Description
Lactulose
Pharmacokinetic
Absorption
Poorly absorbed from the GI tract when given PO and
PR (no enzyme capable of hydrolysis of lactulose is
present in GI tissue).
Half Life: 1.7 – 2 hours.
Metabolism
In the colon, lactulose is broken down primarily to
lactic acid. Metabolized in the colon by bacteria.
Elimination
Less than 3% is excreted in the urine. Doses reach
the colon virtually unchanged.
Onset
24 to 48 h.
Mechanism of Action
• Lactulose is a synthetic sugar used in the treatment of
constipation and liver disease. It consists of the
monosaccharides fructose and galactose. In the colon,
lactulose is broken down primarily to lactic acid, and also
to small amounts of formic and acetic acids, by the
action of via evolved-beta galactosidase from colonic
bacteria, which results in an increase in osmotic
pressure and slight acidification of the colonic contents.
This in turn causes an increase in stool water content
and softens the stool. In treating heptic diseases
(hepatic encephalopathy) it is thought that lactulose
draws out ammonia from the body in the same way that
it draws out water into the colon.
Therapeutic Uses of Lactulose
ADRs of Lactulose
Doses of Lactulose
Precautions of Lactulose
Mechanism of Action of Lactulose
Absorption
Poorly absorbed from the GI tract when given PO and
PR (no enzyme capable of hydrolysis of lactulose is
present in GI tissue).
Half Life: 1.7 – 2 hours.
Metabolism
In the colon, lactulose is broken down primarily to
lactic acid. Metabolized in the colon by bacteria.
Elimination
Less than 3% is excreted in the urine. Doses reach
the colon virtually unchanged.
Onset
24 to 48 h.
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Mechanism of Action
• Lactulose is a synthetic sugar used in the treatment of
constipation and liver disease. It consists of the
monosaccharides fructose and galactose. In the colon,
lactulose is broken down primarily to lactic acid, and also
to small amounts of formic and acetic acids, by the
action of via evolved-beta galactosidase from colonic
bacteria, which results in an increase in osmotic
pressure and slight acidification of the colonic contents.
This in turn causes an increase in stool water content
and softens the stool. In treating heptic diseases
(hepatic encephalopathy) it is thought that lactulose
draws out ammonia from the body in the same way that
it draws out water into the colon.
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Mechanism of Action
Lactulose is useful in treating hyperammonemia (high
blood ammonia), which can lead to hepatic
encephalopathy.Lactulose helps trap the ammonia (NH3)
in the colon and bind to it. It does this by using gut flora
to acidify the colon, transforming the freely
diffusible ammonia into ammonium (NH4+) which can no
longer diffuse back into the blood. It is also useful for
preventing hyperammonemia caused as a side effect of
administration of valproic acid.
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Therapeutic Uses
Treatment of constipation; prevention and
treatment of portal-systemic encephalopathy,
including stages of hepatic precoma and coma.
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ADRs
• Nausea
• Cramps
• Diarrhea
• Weakness
• Irregular heart beat
• Mood changes
• seizures
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Doses
• PO 30 to 45 mL 3 to 4 times daily. Adjust
dosage to produce 2 to 3 soft stools/day. Hourly
doses of 30 to 45 mL may be used for rapid
laxation initially; once achieved, reduce to
recommended daily dose.
• PR 300 mL with 700 mL water or physiologic
saline solution via rectal balloon catheter; retain
for 30 to 60 min. May repeat every 4 to 6 h.
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Precautions
• Before using this medication, tell your doctor or
pharmacist your medical history, especially
of diabetes.
• Do not take any laxative medications while using
this drug. Frequent use or overuse of laxatives can
cause a severe loss of body water (dehydration).
This is especially likely to occur in children or the
elderly. Contact your doctor immediately if you
develop any of the following symptoms
of dehydration: muscle weakness, muscle cramps,
dizziness.
