Rectal methadone in cancer patients with pain. A preliminary clinical and pharmacokinetic study.
BACKGROUND
Cancer pain can be treated in most cases with oral analgesics. However, during their clinical history, 53% to 70% of patients will need alternative routes of opioid administration. The rectal administration of opioids is a simple alternative route for many patients. There are no data in the literature regarding the pharmacodynamics and pharmacokinetics of rectal methadone.


METHODS
We evaluated the analgesia, tolerability and absorption profile of methadone hydrochloride in six opioid-naive cancer patients with pain. A blood sample was collected before administration of a single dose of drug (10 mg) and then again after fixed times. At these fixed times the patients were asked about pain, nausea and drowsiness by means of a visual analogue scale of 0-100 mm (VAS).


RESULTS
Pain relief was statistically significant as early as 30 minutes and up to eight hours after methadone administration. None of the patients reported significant side effects. The pharmacokinetics of rectal methadone showed rapid and extensive distribution phases followed by a slow elimination phase.


CONCLUSIONS
Rectal methadone can be considered an effective analgesic therapy for patients with cancer pain for whom oral and/or parenteral opioids are not indicated or available.
Ripamonti
C
C
Pain Therapy and Palliative Care Division, National Cancer Institute, Milan, Italy.
Zecca
E
E
Brunelli
C
C
Rizzio
E
E
Saita
L
L
Lodi
F
F
De Conno
F
F
D000285:Administration, Rectal; D000328:Adult; D000701:Analgesics, Opioid / Q000009:adverse effects / Q000493:pharmacokinetics*; D015179:Colorectal Neoplasms / Q000097:blood / Q000150:complications*; D005260:Female; D006258:Head and Neck Neoplasms / Q000097:blood / Q000150:complications*; D006801:Humans; D008297:Male; D008691:Methadone / Q000009:adverse effects / Q000493:pharmacokinetics*; D008875:Middle Aged; D010146:Pain / Q000097:blood / Q000188:drug therapy* / Q000209:etiology
D000701:Analgesics, Opioid; D008691:Methadone