Laxative prescribing in relation to opioid use and the influence of pharmacy-based intervention.

Introduction: Opioid-induced constipation is a common problem and can cause serious complications. It is widely advised that laxatives should be started concurrently with opiates, unless there is a clear indication not to do so.

Objective: This study was undertaken to estimate how often laxatives were started concurrently with opiates and to describe the effect of pharmacy-based interventions to promote the use of laxatives in patients starting opioids.

Methods: Twenty-six community pharmacies identified all patients who received a first prescription for a strong opioid during January and February of 1998, 1999 or 2000. Pharmacists collected information on patient, drug and prescriber characteristics (age, gender, use of opiates and laxatives). A separate questionnaire was used to collect data on pharmacy-based interventions to promote the simultaneous prescribing of laxatives with the opiates.

Results: Overall, 37% of the patients receiving an opioid started taking laxatives within 5 days. The percentage of patients who received laxatives simultaneously with opioids increased from 31% in 1998 to 35% in 1999 and 42% in 2000. In 117 (43%) of the opioid prescriptions, pharmacy-based intervention had taken place before the prescription date. Of these, 48.7% was accompanied by a laxative. Opioid prescriptions (n=152) without a pharmacy based intervention were accompanied in 27.6%. After adjustment for covariates (including time trends), pharmacy-based intervention increased the probability of concomitant laxative use 1.9 [95% CI 1.1-3.3] times.

Discussion: This study shows that the widely used guideline to start a laxative when prescribing an opioid is not always followed in daily practice. In addition, we showed that pharmacy-based intervention contributed to increasing laxative use in patients receiving opioids.