No external funding was used in this study. The authors declare that there were no conflicts of interest.
The authors thank Landa Colvin-Marion for formulation of the oral tramadol and Kara Smith for assistance with procurement of supplies.
Tramadol metabolite 1 (O-desmethyltramadol)
Tramadol metabolite 2 (N-desmethyltramadol)
Lipoderm, PCCA Inc, Houston, Tex.
Tramadol Twist-a-Dose Transdermal Gel, Wedgewood Pharmacy, Swedesboro, NJ.
Ketaset, Fort Dodge Animal Health, Fort Dodge, Iowa.
Torbugesic, Zoetis Inc, Kalamazoo, Mich.
LL2045 long line catheter, Mila International Inc, Florence, Ky.
Sun Pharmaceutical Industries Inc, Princeton, NJ.
Fagron Inc, Saint Paul, Minn.
Acquity UPLC H-Class UPLC, Waters Corp, Milford, Mass.
TQD, Waters Corp, Milford, Mass.
Tramadol C13d2, Cerilliant, Round Rock, Tex.
Acquity UPLC HSS T3 (1.8 mm), Waters Corp, Milford, Mass.
Ostro Pass-through Sample Preparation Plates, Waters Corp, Milford, Mass.
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