Osmotic Laxative·Gastrointestinal - Laxatives

Movicol/Macrogol

Treatment of chronic constipation, resolution of faecal impaction

PBSOSMOTICMovicol, ClearlaxSachets of powder (Macrogol…UNSCHEDULED+1

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At a glance

Max Dose

8 sachets/day

Onset

1-2 Days

Electrolytes

BALANCED

Caution: Bloating

COMMON

Cautions

Avoid / Cautions

Complete mechanical bowel obstruction, toxic megacolon, perforated gut. Pregnancy Category B1.

Where it stands

Rapid Summary

Overview

Macrogol 3350 (PEG) combined with electrolytes. The absolute gold-standard, safe, highly effective ward laxative. Pulls water into the bowel without causing electrolyte crashes.

Clinical Focus

Must be mixed with exactly 125 mL of water per sachet. Mixing it into a tiny shot glass makes it hypertonic, draining the patient's blood of water into their bowel.

Bottom Line

Movicol/Macrogol is an osmotic laxative for chronic constipation and faecal impaction with excellent tolerability, but requires adequate fluid intake and high-dose regimens are needed for disimpaction.

Formulation & Access

Brand Names

Movicol, Clearlax

Oral Routes

Sachets of powder (Macrogol 3350 + Sodium/Potassium/Chloride). Salty/Lemon taste.

Prescribing & PBS

Unrestricted General Benefit (PBS). OTC.

Indications & Use

Primary

PBSTGA

Treatment of chronic constipation, resolution of faecal impaction.

Clinical Place

The safest and most reliable baseline laxative in hospitals. Superior to Lactulose (less gas) and Docusate (actually works).

Quick reference

Class & Role

Osmotic Laxative — Macrogol 3350 (PEG) combined with electrolytes.

Route / Formulation

Sachets of powder (Macrogol 3350 + Sodium/Potassium/Chloride). Salty/Lemon taste. (Movicol, Clearlax)

Usual Dose & Max

PO 1-3 sachets daily in divided doses. Dissolve each in 125 mL of water. Max 8 sachets/day (Strictly for breaking faecal impaction over 3 days). Maintenance is 1-3 sachets/day.

Key Indication Doses

Chronic Constipation: PO 1-3 sachets daily in divided doses. Dissolve each in 125 mL of water. Faecal Impaction: PO 8 sachets daily (dissolved in 1 Litre of water). Drink over 6 hours. Max 3 days. Renal / Heart Failure: Because it is iso-osmotic (contains electrolytes), it does not cause fluid shifts into or out of the bloodstream.

Best Uses

Key Risks

Gastrointestinal: Bloating, fullness, nausea (from drinking the salty fluid), mild cramping (much less than Senna). Metabolic: The electrolyte balance prevents hyponatremia/hypokalemia even with 8 sachets a day.

Key Interactions

Can speed up transit time, mildly reducing the absorption of other heavily reliant drugs. Separate by 1-2 hours if possible.

Monitoring

Do not allow patients to mix the powder into their morning coffee or juice (unless using Osmolax) as the salts make it taste terrible and ruin the chemistry.

Clinical Pearl

If you mix a Movicol sachet into 50mL of water instead of 125mL, the solution is hypertonic. It will aggressively suck water *out* of the patient's blood into their bowel to dilute it, dehydrating them. The 125mL ratio is chemically mandatory to keep it iso-osmotic.

Access

Movicol, ClearlaxSachets of powder (Macrogol…

Brand: Movicol, Clearlax
Formulation: Sachets of powder (Macrogol 3350 + Sodium/Potassium/Chloride). Salty/Lemon taste.

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