Monograph: |
Lactose
A disaccharide obtained from the whey of milk. White or al-
most while odourless crystalline powder with a slightly sweet
taste.
Lactose may exist in a number of distinct forms depending
upon the crystallisation and drying processes employed. The
forms can vary in the contents of crystalline and amorphous
lactose, the amounts of a- and P-lactose, and in their hydra-
tion states. The a-form of lactose exists in either the anhy-
drous or monohydrate state whereas the p-form exists only in
the anhydrous state. Lactose (Ph. Eur.) and Lactose Monohy-
drate (USNF) are the a-form. Anhydrous Lactose (Ph. Eur..
USNF) specifies the p-form or a mixture of the a- and p-
forms. Commercial lactose is mainly the a-monohydrate.
Slowly soluble I in 5 of water and soluble I in 2.6 of boiling
water: practically insoluble in alcohol. Store in airtight con-
tainers.
A 9.75% solution in water is iso-osmoric with blood.
Adverse Effects and Precautions
Lactose intolerance occurs due to a deficiency of the
intestinal enzyme lactase. Ingestion of lactose by
patients with lactase deficiency leads to a clinical .
syndrome of abdominal pain, diarrhoea, distension. -
and flatulence: symptoms may also occur in persons
without such a deficiency who have ingested exces-
sive amounts of lactose.
Lactose is contra-indicated in patients with galac-
tosaemia, the glucose-galactose malabsorption syn-
drome, or lactase deficiency.
Lactose intolerance. A review of lactose intolerance. The
capacity of the infant intestine to produce lactase. the enzyme
responsible for digesting lactose, is retained into adulthood
only by a minority of the world's population, mostly of north
European descent, in Africa and Asia more than 90% of the
population are lactase deficient. Because of the ubiquity of
lactose in the diet and the consequent frequency of abdominal
symptoms, attempts have been made lo treat lactose intoler-
ance by dietary exclusion (which need not be complete since
lactase deficiency is rarely absolute). An alternative is en-
zyme replacement therapy with p-galactosidase from micro-
organisms, but the role of such therapy
has yet to be fully determined. The findings of one study sug-
gested that. in adults with lactose intolerance, the use of lac-
iose-digestive aids is unnecessary if lactose intake is limited
to the equivalent of 240 mL of milk or less a day.
Pharmacokinetics
Lactose is hydrolysed by lactase in the small intes-
tine to glucose and galactose, which are then ab-
sorbed.
Uses and Administration
Lactose, the carbohydrate component of milk, is less
sweet than sucrose.
Lactose is widely used in pharmaceutical manufac-
turing. In the production of capsules or tablets it
may be employed as a diluent, hulking agent, filler.
or excipient and in powders as a hulking agent. Lac-
tose is also used as a carrier for drugs in dry powder
inhalers. Characteristics such as particle size make
different grades of lactose suitable for different ap-
plications.
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