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Pain Research and Treatment
Volume 2011, Article ID 504034, 5 pages
http://dx.doi.org/10.1155/2011/504034
Research Article

Oral-Parenteral Conversion Factor for Morphine in Palliative Cancer Care: A Prospective Randomized Crossover Pilot Study

1Department of Internal Medicine, Östersund Hospital, 831 83 Östersund, Sweden
2Department of Health Science, Mid Sweden University, 831 25 Östersund, Sweden
3Regional Centre of Oncology, Umeå University Hospital, 901 70 Umeå, Sweden
4Department of General Surgery, Östersund Hospital, 831 83 Östersund, Sweden
5The Research and Development Unit, Jämtland County Council, 831 82 Östersund, Sweden
6Department of Radiation Sciences, Umeå University, 901 85 Umeå, Sweden

Received 20 September 2010; Accepted 13 December 2010

Academic Editor: Ke Ren

Copyright © 2011 Jan Starlander et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Objective. This pilot study clinically tests whether a conversion factor of 2 to 1 is appropriate when changing from oral to parenteral morphine administration in the treatment of cancer-related nociceptive pain and calculates the size of an adequately powered future study. Methods. Eleven outpatients with incurable cancer and well-controlled nociceptive pain were randomly assigned to either intravenous or subcutaneous morphine using half the previous oral 24-hour dose. Each group crossed over after the first three-day period. Serum concentrations of morphine and its metabolites were monitored as well as intensity of pain. Results. Oral to subcutaneous and oral to intravenous quotas of morphine concentrations were approximately 0.9. Subcutaneous to intravenous morphine quotas were 1. Conclusions. The conversion factor of 2 to 1 seems to be a reasonable average but with an obvious need for individual adjustments. Concurrent medications and substantially higher doses of morphine could potentially affect the appropriate conversion factor. An adequately powered study to validate these findings would need at least 121 patients.