What is the mechanism of Avanafil?

Avanafil is a relatively new medication used to treat erectile dysfunction (ED) in men. Developed by Vivus, Inc., it gained FDA approval in April 2012 and has since become a valuable option for individuals experiencing difficulties in achieving or maintaining an erection. Understanding the mechanism of Avanafil involves delving into how it influences the body to enhance erectile function.

The primary mechanism of Avanafil is its action as a phosphodiesterase type 5 (PDE5) inhibitor. PDE5 is an enzyme found predominantly in the smooth muscle cells of the corpus cavernosum, which is a spongy tissue of the penis that fills with blood during an erection. Normally, PDE5 breaks down cyclic guanosine monophosphate (cGMP), a molecule that plays a crucial role in regulating blood flow.

Here's how the process works in detail:

1. **Sexual Stimulation and Nitric Oxide Release:**
During sexual arousal, the body releases nitric oxide (NO) in the corpus cavernosum of the penis. Nitric oxide serves as a neurotransmitter that stimulates the production of cGMP by activating the enzyme guanylate cyclase.

2. **cGMP and Smooth Muscle Relaxation:**
The increase in cGMP levels leads to the relaxation of smooth muscle cells within the walls of the blood vessels in the penis. This relaxation allows the blood vessels to dilate, increasing blood flow into the corpus cavernosum.

3. **Inhibition of PDE5:**
Avanafil inhibits PDE5, which is responsible for breaking down cGMP. By blocking PDE5, Avanafil prevents the degradation of cGMP, thereby prolonging its action. This sustained presence of cGMP ensures continued relaxation of the smooth muscle cells and maintenance of blood flow into the penis.

4. **Erection Sustenance:**
The increased blood flow and dilation of the penile arteries lead to the engorgement and hardening of the penis, resulting in an erection. Avanafil's role is crucial in maintaining this physiological state by ensuring that cGMP levels remain elevated during sexual stimulation.

Avanafil is known for its quick onset of action, usually taking effect within 15 to 30 minutes. Its selective inhibition of PDE5 makes it a more targeted treatment, potentially reducing the incidence of side effects compared to earlier PDE5 inhibitors. Common side effects may still occur, such as headaches, flushing, nasal congestion, and back pain, but these are generally mild and transient.

It is important to note that Avanafil, like other PDE5 inhibitors, does not cause an erection without sexual stimulation. The presence of sexual arousal is a prerequisite for the drug to be effective, as it is the release of nitric oxide that initiates the cascade of events leading to an erection.

In summary, Avanafil enhances erectile function by inhibiting the PDE5 enzyme, thereby sustaining the levels of cGMP in the penile tissue. This mechanism results in prolonged smooth muscle relaxation, increased blood flow, and the maintenance of an erection during sexual activity. Its rapid onset and targeted action make it a valuable option for men seeking treatment for erectile dysfunction.