Tadalafil; a generic form of Cialis®.
A major erectile dysfunction medicine
It was in 1998 when the world became aware of Viagra®, it was the world’s first erectile dysfunction (ED) drug that contains the chemical sildenafil.
A few years later, other companies launched other treatments for erection difficulties. One of the other successful and popular versions was Cialis®, which contains the chemical tadalafil.
All these types of ED treatments are noted as PDE5 inhibitors. That is to say that they act upon an enzyme known as PDE5 (phosphodiesterase type 5), but before we look at their method of action, let us discuss the nature of an erection.
The penis becomes erect during sexual stimulation because of increased penile blood flow; this increase results from the relaxation of the arteries within the penis as well as the smooth muscle of the corpus cavernosum.
The corpus cavernosum is a mass of erectile tissue with large spaces within it that is capable of being distended with blood. It forms the bulk of the body of the penis, (as shown in the diagram).
The blood flow response is triggered after the release of a gas within the blood known as nitric oxide (NO). This occurs from nerve terminals and endothelial cells lining the arteries. This NO release stimulates the synthesis of cyclic guanosine monophosphate (cGMP) in smooth muscle cells and in turn, the cGMP relaxes smooth muscle and increases blood flow to the corpus cavernosum.
Thus, the increase in blood swells the penis results in an erection.
The PDE5 inhibition drugs (such as tadalafil and sildenafil) improve erectile function by increasing the availability of cGMP. If they did not inhibit PDE5, then this enzyme would breakdown more cGMP and in-turn there would be less blood flow in the penis.
It should be noted that without a sexual stimulation that the drug by itself will not initiate the local penile release of nitric oxide, therefore tadalafil’s inhibition of PDE5 will have little to no effect without sexual stimulation.
The most remarked upon difference between the ED drugs like sildenafil and tadalafil is that tadalafil has a longer half-life. Specifically, tadalafil has been tested to operate for about 17 hours, which when compared to sildenafil at 5 hours is considerably longer.
This clinical fact is partly responsible for tadalafil’s nickname of ‘the weekend pill.’
Naturally, there are various potential side effects and contraindications as there are with any drugs, and the drug use leaflet should always be carefully read before use etc. For example, persons consuming heart medications and especially those taking any nitrate-based drugs should not combine their use with tadalafil.
As with any medication, always read the leaflet carefully before use and always seek a physician’s advice.
Tadalafil has been used at 5 mg doses to help alleviate benign prostatic hyperplasia (BPH), which is an enlarged prostate that leads to difficulty in urinating. It has even been used at doses of 40 mg once a day to assist those with pulmonary arterial hypertension (PAH).
The ED doses are 10 mg to 20 mg, typically taken approximately 30 minutes prior to sex on an empty stomach. There is no need to repeat any dose until a minimum of 24-hours has passed.
TadalafilPro™ tablets are double scored. This means that 40 mg tablets can be split into two for 20 mg each and split again into four for 10 mg a piece.