PDE5 Inhibitor — Erectile Dysfunction Pregnancy: eMC §4.6: 'Spedra is not indicated for use in women. There are no data from the use of avanafil in pregnant women. Animal studies do not indicate direct or indirect harmful effects with respect to pregnancy, embryonal/foetal development, parturition, or postnatal development.' Breast-feeding: no data on use during breast-feeding. Fertility: no effect on sperm motility or morphology after single 200 mg oral doses in healthy volunteers, and daily avanafil 100 mg over 26 weeks was not associated with untoward effects on sperm concentration, count, motility or morphology.

Avanafil

Brand names: Spedra

Avanafil is an oral, rapid-onset phosphodiesterase type-5 (PDE5) inhibitor used on demand for erectile dysfunction. It is valued for its faster onset and short duration relative to some other agents in the class.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 100 mg taken as needed approximately 15 to 30 minutes before sexual activity; based on individual efficacy and tolerability the dose may be increased to a maximum dose of 200 mg or decreased to 50 mg

Route: Oral — may be taken with or without food, but if taken with food the onset of activity may be delayed compared with the fasted state

Frequency: As needed before sexual activity; 'The maximum recommended dosing frequency is once per day.' Sexual stimulation is required for a response to treatment

Max: 200 mg, once per day maximum dosing frequency. With moderate CYP3A4 inhibitors the maximum recommended dose should not exceed 100 mg, with at least 48 hours between doses (the US label caps this at 50 mg per 24 hours)

SOURCE: eMC UK SPC 'Spedra 100 mg tablets' §4.2, quoted verbatim, for use in adult men. ELDERLY (≥65 years): 'Dose adjustments are not required in elder patients. Limited data are available in elder patients aged 70 years or above.' HEPATIC IMPAIRMENT: contraindicated in severe impairment (Child Pugh class C); patients with mild to moderate impairment (Child-Pugh class A or B) 'should initiate treatment with the minimum efficacious dose and adjust posology based on tolerance.' DIABETES: no dose adjustment required. CYP3A4 INHIBITORS: co-administration with potent CYP3A4 inhibitors (ketoconazole, ritonavir, atazanavir, clarithromycin, indinavir, itraconazole, nefazodone, nelfinavir, saquinavir, telithromycin) is contraindicated; with moderate CYP3A4 inhibitors (erythromycin, amprenavir, aprepitant, diltiazem, fluconazole, fosamprenavir, verapamil) 'the maximum recommended dose of avanafil should not exceed 100 mg, with an interval of at least 48 hours between doses.' PAEDIATRIC: 'There is no relevant use of Spedra in the paediatric population in the indication of erectile dysfunction' — verify any under-18 use against a children's formulary. US CROSS-CHECK (differs — do not merge): starting dose 100 mg taken as early as approximately 15 minutes before sexual activity, increased to 200 mg (as early as ~15 minutes before) or decreased to 50 mg (approximately 30 minutes before), using the lowest dose that provides benefit; do not use with strong CYP3A4 inhibitors; with a moderate CYP3A4 inhibitor the dose should be no more than 50 mg in a 24-hour period; on stable alpha-blocker therapy the recommended starting dose is 50 mg. §4.4 of the SPC was truncated at the source-fetch limit.

Dose adjustments

Renal

eMC §4.2: 'Dose adjustments are not required in patients with mild to moderate renal impairment (creatinine clearance ≥ 30 mL/min). Spedra is contraindicated in patients with severe renal impairment (creatinine clearance < 30 mL/min).' Patients with mild or moderate renal impairment (creatinine clearance ≥30 mL/min but <80 mL/min) enrolled in phase 3 studies showed decreased efficacy compared with those with normal renal function.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or to any of the excipients
Patients using any form of organic nitrate or nitric oxide donors (such as amyl nitrite)
Co-administration with guanylate cyclase stimulators such as riociguat (risk of symptomatic hypotension)
Myocardial infarction, stroke or life-threatening arrhythmia within the last 6 months
Resting hypotension (blood pressure < 90/50 mmHg) or hypertension (blood pressure > 170/100 mmHg)
Unstable angina, angina with sexual intercourse, or congestive heart failure categorised as New York Heart Association Class 2 or greater
Severe hepatic impairment (Child-Pugh C)
Severe renal impairment (creatinine clearance < 30 mL/min)
Loss of vision in one eye because of non-arteritic anterior ischaemic optic neuropathy (NAION), whether or not connected with previous PDE5 inhibitor exposure; known hereditary degenerative retinal disorders
Patients using potent CYP3A4 inhibitors (ketoconazole, ritonavir, atazanavir, clarithromycin, indinavir, itraconazole, nefazodone, nelfinavir, saquinavir, telithromycin)

Side effects

Headache, flushing, nasal congestion and back pain — 'The most common adverse reactions reported in clinical studies were headache, flushing, nasal and sinus congestion and back pain' (common)
Dizziness, dyspepsia, nausea, vomiting, palpitations and sinus congestion (common/uncommon); vision blurred, hot flush, hypertension and exertional dyspnoea (uncommon)
Fatigue, asthenia, chest pain, influenza-like illness and peripheral oedema (uncommon); insomnia, premature ejaculation and somnolence (uncommon)
Muscle tightness, flank pain, myalgia and muscle spasms; rash; pollakiuria; penis disorder, spontaneous penile erection and genital pruritus (uncommon)
Investigations: hepatic enzyme increased, abnormal electrocardiogram, heart rate increased, blood pressure increased, blood in urine, prostate specific antigen increased, blood bilirubin and creatinine increased (uncommon/rare). Class effects reported with other PDE5 inhibitors — NAION, sudden loss of hearing and priapism — were not reported during avanafil clinical trials but are covered by §4.4 warnings

Interactions

Organic nitrates and nitric oxide donors — contraindicated; avanafil potentiates their hypotensive effect (the US label states that where nitrate administration is medically necessary in a life-threatening situation, at least 12 hours should elapse after the last avanafil dose, under close medical supervision with haemodynamic monitoring)
Guanylate cyclase stimulators such as riociguat (and vericiguat, US label) — contraindicated
Potent CYP3A4 inhibitors (ketoconazole, ritonavir, atazanavir, clarithromycin, indinavir, itraconazole, nefazodone, nelfinavir, saquinavir, telithromycin) — contraindicated
Moderate CYP3A4 inhibitors (erythromycin, amprenavir, aprepitant, diltiazem, fluconazole, fosamprenavir, verapamil) — maximum avanafil dose 100 mg with at least 48 hours between doses (UK); maximum 50 mg per 24 hours (US)
Alpha-blockers — concomitant use may lead to symptomatic hypotension in some patients; other antihypertensives and substantial amounts of alcohol (greater than 3 units) may also lead to hypotension (US §5.6, 5.7). PDE5 inhibitors potentiate the anti-aggregatory effect of the nitric oxide donor sodium nitroprusside at supratherapeutic doses in vitro

Clinical monograph

How it works

It selectively inhibits PDE5, preventing breakdown of cyclic GMP in the corpus cavernosum so that, with sexual stimulation, smooth-muscle relaxation and penile blood flow are enhanced.

Prescribing in practice

Absolutely contraindicated with any nitrate or nicorandil because the combination can precipitate profound, life-threatening hypotension.
Avoid co-administration with alpha-blockers and other antihypertensives unless the patient is haemodynamically stable, owing to additive blood-pressure lowering.
Reduce exposure or avoid with potent CYP3A4 inhibitors and in significant hepatic or renal impairment as detailed in the SPC.

Monitoring

No routine laboratory monitoring is required, but cardiovascular fitness for sexual activity and blood-pressure tolerability should be assessed clinically.

Counselling the patient

Take before anticipated sexual activity; effect needs sexual stimulation to work.
Seek urgent care for an erection lasting several hours (priapism) or sudden vision or hearing loss.
Never combine with nitrate-containing heart medicines or recreational 'poppers'.

Evidence & guidelines

Licensed for erectile dysfunction on the basis of randomised on-demand trials demonstrating improved erectile function scores versus placebo.

Reference: NICE NG44 (Erectile Dysfunction); EAU Sexual Dysfunction Guidelines 2024; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Drugs

Vardenafil · PDE5 Inhibitor — Erectile Dysfunction

Pathways