  • Increased heart rate
  • Chest pain
  • Swollen feet or ankles
  • Hand or feet numbness
  • Tingling hands or feet
  • Depression
  • Anxiety
  • Urinary problems

Adverse Reactions to Hydralazine

  • Cardiovascular disorders such as mitral valvular disease, heart failure with elevated cardiac output, dissecting aortic aneurism, severe palpitations, chest pain, decreased blood pressure, dizziness, tachycardia, and right ventricular failure secondary to pulmonary hypertension, and peripheral edema. Hydralazine is contraindicated in patients with coronary artery disease, this is secondary to hydralazine’s sympathetic nervous system stimulation. This may result to rising in cardiac output and oxygen demand that may lead to myocardial ischemia.
  • Immune system disorders like drug-induced lupus erythematosus, usually develop more than 6 months from the beginning of treatment. This is usually presented by joint pain, body pain, and fever. Other conditions that are related to the immune system are rheumatoid arthritis, vasculitis, serositis, toxic epidermal necrolysis, and serum sickness.
  • Hematologic disorders like hemolytic anemia, thrombocytopenia, blood dyscrasia, and agranulocytosis.
  • Gastrointestinal diseases like diarrhea, vomiting, and nausea
  • Disease of the kidneys and urinary tracts such as glomerulonephritis, dysuria, fluid, proteinuria, hematuria, elevated creatinine level, and sodium retention.
  • Hepatobiliary disorders like drug-induced liver injury, hepatotoxicity, hepatomegaly, and hepatitis. Symptoms include yellowish discoloration of skin or sclera, dark-colored urine, abdominal pain, and pruritus.
  • Neurologic disorders include polyneuritis as presented by paresthesia, numbness, and tingling sensation.
  • Others: conjunctivitis, nasal congestion, lacrimation

Hydralazine Overdose

The following symptoms may be presented in patients experiencing hydralazine overdose:

  • Hypotension
  • Increased or irregular heart rate
  • Generalized flushing
  • Headache
  • Dizziness
  • Pain at the chest/jaw/left arm
  • Loss of consciousness
  • Seizure
  • Difficulty breathing
  • Complications include myocardial ischemia, cardiac arrhythmia, subsequent myocardial infarction, and shock.

If an overdose happens outside a healthcare facility, call emergency services immediately or any poison control helpline.

Drug Interactions with Hydralazine

Before taking hydralazine or any medication, consult first with the doctor or pharmacist if there is any drug combination that should be avoided. Drug interactions may change how effective other medications are or it may increase the risk of serious side effects. Make a list of all the medicine, including the prescription and nonprescription drugs, vitamins, and herbal supplements as well. It is important not to start, stop, or change medication, or its dosage without consulting the doctor first.

Here are some products that may have interactions with hydralazine:

  • MAO inhibitors. MAOIs can raise the risk of side effects of hydralazine such as hypotension.
  • Medications for hypertensive emergencies. Hydralazine, when used with antihypertensives, may result in a severe drop in blood pressure.

Other medications include:

  • Glucose elevating medicines
  • Cough and cold preparations
  • Diet aids or weight loss pills
  • Non-steroidal anti-inflammatory drugs
  • Muscle relaxants
  • Antidepressants
  • Tranquilizers

Nursing Considerations for Hydralazine

  • Gather the patient’s health information. These include past and present medical history specifically the history of heart attack, coronary artery disease, rheumatic heart disease, liver or kidney increase. For a patient with a history or current heart problem, taking Hydralazine may worsen the condition. Make sure to inform the doctor before starting using hydralazine.
  • Obtain the list of medicine the patient is currently taking, both prescription and non-prescription drugs, vitamins, nutritional supplements, and herbal medicine. Also, review the history of allergies to medications, foods, and others. Tell the patient to ask for the list of ingredients of hydralazine to know first if the patient is allergic to any of its components.
  • Hydralazine is under category C pregnancy drug. If the patient is pregnant or planning to get pregnant, advise the patient to talk to their doctor first before taking hydralazine.
  • In the case of a pregnant woman that requires hydralazine, closely monitor the maternal vital signs and fetal heart rate pattern after administration of medicine. Possible hypotension may happen in response to the medicine. Provide assistance to the pregnant woman when getting out of her bed. Implement risk fall precautions based on facilities’ practices.
  • Observe if preeclampsia or eclampsia is present in the pregnant patient, and eclampsia may result in contracted intravascular volume. In giving antihypertensive medicine, the goal is not to decrease the pressure in the artery too fast because it may compromise the uteroplacental perfusion that may result in interrupted fetal oxygenation.
  • If the patient is scheduled for surgery or is planned to undergo any surgical procedure, including dental, the patient must tell the doctor and dentist that they are taking hydralazine.
  • Advise the patient to take hydralazine with meals. Their doctor may prescribe certain diets, like low-salt foods. Strict compliance must be followed.
  • Inform the patient to consult the doctor first before using alcohol. Alcoholic beverages may increase the risk for severe side effects of hydralazine.
  • Hydralazine can make the patient dizzy. Avoid driving, using heavy machinery, or any activity that requires alertness. Using alcohol and cannabis can aggravate dizziness. If the patient is under hydralazine treatment, Avoid taking these substances.
  • Elderly patients can be more sensitive to the side effects of hydralazine, especially dizziness. Fall prevention strategies should be implemented.
  • For breastfeeding mothers, hydralazine passes to the breast milk. However, according to studies, it will unlikely harm the baby.
  • Advise the patient to report immediately if they experience joint or chest pain, malaise, and fever. Especially among patients treated with hydralazine for a long time (more than 6 months). Prolonged treatment with hydralazine causes systemic lupus erythematosus-like symptoms.
  • Use with caution in a patient with mitral valvular disease, it may increase pulmonary artery pressure.
  • Advise the patient not to discontinue abruptly and without the doctor’s order. It may cause a sudden increase in blood pressure, and worst it can put the patient at higher risk for heart problems like chest pain and heart attack.
  • Instruct the patient to get up slowly when rising from a lying or sitting position. This is is to reduce the risk of dizziness.
  • Review to the patient the side effect of hydralazine. If any of those side effects last or worsen, tell their physician immediately.
  • Remind the patient about the doctor’s instructions when taking hydralazine. Also the importance of taking the medication regularly to receive the maximum benefit from it. You can suggest taking it at the same time each day.
  • Discuss to the patient the importance of taking this medicine even at times that they feel better. Most patients with high blood pressure do not feel any symptoms at first. To be able to get the full benefit of this medicine, it is important to take it accordingly.
  • Educate the patient about the symptoms of allergic reaction such as rashes, difficulty breathing, swelling of lips, eyes, and face. Respiratory distress and circulatory collapse are signs of an anaphylactic reaction. Call medical help right away if they experience any of those signs.
  • Since hydralazine is a blood pressure reducing agent, have the patient’s blood pressure monitored regularly. At home, the patient can check their own blood pressure, so having their own monitoring machine is highly recommended. They can take their blood pressure and heart rate and make them recorded in a notebook. Important details that should be included are date, time of day, and blood pressure reading. The patient can bring this log to the follow-up visit with the physician.
  • While taking this medication, changing lifestyles such as exercise, dietary modification, weight management, and stress reduction programs can be beneficial. The patient can discuss it with the doctor to know more about this changing of old habits and ways that can help the medication works better. It is important to consult with your doctor first, especially concerning the diet changes.
  • In case of a missed dose, tell the patient to take it as soon as they remember. If it is almost the time for the next dose, skip the missed dose and take the next dose at the regular time. Do not double dose the medication.
  • The doctor may order certain laboratory tests such as complete blood count and antinuclear antibody titer test to monitor the improvement of the patient’s condition and to check for any side effects. Urine analysis may also be required to detect initial signs of glomerulonephritis.
  • Advise the patient to store the medicine at room temperature and keep out away from light and moisture.
  • Keep the medicine away from children and pets.
  • Remind the patient to attend all follow-up appointments with the doctor to monitor their condition.
  • For patients taking the oral liquid form of hydralazine, the solution can be mixed with fruit juice or applesauce. Make sure to mix it properly, consume it immediately right after mixing, and take all of the mixtures to have the complete dose of the medicine.
  • Remind the patient to not take any medication without consulting the doctor first, especially over-the-counter medicine for cough and colds, appetite, allergies, and sinus problems. Taking hydralazine along with these medications may increase blood pressure.
  • In patients with preeclampsia or eclampsia, expect side effects such as tachycardia, palpitations, chest pain, gastric upset, chest pain, and headache. Educate the patients about these signs and these are commonly seen at the initial dose of the treatment and expected to subside during the course of the treatment. However, if these signs persist and got worsen, inform the doctor immediately.
  • Inform the patient that hydralazine can be taken with or without food. However, taking it with food may increase the metabolism of the drug compared to when taking it on an empty stomach.

Nursing Care Plan for Patients on Hydralazine

Possible Hydralizine Nursing Diagnoses

Nursing Assessment

Hydralazine Nursing InterventionsRationaleAssess the patient for signs and symptoms of hypertension, hypertensive crisis, pre-eclampsia or eclampsia.To confirm the indication for administering hydralazine.
Assess if the patient has any of the following conditions: Heart attack or myocardial infarction in the last 30 daysCoronary artery diseaseIncreased intracranial pressureStrokeHypokalemiaHydralazine should be used in caution in patients with hypokalemia as it can decrease the serum potassium levels. Hydralazine is contraindicated may worsen some medical conditions such as myocardial infarction, coronary artery disease, and stroke. Studies also show that hydralazine can increase intracranial pressure (ICP).
Check the patient’s allergy status.Previous allergic reactions to hydralazine may render the patient unable to take it. Alternatives to hydralazine should therefore be considered in case of allergy.
Assess if the patient is pregnant or lactating.Hydralazine belongs to pregnancy category C and should be prescribed with caution in pregnant women with preeclampsia/ eclampsia.  Lactating mothers on hydralazine should have their infant’s blood pressure to be monitored as well.
Assess the patient’s vital signs, particularly the blood pressure.Hydralazine may cause hypotension.
Assess the patient’s mucous membranes and his/her ability to swallow.To check for any potential problems with administration, hydration, and absorption.
To ensure that the right form of hydralazine is given.

Nursing Planning and Intervention

 Hydralazine Nursing InterventionsRationale
Administer hydralazine on an empty stomach, ideally 1 to 2 hours prior to main meals.To ensure optimal absorption and therapeutic action by hydralazine, as well as to reduce possible side effects.
Conduct a medication review. Ensure that the patient does not take hydralazine with any monoamine oxidase inhibitors (MAOI).MAOIs can increase the effect of hydralazine, which may lead to hypotension.  
Educate the patient about the action, indication, common side effects, and adverse reactions to note when taking hydralazine. Instruct the patient on how to self-administer hydralazine.To inform the patient on the basics of hydralazine, as well as to empower him/her to safely self-administer the medication.
Monitor the patient’s input and output and commence stool chart.Hydralazine may cause diarrhea. Early detection of either side effect can help institute a bowel program and relieve them effectively.
Encourage the reduction of alcohol consumption.Alcohol can increase the likelihood of hypotension when the patient is taking hydralazine.
Encourage the patient to change position slowly.To prevent orthostatic hypotension.
If unable to swallow, hydralazine can be crushed and dispersed in water.Hydralazine can usually be crushed without affecting its effectiveness or potency.

Nursing Evaluation

Hydralazine Nursing InterventionsRationale
Ask the patient to repeat the information about hydralazine.To evaluate the effectiveness of health teaching on hydralazine.
Monitor the patient’s blood pressure levels.To ensure that the hydralazine did not cause any hypotension.  
Monitor the patient’s serum electrolytes and renal function.         To check if the drug has caused hypokalemia or kidney injury.

Nursing References

Ackley, B. J., Ladwig, G. B., Makic, M. B., Martinez-Kratz, M. R., & Zanotti, M. (2020). Nursing diagnoses handbook: An evidence-based guide to planning care. St. Louis, MO: Elsevier.  Buy on Amazon

Gulanick, M., & Myers, J. L. (2022). Nursing care plans: Diagnoses, interventions, & outcomes. St. Louis, MO: Elsevier. Buy on Amazon

Ignatavicius, D. D., Workman, M. L., Rebar, C. R., & Heimgartner, N. M. (2018). Medical-surgical nursing: Concepts for interprofessional collaborative care. St. Louis, MO: Elsevier.  Buy on Amazon

Silvestri, L. A. (2020). Saunders comprehensive review for the NCLEX-RN examination. St. Louis, MO: Elsevier.  Buy on Amazon


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The medical information on this site is provided as an information resource only and is not to be used or relied on for any diagnostic or treatment purposes.

This information is intended to be nursing education and should not be used as a substitute for professional diagnosis and treatment.

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Anna Curran. RN, BSN, PHN

Anna Curran. RN-BC, BSN, PHN, CMSRN I am a Critical Care ER nurse. I have been in this field for over 30 years. I also began teaching BSN and LVN students and found that by writing additional study guides helped their knowledge base, especially when it was time to take the NCLEX examinations.

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