children. Possible adverse effects of
methylphenidate include loss of appe-
tite, tremors, sleeplessness, and rashes.
methylprednisoloneA corticosteroid
drugused to treat severe asthma, skin
inflammation, inflammatory bowel dis-
ease, and certain types of arthritis.
Adverse effects are the same as for
other corticosteroid drugs.
methysergideA drug used to prevent
migraineand cluster headaches. Methy-
sergide is usually given only under
hospital supervision, when other treat-
ments have been ineffective.
Adverse effects of this drug can in-
clude dizziness, drowsiness, and nausea.
Long-term treatment may cause chest
pain, kidney failure, or leg cramps.
metoclopramideAn antiemetic drug.
It isused to prevent and treat nausea
and vomiting, including that associated
with migraine or caused by anticancer
drugs, radiotherapy, or anaesthetic drugs.
Metoclopramide may be given with a
premedication to reduce the risk of
inhaling vomit when under an anaes-
thetic. Adverse effects can include dry
mouth, sedation, or diarrhoea. Large
doses may cause uncontrollable move-
ments of the face, mouth, and tongue.
metolazoneA diuretic drug used to
treat hypertension. Metolazone is also
given to reduce oedemain people with
heart failure, kidney disorders, cirrhosis
of the liver, or premenstrual syndrome.
It is also used to treat certain types of
kidney stone (see calculus, urinary
tract). Adverse effects can include weak-
ness, lethargy, and dizziness.
metoprololA cardioselective beta-blocker
drugthat is used to treat angina pec-
torisand hypertensionand to relieve
symptoms of hyperthyroidism. It is also
given after a myocardial infarctionto
reduce the risk of further damage to the
heart. Adverse effects of metoprolol
include lethargy, cold hands and feet,
nightmares, and rash.
metronidazoleAn antibiotic drugused
to treat infections caused by anaerobic
bacteria, such as a dental abscessand
peritonitis. Metronidazole is also used
to treat protozoan infections, such as
trichomoniasisand amoebiasis. Adverse
effects include nausea and vomiting,loss of appetite, abdominal pain, and
dark-coloured urine. Alcohol should be
avoided during treatment.
mexiletineAn antiarrhythmic drugused
to treat certain heart-rhythm disorders,
usually after a myocardial infarction.
Possible adverse effects include nausea,
vomiting, dizziness, and tremor.
mianserinAn antidepressant drugused
to treat severe depression, especially
that accompanied by anxietyor insom-
nia. Mianserin usually takes several
weeks to become fully effective. Possi-
ble adverse effects include dry mouth,
blurred vision, constipation, dizziness,
and drowsiness. Rarely, prolonged use
may reduce blood cell production; regu-
lar blood countsare therefore carried
out during treatment.
miconazoleAn antifungal drugused to
treat tineaskin infections, such as ath-
lete’s foot, vaginal candidiasis(thrush),
and fungal infections of internal organs.
Miconazole in the form of a cream or
vaginal suppository may, in rare cases,
cause a burning sensation or a rash.
micro-A prefix meaning small, as in
microorganisms(tiny organisms).
microangiopathyAny disease or dis-
order of the small blood vessels. It may
be a feature of conditions such as dia-
betes mellitus, septicaemia, eclampsia,
glomerulonephritis, and advanced can-
cer. When microangiopathy occurs with
these conditions, the small blood ves-
sels become distorted, and red blood
cells are damaged. This causes micro-
angiopathic haemolytic anaemia (see
anaemia, haemolytic)
microbeA popular term for a microor-
ganism, particularly a harmful type that
causes disease.
microbiologyThe study of microor-
ganisms, particularly those that are
pathogenic (disease-causing).
microcephalyAn abnormally small head,
usually associated with learning difficul-
ties. Microcephaly may occur if the brain
is damaged before or during birth, or if
there is injury or disease in early infancy.
microdiscectomySurgery to relieve
pressure on the spinal cord, or a nerve
root emerging from it, that is caused by
protrusion of the soft core of an inter-
vertebral disc (see disc prolapse). TheMETHYLPREDNISOLONE MICRODISCECTOMYM