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PDE5 Inhibitor — Pulmonary Arterial Hypertension / Raynaud's Phenomenon Pregnancy: Avoid — insufficient data for PAH use in pregnancy; PAH itself carries very high maternal mortality

Sildenafil

Brand names: Revatio (PAH), Viagra (ED)

Adult dose

Dose: PAH: 20 mg 3 times daily; Raynaud's (off-label): 25–100 mg once daily
Route: Oral (tablet or oral suspension)
Frequency: 3 times daily (PAH); once daily (Raynaud's)
Max: 20 mg TDS (PAH licensed dose — higher doses not shown superior in SUPER-2)
Take without regard to food. Onset: 30–60 minutes. PAH: Revatio 20 mg formulation — distinct from Viagra 25/50/100 mg (ED). In Raynaud's: used off-label for digital ulcer prevention in systemic sclerosis. Avoid nitrates concurrently — severe hypotension.

Paediatric dose

Route:
Seek specialist opinion — paediatric PAH under specialist cardiology; caution: STARTS-2 showed increased mortality with higher doses in children

Dose adjustments

Renal

CrCl <30 mL/min: start at 20 mg BD; renal failure: active metabolite accumulates

Hepatic

Start at lower dose; Child-Pugh C — avoid

Clinical pearls

  • SUPER-1 trial: sildenafil 20 mg TDS improved 6MWD and haemodynamics in PAH — established as first-line PAH therapy
  • STARTS-2 (paediatric): higher doses (40/80 mg TDS) associated with increased mortality — MHRA warning; 20 mg TDS only if paediatric use considered
  • Riociguat is an absolute contraindication — both enhance cGMP pathway and cause unpredictable severe hypotension
  • In digital ulcers (scleroderma): sildenafil reduces frequency of new ulcers (SEDUCE trial)
  • Combination upfront therapy (e.g., sildenafil + ambrisentan — AMBITION trial) now preferred over monotherapy in eligible PAH patients

Contraindications

  • Concurrent nitrates or nitric oxide donors (absolute — severe hypotension)
  • Concurrent riociguat (absolute)
  • Severe hepatic impairment
  • Recent stroke or MI (<6 months)
  • Hereditary degenerative retinal conditions

Side effects

  • Headache
  • Flushing
  • Epistaxis
  • Dyspepsia
  • Visual disturbances (blue tinge, blurred vision)
  • Hypotension
  • Nasal congestion
  • Priapism (rare)

Interactions

  • Nitrates — absolute contraindication (profound hypotension)
  • Riociguat — absolute contraindication
  • Alpha blockers — additive hypotension
  • CYP3A4 inhibitors (ketoconazole, ritonavir, erythromycin) — increase sildenafil levels — reduce dose
  • CYP3A4 inducers (rifampicin) — reduce efficacy

Monitoring

  • Blood pressure (especially at initiation)
  • 6-minute walk distance (6MWD)
  • Echocardiography and RHC for PAH response
  • Visual symptoms
  • Pulmonary function

Reference: BNFc; BNF 90; SUPER-1 Trial; STARTS-2 Trial; NICE TA235 (Sildenafil for PAH); ESC/ERS PAH Guidelines 2022. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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