How do the medications work?
Viagra, Levitra and Cialis have one main thing in common they all target phosphodiesterase-5 or PDE-5, an enzyme that’s responsible for sexual dysfunction. In order to understand how the drugs work, you must first understand how erections are formed. Erections can only be attained when a man’s arteries, veins, and nerves are healthy and in good shape. He also has to have sufficient testosterone levels and an open state of mind. Besides these requirements, the arousal impulses must also be transmitted between nerves, and the smooth muscle cells in the arteries must be relaxed for the blood to flow more freely into the penis. These can all be done by nitric oxide (NO). Nitric oxide triggers the production of cyclic guanosine monophosphate (cGMP) in the arteries. This is the chemical responsible for an improved blood flow to the penis. However, PDE-5 is also produced by the penis tissues, and this enzyme breaks down cGMP.
Prolactin is normally inhibited (suppressed) by the hypothalamic (brain) hormone, dopamine. This hormone, dopamine normally travels down the pituitary stalk (connects the brain to the pituitary gland) in the blood vessels to inhibit prolactin production. Drugs known as dopamine agonists act like dopamine to inhibit prolactin production. Dopamine agonists available in the U.S. include cabergoline (Dostinex), bromocriptine (Parlodel) and pergolide (Permax). A very effective drug, quinagolide (Norprolac), is only available in Europe and Canada. Dostinex is a long acting drug and can be taken once or twice a week; bromocriptine is given up to 3 times a day; pergolide is usually given once each day. All of these drugs act on the tumor in the same way – by inhibiting or reducing the amount of prolactin made by the tumor and thus causing the tumor to shrink. Over 90% of patients treated with one of these medications have a decrease in prolactin and a decrease in tumor size. Some patients are
Cholesterol lowering medications work in three main ways depending on the type of medication prescribed. Some raise the HDL, or “good” cholesterol levels, some lower the LDL, or “bad” cholesterol levels, and some work with your liver and intestines to expedite the secretion of cholesterol. Statins are the most popularly prescribed cholesterol medications and include brand names such as Lipitor, Crestor, and Zocor. They interrupt the binding process of LDL particles in your bloodstream. The type of medication prescribed to you will depend on your medical history and individual cholesterol levels.
Prolactin is normally inhibited (suppressed) by the hypothalamic (brain) hormone, dopamine. This hormone, dopamine, normally travels down the pituitary stalk (connects the brain to the pituitary gland) to inhibit prolactin production. Drugs known as dopamine agonists act like dopamine to inhibit prolactin production. Dopamine agonists available in the U.S. include cabergoline and bromocriptine. Pergolide (Permax) was recently removed from the market because of heart problems in patients with Parkinson’s disease – see below for more details. A very effective drug, Norprolac (quinagolide), is only available in Europe and Canada. Cabergoline is a long acting drug and can be taken once or twice a week. Bromocriptine is usually given 3 times a day, always taken with food. These drugs act on the tumor in the same way – by inhibiting or reducing the amount of prolactin made by the tumor and causing the tumor to shrink. Over 90% of patients treated with one of these medications have a decrease
