Medicines

How Viagra tablet works in erectile dysfunction: an accidental discovery

How Viagra tablet works Posted On
Posted By SUMIT SHARMA

Introduction 

Today, I will explain the most fascinating and famous sexual medicine – Viagra. Here, we will see how Viagra tablet works in erectile dysfunction. 

Ok. Let me start my write-up with a serendipitous story of Viagra

In 1989, a pharmaceutical company – Pfizer, introduced a new molecule – Sildenafil Citrate

Initially, scientists worked on sildenafil for heart disease conditions like angina pectoris

During this research, sildenafil was given to heart disease patients. Then, an unexpected side effect was observed – erection of the penis.  

After this unexpected result, the scientists instantly reworked the clinical trial. Then instead of investigating sildenafil on heart disease, they started working on sildenafil for erectile dysfunction problems. 

In this way, sildenafil was accidentally discovered for erectile dysfunction. 

So, we have seen how sildenafil was discovered accidentally to permanently as a sex tablet. 

In this post, we will know everything about Viagra (sildenafil) drug. Let’s start the topic with basics concepts – 

 

What is erectile dysfunction?

Erectile dysfunction (ED) is a type of common sexual problem in men where you may have the following characteristics – 

  • Inability to achieve a complete erection of your penis, or
  • Inability to maintain the hardness of your erection that is required for satisfactory sexual performance, or
  • Low sexual desire or interest

 

This condition is also called “Impotence.

 

 

What percentage of guys have erectile dysfunction?

A survey in 2021 found that 53% – 59% of men in the US tell the erectile dysfunction (ED) problem, which has affected their relationship. 

We don’t have an exact number of data because men usually do not talk about it. 

But ED affects a lot of people. The incidence of ED goes up with age. 

A population-based study published in the journal BJU International, 2019 was observed 13.1 to 71.2% of erectile dysfunction globally. 

According to this study, ED is strongly associated with cardiovascular diseases like hypertension, angina pectoris, myocardial infarction, and ischemic heart disease.

The risk factors of heart disease and erectile dysfunction are generally similar –

  • Smoking
  • Increase age 
  • Diabetes
  • Hypertension
  • High cholesterol
  • Obesity

 

As per CDC, diabetes patients are three times more likely to have ED.

It is also associated with dyslipidemia, BPH (Benign Prostate Hypertrophy), and dementia.

Although ED is not a life-threatening problem but never underestimate your erectile dysfunction. Because it may be a strong risk marker of severe heart diseases and other medical conditions. 

 

What is Viagra?

Viagra is a popular brand that contains a medicine called Sildenafil citrate. It is also known as “blue diamond pills.”

How Viagra tablet works

It is a prescription-based drug and belongs to a group of medicines called PDE-5 (phosphodiesterase 5) inhibitors.

Well! There are four medicines used in this class – Sildenafil, Tadalafil, Avanafil, and Vardenafil. Currently, Sildenafil and Tadalafil are most commonly used.

Many countries have shown the most interest in Viagra: Greece, India, Australia, Canada, the UK, and the US. 

Viagra (or sildenafil) is a first-line drug used to treat erectile dysfunction (ED). 

Although, sildenafil does not give a permanent solution because it does not cure erectile dysfunction.

This drug gives only short-term sexual satisfaction. 

Sildenafil has also got approval from the FDA to treat pulmonary arterial hypertension (PAH). 

According to a study, sildenafil is occasionally used as an off label in the treatment of certain conditions – 

  • secondary Reynaud phenomenon (reduce blood flow towards fingers or toes due to underlying medical condition)
  • female sexual arousal disorder – FSAD (reduced excitement, sensation, or pleasure during sexual activity)
  • altitude-induced hypoxemia (severe lack of oxygen at high altitude)

 

Sildenafil citrate is also available in various brands with different prices – 

  • Penegra 25 mg, 50 mg & 100 mg (4 tablets in a strip, Price may vary as per strength Rs. 153 to 323) – Zydus Cadila
  • Viagra 50 mg & 100 mg (2 tablets in a strip, Price may vary as per strength Rs. 525 to 1055) – Pfizer ltd.
  • Caverta 25 mg, 50 mg & 100 mg (4 tablets in a strip, Price may vary as per strength Rs. 154 to 370) – Sun pharma
  • Silnafil 25 mg (10 tablets in a strip, Price Rs. 288) – Emcure Pharma Ltd. 
  • Vigore 50 mg and 100 mg (4 tablets in a strip, Price may vary as per strength Rs. 78 to 116) – Zydus Healthcare Ltd.

How Viagra tablet works

 

 

  • Vega 50 mg and 100 mg (4 tablets in a strip) – Mankind Pharmaceutical Ltd.

How Viagra tablet works

Does Viagra work to treat ED? 

Yes, it works. According to a study published in the Journal of Sexual Medicine, 2016 Sildenafil was found a highly effective and well-tolerated drug in treating erectile dysfunction. 

Another study published in European Urology; 2001 where overall efficacy of Viagra was found 77%.

 

But how does Viagra work to treat ED?

To better understand how Viagra tablet works, it is important to understand how normal sexual arousal occurs and what happens in erectile dysfunction. 

Normal sexual arousal 

Your erectile tissue or penis is well controlled by the autonomic nervous system.

The parasympathetic nervous system is stimulated during erection (enlarged penis). Whereas the sympathetic nervous system gets activated during ejaculation (discharge of semen). 

When you get to prepare for sex. Then sexual stimulation is occurred by neurons. During an erection, parasympathetic nerves get activated.

How Viagra tablet works

 

As a result of sexual stimulation, impulses from the brain hit the nerves around your penis. Then, it releases Nitric oxide (NO) in the endothelium of your blood vessels.

After releasing NO, it stimulates the Guanylyl cyclase (GC) enzyme, which increases the level of cyclic guanosine monophosphate (cGMP) inside the corpus cavernosum part of your penis. 

Due to this, the increased cGMP level activates the protein kinase G (PKG) enzyme, which inhibits the entry of calcium ions (Ca+2).

The reduction of intracellular calcium into the corpus cavernosum help in relaxing the smooth muscles that lead to vasodilation. 

Eventually, these events increase the flow of blood into your penis, which is responsible for erection.

How Viagra tablet works

 

Erectile dysfunction

In erectile dysfunction, a special enzyme is released called PDE-5 (Phosphodiesterase-5).

PDE-5 has a vital role in the regulation of intracellular cGMP. This cGMP helps in the contraction and relaxation of smooth muscles. 

The PDE-5 decreases the cGMP level, leading to sexual dysfunction or erectile dysfunction.

How Viagra tablet works

 

Effects after taking Viagra (mechanism of action) 

Sildenafil is a potent, selective PDE-5 inhibitor. This drug inhibits the phosphodiesterase enzyme that leads to widening blood vessels and increases blood circulation into the penis. 

How viagra tablet works

 

How quickly does Viagra work?

When you take the Viagra tablet, it quickly enters your bloodstream. It begins to work within 30 mins because the onset of action of sildenafil is 30 mins. 

You may get the maximum effect of Viagra within 1 hour. So, you should take a Viagra tablet 1 hour before sexual activity. 

Viagra does not work just by taking it. You must be sexually aroused with your partner to get a better result. 

How Viagra tablet works

 

How long does Viagra last?

The half-life of Viagra is 3 to 5 hours. This means 50% of Viagra eliminate from your body through urine. 

So, the effect of Viagra starts to reduce after 5 hours. But it doesn’t mean you can take another dose after 5 hours. 

Since Viagra takes 18 hours to thoroughly wash out from your body. So, you must take only a single dose in a day

How Viagra tablet works

 

 

How Viagra tablet works

Does the penis change in size before and after Viagra?

According to a research study, the average penis size falls within the following ranges: – 

 

  • 9.16 centimeters is the average length of a flaccid penis (about 3.6 inches)
  • 13.24 cm is the average length of a flaccid stretched penis (about 5.3 inches)
  • 13.12 cm is the average length of an erect penis (about 5.2 inches)
  • A flaccid penis has an average circumference of 9.31cm (about 3.7 inches)
  • 11.66 cm is the average circumference of an erect penis (about 4.6 inches)

 

If your penis size does not fall in these ranges. And you are struggling with decreased penis size or penis shrinkage. These problems are related to age, medication, smoking, and excessive weight.

 

Here, Viagra helps to make your penis more rigid and more erect. Before taking Viagra medicine, you may have decreased penis size. It generally happens in erectile dysfunction. In this condition, you are unable to achieve or maintain an erection.

 

But after taking the Viagra medicine, you can expand your penis gradually because Viagra allows you to achieve erections by increasing the blood flow towards your penis. 

How Viagra tablet works
Viagra before and after photos

 

What to consider before taking Viagra to ensure the best results?

Viagra or sildenafil comes as a pill in three strengths – 25 mg, 50mg, and 100 mg. The usual starting dose is 50 mg, and it is recommended dose for erectile dysfunction.

Viagra 50 mg can give you satisfactory penile erection for sexual activity. 

You can take it as required one hour before sex

How Viagra tablet works

To increase your chances of getting the optimum effects from using Viagra, there are a few things you should think about. These consist of:

1. Before You Take Viagra, Check for Drug Interactions

Certain drugs may cause severe drug interaction with Viagra. So, ensure you are not taking antihypertensive drugs (such as prazosin, tamsulosin, alfuzosin, amlodipine) and heart disease medications (such as nitrates, nicorandil). 

 

2. Sexually aroused before taking Viagra

Viagra does not work by itself. You need to be sexually aroused before taking Viagra medicine. As soon as Viagra begins to work, it helps maintain an erection even after ejaculation. So, you should take Viagra before sexual arousal. 

 

3. Ensure you are empty stomach before taking Viagra

Viagra works best when taken on an empty stomach or 2 hours after the meal because Viagra has a good response on an empty stomach. You may take a light meal before taking Viagra.

You should avoid high-fat meals (such as a cheeseburger, pizza, and french fries) while taking Viagra. These foods may decrease the rate of absorption of Viagra.

 

4. Avoid excessive alcohol before taking Viagra

According to some research, drinking moderate amounts of alcohol while taking Viagra is safe. However, drinking too much alcohol before taking Viagra can reduce your chances of getting an erection. So, it is best to avoid alcohol before taking Viagra.

 

What are the common side effects of Viagra?

Most people do not notice side effects. But the vasodilatory effect of Viagra may cause some common side effects –

1. Headache 

2. Flushing (redness of skin especially face)

3. Dizziness (or vertigo)

4. Hypotension (low blood pressure)

5. Loose motion

 

In many clinical studies, other side effects have been observed  –  

  • Nasal congestion
  • Body pain 
  • Visual disturbances (color discrimination of blue and green color)

 

What are the serious side effects of Viagra? 

Viagra may also cause some dangerous side effects, but it is infrequent (or very rare). You must consult your doctor if you get the following side effects because this is a medical emergency – 

1. Priapism – If you get a continued erection till 4 to 6 hours is called Priapism. If it is not treated, it can damage your erectile tissue, leading to impotence. 

2. Ototoxicity (hearing loss) – If you are unable to hear after experiencing Viagra. 

3. Seizure and syncope (fainting) 

 

Who should not take Viagra?

You need to require extra caution or avoid Viagra tablets in certain conditions – 

1. Viagra with other medicines 

a. Co-administered with nitrates and nicorandil

In 1998, FDA received 69 deaths reports after taking Viagra during sex. Among these, 20 people dead due to a combination of sildenafil and nitrates. 

You should strictly avoid sildenafil if you are on nitrates medicines (for treatment of angina pectoris) like Glyceryl trinitrate (GTN, Nitroglycerine), Isosorbide dinitrate (sublingual route), and Isosorbide mononitrate. 

Sildenafil also significantly drops your blood pressure while taking nicorandil drug (potassium channel opener).

Sildenafil may interact with nitrates and nicorandil, which leads to a synergistic effect. Due to this, it may cause severe life-threatening hypotension

How Viagra tablet works

 

b. Co-administered with alpha-blockers 

When you take sildenafil with antihypertensives drugs especially alpha blockers like Prazosin (Minipress), Tamsulosin (Veltam), Alfuzosin (Alfusin), etc.

These drugs significantly lower your blood pressure after interacting with sildenafil. 

You can experience symptoms such as dizziness, fainting, and light-headedness.  

 

c. Co-administered with amlodipine 

Sildenafil also decreases your blood pressure if you are already taking the amlodipine drug.  

 

d. Co-administered with ritonavir 

Ritonavir is an antiviral drug used to treat human immunodeficiency virus (HIV) infection.

If you take sildenafil during ritonavir therapy. Then you need to require extra caution because ritonavir 11 times increases the plasma concentration of sildenafil. It could be dangerous. 

 

2. Previous history of NAION

In NAION (non-arteritic anterior ischemic optic neuropathy), blood flow is already less to the optic nerve. If you take sildenafil in this condition, it may cause sudden vision loss.

 

3. Previous history of heart disease

You can’t take sildenafil if you are a patient of severe heart disease like ischemic heart disease (coronary artery disease), unstable angina, myocardial infarction, hypertension (BP >170/110 mmHg), and stroke. 

 

4. Previous history of Priapism 

You must consult your sexologist if you have had Priapism or Peyronie’s disease or any anatomical deformation of your penis in the past. 

 

5. Low blood pressure condition 

You need to avoid sildenafil in low blood pressure condition because sildenafil itself cause decrease blood pressure. If you take in this condition, you could dangerously drop your blood pressure. 

 

6. kidney disease 

According to a study, sildenafil is also associated with kidney disease. You need to consult your doctor before taking sildenafil while having kidney disease. 

 

7. Liver disease 

As per a study in 2017, sildenafil is rarely associated with hepatotoxicity. So, it is better to avoid sildenafil, even in liver disease

 

Can I take Viagra and Dapoxetine together?

Dapoxetine is an antidepressant drug used in the treatment of premature ejaculation. 

Premature ejaculation is also a type of sexual dysfunction where men release semen sooner, just before the beginning of sexual intercourse. 

Dapoxetine belongs to a group of medicine called SSRI (Selective Serotonin Reuptake Inhibitors). It helps to treat premature ejaculation by increasing serotonin content in your neurons. 

According to a study published in the International Journal of Impotence Research, 2019, sildenafil/dapoxetine combination therapy significantly improves erectile dysfunction and premature ejaculation conditions with mild side effects.

If you have premature ejaculation with erectile dysfunction problem. In that case, you may take sildenafil and dapoxetine medicines together under the proper medical supervision. 

These drugs are available in the market as an FDC (fixed-dose combination) – Sildenafil 50 mg and dapoxetine 30 mg. 

The combination of sildenafil and dapoxetine is also available in the market with different brand names and prices –

  • DA Sutra 30X (4 tablets in a strip, Rs. 264) – Hetero Drugs Ltd.
  • Duraforce tablet (4 tablets in a strip, Rs. 199) – Akumentis Healthcare Ltd.
  • Manforce Staylong tablet (4 tablets in a strip, Rs. 264) – Mankind pharma ltd.
  • Suhagara force (4 tablets in a strip, Rs. 239) – Cipla

 

Can women take sildenafil?

Still, sildenafil is not officially licensed to use in females. However, sildenafil is occasionally used as an off-label in treating female sexual arousal disorder (FSAD).

This drug can be prescribed in those women who have low sexual desire. As per a study, sildenafil drug can be the last option in the treatment of FASD. 

 

Conclusion 

That’s all about Viagra. 

In this post, we have seen how Viagra was discovered and how Viagra tablet works in erectile dysfunction. 

Initially, the journey of sildenafil started for heart disease. But during research, how did scientists change its indication after sildenafil’s unexpected side effects.

Many research studies have shown that sildenafil is a highly effective and well-tolerated drug.

Sildenafil can be safe only in erectile dysfunction conditions. But it can be hazardous if you are dealing with pre-existing medical conditions like heart disease and taking concomitant drugs like nitrates. 

You must consult your doctor before taking the sildenafil drug.

If you found this post (How Viagra tablet works) informative, please share it on social media.

Have questions? 

Let me know in the comments below. I will try my best to answer all of them. 

 

FAQ

Q1. Can I get Viagra without a prescription? 

Ans. No. Since Viagra is a prescription medicine, it could be dangerous if you take this drug without medical supervision. 

Q2. Does Viagra make you last longer?

Ans. Viagra works best if you have difficulty in erections during sex. Still, it does not delay your semen release when you are on orgasming. So, viagra is not the first choice in premature ejaculation. The combination of sildenafil and Dapoxetine gives you the best result in last longer effect. 

Q3. How do you know if you need Viagra?

Ans. If you cannot get enough erection during sex or if you don’t have a sexual desire with your partner. It indicates a problem of erectile dysfunction. In this condition, you may need Viagra. 

Q4. Does tadalafil work better than sildenafil?

Ans. Although, tadalafil and sildenafil have similar efficacy. But, according to a study, tadalafil is a better choice than sildenafil because tadalafil gives quick action (15 mins.), longer duration of action (half-life 18 hours), and minimum side effects. 

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2 thoughts on “How Viagra tablet works in erectile dysfunction: an accidental discovery
  1. Dr Arvind Singh

    Nice blog

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