Noxap (Nitric Oxide)

• Noxap is used to treat conditions involving elevated pulmonary vascular resistance.
• Persistent pulmonary hypertension of the newborn (PPHN): improves oxygenation by reducing pulmonary artery pressure and enhancing blood flow to the lungs.
• Acute respiratory distress syndrome (ARDS): lowers pulmonary hypertension to support ventilation and oxygen exchange.
• Pulmonary hypertension (adult): provides selective vasodilation to improve exercise capacity, symptoms, and overall cardiopulmonary function.

• Nitric Oxide activates soluble guanylate cyclase in pulmonary vascular smooth muscle, increasing intracellular cyclic GMP levels. Elevated cGMP leads to relaxation of smooth muscle cells, resulting in selective dilation of the pulmonary vasculature while systemic vessels remain largely unaffected, thereby reducing pulmonary arterial pressure and improving oxygenation.

Adverse reactions may occur with inhaled nitric oxide therapy.

Common Side Effects

• Methemoglobinemia: elevated methemoglobin levels causing reduced oxygen delivery.
• Nitrogen dioxide formation: respiratory irritation from NO2 exposure.
• Transient hypotension: mild systemic blood pressure drop.
• Rebound pulmonary hypertension: increase in pressure after abrupt discontinuation.
• Headache or dizziness.
• Nausea or vomiting.

Serious or Rare Side Effects

• Severe hypotension leading to organ hypoperfusion.
• Bleeding complications, especially when combined with anticoagulants.
• Renal dysfunction or acute kidney injury.
• Pulmonary edema.
• Allergic reactions such as rash or anaphylaxis.

• Use Noxap under close clinical monitoring and adhere to recommended guidelines.
• Dose titration: adjust concentration based on patient response and arterial blood gas measurements.
• Monitoring: continuously monitor methemoglobin levels and nitrogen dioxide concentrations.
• Withdrawal: taper the gas slowly to avoid rebound pulmonary hypertension.
• Contraindications: avoid in patients with known hypersensitivity to nitric oxide or its delivery system.
• Drug interactions: be cautious when co‑administered with phosphodiesterase inhibitors or other vasodilators.
• Store at ambient temperature: keep cylinders upright, protect from heat and direct sunlight, and ensure proper ventilation in storage area.

Nitric oxide can interact with several medications, requiring careful management.

Major Interactions (Avoid)

• Phosphodiesterase‑5 inhibitors (e.g., sildenafil): additive pulmonary vasodilation may cause severe hypotension.
• Other nitric oxide donors: risk of excessive vasodilation and methemoglobinemia.
• Inhaled anesthetics (e.g., sevoflurane): may potentiate hypotensive effects.

Moderate Interactions (Monitor Closely)

• Anticoagulants (e.g., heparin): increased risk of bleeding.
• Methylene blue: may interfere with nitric oxide metabolism and reduce efficacy.
• Systemic vasodilators (e.g., nitroglycerin): monitor blood pressure for additive effects.