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Sildenafil (Viagra / Revatio)

PDE5 Inhibitorprescriptionoral · inferred

Selective PDE5 inhibitor for erectile dysfunction (Viagra) and pulmonary arterial hypertension (Revatio). Onset 30-60 minutes, duration 4-6 hours. Metabolized by CYP3A4 to active N-desmethyl metabolite (~50% potency, ~20% of pharmacologic effect). Take on empty stomach for faster onset.

Projected serum levels — 50 mg, as needed (shown daily)

Sildenafil (Viagra / Revatio)
Sildenafil (Viagra / Revatio) modeled serum levels, 50 mg as needed (shown daily) over 15 days Population-based pharmacokinetic estimate. Steady state reached after approximately 1 days. 0 5 10 15 20 Day 0 Day 4 Day 8 Day 11 Day 15 Time on a regular schedule ≈ steady state · day 1

Maintenance schedule: 50 mg as needed (shown daily) (oral).

Modeled steady state after ~1 days: peak ≈ 17.8 mg, trough ≈ 0.15 mg body load. Population-based estimate over 15 days for a 50 mg dose at a 70 kg reference body mass — the interactive app scales curves to your doses, timing, and body mass.

Key facts

Category
PDE5 Inhibitor
Route modeled
Oral
Model confidence
inferred
Half-life
4 h
Common dose
50 mg
Suggested maximum
100 mg/day
Reference dose range
25–100 mg (single dose)
Suggested cadence
as needed (shown daily)
Validated against
100 mg oral — Cmax 0.45 mg/L at 1 h

Documented interactions

  • contraindicated
    Efavirenz (Sustiva) + Sildenafil (Viagra / Revatio) CYP induction

    Efavirenz (Sustiva) inducer of CYP3A4 predicted to change Sildenafil (Viagra / Revatio) AUC by ~0.15x

  • contraindicated
    Rifampin + Sildenafil (Viagra / Revatio) CYP induction

    Rifampin inducer of CYP3A4 predicted to change Sildenafil (Viagra / Revatio) AUC by ~0.15x

  • danger
    Amlodipine (Norvasc) + Sildenafil (Viagra / Revatio) CYP inhibition

    Amlodipine (Norvasc) reversible_inhibitor of CYP3A4 predicted to change Sildenafil (Viagra / Revatio) AUC by ~2.27x

  • danger
    Ashwagandha (KSM-66) + Sildenafil (Viagra / Revatio) CYP inhibition

    Ashwagandha (KSM-66) reversible_inhibitor of CYP3A4 predicted to change Sildenafil (Viagra / Revatio) AUC by ~2.27x

  • danger
    Berberine + Sildenafil (Viagra / Revatio) CYP inhibition

    Berberine reversible_inhibitor of CYP3A4 predicted to change Sildenafil (Viagra / Revatio) AUC by ~2.27x

  • danger
    Black Seed Oil (Nigella sativa / Thymoquinone) + Sildenafil (Viagra / Revatio) CYP inhibition

    Black Seed Oil (Nigella sativa / Thymoquinone) reversible_inhibitor of CYP3A4 predicted to change Sildenafil (Viagra / Revatio) AUC by ~2.27x

Serum checks 218 modeled interaction pairings for sildenafil (viagra / revatio) across your whole stack — absorption conflicts, enzyme inhibition, and nutrient depletion included.

Research behind this entry

  1. Oral sildenafil in the treatment of erectile dysfunction Goldstein I et al. · New England Journal of Medicine, 1998 DOI

    Landmark NEJM dose-response trial showing 69% of intercourse attempts were successful with sildenafil versus 22% with placebo, establishing PDE5 inhibitors as first-line ED therapy.

  2. Sildenafil (Viagra) for male erectile dysfunction: a meta-analysis of clinical trial reports Moore RA et al. · BMC Urology, 2002 DOI

    Meta-analysis of 10 RCTs (3,254 men) finding dose-optimized sildenafil achieved at least 60% success in 49% of men versus 11% with placebo, with consistent efficacy across ED etiologies.

  3. Onset and duration of action of sildenafil for the treatment of erectile dysfunction Padma-Nathan H et al. · British Journal of Clinical Pharmacology, 2002 DOI

    Pharmacodynamic study establishing sildenafil onset of action at 14 minutes (earliest), clinical efficacy within 30 minutes, and duration of action of 4-5 hours post-dose.

3 published studies referenced in the app, each with a plain-language summary.