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Clinical pharmacy PharmD program Third level Phytochemistry-1 (PG-504)

4) Lactulose

• A semi-synthetic disaccharide, prepared by alkaline rearrangement of lactose.

• On hydrolysis by acid: Lactulose ➔ Galactose + Fructose

Pharmacological effects and uses:

• Used in chronic constipation. The orally ingested lactulose is poorly absorbed

and reaches colon unchanged where it is metabolized by bacteria into acetic &

lactic acids that irritate the colon mucosa causing laxative effect.

• It decreases the blood-ammonia in the portal system, as the acidified stools

+
“acetic + lactic acid” trap ammonia as NH4 ion and reabsorption are prevented
“Decrease = 25-50% of blood ammonia”.

• Usual dose: a) Laxative effect: 10 – 20 g daily.

b) To decrease blood ammonia: 20 – 30 g daily

B) Non-reducing Disaccharides:

Here the two sugars are linked together through their anomeric carbons.

They do not reduce Fehling’s solution, do not form osazone and cannot give rise

to mutarotation.

Having 1 ➔ 2 linkage, Natural: e.g., Sucrose

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