Neophyr (Nitric Oxide)

Neophyr is a pulmonary vasodilator used in conditions where elevated pulmonary arterial pressure is a primary concern.

• Pulmonary hypertension: reduces pulmonary arterial pressure and improves oxygenation.
• Persistent pulmonary hypertension of the newborn (PPHN): promotes pulmonary vasodilation to facilitate transition to extra‑uterine life.
• Right ventricular failure secondary to pulmonary hypertension: decreases right‑ventricular afterload and supports cardiac output.

• Inhaled nitric oxide diffuses into pulmonary vascular smooth‑muscle cells, where it activates soluble guanylate cyclase. This enzyme catalyzes the conversion of GTP to cyclic GMP, leading to smooth‑muscle relaxation, selective dilation of pulmonary vessels, and a consequent reduction in pulmonary arterial pressure without significant systemic effects.

Inhaled nitric oxide is generally well tolerated, but adverse reactions can occur.

Common Side Effects

• Headache: mild to moderate intensity.
• Flushing: transient warmth and redness of the skin.
• Nausea: occasional upset stomach.
• Cough: irritation of the airway during inhalation.
• Systemic hypotension: mild drop in blood pressure.
• Methemoglobinemia (low levels): mild elevation of methemoglobin.

Serious or Rare Side Effects

• Severe methemoglobinemia: symptomatic cyanosis requiring intervention.
• Rebound pulmonary hypertension: sudden rise in pressure after abrupt discontinuation.
• Nitrogen dioxide (NO₂) toxicity: pulmonary irritation from gas contaminants.
• Significant hypotension: may lead to dizziness or syncope.
• Hemorrhage: increased bleeding tendency in vulnerable patients.

Neophyr should be used with careful clinical monitoring and adherence to safety guidelines.

• Pregnancy: safety not established; prescribe only if potential benefit justifies the risk.
• Breastfeeding: insufficient data; consider risk versus benefit.
• Methemoglobin monitoring: regularly assess levels during therapy.
• Concomitant vasodilators: increased risk of systemic hypotension; adjust therapy as needed.
• Neonates and infants: require specialized dosing and close observation.
• Store at ambient temperature: keep cylinders upright, protect from heat and direct sunlight.

Inhaled nitric oxide can interact with other agents that affect vascular tone or nitric oxide pathways.

Major Interactions (Avoid)

• Phosphodiesterase‑5 inhibitors (e.g., sildenafil): additive pulmonary vasodilation may cause severe hypotension.
• Nitroglycerin or other systemic nitrates: risk of profound systemic blood pressure reduction.

Moderate Interactions (Monitor Closely)

• Inhaled anesthetics (e.g., sevoflurane): may enhance nitric oxide metabolism, requiring dose adjustment.
• Bronchodilators (e.g., albuterol): potential synergistic effect on airway smooth muscle.
• Anticoagulants: monitor for increased bleeding risk due to vascular changes.
• Oxygen therapy: ensure appropriate FiO₂ to avoid nitrogen dioxide formation.