What antihypertensive (anti-hypertensive) medication can be used as needed (prn, pro re nata)?

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Last updated: March 12, 2025View editorial policy

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From the Guidelines

Labetalol is the most appropriate antihypertensive medication to be used as needed (prn, pro re nata) due to its effectiveness in various hypertensive emergencies and its ability to leave cerebral blood flow relatively intact 1. When considering antihypertensive medications for as-needed use, several factors such as onset of action, duration of effect, and potential side effects must be taken into account.

  • Labetalol is a commonly used medication in hypertensive emergencies, including malignant hypertension, hypertensive encephalopathy, and acute ischemic stroke 1.
  • It has a relatively rapid onset of action and can be administered orally or intravenously, making it a versatile option for different clinical scenarios.
  • Other medications like nitroprusside and nicardipine can also be used in hypertensive emergencies, but they may have more significant side effects or require closer monitoring 1.
  • The use of antihypertensive medications on an as-needed basis should be reserved for urgent situations or as a bridge until regular antihypertensive therapy takes effect, as they can cause rapid and unpredictable blood pressure fluctuations.
  • It is essential to monitor blood pressure before and after administration of any antihypertensive medication to ensure an appropriate response without excessive drops.
  • In clinical practice, labetalol's properties make it a preferred choice for as-needed use in managing acute blood pressure elevations, especially when considering the potential impact on morbidity, mortality, and quality of life 1.

From the Research

Antihypertensive Medications Used as Needed

  • According to the study 2, as-needed (PRN) labetalol and hydralazine can be used for the treatment of acute hypertension in hospitalized medicine patients.
  • The study 2 found that oral hydralazine was the most common PRN antihypertensive medication administered, with 521 doses given to 250 patients.
  • Labetalol is also mentioned in the study 3 as a rapid-acting intravenous antihypertensive agent that can be used to treat hypertensive emergencies.

Administration and Usage

  • The study 2 noted that 36% of PRN administrations were given for a systolic blood pressure (SBP) <180 mmHg and diastolic blood pressure (DBP) <110 mmHg, which is less than the cut-point for acute severe hypertension.
  • The study 2 also found that no serious adverse events were related to PRN antihypertensive administration, suggesting that as-needed use of these medications can be safe and effective.

Other Antihypertensive Medications

  • Nifedipine is mentioned in the study 4 as an antihypertensive medication that can be used in combination with other agents, but its use as a PRN medication is not specifically discussed.
  • The study 3 notes that nifedipine, nitroglycerin, and hydralazine should not be considered first-line therapies in the management of hypertensive crises due to their potential toxicities and adverse effects.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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