The dose-response relationship of controlled-release codeine (Codeine Contin) in chronic cancer pain

The improved pain control provided by regular dosing of opioid analgesics in patients with severe cancer pain has been well established. However, the treatment of mild-to-moderate cancer pain is often limited to "as needed" dosing with fixed combinations of codeine or oxycodone plus a nonopioid analgesic, which do not allow optimal titration of the individual components. This randomized double-blind study was designed to evaluate the efficacy of controlled-release codeine (Codeine Contin) in patients with cancer pain, and to estimate its dose equivalence to a standard combination of acetaminophen plus codeine. Twenty-four patients with at least moderate cancer pain were randomized to Codeine Contin 100, 200, or 300 mg every 12 hr or acetaminophen plus codeine (600 mg/60 mg) every 6 hr. On days 1 and 4 of dosing, pain intensity and pain relief were assessed hourly for 12 hr. The sum of pain intensity differences (SPID) from baseline and the total pain relief (TOTPAR) scores demonstrated a dose-response relationship for Codeine Contin on days 1 and 4 that was statistically significant on day 1 and suggested greater analgesic efficacy on day 4, compared with day 1. Codeine Contin 150 mg every 12 hr was estimated to be equianalgesic to acetaminophen plus codeine (600 mg/60 mg) given every 6 hr. Because a similar equivalence was also demonstrated from analysis of adverse event data, it is concluded that Codeine Contin 150 mg produces analgesia and a side-effect profile similar to a 40% lower dose of codeine provided by the combination.(ABSTRACT TRUNCATED AT 250 WORDS)