Medically reviewed by Thomas Fischer (Pharmacist). This article was written according to medical standards. More Info

Medically reviewed by Thomas Fischer (Pharmacist)More Info

Phosphodiesterase 5 inhibitors, also known as PDE-5 inhibitors, are prescription drugs. The first drugs have been around since the mid-1980s and are commonly used to block degradative enzymes. These enzymes are a form of protein that can degrade molecules. 

This article will look at PDE-5 inhibitors in more detail. It will specifically focus on what to know and look out for before you consider buying them online. 

What Are PDE-5 Inhibitors Used For?

PDE-5 inhibitors assist in the regulation of blood flow to the pulmonary arteries. PDE-5 inhibitors stop or block phosphodiesterase type 5 enzymes. PDE-5 enzymes are found in blood vessel walls, and are widespread throughout the body, and more specifically in the lungs and penile tissue.

A similar type of cell can be found in the blood vessels of the lungs and those of the penis. PDE-5 inhibitors are thus often prescribed in the treatment of erectile dysfunction (ED). When these enzymes are stopped, blood vessels can relax, and more blood can flow to specific parts of the body, in this case, the penis. 

Erection

PDE-5 inhibitors are often used in the treatment of high blood pressure, specifically in the heart and lung arteries. This condition is known as pulmonary hypertension, more commonly referred to as high blood pressure. PDE-5’s are used to regulate or increase blood flow to the lungs and heart. This, in turn, lowers blood pressure.

PDE-5 inhibitors are also used in the treatment of enlarged prostate glands. This condition is known as benign prostatic hyperplasia (BPH).

Most PDE-5 inhibitors are taken orally, and this drug class does require a prescription from a medical doctor. It is not possible to get PDE-5 inhibitors as an over the counter (OTC) treatment option. 

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Which Active Substances Are Found In PDE-5 Inhibitors?

There are four significant PDE-5 inhibitors on the market to treat ED. These are Viagra, Cialis, Levitra, and Stendra. There are also generic versions of these known brands on the market. All PDE-5 inhibitor brand names and their generic alternatives are available with a prescription only. These drugs cannot be obtained over the counter without a valid one. 

All PDE-5 inhibitor brand names and their generic alternatives are available with a prescription only. These drugs cannot be obtained over the counter without a valid one. 

Sildenafil (Brand Names: Viagra & Revatio)

Sildenafil citrate, the active ingredient in Viagra, was the first to receive FDA approval and was the first to market. This PDE-5 inhibitor was launched in 1998. 

Viagra Definition

Sildenafil is mainly used in the treatment of erectile dysfunction (Viagra) and pulmonary arterial hypertension (Revatio). Pfizer manufactures Viagra, and in 2017 a generic or non-branded version of the active ingredient sildenafil citrate was put to market by a generic manufacturer. This is simply known as Sildenafil.

Tadalafil (Brand Names: Cialis & Adcirca)

The active ingredient in Cialis and Adcirca is Tadalafil. Cialis is prescribed to treat erectile dysfunction and Adcirca to treat pulmonary hypertension.

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Tadalafil is available as a generic or non-branded version known as Tadalafil. Tadalafil is only available with a prescription. It cannot be purchased over the counter or without medical consultation.

Vardenafil (Brand Names: Levitra, Staxyn, and Vivanza)

The active ingredient vardenafil hydrochloride can be found in Levitra, one of the four best-known ED treatment brands. It is also available as a generic oral ED medication, and with prescription only. 

The generic alternative is known as Vardenafil, named after the active ingredient. Staxyn and Vivanza contain the same active ingredient but are lesser-known brands. Staxyn is a version of Levitra that dissolves, and it is still taken orally, but not in tablet format. 

Avanafil (Brand Name: Stendra)

Stendra is one of the lesser-known ED prescription medications available. It contains the active ingredient avanafil and is sold under two trademark names, Stendra or Spedra.

Stendra does not yet have a generic alternative. It is newer to the market and was approved by the US FDA in 2012. Avanafil is, therefore, less comparable with the other ED treatment brands and PDE-5 inhibitors active ingredients noted in this article.

Users should be mindful when offered a cheaper generic alternative, as this will be a counterfeit PDE-5 inhibitor product.

How Do Phosphodiesterase 5 Inhibitors Work in the Body?

The straightforward answer to how PDE-5 inhibitors work is that they open up blood vessels or arteries. Open blood vessels or arteries result in increased blood flow to specific parts of the body. PDE-5 inhibitors specifically target organs such as the heart, lungs, and the penis. These PDE-5s stop an enzyme or protein in the arterial walls and help regulate blood flow to the pulmonary arteries and the penis.

By blocking PDE-5s from working, the blood vessels can relax, open up, and more blood can flow to the specific parts of the body. This process is known as vasodilation or the dilation of blood vessels. Dilated arteries decrease blood pressure, in the case of pulmonary hypertension. 

In instances of treatment for ED, they work a little differently. When sexually aroused, nitric oxide is produced by the body with the help of cyclic guanosine monophosphate (cGMP). This relaxes the muscle layer of the blood vessels, allowing for blood flow into the penis, causing an erection. 

In some people, PDE-5 attacks this enzyme, resulting in restricted blood flow, and no erection. The inhibitor blocks the PDE-5 from doing this, allowing things to occur as expected.

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How Are Phosphodiesterase 5 Inhibitors Taken?

PDE-5 inhibitors are mostly taken orally. There are slight differences between the various options of PDE-5 inhibitor brands currently on the market.

As an example, Sildenafil or Viagra is ideal for occasional use, and the effects can last up to 5 hours. Should these options not work, Vardenafil or Levitra may be an alternative to try. Tadalafil or Cialis is another option. It is usually taken as a dose of between 20mg to 40mg, and it has an added benefit of lasting for up to 36 hours. It’s also available in a daily dose of a much smaller amount, 2.5-5mg only.

The best option will always be part of a comprehensive treatment plan, as prescribed by a qualified and registered healthcare professional. They will consider the patient’s symptoms, current medical status, and medical history to find the best possible option. This is the main reason that PDE-5 inhibitors are not available without a prescription.

ED medication may take a while to work, and it may not work at first. It is recommended to try ED treatments at least four times. If the ED treatment has still not had the desired outcome, a patient should consult their healthcare practitioner and consider one or a combination of the following options.

What Are The Side Effects Of PDE-5 Inhibitors?

The FDA approved PDE-5 inhibitors on the market have an excellent safety profile. However, as with any medication, there are risks associated with taking them.

Most of the commonly known side effects do not last long and some of these may disappear over time, as the patient adjusts or gets used to the medication. The most common side effects include, but is not limited to the list below: 

Some of the more severe but less common side effects include, but is not limited to: 

The PDE-5 inhibitors are deemed to be safe and effective for use by some patients with cardiac conditions and high blood pressure, i.e., chronic coronary heart disease and hypertension. 

It is always required that a person seeking ED treatment speak to a medical professional and disclose any chronic disease. These conditions will affect and influence the treatment plan as it may lead to adverse side effects. 

PDE-5 Inhibitors - Interaction With Other Drugs

The use of PDE-5 inhibitors with other drugs may be safe. However, it is crucial to disclose any other medication used to the medical professional. This reason is that it may affect and influence how the PDE-5 inhibitors function. Taking PDE-5s in conjunction with other drugs may further lead to people experiencing ordinary and or even adverse side effects. 

PDE-5 inhibitors should not be taking with the following medications:

Patients using PDE-5 inhibitors should ideally also avoid consuming large amounts of alcohol. The manufacturers of ED recommend no more than three to five units of alcohol.

The Contraindications Of PDE-5 Inhibitors

PDE-5 inhibitors are contraindicated with certain pre-existing medical conditions such as:

All users should first and always consult a medical healthcare practitioner before taking PDE5 inhibitors. Contraindications like severe side effects could be ruled out by asking a medical practitioner and disclosing your full medical history. 

Assumption About the Cost Of PDE-5 Inhibitors

PDE-5s are not covered by medical insurance when used in the treatment of ED. Prices vary between brands and between dispensing pharmacies. Generic alternatives to known PDE-5 inhibitor brands are available and are often a more cost-effective treatment option.

Some pharmacies may also offer coupons that could lower the price. Payment options like cash versus credit may also affect the cost of PDE-5 inhibitors. Some manufacturers and pharmacies may also offer trial packs as a ‘try before you buy’ option, to ensure that the treatment is effective before committing to longer-term treatment plans.

The following guidelines may assist in finding the most cost-effective treatment plan for users.

Sildenafil is deemed to be a cost-effective PDE-5 inhibitor option for treating ED. It is moderately priced in comparison to other drugs. It has a generic alternative, and when prescribed for severe heart and lung conditions, it may be covered by medical insurance plans.

Tadalafil is a more expensive option. It is available as the branded version Cialis, or as a generic option. When prescribed for the treatment of BPH or PAH, it may be covered by medical insurance. 

Vardenafil is also a more expensive option, and it is available as a generic and under the brand name Levitra. Much like Sildenafil and Tadalafil, it may be covered by medical insurance when prescribed for specific medical treatments.

Article Sources

We at Cialis-Online-Prescription.com only use accredited sources and references for content creation. Read our editorial guidelines to learn more about how we determine medical facts and prepare our content in a technically correct, reliable and trustworthy manner.
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