Emma
Erectile dysfunction is a topic that is widely discussed among men. It can have a serious impact on both the physical and mental health of patients and greatly affect their quality of life. Fortunately, the introduction of PDE5 inhibitors has drastically improved the situation.
Currently, the most commonly used treatment for ED is the administration of oral PDE5 inhibitors. But, how exactly do PDE5 inhibitors work to treat this condition? In this discussion, we will explore what PDE5 inhibitors are and how they function in treating ED.
What are the causes of ED?
There are three main causes of ED:
- ED due to organic etiology
- Psychological etiology leads to ED
- ED due to mixed etiology
And most patients belong to the third type: mixed ED. However, no matter what the cause of ED is, from the perspective of anatomy and physiology, the performance of the patient is insufficient blood supply to the cavernous body of the penis. Therefore, if the arterial blood supply of the cavernous body can be increased, ED can be effectively treated.
With this understanding, we can explore the relationship between PDE5 inhibitors and the treatment of ED.
Mechanism of PDE5 Inhibitors
PDE5, or phosphodiesterase type 5, is primarily distributed within the arterial vascular smooth muscle of the corpus cavernosum. Its primary function is to hydrolyze cyclic guanosine (cGMP) within the body. Guanylic acid, in turn, is a substance that relaxes vascular smooth muscle. Therefore, PDE5 can inhibit the relaxation of cavernous body smooth muscle, leading to arterial vasoconstriction and reduced blood flow, resulting in insufficient blood supply to the cavernous body.
To put it another way, consider inflating a balloon with an inflator. If the pipe connecting the inflator is squeezed by a thread, gas cannot pass smoothly through the pipe and enter the balloon during inflation. Consequently, the balloon will not be filled smoothly. PDE5 functions similarly to a choked pipe in this analogy.
PDE5 inhibitors can prevent PDE5 from hydrolyzing cGMP (cyclic guanylic acid), increasing the cGMP concentration and prolonging its existence time within the cavernous body. When the cGMP concentration increases, the smooth muscle of the cavernous blood vessels can expand, leading to congestion and an increase in blood supply, ultimately resulting in a fully erect penis.
To continue with the ballooning example, PDE5 inhibitors not only loosen the thread on the pipe but also expand its diameter, effectively enhancing blood flow to the cavernous body and treating ED.
Types of PDE5 Inhibitors
There are currently three common PDE5 inhibitors: sildenafil, tadalafil, and vardenafil. The mechanisms of action of these three drugs are similar.
- The recommended doses of sildenafil for on-demand use are 50mg and 100mg, respectively, and the effective rates are 77% and 84%, respectively. During the course of treatment, the dosage can be adjusted according to the curative effect and adverse reactions.
- The recommended doses of tadalafil for on-demand use are 10mg and 20mg, and the effective rates are 67% and 81%, respectively.
- The recommended doses of vardenafil for on-demand use are 10mg and 20mg, and the effective rates are 76% and 80%, respectively.
Precautions for the use of PDE5 inhibitors
When using PDE5 inhibitors, it is important to pay attention to the following:
- Do not take it together with nitrate drugs, including nitroglycerin, isosorbide dinitrate, and isosorbide mononitrate, among others. Taking these medications together with PDE5 inhibitors can lead to hypotension, which can be serious or even life-threatening. Ideally, the two drugs should be taken at least 24 hours apart.
- Do not take inhibitors that inhibit the enzymes responsible for metabolizing PDE5 inhibitors. PDE5 inhibitors rely on liver drug enzymes, such as CYP3A4 and CYP2C9, for metabolism. Thus, inhibitors such as ketoconazole, erythromycin, itraconazole, cimetidine, and saquinavir can have a significant effect on PDE5 inhibitors.
- Avoid PDE5 inhibitors if you have heart failure of grade 2 or above, refractory arrhythmia, myocardial infarction, unstable angina within the last three months, refractory hypertension, hypotension (less than 90/50mmHg), or have had a stroke within the last six months. These precautions will help to avoid any unintended accidents.
It is worth noting that not all cases of male ED can be resolved with medication as there are various causes, including psychological factors, and illnesses, among others. For optimal safety and efficacy, it is recommended that you undergo a comprehensive medical examination at a hospital and use the medication with guidance from a physician to avoid any unexpected side effects.
