Decontamination

Gastrointestinal decontamination with activated charcoal

For metformin poisoning, offer gastrointestinal decontamination with activated charcoal to alert and cooperative patients who are able to protect their airway and present within:

2 hours after ingesting an immediate-release preparation
4 hours after ingesting a modified-release preparation.

If the patient is intubated, activated charcoal can be given any time after ingestion via a nasogastric or orogastric tube—confirm correct placement of the nasogastric or orogastric tube beforehand.

Whole bowel irrigation

If the patient has ingested a large dose (more than 50 g in adults) of a modified-release metformin preparation, consider whole bowel irrigation within 4 hours of the estimated ingestion time. Patients must be able to protect their airway or be intubated to undergo whole bowel irrigation. If the patient is intubated, the whole bowel irrigation preparation is given via a nasogastric or orogastric tube—confirm correct placement of the nasogastric or orogastric tube beforehand.

Discuss the need for whole bowel irrigation and which preparation to use (see Examples of macrogol 3350 (with electrolytes) preparations used for whole bowel irrigation) with a clinical toxicologist. Do not initiate whole bowel irrigation in a patient at significant risk of pulmonary aspiration or with established ileus. During treatment, examine patients hourly for signs of ileus, in particular increasing abdominal distension.