Cialis, properly Tadalafil, is a phosphodiesterase Type 5 (PDE5) inhibitor; a pharmaceutical, it can generally only be obtained via a prescription only. Like the more popular Viagra, its main purpose for use is the treatment of erectile dysfunction, and which it does through fairly similar mechanisms. It works by promoting the flow of blood into the penis to improve the erection; it does not, however, induce sexual arousal (as is the case for all ED drugs) – one must already be sexually stimulated to get the sexual stimulation for which it is primarily used.
Like all drugs and pharmaceuticals, this one does have some side effects; these include, but are not limited to, the following: headache, flushing of the face, and, very rarely, vision impairment. Available in two different doses (10mg and 20mg), individuals who are considering taking Cialis should be careful and talk to their doctor about potential pharmacological interactions between Cialis and any other medications and supplements they may be taking. Since Cialis is metabolized in the liver by the Cytochrome P450 3A4 enzyme, there is the potential for furanocoumarins found in grapefruits (as well as some other citrus fruits, though in much lesser quantities) to potentiate the effect of this drug, resulting in far more of the active molecules binding to its analogous biochemical active sites within the body. This can possibly lead to overdose. It should not be taken by men who have liver disease or problems with the health of their heart, as well as those with a rare inherited form of eye disease.
Cialis was approved for use by the United States of America’s Food and Drug Administration (FDA) in 2003 as the third such ED-treating drug following the billions of dollars in sales seen by Viagra, the first in this class; in 2009 the FDA approved it for the treatment of pulmonary arterial hypertension. Discovered by GlaxoSmithKline in the early 1990s, it was developed and commercialized by Eli Lilly later that decade before the exclusive commercialization rights within the USA for the treatment of pulmonary arterial hypertension were sold to United Therapeutics in 2008.
Cialis begins to work after around an hour (LeFever Kee’s Pharmacology gives onset of action as 15 to 60 minutes and recommends a dose of 5mg by mouth), though it can take several hours before the optimal experience is achieved. It can, however, remain in the blood for up to a day and a half (36 hours). With a half-life of 17.5 hours, there is still a quarter of the active dose after 35 hours. Upon metabolization, it is excreted via the urine and feces. It can take several doses for the desired effects to be felt; doctors recommend taking it no few than eight times before looking into switching to another medication.
It can be rather expensive for some; in South Africa, a single 10mg pill can cost upwards of thirty to forty dollars as of 2015. As of 2017, a single 10mg pill costs around $20 in Canada; doubling the dose to 20mg, however, only increases the price per pill by around five dollars. However, a generic version has been put on the market in the United Kingdom, greatly reducing the cost for British men.
Cialis can be synthesized from the D isomer of tryptophan methyl ester; its molecule is formed from twenty-two carbon atoms, three nitrogen atoms, four oxygens, and nineteen hydrogen atoms. With a molar mass of almost 400 grams per mole, it is not too heavy of a biomolecule.
Medical Practitioner (General Practice) with postgraduate diplomas in Cape Town. My special interest is erectile dysfunction.