Hydralazine Accord-Uk (Hydralazine Hydrochloride)

• Hydralazine is a direct vasodilator used in the management of cardiovascular conditions that involve elevated vascular resistance.
• Hypertension: Reduces systemic blood pressure by relaxing arteriolar smooth muscle.
• Congestive heart failure: Lowers afterload, improving cardiac output in patients with reduced ventricular function.
• Pregnancy‑induced severe hypertension: Provides rapid blood pressure control in obstetric emergencies such as preeclampsia.

• Hydralazine acts directly on vascular smooth muscle by interfering with calcium influx and inhibiting the release of norepinephrine, leading to relaxation of arterioles. This vasodilation decreases peripheral vascular resistance, which in turn lowers arterial pressure and reduces cardiac afterload. The effect is independent of autonomic receptors, allowing rapid onset of blood‑pressure reduction.

Hydralazine may be associated with a range of adverse reactions, varying from mild to serious.

Common Side Effects

• Headache: mild to moderate pain often occurring shortly after dosing.
• Tachycardia: increased heart rate as a reflex response to vasodilation.
• Flushing: warmth and redness of the skin, especially on the face.
• Nausea: upset stomach, sometimes accompanied by vomiting.
• Edema: peripheral swelling, typically in the ankles.
• Dizziness: light‑headed sensation, particularly when standing quickly.

Serious or Rare Side Effects

• Lupus‑like syndrome: fever, joint pain, and rash resembling systemic lupus.
• Severe hypotension: abrupt and dangerous drop in blood pressure.
• Myocardial infarction: chest pain indicating possible heart attack.
• Thrombocytopenia: markedly reduced platelet count leading to bleeding risk.
• Anaphylaxis: life‑threatening allergic reaction with airway compromise.

When prescribing hydralazine, clinicians should observe several safety considerations to minimize risk.

• Blood pressure monitoring: check systolic and diastolic values regularly to avoid excessive hypotension.
• Cardiac assessment: evaluate for coronary artery disease before initiation, as reflex tachycardia may worsen ischemia.
• Pregnancy caution: use only when benefits outweigh risks, given limited safety data.
• Renal impairment: adjust therapy and monitor renal function closely.
• Concomitant β‑blocker use: consider adding a β‑blocker to control reflex tachycardia.
• Store at room temperature: keep in the original container, protect from moisture and direct sunlight.

Hydralazine can interact with several medicines, altering its efficacy or safety profile.

Major Interactions (Avoid)

• Direct vasodilators (e.g., nitroglycerin): combined effect may cause severe hypotension.
• Monoamine oxidase inhibitors (MAOIs): risk of hypertensive crisis when used together.
• β‑blockers: may mask tachycardia, requiring careful monitoring.

Moderate Interactions (Monitor Closely)

• Diuretics: additive blood‑pressure lowering effect, may necessitate dose adjustment.
• ACE inhibitors or ARBs: enhanced antihypertensive response, monitor for hypotension.
• Lithium: hydralazine may increase lithium levels, increasing toxicity risk.
• NSAIDs: may reduce antihypertensive efficacy of hydralazine.