Constipation is a common problem facing many people,1 up to a third of adults experience constipation. It is more common as we get older and it is twice as common in women than men.2 Constipation in adults generally relates to diet and life style, however it can also be caused by medications, e.g. in up to 95% of patients taking opioids.3

Polyethylene glycol is widely used to manage constipation. It works by hydrating, softening and increasing the bulk of stools, making them easier to pass.4 They were first used in high doses to prepare patients for gastrointestinal interventions (e.g. colonoscopy) and electrolytes were added to reduce the risk of large electrolyte shifts.5 To manage constipation, lower doses are used and formulations such as OsmoLax® were developed without electrolytes with the aim of improving taste, patient acceptance and adherence.4

Until recently we did not have evidence to guide which form of polyethylene glycol, with or without electrolytes, would be better for the management of constipation. To address this we conducted a network meta-analysis. Our research found the added electrolytes did not improve the efficacy or safety polyethylene glycol in the management of constipation. Even though evidence was limited, the data suggested that polyethylene glycol without electrolytes may improve patient compliance. For example, there was a trend for more patients being willing to continue with polyethylene glycol alone than with added electrolytes (85% vs 63%, p=0.07, not statistically significant).4

Healthcare professionals can be confident that both forms of polyethylene glycol are effective and well tolerated therapies for managing constipation, but the added electrolytes may impact patient acceptance and adherence to therapy. As a result of this network meta-analysis, it is my opinion that if you are going to recommend an osmotic laxative to manage constipation, polyethylene without electrolytes should be considered first.


About the Author
A/Prof. John A Gullotta AM - B.Med (Hons), B.Pharm (Syd.), FRACGP, FAMA

Associate Professor John Gullotta, has been a practicing GP and pharmacist in Matraville, Sydney, since 1992.  A/Prof. Gullotta has an extensive involvement in academia, medical organisations, media and community service.

He served as President of the Australian Medical Association (NSW), the state's peak medico-political body, from 2004 to 2006. He was also an AMA Federal Councillor from 2005-2016 and is past Chair of the Federal AMA Therapeutics Committee. In 2006 he was admitted to the Australian Medical Association Role of Fellows in recognition of the sterling service and many years of dedication to the AMA.

His extensive contribution to the profession was acknowledged when in 2007 he was appointed Member in the Order of Australia, AM for “service to medicine through a range of executive roles with professional medical associations and as a general practitioner, and to the Italian community”.

References

1.  Selby W, Corte C. Managing constipation in adults. Australian Prescriber 2010; 33: 116-119.
2.  Peppas G, Alexiou VG, Mourtzoukou E, Falagas ME. Epidemiology of constipation in Europe and Oceania: a systematic review. BMC.Gastroenterol. 2008; 8: 5.
3.  Benyamin R, Trescot AM, Datta S, Buenaventura R, Adlaka R, Sehgal N, Glaser SE, Vallejo R. Opioid complications and side effects. Pain Physician 2008; 11: S105-S120.
4.  Katelaris P, Naganathan V, Liu K, Krassas G, Gullotta J. Comparison of the effectiveness of polyethylene glycol with and without electrolytes in constipation: a systematic review and network meta-analysis. BMC.Gastroenterol 2016; 16: 42.
5.  Klaschik E, Nauck F, Ostgathe C. Constipation--modern laxative therapy. Support.Care Cancer 2003; 11: 679-685.