A bloodstained discharge may be due to
a noncancerous breast disorder such as
f i b r o a d e n o s i s
(general lumpiness of the
breast) or a cancerous tumour.
n itra te d ru g s
• Glyceryl trinitrate •Isosorbide dinitrate
• Isosorbide mononitrate
A group of
v a s o d i l a t o r d r u g s
used to treat
prevent attacks
a n g i n a p e c t o r i s
(chest pain due to impaired blood sup-
ply to the heart) and to treat severe
h e a r t
f a i l u r e
(reduced pumping efficiency).
Possible side effects of nitrate drugs
include headaches, flushing of the skin,
and dizziness.
T o l e r a n c e
(the need for
greater amounts of a drug for it to have
the same effect) may develop when some
nitrate drugs are taken regularly. To avoid
this, a change in dosage, frequency, or
timing of the drug, or prescription of a
different nitrate drug, may be required.
n itra z e p a m
b e n z o d i a z e p i n e d r u g
used in the short-
term treatment of
i n s o m n i a .
is long-acting and may cause a hangover
effect, with drowsiness and lighthead-
edness, the following day. Regular use
over several weeks can lead to reduced
effectiveness as
t o l e r a n c e
Nitrazepam can lead to drug depen-
dence and to withdrawal symptoms,
such as nervousness and restlessness.
n itric o x id e (N O )
A gas that is produced both outside the
body as a pollutant (for example, in car
exhaust fumes)
and inside the body,
where it takes the form of a molecule
that acts as a messenger between cells.
Nitric oxide causes blood vessels to
dilate, affecting the flow of oxygenated
blood and regulating blood pressure.
Overproduction of nitric oxide is asso-
ciated with various disorders, including
t o x i c
s h o c k s y n d r o m e ,
r h e u m a t o i d
a r t h r i t i s
i m p o t e n c e
a n g i n a .
The control of
nitric oxide is an important element of
many drug treatments.
n itrite s
Salts of nitrous acid (a nitrogen-contain-
acid). To preserve
nitrite is added in small amounts, to-
gether with potassium nitrate and salt, to
inhibit the growth of potentially harmful
bacteria. In large amounts, nitrites can
cause dizziness, nausea, and vomiting.
n itro fu ra n to in
a n t i b i o t i c d r u g
that is used in the
treatment of
u r i n a r y t r a c t i n f e c t i o n .
furantoin should be taken with food to
reduce the risk of stomach irritation,
w hich can cause abdominal pain and
nausea. More serious side effects, such
as breathing difficulty, numbness, and
jaundice (yellowing of the skin and the
whites of the eyes), occur rarely.
n itro g e n
A colourless, odourless gas that makes
7 8
per cent of the Earth’s atmos-
phere. Atmospheric nitrogen has no
biological action.
Nitrogen gas cannot be utilized by the
body, but compounds of nitrogen are
essential to life. The most important of
such compounds are
a m i n o a c i d s ,
building blocks of
p r o t e i n s ,
which repre-
sent the fundamental structural substances
of all cells and tissues. Humans cannot
make certain amino acids (called essential
amino acids), w hich must be obtained
from the diet in the form of animal and
plant proteins. The proteins are then
broken down by digestion into their
constituent amino acids to be absorbed
and reconstituted into the specific pro-
teins needed by the body. These processes
of protein breakdown and reconstitution
produce a variety of nitrogen-containing
waste products, prim arily
u r e a ,
are excreted by the body in the urine.
(See also
n i t r a t e d r u g s ; n i t r i t e s . )
n itro g ly c e rin e
A former name for
g l y c e r y l t r i n i t r a t e ,
n i t r a t e d r u g .
N itro lin g u a l P u m p s p ra y
The brand name for an aerosol prepara-
tion of
g l y c e r y l t r i n i t r a t e .
This is sprayed
under the tongue to treat
a n g i n a p e c t o r i s
(chest pain due to impaired blood sup-
ply to the heart muscle).
n itro p ru s s id e
a n t i h y p e r t e n s i v e
d r u g
given as an
infusion in the emergency treatment of
h y p e r t e n s i o n
(high blood pressure).
n itro u s o x id e
A colourless gas, also called laughing
gas, that has a sweet smell and the
chemical formula N 2O. Nitrous oxide is
used with oxygen to provide
a n a l g e s i a
(pain relief) and light anaesthesia (see
a n a e s t h e s i a , g e n e r a l )
at the site of a seri-
ous accident or during childbirth, dental
procedures, and minor surgery For major
surgery, w hich requires deeper anaesthe-
sia, a nitrous oxide and oxygen mixture
needs to be combined with other drugs.
The advantages of the combination of
nitrous oxide and oxygen over other
agents are its rapid action and nonflam-
oxide may include nausea and vomiting
during the recovery period.
n its
The eggs of
l i c e .
Both head lice and
p u b i c
l i c e
produce eggs, w hich they stick to the
base of hairs growing from their host’s
head or pubic area. Nits are tiny, mea-
suring only about
0 .5
mm in diameter.
They are light brown when newly laid
and white when hatched. Hatching takes
place within about eight days of being
laid. Louse infestations are frequently
identified by the presence of nits.
n o c a r d io s is
An infection caused by a funguslike
bacterium present in soil. The infection,
w hich is acquired through inhalation,
usually starts in the lung and spreads to
the brain and tissues under the skin.
Nocardiosis is rare, except in people
w ith
i m m u n o d e f i c i e n c y d i s o r d e r s
or those
already suffering from a serious disease.
The resulting illness, similar to pneu-
monia with fever and cough, fails to
respond to
a n t i b i o t i c d r u g
treatment, and progressive lung damage
occurs. Brain abscesses may follow.
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