Quality of analgesic treatment in patients with advanced prostate cancer: do we do a better job now? The Swiss Group for Clinical Cancer Research (SAKK) experience

GOALS OF WORK: The aim of this study was to evaluate pain intensity and the application of the WHO guidelines for cancer pain treatment in patients with prostate cancer treated at Swiss cancer centers. MATERIALS AND METHODS: We analyzed a series of five multicenter phase II clinical trials which examined the palliative effect of different chemotherapies in patients with advanced hormone-refractory prostate carcinoma. Of 170 patients, 1,018 visits were evaluable for our purpose, including ratings of pain intensity by patients and prescribed analgesics. MAIN RESULTS: No or mild pain was indicated by patients in 36 to 55% of the visits, more than mild pain in 30 to 46%. In 21% of the visits, the WHO pain treatment criteria (treatment according to one of the three steps; oral, rectal or transdermal application of the main dose; administration on a regular schedule) were fulfilled, and the Cleeland index was positive according to all recommendations. In 6% of the visits, neither the WHO criteria were fulfilled nor was the Cleeland index positive. This indicates insufficient pain treatment not following the WHO guidelines and that the prescribed analgesics were not sufficiently potent for the rated pain intensity. CONCLUSIONS: In this selective Swiss sample, the standard of analgesic treatment is high. However, there is still scope for improvement. This cannot solely be solved by improving the knowledge of the physicians. Programs to change the patients' attitude towards cancer pain, training to improve the physicians' communication skills, and institutional changes may be promising strategies.

In vitro evaluation of differences in phase 1 metabolism of ketamine and other analgesics among humans, horses, and dogs

OBJECTIVE: To investigate cytochrome P450 (CYP) enzymes involved in metabolism of racemic and S-ketamine in various species and to evaluate metabolic interactions of other analgesics with ketamine. SAMPLE POPULATION: Human, equine, and canine liver microsomes. PROCEDURES: An analgesic was concurrently incubated with luminogenic substrates specific for CYP 3A4 or CYP 2C9 and liver microsomes. The luminescence signal was detected and compared with the signal for negative control samples. Ketamine and norketamine enantiomers were determined by use of capillary electrophoresis. RESULTS: A concentration-dependent decrease in luminescence signal was detected for ibuprofen and diclofenac in the assay for CYP 2C9 in human and equine liver microsomes but not in the assay for CYP 3A4 and methadone or xylazine in any of the species. Coincubation of methadone or xylazine with ketamine resulted in a decrease in norketamine formation in equine and canine liver microsomes but not in human liver microsomes. In all species, norketamine formation was not affected by ibuprofen, but diclofenac reduced norketamine formation in human liver microsomes. A higher rate of metabolism was detected for S-ketamine in equine liver microsomes, compared with the rate for the S-enantiomer in the racemic mixture when incubated with any of the analgesics investigated. CONCLUSIONS AND CLINICAL RELEVANCE: Enzymes of the CYP 3A4 family and orthologs of CYP 2C9 were involved in ketamine metabolism in horses, dogs, and humans. Methadone and xylazine inhibited in vitro metabolism of ketamine. Therefore, higher concentrations and diminished clearance of ketamine may cause adverse effects when administered concurrently with other analgesics.