Side Effects and Drug

Cialis is the brand name of the drug tadalafil, which is most commonly prescribed for erectile dysfunction. The formula for tadafil is C22H19N3O4. Tadalafil is a phosphodiesterase-5 type (PDE-5) inhibitor; it inhibits the PDE-5 enzyme, which in turn prevents the destruction of cyclic guanosine monophosphate (cGMP). The resulting muscle relaxation increases blood flow to the penis.

Tablets are usually almond-shaped, and come in 2.5, 5, 10, or 20 mg doses. When manufactured by the Indian pharmaceutical company Cipla under the brand name Tadacip, the pills are also almond-shaped and light orange in color (Tadafil, 2016). Generally, doses of 10mg are recommended as a starting dose for complaints of erectile dysfunction. Some patients may respond to doses as low as 5 mg, whereas others may need 20 mg to notice effects. Effects last up to 36 hours, and can start working in about 30 minutes. The drug should not be taken more than once per day. The drug can be taken with or without food, but it is recommended to avoid grapefruit or grapefruit juice ("Cialis").

In addition to being prescribed for erectile dysfunction, Cialis can be used to relieve the symptoms of benign prostatic hyperplasia (BPH), also known as an enlarged prostate. Symptoms of BPH may include "difficulty in beginning the flow of urine, weak stream, and the need to urinate frequently or urgently," (Webmd, 2016). The same muscle relaxation effects tadalafil has on the penis are also effective for relaxing the smooth muscles in the bladder and prostate, thereby alleviating the effects of BPH. When prescribed for BPH, lower doses, in the range of 2.5mg are recommended for daily intake. Tadalafil is also branded as Adcirca when it is indicated for the treatment of pulmonary arterial hypertension.

Innocuous side effects of tadalafil include headache, muscle pain, stomach upset, and dizziness. Of those, the most common side effect is headache, followed by dyspepsia, both of which increase in tandem with dose. More serious side effects associated with tadalafil include an allergic reaction like a rash, difficulty breathing or swallowing, or sudden lack of vision. These are side effects that warrant immediate medical attention. Likewise, priapism, an erection lasting longer than four hours, is also a potentially unsafe side effect. The most important contraindication is if the patient is also taking nitrates, as tadalafil potentiates the hypotensive effects of nitrates ("Highlights of Prescribing Information," 2003). In other words, taking tadalafil with nitrates could result in unsafe sudden drops in blood pressure. Common nitrates include nitroglycerin, isosorbide dinitrate, and isosorbide mononitrate, medications that may have been prescribed for chest pain (Cialis.com). Recreational drugs like poppers (amyl nitrate) will have the same contraindication. Another pharmaceutical contraindication is with Adempas (riociguat), used to treat pulmonary arterial hypertension ("Cialis"). A history of chest pain, heart disease, heart attack, kidney disease, and other chronic problems may also render a patient unable to take tadalafil safely.