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Phospho-Dieste Rase-5 (PDE5) Inhibitors

  1. Sildenafil
  2. Tadalafil
  3. Vardenafil

  • Oral

  • Sildenafil 12.5 mg daily, typically used with Bosentan 125 mg daily (an endo- thelin-1 antagonist)

  • Inhibition of phosphodiesterase iincreasing cyclic guanosine monophosphate in smooth muscle cell leading to vasodilation

Off-label

  • Sildenafil: 
    • Raynaud phenomenon or digital ulcerations associated to systemic sclerosis
    • Accelerate healing of chronic + non-healing skin ulcers in patients with antiphospholipid antibodies

  • Hypersensitivity
  • Patients on nitrates or nitric oxide donors
  • * Precaution with history of myocardial infarction, angina, hypo- / hypertension

  • Headache
  • Flushing
  • Dyspepsia
  • Nasal congestion

  • Sildenafil: CYP3A4 substrate > CYP2C9

* For further reading refer to a pharmacology source