Table 4:

Advantages and disadvantages of the inhaled route for administration of PAH Medications

Advantages	Disadvantages
Local delivery, potentially higher concentration of medication in the target organ, which enhance the efficacy	Irritant effects on airways
Avoidance of systemic adverse effects, including systemic hypotension	Limitation of medication dose due to airway symptoms
Delivery to ventilated areas, vasodilatation improves V˙/Q˙ and gas exchange	Delivery systems can be cumbersome and time consuming
Potentially lower total dose of medication with less frequent administrations and lower cost	May be very costly
Rapid drug absorption and fast onset of effect
Avoidance of the first-pass metabolism due to the low enzymatic activity of the lung

V˙/Q˙= ventilation/perfusion ratio