NITRITES
WHAT
THEY ARE AND HOW THEY WORK
These chemicals are yellow, volatile, and flammable
liquids that have a fruity odor. The nitrites
are part of a large class of drugs (including amyl nitrite, butyl nitrite, isobutyl nitrite, and the
nitrates like nitroglycerin) that
relax the smooth muscles that control the diameter of blood vessels and the iris of the eye, keep the anus closed, and
keep us from dribbling urine. When
these muscles relax, the blood vessels enlarge and blood pressure falls, more light is let into the eye,
and the bowels are let loose.
The medical uses of
these compounds have a long and successful history, beginning with the synthesis of nitroglycerin in 1846. That's right—nitroglycerin, the explosive that we all know about, is also a very important drug. Chemists first noticed that just a bit of it on the tongue produced a severe headache (they did not know that this was because it dilated blood vessels); within a year it was
medically used by placing it under the
tongue to relieve heart pain caused by
blocked blood vessels. Like all of
these compounds, nitroglycerin relaxes blood vessels, and today it is very commonly used to relieve the pain that patients with heart disease feel when one of the vessels supplying
blood to their heart has a spasm (angina pectoris). Remember the scene in
movies when an old person grabs his
heart, falls to the floor, and struggles to
get his medicine out of his pocket?
Then the bad guy takes the medicine away and the victim dies? Almost certainly, it was nitroglycerin that
he needed.
The nitrites, like the amyl nitrite
"poppers" that some people use for recreation, have the same basic effects as nitroglycerin. They were first synthesized and used medically in 1857, but soon physicians found them to be short lasting and unreliable, so nitroglycerin
under the tongue has remained the
medicine of choice. Amyl nitrite is
now used clinically only when the very rapid absorption through inhalation is
necessary for some cardiac medical
procedures.
The side effects of nitrates and nitrites are common and consistent, and they are related to the dilation of blood vessels.
When physicians prescribe these
drugs, they tell their patients to expect headache, flushing of the skin, dizziness, weakness, and perhaps loss of
consciousness if body position is
changed rapidly.
As with almost all
drugs, there is a lot we don't know about how they work. In this case, we really don't know exactly
why the nitrites have the mental
effects that make them attractive for some people to use. Users report a
physical sensation of warmth, a giddy feeling, and a pounding heart. The psychological sensations are the removal
of inhibitions, skin sensitivity, and
a sense of exhilaration and acceleration before sexual orgasm. There is a rather common visual
disturbance consisting of a bright
yellow spot with purple radiations.' These effects may arise from the dilation of some blood vessels in the brain.
Finally, some people use these drugs not for the mental effects but for their
muscle-relaxing properties to permit
anal intercourse.
