PDE5 inhibitors, or phosphodiesterase type 5 inhibitors, are drugs used to treat penile problems in men, especially the erectile dysfunction. Initially, these drugs were used for an absolutely different purpose — for treating angina or hypertension. A firm erection was just a side effect, yet quite beneficial. Soon, they were repurposed, namely they were prescribed for men who suffered in the context of sexual activity.
The point is, erection occurs thanks to nitric oxide produced by endothelial cells as a result of sexual stimulation. As nitric oxide diffuses into the smooth muscle cells, it causes the formation of cGMP which in turn is the reason why blood flow increases. However, it is often the case that enzyme phosphodiesterase-5 speeds up the degradation of cGMP. PDE5 inhibitors avert this process, therefore cGMP keeps accumulating in the vascular smooth muscle causing the blood vessels to dilate, hence a prolonged erection.
PDE5 inhibitors in Erectile Dysfunction Treatment
The ultimate goal of all ED drugs is the same — bringing the sexual order to men’s lives back. But you may wonder which of these are more effective and in demand. Generally, people turn to the following ED drugs: tadalafil (Cialis), sildenafil (Viagra) and vardenafil (Levitra). Choose the one that suits you best, even in terms of pricing — all of them have the same mechanism of action and the side effects hardly differ, too. However, remember that levity is bad. Consult your private doctor first to discuss all pros and cons of each medication and assess any possible risk.
Dosage and administration
As with any other group of medications, the way you take PDE5 inhibitors depends on your age, health condition and reaction of the body. That’s why we have been constantly reminding to go to your healthcare provider. There are, however, the official recommended doses for each ED drug:
- Tadalafil (Cialis): take orally from 5 to 20 mg of the drug with or without food one or two hours before sexual intercourse. The action of the drug can last up to 36 hours.
- Sildenafil (Viagra): the recommended peroral dose ranges from 25 to 100 mg one hour before sexual intercourse. Take the drug on an empty stomach. Sildenafil works for about 5 hours.
- Vardenafil (Levitra): from 10 to 20 mg orally with or without food, once again one hour before sexual intercourse. The drug is in action 5-6 hours.
Precautions and contradictions
For people with hypotension, hypertension and heart failure, ED drugs are not recommended because they surely use other medications with similar effect. Thus the drug action will be either doubled or offset.
Do not use PDE5 inhibitors with alpha-blockers (Alfuzosin, Doxazosin, Prazosin) and nitrates (Nitroprusside, Isosorbide), which stimulate cGMP production, as blood pressure can drop to an excessively low level.
Also avoid grapefruit juice, too much alcohol and fatty food to make the most of ED medications.
Side effects
The most common side effects of ED drugs include headache, dizziness, flushing, stuffy nose and indigestion. Usually the symptoms are mild and go away in a matter of days. If they persist, it may be about time you consulted a doctor.
Among rarer, but rather severe side effects are irregular heartbeat, severe headache, hearing damage, priapism (when an erection is painful and occurs for a long time after the sexual stimulation), blurred vision, allergic reactions and even heart attack.
Most of the side effects are unlikely to happen in most cases, however they were seen to occur in some patients on rare occasions. To check the whole list of adverse reactions, read the official information on a website or ask a medical expert.