Randomized Controlled Trial
Paracetamol and opioid pathways: a pilot randomized clinical trial.
Fundam Clin Pharmacol. 2013 Jun 1;27(3):339-45.
Review
The effect of paracetamol and tropisetron on pain: experimental studies and a review of published data.
Basic Clin. Pharmacol. Toxicol. 2013 Feb 1;112(2):124-31.
Randomized Controlled Trial
Analgesic efficacy and safety of tramadol/ acetaminophen combination tablets (Ultracet) in treatment of chronic low back pain: a multicenter, outpatient, randomized, double blind, placebo controlled trial.
J Rheumatol. 2004 Dec 1;31(12):2454-63.