Sweetman 1987.

Methods	RCT; parallel group design (3 groups); randomisation procedure not described Follow‐up time: 7 days. Outcome measurements at baseline, 1, and 7 days
Participants	Population and setting: 122 participants, 57 women, 65 men, aged 15 to 72 years Ambulant outpatients from 12 general practitioners Inclusion criteria: acute LBP, current episode longer than 24 hours and less than 28 days Exclusion criteria: signs of nerve root compression, arthritis, ankylosing spondylitis, spinal infections, malignancy, renal or hepatic disease, peptic ulcers, pregnant or lactating women, sensitivity to test medications
Interventions	NSAID (i): mefenamic acid 500 mg, one tablet t.i.d. + placebo chlormezazone and paracetamol, two capsules t.i.d. (N = 40) Reference treatment (ii): chlormezanone 100 mg and paracetamol 450 mg, two capsules t.i.d. + placebo mefenamic acid, one tablet t.i.d. (N = 42) Reference treatment (iii): ethoheptazine 75 mg, meprobamate 150 mg and aspirin 250 mg two capsules t.i.d. + placebo (either mefenamic acid placebo or chlormezazone + paracetamol placebo) t.i.d. (N = 40)
Outcomes	Pain, adverse events
Notes	1. Mixed population of acute and recurrent LBP (about half of the participants had chronic LBP with an acute flare), no distinction made 2. We were unable to find contact details to ask for clarification (21 October 2019)