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Motidone
COMPOSITION
Each tablet contains Domperidone 10 mg.
DESCRIPTION
MOTIDONE TABLET 10 MG is an oblong shaped tablet, pink in colour with
marking "DUO".
PHARMACODYNAMICS
Pharmacologicaly, domperidone is a dopamine antagonist with antiemetic
properties similar to those of metoclopramide and certain neuroleptic drugs.
Unlike these drugs, however, domperidone does not readily cross the blood
brain barrier. It seldom causes extra-pyrimidal side effects, but does cause
a rise in prolactin levels. Its antiemetic effect may be due to a
combination of peripheral (gastro-kinetic) effects and antagonism of central
dopamine receptors in the chemo-receptor trigger zone which lies in the area
postrema and is regarded as being outside the blood brain barrier. Animal
studies have shown that domperidone has no effect on plasma concentrations
of homovanillic acid, a metabolite of dopamine. it also antagonises the
behavioural effects of dopamine much more effectively when administered
intracerebrally than when given systemically. These findings, together with
the low concentrations found in the brain, indicate a predominantly
peripheral effect of domperidone on dopamine receptors.
Studies in humans have shown intravenous and oral domperidone to increase
the duration of antral and duodenal contractions, to increase the gastric
emptying of liquids and semi solids in healthy subjects and in patients in
whom, it was delayed, and to increase lower oesophageal sphincter pressure
in healthy subjects. Domperidone has no effect on gastric secretion.
PHARMACOKINETICS
Domperidone is rapidly absorbed following intramuscular and oral
administration with peak plasma concentrations occurring at approximately 10
and 30 minutes respectively. Systemic bioavailability of oral domperidone is
13 to 17%. The low oral bioavailability is probably due to "first-pass" gut
wall and hepatic metabolism. Oral bioavailability is decreased by prior
administration of cimetidine or sodium bicarbonate. The time of peak
absorption is slightly delayed and the AUC somewhat increased when the oral
drug is taken after a meal.
Oral domperidone does not appear to accumulate or induce its own metabolism;
a peak plasma level after 90 minutes of 21 ng/ml after two weeks oral
administration of 30 mg per day was almost the same as that of 18 ng/ml
after the first dose. Domperidone is 91-93% bound to plasma proteins.
Distribution studies with radiolabelled drug in animals have shown wide
tissue distribution with low brain concentration. Small amounts of drug
cross the placenta in rats and the drug is excreted in the breast milk of
this species.
Domperidone undergoes rapid and extensive hepatic metabolism by
hydroxylation and N-dealkylation. Urinary and faecal excretion amounts to 31
and 66% respectively of the oral dose. The proportion of the drug excreted
unchanged is small (10% of faecal excretion and approximately 1 % of urinary
excretion).
The plasma half-life after a single oral dose is 7-9 hours in healthy
subjects but is prolonged in patients with severe renal insufficiency.
INDICATIONS
The dyspeptic symptom complex that is often associated with delayed-gastric
emptying, gastro-oesophageal reflux and oesophagitis:
- epigastric sense of
fullness, early satiety, feeling of abdominal distension, upper abdominal
pain;
- bloating, eructation, flatulence;
- nausea and vomiting;
- heartburn with or without regurgitations of gastric contents in the mouth.
Nausea and vomiting of functional, organic, infectious or dietetic origin or
induced by radiotherapy or drug therapy. A specific indication is nausea and
vomiting induced by dopamine agonists, as used in Parkinson's disease (such
as L-dopa and bromocriptine).
RECOMMENDED DOSAGE
Domperidone should be taken 15-30 minutes before meals, and if necessary,
before retiring.
Adults: 10 mg three to four times daily. If necessary, this dose can
be doubled after two weeks if insufficient response.
In patients with renal insufficiency: (creatinine serum levels
> 6 mg/100 mL ie. > 0.6 mmol/L) the elimination half-life drug of
domperidone was increased from 7.4 to 20.8 hours but plasma drugs were lower
than in healthy volunteers. Since very little unchanged drug is excreted via
the kidneys, it is unlikely that the dose needs to be adjusted for single
acute administration in patients with renal insufficiency. However, on
repeated administration, the dosing frequency will need to be reduced to
once or twice daily depending on the severity of the impairment, and the
dose may need to be reduced.
Food: Oral domperidone is recommended to be taken before
meals. If taken after meals, absorption of the drug is somewhat delayed.
CONTRAINDICATIONS
Domperidone should not be used whenever stimulation of gastric motility
might be dangerous e.g. in the presence of gastrointestinal haemorrhage,
mechanical obstruction or perforation.
Domperidone is also contraindicated in the following:
- in patients with known intolerance to the drug
- in patients with a prolactin-releasing pituitary tumour (prolactinoma)
- prophylaxis of post-operative vomiting or for chronic administration
WARNINGS AND PRECAUTIONS
Prolactin levels: There are limited safety data in long term
use (ie. beyond six months) of domperidone. However, it has been shown to
produce an increase in plasma prolactin. The raised level persists with
chronic administration but falls to normal on discontinuing the drug.
It has been shown in vitro that about 1/3 of breast cancers are prolactin
dependent and hence this point must be considered when prescribing for a
patient with a past history of breast cancer.
Endocrine disturbances such as galactorrhoea, amenorrhoea, gynaecomastia and
impotence have been reported with drugs which stimulate prolactin release.
Use with impaired hepatic function: Since domperidone is
extensively metabolised in the liver, it should be used with caution in
patients with hepatic impairment.
INTERACTION WITH OTHER MEDICAMENTS
Concomitant administration of anticholinergic drugs may antagonise the
anti-dyspeptic affect of domperidone. If administered prior to atropine,
domperidone reduces the relaxant effect of atropine upon the lower
oesophageal sphincter, but has no reversing effect if atropine is
administered first. Since domperidone has gastro-kinetic effects it could
influence the absorption of concomitantly orally administered drugs,
particularly those of sustained release or enteric coated formulations.
However, in patients already stabilized on digoxin, paracetamol or
haloperidol concomitant administration of domperidone did not influence the
blood levels of these drugs.
Concomitant use with antacids and antisecretory drugs with domperidone will
reduce its oral bioavailability. Dosing with these 2 agents should be
separated from dosing of domperidone by at least 2 hours.
In patients stabilised on digoxin, paracetamol or haloperidol administration
of domperidone did not influence the blood levels of these drugs.
Domperidone has been used with neuroleptics without potentiation of their
activity.
Dopaminergic: Antagonism of hypoprolactin effect of bromocriptine.
PREGNANCY AND LACTATION
Use in pregnancy: There are no adequate and well controlled
studies in pregnant women and hence this drug should be used during
pregnancy only if clearly needed.
Use in lactation: The drug is excreted in breast milk of
lactating rats and probably also in humans. It is therefore not recommended
for nursing mothers unless the expected benefits outweigh any potential
risk.
SIDE EFFECTS
Mild and transient abdominal cramps and dry mouth have been reported rarely.
There have been no extrapyramidal side effects reported during controlled
therapeutic trials although a few anecdotal reports of such effects have
been published.
- May induce an increase in the plasma prolactin level which may be
associated with galactorrhoea and less frequently with gynaecomastia.
- Rashes and other allergic reactions.
- Acute dystonic reactions.
Central Nervous System: Dry mouth, headache, insomnia,
dizziness, thirst, lethargy, irritability, extrapyramidal reactions (rare).
Gastrointestinal: Abdominal cramps, diarrhoea, regurgitation,
changes in appetite, nausea, heartburn, constipation.
Dermatologic: Rash, pruritus, urticaria.
Urinary: Urinary frequency, dysuria.
Cardiovascular: Oedema, palpitations.
Musculoskeletal: Leg cramps, asthenia.
Other: Conjunctivitis, stomatitis, drug intolerance.
There have been reports of adverse effects possibly related to increases in
serum prolactin. These effects include: Gynecomastia, breast tenderness,
swelling of the breasts, irregular menses, amenorrhoea, a decrease or loss
of libido, breast secretion and lactation. These effects occurred in
patients who received up to 120 mg per day in four divided doses.
SYMPTOMS & TREATMENT OF OVERDOSE
Overdosage: Symptoms of overdosage may, include drowsiness, disorientation
and extrapyramidal reactions, particularly in children. Acute toxicity
studies in animals resulted in primarily central nervous system symptoms.
Treatment:
- Gastric lavage
- Activated charcoal and close observation of the patient are recommended.
- Anticholinergic, anti-Parkinson drugs or antihistamines with
anticholinergic properties may be helpful in controlling the extrapyramidal
reactions.
PACK SIZES
Containers of 500's.
Blister pack of 10 x 10's and 50 x 10's.
STORAGE
Store below 25°C. Protect from light.
KEEP OUT OF REACH OF CHILDREN.
SHELF LIFE
3 Years
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