Wiffen, P.J., & McQuay, H.J. (2010). Oral morphine for cancer pain. Cochrane Database of Systematic Reviews 2010(8).doi: 10.1002/14651858.CD003868.pub2
To determine the efficacy of oral morphine in bringing relief from cancer pain; to assess the incidence and severity of side effects associated with oral opioids
The search retrieved 133 studies; 62 met inclusion criteria. After elimination of duplicates, the group for analysis included 54 studies. There were insufficient data to perform meta-analysis. Study quality was evaluated using the Jadad scale. Overall, the quality of studies was high, with a median score of 4 on a five-point scale. Studies included comparisons of modified- and immediate-release opioids, comparisons of morphine versus other drugs, and comparisons of the effects of morphine delivered by different routes and delivery mechanisms.
The 54 studies involved a total sample of 3,749 participants. Sample range was 11–699.
The literature demonstrates the effectiveness of morphine with titration to effect. The range of doses used in studies varied widely, with the maximum dose recorded being 2000 mg/day. Mean daily dose was 110–250 mg/day. This shows effectiveness over a wide range and that oral morphine, at the correct dose for the individual, is as effective as other opioids and morphine adminstered through nonoral routes. Limited evidence shows that transdermal fentanyl is faster than oral morphine at dealing with breakthrough pain. Some evidence shows that transmucosal fentanyl may be superior to oral morphine in the treatment of breakthrough pain and that fentanyl patches are associated with fewer side effects at the same level of analgesia. Oxycodone, hydromorphone, and morphine provide comparable pain control and are associated with similar adverse events. A small number of patients appear to develop intolerable side effects as the result of using oral opioids. Findings support the effectiveness of various forms of opioids for pain control, and the appropriateness of dose titration across a wide range, with specific medication selected according to each patient's responses and preferences.
These findings show that titrating to pain relief, using modified-release opioids, is possible.