UK Clinical Pharmacy Association

Issues for surgery

Risk of constipation if omitted, particularly in patients with chronic laxative use, which may further be exacerbated by medication administered perioperatively, e.g. opioids.

Risk of fluid imbalance and hypokalaemia with chronic or excessive use, which may further be exacerbated if continued during prolonged periods of fasting.

Advice in the perioperative period

Elective surgery

Continue, if required.

Except:

  • for patients having bowel cleansing preparations prior to surgery – stop when bowel preparation starts
  • Manevac® (senna + ispaghula husk) combination product – see Ispaghula husk drug record.

Check electrolytes pre-operatively in patients with chronic or suspected excessive stimulant laxative use.

Emergency surgery 

Continue, if required.

Except:

  • for patients with suspected bowel obstruction or perforation
  • Manevac® (senna + ispaghula husk) combination product – see Ispaghula husk drug record.

Check electrolytes in patients with chronic or suspected excessive stimulant laxative use.

Post-operative advice

Resume post-operatively, if needed, once enteral intake resumed.

If concomitant use of opioids or other medication that may cause constipation, or antibiotics that may cause diarrhoea, monitor response to treatment and adjust dose accordingly.

Review if patient develops reduced gastrointestinal motility (e.g. ileus) post-operatively.

Patients undergoing colorectal surgery

Review the need for stimulant laxatives post-operatively.

Interactions with common anaesthetic agents

Hypokalaemia

Senna may cause hypokalaemia (mainly in cases of misuse or overdose). Concomitant use with medications that prolong the QT-interval, e.g. desflurane, isoflurane, sevoflurane and possibly thiopental, increases the risk of torsades de pointes. Monitor serum potassium and QT-interval with concomitant treatment. 

Interactions with other common medicines used in the perioperative period

Hypokalaemia

Senna may cause hypokalaemia (mainly in cases of misuse or overdose). Hypokalaemia increases the risk of torsades de pointes with medicines which prolong the QT-interval, e.g. antiemetics (haloperidol, ondansetron), antimicrobials (ciprofloxacin, clarithromycin, erythromycin), corticosteroids and loperamide. Monitor serum potassium and QT-interval with concomitant treatment. 

Further information

None relevant.

References

Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press http://www.medicinescomplete.com [Accessed on 23 March 2024]

Summary of Product Characteristics – Senokot® (senna) 7.5 mg Tablets 12 Years Plus. Reckitt Benckiser Healthcare (UK) Ltd. Accessed on 23 March 2024 via www.medicines.org.uk [date of revision of the text December 2020]

Baxter K, Preston CL (eds), Stockley’s Drug Interactions (online) London: Pharmaceutical Press. http://www.medicinescomplete.com [Accessed 23 March 2024]