Macrogol 3350 with KCl/NaHCO3/NaCl

How it works

The macrogol polymer osmotically retains water in the bowel lumen to soften and bulk the stool, while the added electrolytes are formulated to be near-isotonic and minimise net shifts of sodium, potassium and water across the gut wall.

Prescribing in practice

• Contraindicated in intestinal obstruction or perforation, ileus and severe inflammatory bowel disease; use caution in significant cardiovascular impairment because of the added electrolyte and fluid load.
• The electrolyte content means caution is needed in renal impairment and when co-prescribed with other drugs affecting fluid or electrolyte balance.
• Each sachet must be dissolved in water before use; the reconstituted solution may be kept refrigerated for a limited period and discarded thereafter.

Monitoring

Consider monitoring serum electrolytes when used at high impaction doses, in renal impairment, or in patients taking diuretics or other drugs that disturb electrolyte balance.

Counselling the patient

• Mix each sachet in water as directed and drink enough fluid through the day.
• Tell your prescriber if you have kidney or heart problems before regular use.
• Stop and seek advice if you get severe bloating, abdominal pain or vomiting.

Evidence & guidelines

Electrolyte-containing macrogol preparations are an established, evidence-based first-line treatment for chronic constipation and faecal impaction in UK practice.