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Morphine kinetics in cancer patients
Author(s) -
Säwe J,
Dahlström B,
Paalzow L,
Rane A
Publication year - 1981
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1038/clpt.1981.214
Subject(s) - morphine , medicine , bioavailability , volume of distribution , pharmacokinetics , clinical pharmacology , anesthesia , oral administration , pharmacology
Oral and intravenous morphine kinetics were studied in seven patients with cancer who needed continuous treatment with morphine because of severe chronic pain. Single oral (20 to 30 mg) and intravenous (4 mg) doses were given on separate days, followed by repetitive blood sampling for morphine analysis by gas chromatography. Volume of distribution ranged from 0.95 to 3.75 l/kg and serum clearance from 5.0 to 16.1 ml/min/kg. Oral morphine in doses that were more than five times the intravenous dose gave concentrations (at 10 and 120 min after dose) between 38 and 112 ng/ml. During the 0.25‐ to 8‐hr period after the oral dose serum concentrations were higher than after the intravenous dose. There was a variation in oral bioavailability of 15% to 64% and an interindividual variation in terminal half‐life from 58 to 467 min. These data warrant careful adjustment of the oral dose under close supervision of the patient at the onset of therapy. Clinical Pharmacology and Therapeutics (1981) 30, 629–635; doi: 10.1038/clpt.1981.214