WAFI 100/MG FC TAB 4/FC TAB

Indications

Approved Uses

Erectile dysfunction in adult men

Dosage & Administration

Dosing by Condition

Erectile dysfunction: Initial 50 mg approximately 1 hour before sexual activity; may adjust to 25 mg or 100 mg based on response and tolerability; max 100 mg per dose, once daily. Pulmonary arterial hypertension: 20 mg three times daily.

Initial Dose

50 mg approximately 1 hour before sexual activity (for erectile dysfunction)

Maintenance Dose

25mg to 100mg as needed for erectile dysfunction, based on efficacy and tolerability.

Maximum Dose

100mg in a 24-hour period for erectile dysfunction.

Children's Dosage

Not approved for children under 18 years for erectile dysfunction. For PAH in pediatric patients, dosing is weight-based and specialist-directed.

Dose Adjustment Notes

Reduce starting dose to 25 mg in elderly (>65 years), hepatic impairment, severe renal impairment (CrCl <30 mL/min), or concurrent use of CYP3A4 inhibitors

How to Take

Swallow 1 tablet whole with water by mouth, taken as needed about 30-60 minutes before sexual activity; may be taken with or without food, but a high‑fat meal can delay onset; do not take more than once in 24 hours.

Safety & Warnings

Contraindications

Contraindicated with: (1) concomitant nitrates in any form or nitric oxide donors (e.g., amyl nitrite), (2) concomitant guanylate cyclase stimulators (e.g., riociguat), and (3) known hypersensitivity to sildenafil or any excipient. Other items listed (e.g., severe hepatic impairment, recent MI/stroke, severe hypotension, retinitis pigmentosa) are generally warnings/precautions or situations where use is not recommended rather than absolute contraindications.

Warnings & Precautions

Key warnings/precautions: assess cardiovascular fitness for sexual activity and avoid use in unstable cardiovascular disease; risk of hypotension (especially with alpha-blockers/antihypertensives); priapism risk-use caution with penile anatomical deformity or predisposition (sickle cell disease, leukemia, multiple myeloma); advise urgent care for sudden vision loss (NAION) or sudden hearing loss; caution in bleeding disorders or active peptic ulcer; avoid combining with other PDE5 inhibitors.

Age Restriction

Not approved for use in individuals under 18 years for erectile dysfunction.

Drug Interactions

Drug Interactions

Major interactions: (1) nitrates/NO donors-contraindicated (profound hypotension), (2) riociguat-contraindicated (marked hypotension), (3) potent CYP3A4 inhibitors (e.g., ritonavir/cobicistat, ketoconazole/itraconazole, clarithromycin/erythromycin)-increase sildenafil exposure; dose limitation/avoidance may be needed, (4) CYP3A4 inducers (e.g., rifampin, carbamazepine, phenytoin, St John’s wort)-reduce effect, (5) alpha-blockers and other antihypertensives (including amlodipine)-additive BP lowering; separate dosing/start low and monitor, (6) other PDE5 inhibitors-avoid duplication.

Interaction Severity

MAJOR/Contraindicated: nitrates (e.g., nitroglycerin, isosorbide) and riociguat (risk of profound hypotension). MAJOR: strong CYP3A4 inhibitors (e.g., ritonavir/cobicistat, ketoconazole/itraconazole, clarithromycin) markedly increase exposure-avoid or use major dose reduction per labeling. MODERATE: alpha-blockers and other antihypertensives (additive BP lowering). MODERATE: CYP3A4 inducers (e.g., rifampin) may reduce efficacy.

Food Interaction

A high-fat meal can delay the onset of effect (and may reduce/slow peak exposure); otherwise no specific food restriction.

Special Populations

Children

Not approved for children under 18 years for erectile dysfunction. For PAH in pediatric patients, dosing is weight-based and specialist-directed.

Elderly

Start at 25 mg due to reduced clearance; titrate based on response and tolerability.

Kidney Impairment

CrCl 30-80 mL/min: no dose adjustment. CrCl <30 mL/min (severe renal impairment): consider a starting dose of 25 mg and titrate cautiously.

Liver Impairment

Hepatic impairment (ED dosing): consider a lower starting dose of 25 mg in hepatic impairment (e.g., cirrhosis); titrate based on response/tolerability. Severe hepatic impairment: use is not recommended/avoid due to limited data and increased exposure (not an absolute contraindication in most labeling).

Storage & Patient Advice

Missed Dose

Erectile dysfunction (as needed): not applicable-take only when needed; do not take an extra dose to ‘make up’ for a missed opportunity. Pulmonary arterial hypertension (scheduled use): take as soon as remembered unless close to the next dose; do not double doses.

Stopping the Medicine

For erectile dysfunction: may stop at any time (no taper required). For pulmonary arterial hypertension (PAH): do not stop abruptly; consult the prescriber before discontinuation.

Pharmacology

Mechanism of Action

Inhibits phosphodiesterase type 5 (PDE5), enhancing nitric oxide-mediated increases in cGMP in the corpus cavernosum, leading to smooth muscle relaxation and increased penile blood flow in response to sexual stimulation.

Onset of Action

Usually 30-60 minutes; some patients may notice effect as early as ~15-30 minutes.

Half-Life

3-5 hours

Bioavailability

Approximately 41% (range 25-63%)

Metabolism

Hepatic metabolism primarily via CYP3A4 (major) and CYP2C9 (minor) to an active metabolite (N-desmethyl sildenafil).

Protein Binding

Approximately 96%

Product Information

Available Dosage Forms

Film-coated tablet (this product); sildenafil is also available in some markets as tablets, powder for oral suspension, and injection (IV) for pulmonary arterial hypertension.

Composition per Dose

Each film-coated tablet: Sildenafil 100 mg (as sildenafil citrate)

Generic Availability

Yes

Mechanism

PDE5 Inhibitor

Onset Time

30-60 minutes

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