Goals of work: The purpose of this trial was to evaluate the effect of long-term treatment with either oral sustained-release hydromorphone (HM) or morphine (M) on nausea, emesis, and constipation.
Materials and methods: In a prospective, open-labeled, controlled trial, 100 outpatients with cancer pain and treatment with HM or M were enrolled. Mobility, pain, and gastrointestinal symptoms were assessed by the ECOG performance status, selected items of the EORTC questionnaire and Numerical Rating Scales (NRS). Data were analyzed using descriptive and confirmatory statistics (paired t-test, chi square test, Poisson regression).
Main results: Demographic and medical data were comparable in both treatment groups. Taking into account different conversion factors, opioid doses (M 94.4 mg/d vs. HM 137.6 [HM/M = 1:5], p = 0.05 and HM 206.4 [HM/M = 1:7.5], p = 0.0002, respectively) were higher under hydromorphone and NRS of pain (M 2.3 vs. HM 3.6, p = 0.0002) lower under morphine. Nausea and emesis did not attenuate in 33% of patients. NRS of nausea (M 2.5 vs. HM 1.5; p = 0.01), incidences of emesis (M 0.7/d vs. HM 0.1/d, p = 0.0001), the consumption of antiemetics (M 26 vs. HM 14, p = 0.01), and the number of constipated patients (M 8 vs. HM 2, p = 0.04) were higher in the morphine group. An extended use of substances for symptom control revealed constipating effects (M 31 vs. HM 13, p = 0.0003) and was associated with a higher incidence of constipation in the morphine group.
Conclusions: Symptom control in outpatients with cancer pain may be complicated by a symptom controlling medication. Particularly, antiemetics revealed potentially constipating effects. Despite lower opioid doses, morphine provided a better pain control but produced more side effects. Comparing hydromorphone with morphine, it remains unclear if fewer incidences of constipation and nausea in the hydromorphone group were related to pharmacodynamic effects or to a less effective pain control with significantly higher NRS for pain. However, the conversion factor of oral hydromorphone and morphine needs to be questioned.