Premium
Steady‐state pharmacokinetics of oral sustained‐release morphine sulphate in dogs
Author(s) -
DOHOO S.
Publication year - 1997
Publication title -
journal of veterinary pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.527
H-Index - 60
eISSN - 1365-2885
pISSN - 0140-7783
DOI - 10.1046/j.1365-2885.1997.00816.x
Subject(s) - pharmacokinetics , dosing , radioimmunoassay , morphine , oral administration , serum concentration , area under the curve , pharmacology , steady state (chemistry) , medicine , drug administration , chemistry , anesthesia
The pharmacokinetics of steady‐state oral sustained‐release morphine sulphate (OSRMS) were studied in dogs. Beagles ( n = 6) were randomly assigned to one of two treatment groups. Treatments included 15 mg OSRMS every 8 h for 4 days, or 15 mg OSRMS every 12 h for 4 days. Serum samples, drawn at intervals for the final 24 h of drug administration were analysed for morphine concentration using radioimmunoassay. Pharmacokinetic analysis revealed that there were no significant differences between trough serum concentrations for the concentration–time curves within either treatment group, indicating that steady‐state pharmacokinetics had been achieved. There were no significant differences in time to maximum serum concentration among the three sections of the concentration–time curve for the 8‐h group or between the two sections of the curve for the 12‐h group. Area under the concentration–time curve and maximum serum concentrations were significantly greater for the section of the curve following dosing at 7:30 h than following dosing at 19:30 h in the 12‐h treatment group. This chronopharmacokinetic variability was not present in the 8‐h treatment group. OSRMS provides sustained periods of elevated serum concentrations following administration every 8 or 12 h at a clinically applicable dosage. The clinical implications of the chronopharmacokinetic variability seen with 12‐hourly administration are not known. This formulation has potential for the treatment of chronic pain in dogs, but further studies of efficacy and safety following long‐term administration are required.