Avanafil and sildenafil are both PDE5 inhibitors. What is the difference between them?

A friend left a message to Huazi, saying that the medicine prescribed by the doctor is called Avanafil, a new drug launched in September 2021. He had been using Sildenafil before, so what is the difference between Avanafil and Sildenafil, and what should be paid attention to when using them?

Huazi told him that Avanafil was launched in the United States as early as April 2012, but it was launched in China later. Avanafil and sildenafil are the same type of drugs, both of which are phosphodiesterase type 5 (PDE5) inhibitors. However, sildenafil is the first generation of PDE5 inhibitors, while Avanafil is the fourth generation.

1. Both are PED5 inhibitors

In terms of pharmacological mechanism, avanafil and sildenafil are the same and can both inhibit PDE5. When men are sexually stimulated, the cavernous blood vessels release nitric oxide (NO), which in turn leads to increased release of cyclic guanosine monophosphate (cGMP), causing the cavernous muscles to relax and blood perfusion to increase.

However, some middle-aged and elderly men suffer from erectile dysfunction (ED) due to reduced blood perfusion due to aging, excessive psychological stress, chronic diseases, vascular stenosis and other factors. PDE5 inhibitors inhibit PDE5, reduce the decomposition of cGMP, increase the level of cGMP in blood vessels, increase its effect, thereby increasing blood perfusion and improving ED symptoms.

Second, there are differences in adverse reactions between the two

Sildenafil is a first-generation PDE5 inhibitor that has a significant effect on improving ED. When it was first introduced, it was even called "Viagra". However, during its use, the main factor that affects patients' medication is the occurrence of adverse reactions.

Common adverse reactions of sildenafil include headache, facial flushing, nasal congestion, indigestion and visual impairment. Sildenafil can increase the antihypertensive effect of other antihypertensive drugs, and severe hypotension may occur if used in combination with antianginal nitrate drugs.

Avanafil and sildenafil have different chemical structures, and their absorption and distribution in the human body are quite different. In relevant clinical trials, the incidence of adverse reactions of avanafil was significantly lower than that of sildenafil. When used in combination with other antihypertensive drugs and nitrates, the effect of avanafil on blood pressure was also lower than that of sildenafil.

3. There is a difference in the duration of action between the two

After taking sildenafil orally on an empty stomach, it will reach its peak blood concentration after 60 to 120 minutes. However, if it is taken with a high-fat meal, the absorption rate will be reduced, the peak time will be delayed by an average of 60 minutes, and the peak blood concentration will decrease by an average of 29%.

In actual application, most of the time it is taken after "eating and drinking", so when using sildenafil, it is necessary to calculate the time of taking the medicine, otherwise there will likely be an embarrassing situation where the atmosphere is there but the drug effect is not yet achieved.

Avanafil takes effect in about 15 minutes after oral administration, reaches the peak blood concentration in 30-45 minutes, and eating does not affect the medication. You can take the medication at any time as needed to achieve immediate results.

4. Differences in metabolic time between the two

Avanafil is metabolized faster than sildenafil and will be broken down and excreted faster. From the perspective of pharmacokinetic, drugs with faster metabolism are safer. Because drugs with slower metabolism are more likely to accumulate and cause toxic reactions. Especially for the elderly over 65 years old, the body's metabolic function will be further reduced, making it more likely to have toxic side effects.

You don't have to worry about the fast metabolism affecting the efficacy of the drug, because for "medication", it is enough to last for a few dozen minutes. The existing PDE5 inhibitors can meet the needs. So from the perspective of safe medication, avanafil is more suitable for the elderly.

5. The dosage of the two drugs is different

The commonly recommended dose of sildenafil is 50 mg, and the maximum dose is 100 mg. If the patient is highly sensitive to the drug or is elderly, the dose can be reduced to 25 mg. It can be taken once a day at most.

The commonly recommended dose of Avanafil is 100 mg, and the maximum dose is 200 mg, which can be reduced to 50 mg depending on the drug response. It can be taken at most once a day.

Considering the prices of the original drugs of both (however, there are many types of generic sildenafil, and it has been included in the national centralized procurement catalog, so the overall price of sildenafil is cheaper than avanafil, it is recommended to choose the appropriate PDE5 inhibitor according to personal tolerance and needs. However, for friends who have time requirements, avanafil greatly shortens the waiting time.

To sum up, both avanafil and sildenafil are phosphodiesterase type 5 (PDE5) inhibitors, and their pharmacological mechanisms are the same. However, they differ in chemical structure and pharmacokinetics. The new generation of avanafil has a faster onset, lower adverse reactions, and better safety, but it is a little more expensive. The drug must be used under the guidance of a doctor. If you have any questions about the use of the drug, please consult a doctor or pharmacist. I am pharmacist Huazi, welcome to follow me and share more health knowledge.