Aims of the study: To assess analgesia and side effects of methadone when morphine or transdermal fentanyl were ineffective in pain control or caused intolerable side effects and to assess the calculation of equianalgesic doses of morphine and methadone.
Patients and methods: Patients received methadone because of inadequate pain control (VAS>5) during morphine treatment (4 patients), transdermal fentanyl (2 patients), morphine, ketamine and transdermal fentanyl (1 patient), tramadol (1 patient) and unsatisfactory analgesia with severe drowsiness during morphine with ketamnine treatment (2 patients). We withdrew previous opioid completely and methadone was administered usually t.i.d. The calculation of the starting doses of methadone was based on Ripamonti et al. study with own modification. Nine patients were treated with oral methadone in water solution and one patient received the drug rectally in suppositories.
Results: The mean time of the methadone treatment was 30 (SD 23, range 7-82) days and the starting doses were increased in 9 of 10 treated patients. The mean daily doses increased from 44.3 (SD 22.4) mg at the beginning till 130 (SD 102) mg at the end of methadone treatment. Good analgesia (VAS<3) was achieved in 5 patients, partial effect (VAS 3-5) in 4 patients, unsatisfactory analgesia was observed in 1 patient (VAS>5) who ceased methadone after 7 days of the treatment. The most frequent side effects were drowsiness (4 patients) and constipation (3 patients). We did not observe serious adverse reactions especially respiratory depression which would cause cessation of the treatment.
Conclusions: The results of this preliminary study confirmed high analgesic efficacy and good adverse event profile of methadone. The calculation of starting doses of methadone seeems to be effective and safe however nearly all patients needed dose increase of starting doses of methadone.