Clinical beta

FMBM is currently in clinical beta. Content is for professional review/testing and must not replace local protocols, senior clinical judgment, or official prescribing references.

Drug Monograph

Sildenafil

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USE IF: ED: PRN use only after nitrate / riociguat / alpha-blocker reconciliation and hemodynamic stability. PAH: scheduled maintenance under cardiology–PH protocol β€” never PRN ED dosing logic.

AVOID IF: - Any nitrate use (GTN, ISMN, ISDN) β†’ severe / life-threatening hypotension - Riociguat β†’ severe hypotension Also avoid: severe hypotension; unstable cardiovascular status (e.g. recent MI, decompensated HF); hypersensitivity β€” reconcile GTN spray, patches, recreational nitrites.

Sildenafil

Phosphodiesterase-5 (PDE5) inhibitor β€” vasodilator

AdultERWardClinicCardiologyPulmonary hypertensionUrologyHigh-yield

Indication

ED (PRN before activity) β€’ PAH (scheduled TID-style regimens per protocol) β€” not interchangeable

At a glance

INDICATIONS (CORE USE)

- ED: erectile dysfunction β€” PRN dosing - PAH: pulmonary arterial hypertension β€” scheduled maintenance (separate indication, product, and dose framework from ED)

ADULT DOSE (STANDARD)

ED (PRN): - 25–100 mg PO ~30–60 min before activity - Start lower if elderly, hepatic impairment, renal impairment, or CYP3A4 inhibition PAH (scheduled): - 20 mg TID per protocol (follow approved product / institution) ED and PAH dosing are NOT interchangeable.

MAX DOSE

ED (PRN): - Product-limited per dose / interval (commonly up to 100 mg per dose β€” verify label) PAH (scheduled): - Protocol / product maximum β€” do not apply ED max logic to PAH

Route

PO

PEDIATRIC DOSE

Specialist / protocol-based only

Do not miss

Must-not-miss safety points

Major warning

- Nitrates (any route): ABSOLUTE contraindication β†’ severe / life-threatening hypotension - Riociguat: contraindicated β†’ profound hypotension risk - Hypotension risk with alpha-blockers, volume depletion, other vasodilators / antihypertensives - Unstable cardiovascular status (e.g. recent MI, severe hypotension, decompensated HF) - Priapism β†’ urgent evaluation if prolonged - Visual and hearing adverse effects: rare but can be serious

Indications

Primary β€” erectile dysfunction

  • Erectile dysfunction (PRN use before sexual activity)

Primary β€” pulmonary arterial hypertension (separate use pattern)

  • Pulmonary arterial hypertension (scheduled maintenance; protocol-based β€” not PRN)

Dosing

STANDARD (ADULT PO)

ED (PRN): - 25–100 mg PO ~30–60 min before activity PAH (scheduled): - 20 mg TID per protocol - Not PRN β€” continuous scheduled therapy

ADULT DOSE

ED (PRN): - Titrate within labeled range - Start lower if frail, hepatic impairment, renal impairment, or CYP3A4 inhibition PAH (scheduled): - Continuous dosing β€” titration by PH team / labeling CYP3A4 inhibitors β†’ ↑ sildenafil exposure β†’ dose reduction per labeling / pharmacy

PEDIATRIC DOSE

Specialist / protocol-based only

MAX DOSE

Indication-specific maxima β€” never use ED limits as PAH limits

Practical Note

- ED vs PAH: different strengths, schedules, and monitoring β€” do not mix instructions - Never combine with nitrates (including intermittent ACS therapy β€” reconcile timing) - Alpha-blockers: additive hypotension β€” separate or stagger dosing per labeling if combination unavoidable - Riociguat: do not co-administer

Warnings

Clinical warnings

  • Hypotension (vasodilators, diuretics, hypovolemia, postural context)
  • Headache, flushing, dizziness
  • Visual disturbance (including rare serious optic neuropathy)
  • Hearing changes / sudden hearing loss (rare)
  • Priapism β€” prolonged painful erection β†’ urgent care
  • Unstable cardiovascular status (e.g. recent MI, severe hypotension, decompensated HF) β€” avoid until cardiology clearance

Contraindications

  • Nitrate therapy
  • Riociguat
  • Severe hypotension
  • Known hypersensitivity

Drug interactions (high-impact)

  • Nitrates β†’ life-threatening hypotension (absolute contraindication)
  • Riociguat β†’ profound hypotension (contraindicated)
  • Alpha-blockers β†’ additive hypotension (caution; dosing separation per labeling)
  • Strong / moderate CYP3A4 inhibitors β†’ ↑ sildenafil exposure β†’ dose reduction per labeling
  • Other vasodilators and antihypertensives β†’ additive BP lowering

Special populations

Pediatrics

Specialist / protocol-based only

Pregnancy

Indication-specific labeling (e.g. Revatio vs Viagra) β€” specialist direction; risk–benefit per OB/PH team when applicable.

Lactation

See lactation references and product labeling.

Renal impairment

Adjust as clinically appropriate; renal impairment may increase exposure β€” reconcile CYP3A4 inhibitors and BP.

Hepatic impairment

Cardiovascular: avoid unstable status (e.g. recent MI, severe hypotension, decompensated HF) β€” nitrate / antianginal reconciliation before any use. Hepatic impairment: lower starting dose / cautious use (CYP3A4 metabolism; inhibitors more consequential).

Elderly

Start lower; increased sensitivity to hypotension and adverse effects β€” early BP and symptom check after initiation or dose change.

Administration

- ED: take before planned activity (PRN timing ~30–60 min) - PAH: scheduled dosing only β€” around-the-clock per protocol - Do not use ED and PAH administration instructions interchangeably

Monitoring

  • Monitor: - BP - Dizziness / near-syncope / syncope - Visual and hearing symptoms
  • Recheck: - After initiation or dose change - Ongoing on PAH therapy (team metrics per protocol) - If persistent hypotension or syncope: reassess nitrates, alpha-blockers, CYP3A4 inhibitors β€” do not continue blindly
  • Hold if:
    - SBP <90 or symptomatic hypotension
    - Syncope / presyncope
    - Severe visual symptoms
    - Priapism β†’ urgent evaluation

Overdose / toxicity

Clinical Picture

- Hypotension - Tachycardia - Visual symptoms

Immediate Actions

- Supportive care - BP support: avoid nitrates; fluids / vasopressors per protocol if needed - Continuous monitoring; widen differential if nitrate co-ingestion possible

Antidote

None

Decontamination

Acute oral overdose: supportive care; toxicology if refractory hypotension or diagnostic uncertainty.

Escalation

ICU / cardiology for refractory shock, ischemia, or airway compromise per protocol.

Clinical pearls

Common mistakes, resistance logic, and bedside traps

High-Yield

  • Never combine with nitrates
  • Ask explicitly about nitrate use before prescribing
  • ED = PRN; PAH = scheduled therapy β€” different logic

Clinical

  • Biggest prescribing error: missed nitrate (patch, spray, tablet, recreational nitrites)
  • Alpha-blocker combination needs caution and labeling-based separation

Safety

  • Priapism is an emergency
  • Riociguat is a hard stop combination

Pharmacy Tool

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Sildenafil 2.5 mg/mL oral suspension

suspension Β· oral

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Pharmacokinetics

- Hepatic metabolism (CYP3A4) - Shorter acting than tadalafil

Mechanism of action

- PDE5 inhibition β†’ ↑ cGMP β†’ smooth muscle relaxation / vasodilation (corpus cavernosum and pulmonary vasculature)

Common brand names

Saudi Arabia

Viagra, Revatio

Global

Viagra (ED), Revatio (PAH), (placeholder β€” verify local formulation)

Common trade names are curated examples only β€” formulations and availability vary. Verify the exact product name with your local pharmacy and national regulator before prescribing or dispensing.

Country practice notes

Global data (no country-specific data available)

  • Follow local antimicrobial stewardship policy, hospital formulary, and national resistance guidance.
  • Confirm dosing, stock, and restrictions with institutional pharmacy and current product labeling.

References

Saudi Arabia

  • SFDA (Saudi Food & Drug Authority)
  • Saudi National Formulary / MOH (where available)

International

  • WHO Model List of Essential Medicines (verify current edition)
  • US FDA or EU EMA product information (when national SmPC is unavailable)
  • FDA / SFDA / EMA product labeling (Viagra vs Revatio indication-specific)
  • ESC / ERS pulmonary hypertension guidance (where applicable)
  • ACC / AHA ACS pathways (nitrate interaction context)