Thursday, April 15, 2021

Drugs Commonly Used In the Treatment of Hypertensive Emergencies

by | September 25, 2020 0

Hypertensive emergency is a clinical situation in which the elevated blood pressure (BP) is immediately life-threatening and needs to be lowered to a safe level (not necessarily to normal) within a matter of minutes to hours using parenteral antihypertensive medications. Symptoms associated with hypertensive emergency are highly variable and reflect the degree of damage to specific organ systems.

The organs primarily affected as a result of a hypertensive emergency are the central nervous system, eyes, heart, and kidneys. Whether treatment can completely reverse end-organ damage is related to two factors: how soon treatment is initiated and the extent of damage at the initiation of therapy.

There are two fundamental concepts in the management of hypertensive emergencies. First, immediate and intensive therapy is required and takes precedence over time-consuming diagnostic procedures. Second, the choice of drugs will depend on how their time course of action and hemodynamic and metabolic effects meet the needs of the emergent situation.

This article contains a list of drugs used in the treatment of hypertensive emergencies. Each drug will be discussed in terms of actions, dose/ Route, onset and duration of action, contraindications and adverse effects.

1. Clevidipine

Clevidipine is an intravenous short-acting dihydropyridine calcium channel blocker indicated for the reduction of blood pressure when oral therapy is not feasible or not desirable. Clevidipine acts by inhibiting transmembrane influx of extracellular calcium ions across membranes of myocardial cells and vascular smooth muscle cells, without changing serum calcium concentrations. This results in inhibition of cardiac and vascular smooth muscle contraction, thereby widening the arterial lumen and reduction of blood pressure.

Dose/ Route: Initial: 1–2 mg/hour; titrate dose to desired BP or to a max of 16 mg/hour
Onset of action: 2 – 4 minutes
Duration of action: 10 – 15 minutes after D/C infusion

Contraindications
Clevidipine is contraindicated in patients with

  • Severe aortic stenosis
  • Allergies to soybeans, soy products, eggs, or egg products
  • Defective lipid metabolism seen in conditions such as pathologic hyperlipemia, lipoid nephrosis, or acute pancreatitis if it is accompanied by hyperlipidemia

Adverse effects

  • Headache
  • Nausea
  • Tachycardia
  • Hypertriglyceridemia
  • Atrial fibrillation
  • Vomiting
  • Acute renal failure
  • Reflex tachycardia
  • Myocardial infaction

2. Enalaprilat

Enalaprilat is an intravenous angiotensin-converting enzyme inhibitor (ACEI) indicated for the treatment of hypertension when oral therapy is not practical. It is the active metabolite of orally administered enalapril.

Enalaprilat acts competitively inhibiting angiotensin-converting enzyme (ACE) from transforming angiotensin I into angiotensin II, thus reducing systemic vascular resistance and arterial BP.

Dose/ Route: 0.625 – 1.25 mg IV every 6 hours
Onset of action: 15 minutes (max, 1 – 4 hours)
Duration of action: 6–12 hours

Contraindications
Enalaprilat is contraindicated in

  • Pregnant patients
  • Patients with a history of angioedema resulting from previous treatment with an ACE inhibitor
  • Patients with bilateral renal artery stenosis

Adverse effects

  • Precipitous fall in BP in high-renin states
  • Hyperkalemia
  • Acute kidney injury in those who are volume-depleted

3. Esmolol hydrochloride

Esmolol is a short-acting, cardioselective, beta-1-blocker approved for supraventricular tachycardia (except for preexcitation syndromes), and for the rapid control of ventricular rate in patients with atrial fibrillation or atrial flutter in perioperative, postoperative, or other circumstances where short-term control of the ventricular rate with a short-acting agent is desirable. It works by blocking beta-adrenergic receptors in the heart, which leads to decreased force and rate of heart contractions.

Dose/ Route: 250–500 mcg/kg for 1 minute, then 50–300 mcg/kg/minute
Onset of action: 1 – 2 minutes
Duration of action: 10 – 20 minutes

Contraindications

  • Hypersensitivity to the active substance or to any of the excipients or other beta-blockers (cross-sensitivity between beta-blockers is possible)
  • Sinus bradycardia, 2°/3° heart block, cardiogenic shock, overt cardiac failure
  • Asthma/ Chronic obstructive pulmonary disease ( COPD )
  • Sick sinus syndrome without permanent pacemaker

Adverse effects

  • Hypotension
  • Thrombophlebitis
  • Painful extravasation
  • Nausea
  • Asthma
  • First-degree heart block
  • Heart failure

4. Fenoldopam mesylate

Fenoldopam mesylate is a dopamine D1 receptor agonist that is used in short-term (up to 48 hours) management of severe hypertension when rapid, but quickly reversible, emergency reduction of blood pressure is clinically indicated, including malignant hypertension with deteriorating end-organ function. It lowers blood pressure through arteriolar vasodilation.

Dose/ Route: 0.1–0.3 mcg/kg/min IV infusion
Onset of action: <5 minutes
Duration of action: 30 minutes

Contraindication

  • Hypersensitivity to fenoldopam and sulfite

Adverse effects

  • Tachycardia,
  • Headache
  • Nausea,
  • Flushing

5. Hydralazine hydrochloride

Hydralazine is a vasodilator used in the management of hypertension when oral therapy not feasible or there is an urgent need to lower blood pressure. It is an intermediate treatment between oral agents and more aggressive therapies such as nitroprusside. It can be given IV or intramuscularly, but there is no appreciable difference in onset of action (20 – 40 minutes) between the two routes. This slow onset minimizes hypotension.

Hydralazine dilates arterioles with little effect on vein. It decreases systemic resistance, which subsequently decreases blood pressure.

Dose/ Route: 10 – 20 mg IV; 10–50 mg IM
Onset of action: 5 – 20 minutes (when used IV); 20 – 30 minutes (when used IM)
Duration of action: 2 – 6 hours (when used IV), 4 – 6 hours (when used IM)

Contraindications

  • Hypersensitivity to hydralazine
  • Coronary artery disease
  • Mitral valve rheumatic heart disease

Adverse effects

  • Tachycardia
  • Flushing
  • Headache
  • Vomiting
  • Aggravation of angina

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