Viagra and Cialis: Similar PDE5 Inhibitors for Erectile Dysfunction
Gui í a de Salud Masculina
Viagra (Viagra, sildenafil) and Cialis (Tadalafil) are used to treat erectile dysfunction (ED) in men.
I. the mechanism of action
1 、similarity
Both of them belong to type 5 phosphodiesterase (PDE5) inhibitors. There is a guanosine monophosphate cyclase (GC) in corpus cavernosum smooth muscle cells. Under sexual stimulation, nitric oxide (NO) releases and activates GC, which converts guanosine triphosphate (GTP) into cyclic guanosine monophosphate (cGMP). CGMP relaxes smooth muscle and blood flows into the corpus cavernosum, resulting in erection, while PDE5 breaks down cGMP,Viagra and Cialis by inhibiting PDE5. Reduce the degradation of cGMP, thereby enhancing erectile function.
2 、Differences
-tadalafil (Cialis) has a higher selectivity to PDE5 and its action lasts for a long time, while sildenafil (Viagra) lasts relatively short.
Second, the characteristics of efficacy
1 、Effective time
Viagra:
-generally on an empty stomach, it takes effect 30-60 minutes after oral administration, which can help men obtain and maintain an erection under sexual stimulation.
Cialis:
It takes a little longer to take effect, usually about 60-120 minutes after oral administration.
2 、Duration
Viagra:
-the efficacy lasts about 4-5 hours.
Cialis:
-its effect lasts for a long time, up to about 36 hours, which is called "weekend pill", which means that men are likely to get a better erectile response as long as they have sexual stimulation for a longer period of time.
Matters needing attention in use
1 、intended for
These two drugs are mainly suitable for male patients with erectile dysfunction, but they need to be clearly diagnosed and other contraindications such as severe cardiovascular disease and hypotension need to be excluded.
2 、Contraindication
-it is prohibited in patients who are taking nitrates (such as nitroglycerin) because a combination of the two can lead to severe hypotension.
-patients with severe hepatorenal dysfunction need to use or adjust the dose carefully.
3 、Adverse reaction
-adverse reactions such as headache, facial flush, nasal congestion and indigestion may occur. The incidence of visual abnormalities (such as color vision changes) caused by Cialis may be lower than that of Viagra.
These drugs must be used under the guidance of a doctor to ensure safety and effectiveness.