Essential BNF Sildenafil Reference Information
BNF Dosing Guidelines
According to BNF guidance, sildenafil for erectile dysfunction should be initiated at 50mg approximately one hour before sexual activity. The dose may be adjusted to 25mg or increased to a maximum of 100mg based on individual response and tolerability. The maximum frequency is once per 24-hour period. Elderly patients or those with hepatic/renal impairment should start with 25mg.
Contraindications and Precautions
The BNF clearly states sildenafil is contraindicated with nitrates due to severe hypotensive effects. Other contraindications include severe cardiovascular disease, recent stroke or myocardial infarction within six months, and severe hepatic impairment. Caution is advised with alpha-blockers, antihypertensives, and in patients with anatomical penile abnormalities or predisposition to priapism.
Drug Interaction Troubleshooting
Critical interactions include nitrates (potentially fatal hypotension), riociguat, and potent CYP3A4 inhibitors like ketoconazole or ritonavir. When co-prescribed with alpha-blockers, ensure patient is stable on alpha-blocker therapy before initiating sildenafil at the lowest dose. Monitor blood pressure carefully during combination therapy.
Common Effectiveness Issues
If sildenafil appears ineffective, verify proper administration timing (30-60 minutes before activity on relatively empty stomach), confirm adequate sexual stimulation, and check for interfering medications or alcohol use. Consider dose adjustment within licensed range or investigate underlying cardiovascular, neurological, or psychological factors affecting response.
Side Effect Management
Common adverse effects include headache, flushing, and nasal congestion. These are usually mild and transient. Serious side effects requiring immediate medical attention include sudden vision or hearing loss, chest pain, or prolonged erection exceeding four hours. Patients should be counselled on when to seek urgent medical care.
Prescribing Considerations
EverydayMeds provides both branded Viagra and generic sildenafil following comprehensive clinical assessment by UK-licensed prescribers. All patients undergo cardiovascular risk evaluation and medication review before treatment approval. Both formulations contain identical active ingredients with equivalent efficacy and safety profiles, allowing patient choice based on preference and cost considerations.
