Constipation and the laxatives polyethylene glycol (PEG), sodium picosulphate (SPS) and lactulose (L) were investigated in outpatients with cancer and on opioid therapy. Randomly selected patients were enrolled in a prospective, controlled, open-label trial. Endpoints were number of patients taking laxatives >28 days, number of patients with a stool-free interval >72 h (sfi72), dosage, numerical rating scale (NRS) for constipation, and European Organization for Research and Treatment of Cancer (EORTC) Quality of Life (QoL) questionnaire scores. The 348 patients had comparable demographic and medical data. In this ambulatory population, mobility scores remained unaffected. Constipation incidence was 5.7%, with sfi72 42, mean NRS 2.3557 and mean QoL 2.1. A total of 53.2% discontinued their laxative medication. Laxative use correlated with higher opioid usage (morphine-equivalent mg/day: no laxative 98.2, SPS 128.2, PEG 139.9, L 154.5). PEG was the most frequently prescribed laxative (PEG 27.3%, SPS 10.3%, L 9.2%). PEG (sfi72 12.6%, NRS 2.2, QoL 2.1) and SPS (sfi72 11.1%, NRS 2.7, QoL 2.2) proved more effective than L (sfi72 15.5%, NRS 3.8, QoL 2.5). In spite of opioid therapy, the incidence of constipation was low in these ambulatory cancer pain patients at an early disease stage. For prevention of constipation, PEG or SPS is recommended instead of L.

Switching the opioid to oral hydromorphone may be a helpful technique to alleviate pain and several symptoms, but it is still not clear to what extent the underlying mechanisms, such as the technique of rotation itself, better dose adjustment, or using a different opioid have an impact.