Table 1

Chronic and bolus i.v. doses of oxycodone, morphine, or saline (control rats) administered to naive, oxycodone-tolerant, and morphine-tolerant adult male DA rats1-a

Treatment Period 1: Naive RatsTreatment Period 2: Tolerant RatsTreatment Period 3: Tolerant Rats
5 mg/24 h i.v. oxycodone (n = 8)20 mg/24 h i.v. morphine (n = 4)
5 mg/24 h i.v. oxycodone (n = 4)
20 mg/24 h i.v. morphine (n = 8)5 mg/24 h i.v. oxycodone (n = 4)
20 mg/24 h i.v. morphine (n = 4)
Oxycodone i.v. infusion, 2.5 mg/24 h for 60 hi.v. bolus dose of morphinei.v. bolus dose of oxycodone
 1,402 nmol (n = 4) 2,220 nmol (n = 4)
 2,803 nmol (n = 4) 3,171 nmol (n = 6)
 3,504 nmol (n = 7) 3,805 nmol (n = 4)
 4,205 nmol (n = 4) 4,756 nmol (n = 4)
 7,008 nmol (n = 4) 9,513 nmol (n = 4)
Morphine i.v. infusion, 10 mg/24 h for 60 hi.v. bolus dose of oxycodonei.v. bolus dose of morphine
 317 nmol (n = 4) 3,504 nmol (n = 4)
 951 nmol (n = 4) 4,205 nmol (n = 6)
 1,585 nmol (n = 8) 4,906 nmol (n = 4)
 2,537 nmol (n = 8) 6,308 nmol (n = 6)
 6,342 nmol (n = 4) 10,514 nmol (n= 4)
i.v. bolus dose of oxycodone
 79 nmol (n = 4)
 159 nmol (n = 4)
 317 nmol (n = 6)
 476 nmol (n = 6)
 1,585 nmol (n = 5)
i.v. bolus dose of morphine
 350 nmol (n = 4)
 701 nmol (n = 4)
 1,402 nmol (n = 4)
 1,752 nmol (n = 4)
 3,504 nmol (n = 4)
i.v. bolus dose of saline (n = 4)
  • 1-a  Each treatment period was followed by a 12-h washout period with saline.