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Letter to the Editor

Editor, - I refer to the article by Dr McDonough (Aust Prescr 2012;35:20-4). I was interested to see in Table 1 that he recommends non-osmotic laxatives to treat chronic constipation and I wondered why this recommendation is made.

Barry Werth
Faculty of Pharmacy
The University of Sydney


Author's comments

Michael McDonough, author of the article, comments:

Thank you for this important question concerning constipation. The recommendation pertains to chronic opioid-related constipation, which is often difficult to manage because of opioid-induced hypomotility. While the use of stimulant laxatives has been suggested,1 the possibility of longer-term adverse consequences (for example melanosis coli) probably should limit their use, if not exclude them. Regarding the use of bulking agents and osmotic and non-osmotic products, there appears to be limited evidence supporting which is the safest and most effective for long-term use.2 However in my clinical experience, osmotic products can cause problems – for example dehydration and electrolyte disturbance. Many patients experience occasional nausea and vomiting, and are often taking multiple medications.

I therefore recommend the strategy of least risk, that is fluids, bulking agents and non-osmotic products like stool softeners in conjunction with diet, exercise and bowel hygiene counselling. If such management fails, referral to a specialist should be considered. That process may include a review of why such commonly recommended management has apparently failed and then starting a trial of osmotic products with ongoing monitoring of safety and efficacy.


Barry Werth

Faculty of Pharmacy, The University of Sydney

Michael McDonough