Page 66 - Community pharmcy practice E-book 2025

01/11/2025, 22:08 Medication Errors & Constipation Management

Lactulose Mechanism of Action

Lactulose → (beta galactosidase from colonic bacteria) → Lactic acid →
Acidification of colon → NH3 to the ammonium ion (NH4)+ → Trapping ammonia
and preventing its absorption → Expels the trapped ammonium ion from the colon
Laxative effect: Osmotic pressure increase

Why Not With Local Aminoglycoside Antibiotics?

Neomycin and possibly other anti-infective agents eliminate certain colonic
bacteria & this may interfere with the desired degradation of lactulose (into lactic
acid) and thus prevent the acidification of colonic contents.
BUT combination could work in some cases: reports that lactulose fermenting
bacteria are relatively resistant to neomycin

Monitoring required in the event of concomitant oral antibiotic therapy

Side Effects of Lactulose

Gas bloating
Flatulence
Excessive dosage leads to diarrhea, hypokalemia
Infants receiving Lactulose may develop hyponatremia and dehydration

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