symptoms of depression but often take
2–3 weeks before benefit is felt. Treat-
ment usually lasts for at least 6 months,
and the dosage is reduced gradually
before being stopped altogether.
Tricyclics may cause drowsiness, dry
mouth, constipation, blurred vision, uri-
nary difficulty, and irregular heartbeat.
SSRIs may cause nausea, indigestion,
and loss of appetite, or allergic reactions
but are less dangerous in overdose than
other antidepressants. MAOIs may inter-
act with foods containing tyramine (for
example, cheese) and other drugs to
cause a dangerous rise in blood pressure,
although one MAOI, moclobemide, is less
likely to cause problems. Antidepressants
are not addictive, but abrupt withdrawal
of some types can result in physical
symptoms and should be avoided.
antidiabetic drugsA group of drugs
used to treat diabetes mellitus, in which
a lack of insulin, or resistance to its
actions, results in raised blood glucose
levels. A wide range of antidiabetics are
used to keep the blood glucose level as
close to normal as possible, and conse-
quently reduce the risk of complications
such as vascular (blood vessel) disease.
Antidiabetic drugs include insulin,
which must be administered by injec-
tion, and oral hypoglycaemicssuch as
glibenclamideand metformin. Acarbose
and guar gumreduce or slow absorp-
tion of carbohydrate from the intestines
after meals. Repaglinidestimulates insu-
lin release from the pancreas for a short
time and may be taken directly before
meals. Rosiglitazonereduces resistance
to the effects of insulin in the tissues
and may be used together with other
hypoglycaemics.
antidiarrhoeal drugsDrugs used to
reduce or stop diarrhoea and to help
regulate bowel action in people with a
colostomyor ileostomy. In most acute
cases of diarrhoea, the only treatment
recommended is oral rehydration therapy.
Antidiarrhoeal drugs include adsorb-
ents, bulk-forming agents such as
kaolin, and antimotility drugs (includ-
ing the opioid drugs, morphine and
codeine, and loperamide), which slow
movement through the intestine. None
of these drugs are suitable for children.
antidiuretic hormoneSee ADH.
antidoteA substance that neutralizes
or counteracts the effects of a poison.
anti-D(Rh 0 ) immunoglobulinAn anti-
serumthat contains antibodies against
Rhesus (Rh) D factor (a substance pre-
sent on the red blood cells of people
with Rh-positive blood). Anti-D(Rh 0 )
immunoglobulin is given routinely at
intervals during normal pregnancy and
at delivery. An additional dose is also
given after an amniocentesis, miscar-
riage, or any event in which the baby’s
blood may enter the mother’s circula-
tion. The injected antibodies prevent
the woman from forming her own anti-
bodies against Rh-positive blood, which
might adversely affect a subsequent
pregnancy. (See also haemolytic disease
of the newborn; Rhesus incompatibility.)
antiemetic drugsA group of drugs
used to treat nausea and vomiting.
Antihistamine drugsand anticholinergic
drugsreduce vomiting in motion sick-
ness, vertigo, and Ménière’s disease.The
most powerful antiemetics are used to
control nausea and vomiting associated
with radiotherapyoranticancer drugs.
These drugs include serotonin antago-
nistssuch as ondansetronand nabilone.
Antiemetics are not normally used in
the treatment of food poisoning be-
cause the body needs to rid itself of
harmful substances. Only certain anti-
emetics can be used to treat vomiting
in early pregnancy because damage to
the developing fetus may occur. Many
antiemetics cause drowsiness.
antifreeze poisoningMost antifreeze
in the UK contains ethylene glycol,
which is poisonous. Drinking antifreeze
initially produces effects similar to alco-
hol intoxication, but vomiting, stupor,
seizures, and coma may follow; acute
kidney failuremay occur within 24–36
hours. Antifreeze poisoning requires
immediate medical attention.
antifungal drugsA group of drugs
used to treat infections caused by fungi.
Antifungal drugs are commonly used to
treat different types oftinea, including
athlete’s footand scalp ringworm. They
are also used for candidiasis (thrush)
and rare fungal infections, such as cryp-
tococcosis, that affect internal organs.ANTIDIABETIC DRUGS ANTIFUNGAL DRUGS
A