Tramadol/acetaminophen combination tablets for the treatment of chronic lower back pain: a multicenter, randomized, double-blind, placebo-controlled outpatient study.
BACKGROUND
Tramadol and acetaminophen (APAP) have both shown efficacy in the treatment of lower back pain. The combination of these 2 agents has demonstrated synergistic analgesic action in animal models at specific ratios.


OBJECTIVE
This study assessed the long-term (3-month) efficacy and safety of tramadol 37.5 mg/APAP 325 mg combination tablets in the treatment of chronic lower back pain.


METHODS
Patients with at least moderate lower back pain (pain visual analog [PVA] score >/=40 mm on a 100-mm scale) were randomized to receive up to 8 tablets of tramadol/APAP per day or placebo for 91 days. Medication was titrated from 1 to 4 tablets/d by day 10. The primary efficacy measure was PVA score at the final visit. Secondary measures included scores on the Pain Relief Rating Scale (PRRS), Short-Form McGill Pain Questionnaire (SF-MPQ), Roland Disability Questionnaire (RDQ), and 36-Item Short-Form Health Survey (SF-36); the incidence of discontinuation due to insufficient pain relief (Kaplan-Meier analysis); and overall assessments of medication by the patients and investigators.


RESULTS
Three hundred eighteen patients (161 tramadol/APAP, 157 placebo) were included in the intent-to-treat population, defined as all patients who took >/=1 dose of study medication and had >/=1 postrandomization efficacy measurement. The mean age of the study population was 53.9 years, 63.2% were female, 90.3% were white, and the mean baseline PVA score was 70.0 mm. There were no significant differences between groups at baseline. Tramadol/APAP significantly improved final PVA scores (P = 0.015) and final PRRS scores (P < 0.001) compared with placebo. Tramadol/APAP also significantly improved RDQ scores (P </= 0.027) and scores on many subcategories of the SF-MPQ, including total score (P = 0.021). The tramadol/APAP group had significant improvements on the role-physical (P = 0.005), bodily pain (P = 0.046), role-emotional (P = 0.001), mental health (P = 0.026), reported health transition (P = 0.038), and mental component summary (P = 0.008) subscales of the SF-36. The cumulative incidence of discontinuation due to insufficient pain relief was 22.1% for tramadol/APAP and 41.0% for placebo (P < 0.001). Treatment-emergent adverse events in the tramadol/APAP group included nausea (13.0%), somnolence (12.4%), and constipation (11.2%).


CONCLUSIONS
In this study, tramadol 37.5 mg/APAP 325 mg combination tablets were effective and had a favorable safety profile in the treatment of chronic lower back pain.
Ruoff
Gary E
GE
Michigan State University College of Medicine, and Westside Family Medical Center, Kalamazoo, Michigan 49009, USA.
Rosenthal
Norman
N
Jordan
Donna
D
Karim
Rezaul
R
Kamin
Marc
M
D000082:Acetaminophen / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D018712:Analgesics, Non-Narcotic / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use; D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use; D002908:Chronic Disease; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004338:Drug Combinations; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D014147:Tramadol / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use; D016896:Treatment Outcome
D018712:Analgesics, Non-Narcotic; D000701:Analgesics, Opioid; D004338:Drug Combinations; D000082:Acetaminophen; D014147:Tramadol