From the Guidelines
For a patient with severely elevated systolic blood pressure who has already received hydralazine, another antihypertensive agent should be added acutely to prevent end-organ damage. When considering the addition of another antihypertensive agent, it is crucial to select an agent that acts through a different mechanism to provide more effective blood pressure control. According to the 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults 1, options for intravenous antihypertensive drugs include:
- Nicardipine, a calcium channel blocker, with an initial dose of 5 mg/h, increasing every 5 min by 2.5 mg/h to a maximum of 15 mg/h
- Labetalol, a combined alpha1 and nonselective beta receptor antagonist, with an initial dose of 0.3–1.0-mg/kg (maximum 20 mg) slow IV injection every 10 min or 0.4–1.0-mg/kg/h IV infusion up to 3 mg/kg/h
- Sodium nitroprusside, a vasodilator, with an initial dose of 0.3–0.5 mcg/kg/min, increasing in increments of 0.5 mcg/kg/min to achieve BP target, with a maximum dose of 10 mcg/kg/min These agents have different mechanisms of action and can be used in conjunction with hydralazine to achieve better blood pressure control. It is essential to monitor the patient closely for response and potential side effects, checking blood pressure every 5-15 minutes initially. The choice of agent should be based on the patient's specific clinical scenario, including the presence of any comorbidities or contraindications.
From the FDA Drug Label
When other potent parenteral antihypertensive drugs, such as diazoxide, are used in combination with hydralazine, patients should be continuously observed for several hours for any excessive fall in blood pressure Profound hypotensive episodes may occur when diazoxide injection and hydralazine injection are used concomitantly
If a patient is already given Hydralazine (hydrochloride) and has severely elevated systolic blood pressure, caution should be exercised when adding another antihypertensive agent. The FDA drug label warns of the potential for profound hypotensive episodes when hydralazine is used in combination with other potent antihypertensive drugs. Therefore, another antihypertensive agent should be added with caution and the patient should be continuously monitored for any excessive fall in blood pressure 2.
From the Research
Management of Severely Elevated Systolic Blood Pressure
In a patient already given Hydralazine (hydrochloride) for severely elevated systolic blood pressure, the decision to add another antihypertensive agent acutely depends on several factors, including the presence of acute end-organ damage and the patient's clinical presentation.
- Hypertensive Emergencies: If the patient has acute end-organ damage, immediate reduction in blood pressure is required, and treatment with a titratable, short-acting, intravenous antihypertensive agent is necessary 3, 4.
- Hypertensive Urgencies: If the patient has severely elevated blood pressure without acute end-organ damage, oral antihypertensive agents can be used to gradually reduce blood pressure 3, 4.
- Choice of Agent: Rapid-acting intravenous antihypertensive agents, such as labetalol, esmolol, fenoldopam, nicardipine, and clevidipine, are available for the management of hypertensive crises 3, 4, 5, 6, 7.
- Avoiding Certain Agents: Sodium nitroprusside, nifedipine, nitroglycerin, and hydralazine should not be considered first-line therapies due to their potential toxicities and side effects 3, 4, 7.
- Newer Agents: Clevidipine, a third-generation dihydropyridine calcium-channel blocker, has been shown to be effective and safe in the management of hypertensive crises, with a potential to reduce mortality compared to nitroprusside 6, 7.