Pulmonary Vasodilators

Property Nitric Oxide Iloprost Sildenafil
Class Inorganic gas Synthetic eicosanoid with prostacyclin activity
Uses ARDS, RVF, PHTN PHTN PHTN, erectile dysfunction
Presentation Aluminium cyclinders with 100/800ppm NO/N2 Synthetic analog of epoprostenol
Route of Administration Inhaled Inhaled PO
Dosing 1-40ppm, via inspiratory limb of ventilator 20mg TDS
Absorption 40% PO bioavailability
Distribution Avidly bound to Hb 95% protein bound, VD of 100L
Metabolism Metabolised to methaemoglobin and nitrite prior to reaching systemic circulation - t1/2 of < 5s Hepatic by CYP450
Elimination Faecal
Mechanism of Action Stimulates cGMP which reduces intracellular Ca2+ Stimulates cAMP which reduces intracellular Ca2++ and smooth muscle growth Inhibits cGMP
Resp Inhibits HPV, improves V/Q matching
CVS ↓ vascular resistance, ↓ PVR in ventilated alveoli and improving V/Q matching. ↑ Capillary permeability. ↓ BP with compensatory ↑ HR ↓ PVR
CNS CBF
Haeme Inhibits platelet aggregation. MetHb Inhibits platelet aggregation
Other Rebound pulmonary HTN on abrupt cessation

References

  1. Peck TE, Hill SA. Pharmacology for Anaesthesia and Intensive Care. 4th Ed. Cambridge University Press. 2014.
  2. Smith S, Scarth E, Sasada M. Drugs in Anaesthesia and Intensive Care. 4th Ed. Oxford University Press. 2011.
Last updated 2017-09-22

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