ANTIVIRAL DRUGS
antiviral drugs
A
COMMON DRUGS
an tiretrovirals
•Didanosine •Efavirenz
• Indinavir •Lamivudine •Nelfinavir
• Nevirapine •Ritonavir •Saquinavir
• Stavudine •Zalcitabine •Zidovudine
others
•Aciclovir •Amantadine •Cidofovir
• Famciclovir •Foscarnet •Ganciclovir
• Idoxuridine •Inosine pranobex •Interferon
• Penciclovir •Ribavirin •Valaciclovir
• Zanamivir
Drugs used in the treatment of infection
by
viruses.
No drugs have been deve-
loped
that
can
eradicate
viruses
completely, and at present
immunization
is the most effective way of preventing
serious viral infections. However, anti-
viral drugs can reduce the severity of
some viral infections (most notably
herpes,
influenza,
viral
hepatitis,
and
cytomegalovirus
infections),
particularly
in people who have reduced immunity.
Advances have also been made in the
treatment of HIV infection (see
anti-
retroviral drugs
).
HOW THEY WORK
Most antiviral drugs destroy viruses by
disrupting the chemical processes neces-
sary for the virus to grow and multiply
within a cell. Some antivirals actually
prevent viruses penetrating the cells.
SIDE EFFECTS
Side effects of antiviral drugs used in
the treatment of HIV infection and AIDS
may
include nausea,
diarrhoea,
and
tiredness. These drugs may also affect
blood chemistry, leading to conditions
such as
anaemia
(a reduced level of the
oxygen-carrying pigment
haemoglobin
in the blood).
Most other antivirals rarely cause side
effects. Antiviral creams may cause skin
irritation and those given by mouth or
injection may lead to nausea, dizziness,
and rarely, in prolonged treatment, to
kidney damage.
antral irrigation
Irrigation (flushing out) of the maxil-
lary antrum, one of the nasal sinuses.
More
commonly
known as a sinus
washout, antral irrigation is used to
treat persistent
sinusitis.
The procedure
is performed less often nowadays since
the introduction of nasal
endoscopy
,
(examination of the nasal cavity using a
flexible viewing tube).
anuria
Complete cessation of urine output.
Anuria may be caused by a severe mal-
function of the kidneys, but a much
more common cause is a complete
blockage of the flow of urine as a result
of enlargement of the prostate gland
(see
prostate, enlarged),
a
bladder tumour,
or a bladder or kidney stone in the (see
calculus, urinary tract).
Failure of the kid-
neys to produce urine may be due to
oxygen depletion as a result of reduced
blood flow through the kidneys, as
occurs in
shock,
or to severe kidney
damage caused by a disease such as
glomerulonephritis.
Anuria requires urgent investigation
to establish the cause and to allow treat-
ment (such as rehydration or removal
of the blockage) to begin. Treatment of
the cause may restore urine production,
but any delay can result in permanent
kidney
damage,
leading
to
uraemia
(excess urea and other waste products
in the blood).
anus
The end of the alimentary tract through
which faeces are expelled from the
body. The anus
is
an
extension
of
the rectum as it passes downwards and
backwards through the pelvic floor.
The orifice at the end of the anal
canal is open only during defaecation;
at other times it is kept closed by the
muscles of the anal sphincter. These
muscles are arranged in two layers: the
internal sphincter, which
cannot be
controlled voluntarily, and the external
sphincter, which can be relaxed at will
for defaecation. Disorders of the anus
include anal cancer (see
anus, cancer of)
and imperforate anus (see
anus, imper-
forate).
(See also
digestive system.)
anus, cancer of
A rare cancer of the skin of the anus.
Possible early signs of anal cancer are
the development of swelling or an ulcer
at the anus, accompanied by bleeding
and discomfort. Treatment is by surgical
removal and/or
radiotherapy
.
anus, imperforate
A rare congenital (present from birth)
abnormality in which the anal opening
is missing or covered over. The severity
of the condition varies from complete
absence of the anal canal to only a layer
of skin covering the anal opening.
Treatment is with surgery. In severe
cases, a
colostomy
may be needed initial-
ly before definitive surgery to construct
an anus. Where surgery simply involves
removal of a layer of skin over the anal
opening,
anal dilation
(a procedure to
enlarge the anus) may be required for
several months afterwards.
anxiety
An
unpleasant
emotional
state
that
ranges from mild unease to intense fear.
Anxiety is a normal response to stressful
situations and prepares the mind and
body to respond effectively. However,
anxiety that occurs without reason may
be a symptom of an
anxiety disorder
or
another
psychological
disorder
such
as
depression
.
SYMPTOMS
A variety of physical symptoms are
associated with anxiety. The most com-
mon
include
palpitations
(a
more
forceful
or
faster
heartbeat),
chest
pains, a feeling of tightness in the chest,
and a tendency to overbreathe (see
hyperventilation
). Muscle tension leads to
headaches and back pains.
Gastrointestinal symptoms of anxiety
include dry mouth (see
mouth, dry
),
bloating, diarrhoea, nausea, and diffi-
culty in swallowing. Other symptoms
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