Article

Sildenafil

Sildenafil is a medication primarily used to treat erectile dysfunction (impotence) in adult men. It belongs to a class of drugs called phosphodiesterase type 5 inhibitors (PDE5 inhibitors).

Sildenafil is the active ingredient in Viagra

Sildenafil is most known by the brand name Viagra. It is a medication primarily used to treat erectile dysfunction, also known as impotence, in men. Sildenafil was originally developed by Pfizer and was approved as a treatment for erectile dysfunction in 1998. In addition to treating impotence, sildenafil is also used to treat high blood pressure in the arteries of the lungs, a condition called pulmonary arterial hypertension.

How does Sildenafil work?

Sildenafil works by inhibiting the enzyme phosphodiesterase type 5 (PDE5). This leads to an increase in cyclic guanosine monophosphate (cGMP) in the body. Consequently, the smooth muscles in the walls of blood vessels relax, particularly in the corpus cavernosum of the penis, allowing for increased blood flow and thereby facilitating erection during sexual stimulation. Sildenafil does not have a direct relaxing effect on smooth muscle; instead, it enhances the effect of nitric oxide, which is released during sexual stimulation and activates guanylate cyclase to increase cGMP levels.

Sildenafil side effects

Common side effects

These side effects may affect between 1 and 10 out of 100 users:

Headache
Facial redness (hot flashes)
Digestive problems such as heartburn
Yrsel
Nasal congestion
Changes in vision, such as blurred vision or light sensitivity

Less common side effects

These occur in 1 to 10 out of 1000 users:

Nausea and vomiting
Rash
Irregular heartbeat
Muscle pain
Fatigue or exhaustion

Uncommon side effects

These affect 1 to 10 of 10,000 users:

Blood pressure changes, which can lead to a feeling of fainting
Stroke or heart attack
Sudden nosebleed
Changes in hearing

Rare and serious side effects

Although rare, some serious side effects can occur:

Sudden vision loss or impairment
Prolonged and sometimes painful erections (priapism) lasting longer than four hours

It is important to contact a doctor immediately if you experience severe symptoms such as sudden vision loss or an erection lasting longer than four hours.

Sildenafil Dosage

The dosage of sildenafil depends on what it is used for and can vary from person to person. Here is a simple guide:

For erectile dysfunction (impotence)

Standard starting dose: 50 mg
When: Take as needed, approximately one hour before sexual activity
How often: At most once per day
Adjustment: The dose can be increased to 100 mg or decreased to 25 mg depending on efficacy and side effects.

Important to remember:

Do not take more than one dose per day
Sildenafil only works if you are sexually stimulated

For pulmonary hypertension (high blood pressure in the lungs)

Usual adult dose: 20 mg three times daily
Time interval: Take doses 6-8 hours apart
For children: Dosage varies based on weight, usually between 10-20 mg three times daily

What to consider when using Sildenafil

Swallow the tablets whole with water
For the treatment of impotence, it is best to take sildenafil on an empty stomach – the effect may be delayed if you take it with food
If you have kidney or liver problems, your doctor may recommend a lower dose.
Older adults (over 65 years of age) generally do not require any dose adjustment.

Remember to always follow your doctor's instructions and never change your dose on your own. If you have questions about your dosage, speak with your doctor or pharmacist.

Pharmacokinetics of Sildenafil

The pharmacokinetics of sildenafil describes how the drug moves through the body, from the time it is taken until it is eliminated. Here is a simple explanation:

Absorption

Fast absorption When sildenafil is taken orally, it is rapidly absorbed into the body. It typically reaches its highest concentration in the blood within 30 to 120 minutes, with a mean of approximately 60 minutes.
The Influence of Food If sildenafil is taken after a high-fat meal, the rate of absorption decreases, and it may take longer to reach maximum concentration, which can slightly reduce the effect.

Distribution

Distribution volume Sildenafil is distributed throughout the body's tissues with an average volume of 105 liters, meaning it does not just remain in the blood but also enters various tissues.
Protein binding Approximately 96% of sildenafil binds to plasma proteins in the blood, which affects how much of the drug is active and available to take effect.

Metabolism

Breakdown in the liver: Sildenafil is broken down in the liver, primarily by an enzyme called CYP3A4, and to a lesser extent by CYP2C9. This process creates a metabolite that also has an effect, but only half as strong as sildenafil itself.
The role of metabolites: This metabolite accounts for approximately 20% of sildenafil's total effect.

Excretion

Elimination via feces and urine: After being metabolized, sildenafil is excreted primarily in the feces (approximately 80%) and, to a lesser extent, in the urine (approximately 13%).
Half-life Sildenafil has a half-life of about 3 to 5 hours, meaning it takes that long for the amount of active drug in the body to be halved.

Alternatives to Sildenafil

There are several alternative treatments to sildenafil (Viagra) for erectile dysfunction (ED). Here are the main options:

Other PDE5 inhibitors

Tadalafil (Cialis):
- Lasts longer than sildenafil, up to 36 hours
- Sometimes called the ”weekend pill” due to its long duration of action
- Starts to work after approximately 2 hours

Vardenafil (Levitra):
- Seems faster than sildenafil
- Good for spontaneous sex because you don't have to take it far in advance

These drugs work similarly to sildenafil by increasing blood flow to the penis.

Topical treatments

Alprostadil (Bondil, Vitaros):
- A medication inserted into the urethra
- Arriving within 10-15 minutes
- Can be used if tablets don't work or aren't suitable

Injection treatment
- Medications injected directly into the penis
- Can be effective when tablets don't work
- Alternatives such as aviptadil and phentolamine are available

Other options

Vacuum pump: A mechanical device that draws blood into the penis
Penile Implants: A Surgical Solution Used in Severe Cases

It is important to remember that all these treatments require a prescription from a doctor. The doctor can help find the best treatment based on individual needs and any other health problems.

Shockwave therapy as an alternative to Sildenafil for erectile dysfunction

Shockwave therapy, also known as extracorporeal shock wave therapy (ESWT), is a non-invasive treatment method that uses mechanical pressure waves to stimulate healing in the body. This method has been used since the 1980s and has been developed to treat various musculoskeletal problems as well as erectile dysfunction.

How does shockwave therapy work?

Mechanism: The treatment generates shock waves that are transmitted into the affected area. These waves create an inflammation-like reaction that increases blood circulation and metabolism, thereby accelerating the body's natural healing processes.
Effect: The shock waves can break down damaged tissue and calcifications, leading to pain relief and improved tissue regeneration.

Use for erectile dysfunction

For erectile dysfunction, shockwave therapy is used to improve blood flow to the penis, which can help restore normal erectile function. The treatment can be particularly useful for those who do not respond well to traditional medications like sildenafil.

Benefits of shockwave therapy

Non-invasive: Requires no surgical procedures.
Fast treatment time: Usually lasts between 5 and 15 minutes per session.
Long-lasting results: Can provide lasting improvements after just a few treatments.

Side effects and precautions

Mild side effects: May include pain during treatment, bruising, or increased pain shortly after treatment1.
Not suitable for everyone: Individuals with certain medical conditions, such as heart problems or those taking blood thinners, should avoid this treatment.

Shockwave therapy is a promising option for those seeking alternatives to medication for erectile dysfunction and other muscle-related issues. However, it is important to consult a doctor or specialist before starting treatment to ensure it is appropriate based on individual health conditions.