1. Preliminary In Vivo Experimental Evidence on Intratumoral Morphine Uptake. Possible Clinical Implications in Cancer Pain and Opioid Responsiveness 
Edoardo Arcuri, MD, Patrizia Ginobbi, PhD, Walter Tirelli, MD, Rino Froldi, PhD, Gennaro Citro, PhD, Angela Santoni, PhD 
Journal of Pain and Symptom Management 
Volume 24, Issue 1, Pages 1-3 (July 2002)
DOI: /S (02)

2. Fig. 1
Morphine muscle (Δ) and tumor (x) concentrations at different times ( h) after intravenous administration of the opioid (10 mg/kg) in two different groups of nude mice injected with 5 × 106 viable human melanoma (M-14…) or glioblastoma (LI—) cultured cells, as evaluated by mass spectrometry. Mice were injected with morphine and sacrificed when tumor diameter reached 1 cm and tumor weight was 500 mg. At the same times, the mean morphine serum concentrations assayed by HPLC (not shown in this figure for sake of simplicity) decreased from 114 (4h) to 30 (72h) ng/ml. Each point represents the mean ± S.E. of at least three experiments.
Journal of Pain and Symptom Management  , 1-3DOI: ( /S (02) )