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Lactulose onset — GPhC CRA MCQ

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ModerateGastro-intestinal TherapeuticsLactulose onsetGPhC CRA

An older woman started lactulose 15 mL twice daily yesterday for uncomplicated constipation. After two doses she has mild bloating but no pain, vomiting, bleeding or obstruction symptoms, and wants to take 60 mL at once. What is the best advice?

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Correct answer: A — Continue 15 mL twice daily, allow two to three days and maintain fluids

Lactulose commonly takes two to three days to work. Two doses without a bowel movement do not justify quadrupling the dose, which could cause diarrhoea, dehydration and electrolyte disturbance. In the absence of red flags, she should continue the prescribed regimen, take suitable fluids and seek review if symptoms persist or warning features develop. Mild early bloating is a recognised effect rather than evidence of obstruction.

Reference: Duphalac 3.335 g/5 mL oral solution SmPC: https://www.medicines.org.uk/emc/product/5525/smpc