Efficacy of sildenafil citrate at 12 hours after dosing: re-exploring the therapeutic window

Clinical Trial

. 2004 Sep;46(3):357-60; discussion 360-1.

doi: 10.1016/j.eururo.2004.04.025.

Ignacio Moncada 
¹
, José Jara, David Subirá, Irene Castaño, Carlos Hernández

Affiliations

Affiliation

• ¹ Urology Department, Hospital General Universitario Gregorio Marañón, Madrid, Spain. [email protected]

• PMID:

  15306108

• DOI:

  10.1016/j.eururo.2004.04.025

Clinical Trial

Ignacio Moncada et al.

Eur Urol.

2004 Sep.

. 2004 Sep;46(3):357-60; discussion 360-1.

doi: 10.1016/j.eururo.2004.04.025.

Authors

Ignacio Moncada 
¹
, José Jara, David Subirá, Irene Castaño, Carlos Hernández

Affiliation

• ¹ Urology Department, Hospital General Universitario Gregorio Marañón, Madrid, Spain. [email protected]

• PMID:

  15306108

• DOI:

  10.1016/j.eururo.2004.04.025

Abstract

Objective:

This open-label study investigated the efficacy of sildenafil citrate at 12 hours postdose among prior treatment responders.

Patients and methods:

Eight 100-mg doses of sildenafil were provided to 40 eligible patients with erectile dysfunction (ED), who were to record the results of each sexual attempt in a patient diary. Each patient was instructed to make a sexual attempt at 1 and 12 hours postdose on 4 occasions (part 1) and only at 12 hours postdose on 4 subsequent occasions (part 2).

Results:

Of 40 enrolled patients, 34 (85%) completed the study. In these evaluable patients, 97% and 74% of patients achieved erections that resulted in successful intercourse at 1 hour and 12 hours postdose, respectively. There was a nonsignificant reduction in the percentage of responders at 12 hours during part 1 versus part 2 of this study (71% versus 78%).

Conclusions:

This study demonstrates that, in the majority of these patients with ED, sildenafil remains clinically active 12 hours after administration. Larger studies may be necessary to confirm and clarify the therapeutic window of sildenafil.

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How Often Can You Take Sildenafil?

In 30 seconds…

You can take Sildenafil, an erectile dysfunction medication, every day, up to the maximum recommended dosage of 100mg. Provided you have no pre-existing health issues, and you’re not taking any other ED medications alongside Sildenafil, it is perfectly safe to take several days in a row (or even every day).

Erectile dysfunction (ED) is extremely common, yet it can shake any man’s confidence. There is a stereotypical view of men’s sexual urges – that all men want sex all the time. This generalisation can make life especially challenging for the 40% of men who have difficulty getting, and keeping, an erection before they hit 40, and over 50% of men who have some difficulty after 40.

A man may fear judgement, or worry that their partner doesn’t feel attractive if their interest in sex – or ability to have sex – changes. ED is often a taboo subject, or at least a subject that you don’t wish to discuss every time you try to have sex. If you’re looking for medication for erectile dysfunction, Sildenafil is likely to be one of the drugs you’re researching, alongside the famous branded drug, Viagra.  

One of the most common questions is about how often you can take Sildenafil. Sex can be pre-planned or spontaneous, and most of us would like the option for sex to be either. Flexibility and variety are important elements of your sex life. Fortunately, Sildenafil can be taken every day, so there’s no need to ration your amount of between-the-sheets action! But there is a daily dose maximum of 100mg.

About Sildenafil and Viagra

Viagra has been popular for decades, and recently Pfizer’s patent for the drug expired – allowing a generic unbranded medication, Sildenafil, to be produced and sold by accredited online pharmacies. Sildenafil is the active ingredient in Viagra, so it’s exactly the same – aside from the brand name. This means it can be taken just as often as Viagra – every day, if you’re seeking the desired effects this often. 

Viagra and Sildenafil are both reliable, safe, and officially-approved medications. Due to the fact that Sildenafil is a PDE5 inhibitor, it causes blood vessels to expand and relax. For this reason, it was originally developed as a drug for cardiac conditions. However, the benefits for erectile dysfunction were soon understood and the medication was pushed to the front line of the battle against ED.

When your brain sends pyschosexual signals down your spinal cord, this encourages an erection. The penis retains the increased blood within it and stays temporarily stiff. Sildenafil acts on the enzymes responsible for muscle contraction within the blood vessels; allowing better blood flow to – and within – the penis. Thus, making erections easier to achieve and maintain if you are sexually aroused.

How Often Should You Take Sildenafil in a Day?

While it’s possible to take Sildenafil every day, there is a restriction on the daily dosage. The maximum dose within a 24-hour period would be 100mg. In any case, studies have shown that a higher dose than 100mg in one day doesn’t have any added benefit – and could increase the chances of side effects.

The most common dosage is 50mg, and this has sufficient effect for the huge majority of men who take Sildenafil for ED. On the rare occasion that 50mg is insufficient or inappropriate, Sildenafil can also be taken in 25mg or 100mg doses. Consult a Manual clinician if you’re in doubt about which dose suits you.

The 50mg dose is usually sufficient to make it easier to gain and maintain an erection for 4-5 hours. If you take Sildenafil, it’ll start to work within approximately 60 minutes. So aside from keeping your Sildenafil close by or in your bedside draw, you don’t need to plan very far in advance before sex – which gives you extra flexibility and peace of mind. Even if you’re a man with a very active sex life, you should be covered.

Another popular ED medication is Cialis – or Tadalafil, the unbranded version of Cialis. This is another PDE5 inhibitor, so it works in a similar way to Sildenafil. However, it gets to work quicker and it can last for up to 36 hours. It’s nicknamed the “weekend pill” for this reason. 

If you’re thinking of taking Tadalafil, wait 24 hours after taking Sildenafil – and vice versa. Multiple ED medications should not be taken at the same time. And there’s no need to try: it won’t help.

“With great power comes great responsibility”

Luckily, most men experience no side effects when they take Sildenafil or Tadalafil. And if side effects do occur, they’re generally very mild – issues like facial flushing or dizziness. 

However, you should always be open and honest in the medical questionnaire before progressing with your treatment. For example, if you’ve had a cardiac issue such as a stroke or heart attack in the previous 6 months, PDE5 inhibitors like Sildenafil and Tadalafil should be avoided. It’s important to give a true account of your health and medical history – to allow your clinicians to supply safe medication for you.

Furthermore, the fact that Sildenafil is an approved medication for ED and used around the globe shouldn’t deter you from reading the accompanying patient information leaflet. Always arm yourself with the information, and remember that everybody’s response to medication is slightly different.

Key Takeaways

Sildenafil can be taken every day, up to the recommended maximum dosage of 100mg. It helps men with erectile dysfunction enjoy more adventure and freedom – because it is a highly-effective and minimally-disruptive medication that can get to work in less than an hour. Whether you go for non-branded Sildenafil medication or the famous Viagra drug, both options are safe, approved, and often very effective – though you’ll still need to be relaxed and sexually aroused for an erection to occur.

For lots of men in the UK, Sildenafil offers an important helping hand. Stress hormones are shown to interfere with a man’s ability to reach an erection, so just knowing it’s nearby can reduce the anxiety about sexual performance – making erections achievable and sex more enjoyable. You can take Sildenafil every day if you need to – or keep it on hand for the occasions when you need assistance.

FAQs

What is Sildenafil?

Sildenafil is a PDE5 inhibitor, expanding and relaxing blood vessels to make erections easier to achieve and maintain. It is the active ingredient in the branded ED medication Viagra, and works exactly the same way.

Do you need a prescription to buy Sildenafil?

You no longer need a prescription to buy Sildenafil or Viagra, however, you do need to fill out a questionnaire at the pharmacy, which will allow the pharmacist to determine if Sildenafil is suitable for you, or not. Be honest and truthful on your questionnaire, to minimise the risk of experiencing side effects from the medication.

How often can you take Sildenafil?

The average dose of Sildenafil is 50mg, which begins to work within an hour and can help you achieve and maintain erections for the next 4-5 hours. However, you can safely take up to 100mg of Sildenafil in any 24hr period. You can take up to 100mg of Sildenafil every day, provided you experience no side effects.

Can you take Sildenafil and Tadalafil at the same time?

No, you should never mix two erectile dysfunction medications together. There is no added benefit to taking Sildenafil and Tadalafil at the same time, and it can be dangerous to do so.

While we’ve ensured that everything you read on the Health Centre is medically reviewed and approved, information presented here is not intended to be a substitute for professional medical advice, diagnosis, or treatment. It should never be relied upon for specific medical advice. If you have any questions or concerns, please talk to your doctor.

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Erectile Dysfunction
articles

How Viagra works for men and women, instructions for use, composition

THERE ARE CONTRAINDICATIONS. POSSIBLE SIDE EFFECTS. A SPECIALIST’S CONSULTATION IS REQUIRED. For men

The author of the article

Ershov Grigory Vasilievich,

Urologist

All authors

The content of the article

• How VIA works gra
• Viagra for men
• Viagra: how to take and how much it works
• Viagra for women
• Viagra and alcohol
• Viagra or Cialis — what is better

Do you know the history of Viagra discovery?

During clinical trials of a new heart drug, scientists noticed a “side effect” in male patients. This observation marked the beginning of a new era in the treatment of erectile dysfunction (ED). The drug Viagra appeared in 1998 and “blew up” the global pharmaceutical market.

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How Viagra works

The famous Viagra contains the active ingredient Sildenafil. The drug is produced in tablets of three dosages – 25 mg, 50 mg and 100 mg.

Viagra acts in the body through a complex chain of biochemical reactions. As a result, they lead to relaxation of the muscular walls of the vessels of the cavernous bodies in the penis and filling them with blood. This ensures a natural response to sexual arousal.

It is important to understand that Viagra does not treat the cause of erectile dysfunction (ED), it simply helps to cope with the consequences. Viagra does not increase sexual desire. If there is no attraction to a partner, then the medicine is useless.

Viagra for men

The drug was created for men and has the only indication for use:

• treatment of erectile dysfunction.

The clinical efficacy of Viagra has been confirmed by numerous world studies.

Here is an example of one of the clinical trials: 12 weeks after the start of taking the drug, an improvement in erection was noted by 76% of patients who received Viagra, and 22% of those who received placebo (that is, “pacifiers”).

The advent of Viagra has changed the lives of millions of men in the world. Patients with erectile dysfunction thanks to her return to a normal sexual life.

Despite the high efficiency, in a number of patients taking the drug does not lead to an improvement in erection. This is due to the wrong medication or the fact that ED is simply a consequence of another disease. In such cases, consultation and examination with a doctor is required.

Viagra: how to take and how much it works

How to take Viagra pills correctly:

• oral, on an empty stomach – coated tablets
• with or without water – orodispersible tablets
• recommended daily dose of 50 mg
• 60 minutes before sexual activity
• multiplicity – no more than 1 time per day
• maximum daily dose 100 mg

the recommended dose may be reduced to 25 mg or increased to 100 mg depending on the efficacy, tolerability of the drug and diseases in the patient

Data from the study of the drug showed that increasing the dose to 200 mg did not lead to an increase in the effect, but side effects (headache, “hot flashes”, dizziness, stomach problems, nasal congestion, visual disturbances) became more frequent.

The drug begins to act 30 minutes after ingestion. Active for 2-4 hours.

Viagra is contraindicated in patients:

• receiving nitrate therapy for heart disease
• in severe liver disease
• for severe heart failure, heart attack, stroke, arrhythmias
• for too high and low blood pressure
• for diseases of the optic nerve
• in case of hypersensitivity to sildenafil and drug components
• under 18

It is safe to take the drug if you follow the instructions and consult your doctor first. All medications taken on a regular basis must be reported. A number of drugs are incompatible with Viagra.

Viagra for Women

Viagra is not intended for use in women for its registered indication. The drug does not affect the sexual arousal of a woman in any way.

Viagra and alcohol

There are no instructions on the incompatibility of alcoholic beverages and Viagra in the instructions.

The drug at a dose of 50 mg did not enhance the hypotensive effect of ethanol at low blood concentrations in healthy volunteers.

But the general recommendation – do not take alcohol in combination with drugs – also applies to Viagra.

Ethanol depresses the central nervous system, increases heart rate, burdens the liver and kidneys.

Viagra has serious restrictions and contraindications.

Therefore, it is better to refrain from taking alcoholic beverages while taking the drug. Then you can not be afraid of imposing the negative effects of drugs and alcohol on the body.

Viagra or Cialis — what is better

Viagra is the first drug, branded and still popular. A little later, his main competitor Cialis appeared. The cardinal differences between drugs are the chemical formula and duration of action. Tadalafil in Cialis “supports” a man for 36 hours. For this reason, the drug quickly became widespread in all countries. Other differences are shown in the table:

Viagra and Cialis are prescription drugs. The selection of therapy should be carried out by a doctor, taking into account the patient’s age, condition, concomitant diseases, and medications already taken.

If the physician recommends both, the patient’s preference and personal experience will help decide which is better.

Viagra was the first effective and safe drug for the treatment of erectile dysfunction. She made a breakthrough in the history of sexual medicine. Analogues and generics, which appeared later, will long remain second in people’s minds. This does not detract from their importance – the choice allows you to expand the circle of users, choose the best remedy for individual indications.

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Viagra: truth and myths

If we say the word “pharmacy”, then your mind will surely give out an association – “medicine”, but if we say “Viagra”, then a little awkwardness and a blush will come to mind. In this article, we debunk the most popular myths about the most famous drug that was awarded the Nobel Prize, and in the history of discoveries, Viagra ranks third in importance after X-rays and antibiotics!
What is success?

What is Viagra

Like many things in our world, the purpose of Viagra was revealed quite by accident. After all, this drug was conceived by Pfizer as a heart drug that would promote blood flow to the heart muscles, lower blood pressure, and get rid of angina pectoris.
The developers only wanted to serve for the benefit of mankind by reducing the development of cardiovascular diseases. But the case “smelled” fried at the stage of clinical trials. The experimental men noted that the drug did not improve the functioning of the heart in any way, but their sex life sparkled with new colors for them. The subjects refused to return the drug. After research, it was decided to start mass production of a drug that would help get rid of erectile dysfunction. And at the stage when the world learned about the existence of Viagra, there was a lot of speculation and even misinformation about what it is and “what it is eaten with”.

Myth #1 – If you put Viagra on a man, he will crave intimacy.

This, of course, is not true. And to explain this conjecture, you need to understand how the drug works. Its basis is sildenafil, which is responsible for increasing blood flow to the male genital organ and for the occurrence of a long and high-quality erection in case of excitation. Viagra has proven effective in a man with problems with potency and erectile dysfunction, can improve the quality of sexual life and return full-fledged vivid sensations from intimacy. But the pill itself is not capable of provoking sexual desire or causing arousal. That is, if you add Viagra to a man who does not plan to have intimacy, the declared effect will not come and he will not run after you. With good intentions and the right actions, the effect of Viagra occurs 30-60 minutes after ingestion.

Myth #2 – Viagra affects everyone equally

Not true. Viagra is positioned as a drug to eliminate impotence and erectile dysfunction. It will not have any effect on a healthy person. It will not work with thrombophlebitis, vasoconstriction and other diseases with a serious violation of blood circulation in the body. You should not expect the effect of Viagra and with a low level of testosterone in a man, with defects in the inner lining of blood vessels and with atherosclerosis. In addition, even under the influence of alcohol, the pill is not able to have the long-awaited effect.

Myth №3 – Viagra is intended for older men who have obvious problems with potency.

It is not true. Viagra can be taken by men from the age of 18, in cases where there are even slight deviations in erection. Often there is a problem when a man is easily and quickly excited, but the quality of erection decreases after a while. Viagra is also indicated in such cases.

Myth #4 – Viagra is a drug that, with regular use, can restore male strength.

It is not true. When you want to cheer up, you take a cool shower and drink coffee. But they do not provide a cure for constant drowsiness and lethargy. Viagra also acts as a “doping”. Permanent use should be agreed with a specialist, because the tablet also has contraindications.

Myth #5 – Viagra has no effect on a woman.

This is partly true. The instruction states that the original drug Viagra is intended exclusively for men. The impact on the circulatory system and stimulation of blood flow to the genitals during intimacy is the same for both men and women. Therefore, one can only suggest that the pill will affect the woman, stimulate the flow of blood to the pelvic organs, which, if the woman is aroused, will increase the quality of intimacy. However, there have been no reliable studies in this area. So you should not abuse and experiment, because there is a large selection of special tools on the market that can solve specifically women’s problems of a sexual nature.

Myth #5 – If one pill doesn’t work, you should take 2.

It is not true. And never do that if you don’t want to end up in the ICU. The fact is that the active substance of Viagra affects the cardiovascular system, kidneys, gastrointestinal tract. To abuse such drugs for the sake of the “wow” effect means knowingly introducing yourself into the risks of dangerous consequences. In addition, after taking 1 tablet of Viagra, it is not recommended to use such substances and preparations for the next 24 hours. You should not use Viagra at all if you:

• Other nitrogen donors were used. They are often used by athletes during the training period. Remember, if you are using another nitrogen donator, then you do not need a potency improver.

• You use steroids. Steroids improve the synthesis and absorption of Viagra by cells, as a result, it should be used in half the dose or not taken at all.

• They abused alcohol. Of course, a glass or two of wine at a romantic dinner will not have a significant impact. But large doses of alcohol when combined with Viagra can lead to serious consequences, up to a heart attack.

• Are you taking blood pressure medication regularly?

Myth #6 – Viagra can help if erectile dysfunction in men is caused by psychological problems.