Background

• Continuous high BP in pulmonary artery > 25mmg Hg. (normal value = 14 mm Hg)
• PAH can be caused by heart disease, lungs disease, LV failure, recurrent pulmonary embolism, advanced liver disease.
• Symptoms include dyspnea, chest pain, syncope, edema, tachycardia and Raynaud's phenomenon (the reduced blood supply causes discoloration and coldness in the fingers, toes).

 

Treatment

• Prostacyclin analogue (PA): causes the vessels in the lung to expand and allow blood to move through with less resistance.
• Endothelin receptor antagonist: blocks endothelin - a vasoconstrictor.
• PDE5 inhibitor: relax blood vessel in the lung.
• CCB, diuretics, anticoagulants, chemotherapeutics (reduce abnormal cell growth)

 

PA:

• Drugs: Epoprostenol (Flolan, IV), Treprostinil (Remodulin, SQ/IV), Iloprost (Ventavis, inhalation)
• MOA: prostaglandin with potent vasodilatory effect and inhibit platelet aggregation. May potentiate effect of antihypertensive and antiplatelet.
• SE: flushing, HA, hypoTN, chest pain, edema. Chronic use: jaw pain. Iloprost (lock jaw)

 

Endothelin receptor antagonist

• Drugs: Bosentan (Tracleer), ambrisentan (Letairis).
• SE: peripheral edema, headache, palpitation, teratogenicity.
• CI in pregnancy, and monitor LFT, many DDI (3A4 substrate)
• Bosentan (Tracleer)
  • CI with concurrent use of cyclosporin or glyburide
  • Caution in patients with hepatic impairment, REMES drug, only available through TAP (tracleer access program).
• Ambrisentan: only available through restricted prescribing LEAP.

 

PDE5 inhibitor

• Drugs: sildenafil (Revatio, Viagra), tadalafil (Adcirca, Cialis)
• SE: drop in BP, dizziness, HA/flushing, priapism, sudden vision loss, sudden decrease of hearing
• Caution use with alpha blocker therapy, use a selective agent like tamsulosin, silodosin.
• CI: concurrent use of nitrates (24 hrs after sildenafil/vardenafil, 48 hr after tadalafil), illicit drugs (amyl nitrate, butyl nitrate, poppers)

 

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