Hydralazine Flashcards
What is the mechanism of action of hydralazine?
Hydralazine is a direct arteriolar vasodilator that reduces afterload by relaxing vascular smooth muscle, leading to decreased systemic vascular resistance.
What are the primary indications for hydralazine?
Hydralazine is used for severe hypertension, hypertensive emergency in pregnancy, and as adjunct therapy in heart failure with reduced ejection fraction (HFrEF), often combined with nitrates.
Is hydralazine a first-line agent for hypertension?
No, hydralazine is typically not first-line but may be used in resistant hypertension or specific cases such as pregnancy-associated hypertension.
Why is hydralazine used in heart failure?
Hydralazine, in combination with isosorbide dinitrate, reduces both afterload and preload, improving survival in heart failure with reduced ejection fraction (HFrEF), particularly in African American patients.
What are the common side effects of hydralazine?
Reflex tachycardia, headache, fluid retention/edema, and angina.
Why does hydralazine cause reflex tachycardia?
Vasodilation leads to decreased blood pressure, triggering a compensatory increase in sympathetic tone, which increases heart rate.
Why does hydralazine cause headache?
Arterial vasodilation can cause cerebral vasodilation, leading to headaches.
How does hydralazine contribute to edema?
Vasodilation leads to fluid retention, which can cause peripheral edema.
Why can hydralazine exacerbate angina?
The reflex tachycardia increases myocardial oxygen demand, which can worsen ischemia in patients with coronary artery disease.
What is a unique autoimmune side effect of hydralazine?
Drug-induced lupus erythematosus (DILE), characterized by systemic lupus-like symptoms.
What are the clinical manifestations of drug-induced lupus from hydralazine?
Rash, fever, arthralgia, myalgia, fatigue, and serositis (pleuritis, pericarditis).
What lab findings are associated with drug-induced lupus?
Positive anti-histone antibodies (highly specific for DILE), but negative or weakly positive anti-dsDNA antibodies.
How can drug-induced lupus from hydralazine be differentiated from systemic lupus erythematosus (SLE)?
Drug-induced lupus is typically milder, lacks renal and CNS involvement, and resolves upon discontinuation of the offending drug.
What is the treatment for hydralazine-induced lupus?
Discontinuation of hydralazine; symptoms usually resolve on their own, but NSAIDs or corticosteroids may be used for severe cases.
In which patients should hydralazine be used with caution?
Patients with coronary artery disease (due to reflex tachycardia worsening angina) and those with rheumatic heart disease affecting the mitral valve.
What medications are often co-administered with hydralazine to counteract side effects?
A beta-blocker (to prevent reflex tachycardia) and a diuretic (to reduce fluid retention).
What is the primary indication for hydralazine in pregnancy?
Hypertensive emergency in pregnancy, as it is considered safe for use.
What is the preferred combination therapy for heart failure in African American patients?
Hydralazine and isosorbide dinitrate, as it has been shown to improve survival in HFrEF.
Why does hydralazine mainly affect arterioles and not veins?
Hydralazine primarily acts on arterial smooth muscle, leading to afterload reduction, whereas nitrates act more on venous dilation to reduce preload.
