Key Takeaways
- Viagra increases blood flow to the penis by relaxing blood vessel muscles during sexual arousal
- The medication requires sexual stimulation to work and does not cause automatic erections
- Proper medical guidance and prescription are necessary for safe and effective use in the Philippines
Viagra (Sildenafil): Mechanism of Action and Role in Erectile Dysfunction
Sildenafil citrate blocks a specific enzyme in the body to help men achieve and maintain erections during sexual activity. The drug requires natural arousal to work and differs from other ED medications mainly in how long it stays active in the body.
How Sildenafil Improves Erection in Men
Sildenafil works as a PDE5 inhibitor that blocks phosphodiesterase type 5, an enzyme found in the smooth muscle cells of blood vessels. When this enzyme is blocked, cyclic guanosine monophosphate (cGMP) levels increase in the penis.
Higher cGMP levels cause the smooth muscles in penile blood vessels to relax. This relaxation allows more blood to flow into the penis, making it easier to achieve an erection.
The medication can start working in as little as 20 minutes, though most men take it 30 to 60 minutes before sexual activity. The effects may last up to 18 hours in some cases.
Sildenafil only enhances the body's natural response. It does not create an erection on its own or increase sexual desire.
Interaction with Sexual Stimulation
Sexual arousal must occur for sildenafil to produce an erection. The drug supports the body's natural mechanisms rather than creating artificial responses.
When a man becomes sexually stimulated, his nervous system releases nitric oxide in the penis. This chemical messenger triggers the production of cGMP, which starts the erection process. Sildenafil keeps cGMP levels high by preventing its breakdown.
Without sexual stimulation, nitric oxide is not released. This means sildenafil will not cause spontaneous erections. The medication requires the complete natural pathway of arousal to function properly.
Comparison with Other ED Medications: Tadalafil, Levitra, and Cialis
All major ED medications work as PDE5 inhibitors but differ in duration and onset time.
Medication | Active Ingredient | Duration | Onset Time |
|---|
Viagra | Sildenafil | 4-6 hours | 30-60 minutes |
Cialis | Tadalafil | Up to 36 hours | 30-60 minutes |
Levitra | Vardenafil | 4-5 hours | 25-60 minutes |
Tadalafil stays active much longer than sildenafil, earning it the nickname "the weekend pill." Men who prefer spontaneity often choose Cialis because they don't need to time it as precisely.
Levitra has a similar duration to Viagra but may work slightly faster in some men. All three medications have comparable effectiveness rates for treating erectile dysfunction. The choice between them often depends on lifestyle preferences, side effects, and cost considerations in the Philippines.
Using Viagra (Sildenafil) in the Philippines: Guidelines, Accessibility, and Safety
Sildenafil citrate requires proper medical guidance and understanding of local regulations for safe use. Patients need to know where to obtain authentic medication, proper dosing instructions, and potential health risks.
Prescription and Availability in Philippine Pharmacies
Sildenafil is a prescription medication in the Philippines. Men seeking erectile dysfunction treatment must first consult with a doctor to receive a valid prescription. Licensed pharmacies throughout the country stock various brands including Viagra, RiteMED Sildenafil, and Andros.
The FDA has warned about counterfeit versions circulating in the market. In 2021, the agency issued an advisory about fake Viagra 100mg tablets sold in unauthorized outlets. These counterfeit products may contain harmful ingredients or incorrect dosages.
Patients should only purchase from FDA-licensed establishments. The agency provides a verification portal at verification.fda.gov.ph where people can check if a product is registered. Local brands like Andros from Unilab offer more affordable alternatives to imported Viagra while maintaining quality standards.
How to Use Sildenafil Citrate: Dosage, Onset, and Administration
The standard recommended dose is 50mg taken approximately one hour before sexual activity. Doctors may adjust the dose based on effectiveness and tolerability. Some patients may need 25mg while others require 100mg.
Key Administration Guidelines:
- Take the tablet orally with water
- Time the dose about 60 minutes before intercourse
- Sexual stimulation is required for the medication to work
- Do not take more than one dose per day
The medication typically begins working within 30 to 60 minutes. Effects can last up to four hours. Food may delay absorption, particularly high-fat meals. Taking sildenafil on an empty stomach may produce faster results.
Precautions, Side Effects, and Drug Interactions
Critical Safety Warning: Sildenafil should never be taken with nitrates or guanylate cyclase stimulators. This combination can cause dangerous drops in blood pressure.
Common side effects include:
- Headache
- Flushing
- Indigestion
- Nasal congestion
- Dizziness
- Vision changes
Men with heart disease need medical evaluation before use. The medication affects blood flow throughout the body, not just the penis. Patients taking medications for HIV should inform their doctor, as some antiretroviral drugs interact with sildenafil.
Sildenafil does not protect against sexually transmitted infections including HIV, hepatitis B, gonorrhea, or syphilis. Proper protection methods remain necessary during sexual activity.
Seek immediate medical attention if an erection lasts longer than four hours. This condition, called priapism, can cause permanent damage. Stop taking the medication and contact a doctor if vision or hearing loss occurs suddenly.
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