[Note: Guaifenesin, a bark extract used since the 1600s as a natural expectorant and mucus thinner, is FDA approved as a non-pharmaceutical compound for that purpose. NSAIDs received a generally low effectiveness rating in a drug/supplement-helpfulness survey of fibromyalgia patients.]
Objectives: Previously, we found that guaifenesin enhances analgesia [pain reduction] induced by paracetamol [aka acetaminophen, a non-selective non-steroidal anti-inflammatory or NSAID].
The aim of the present study was to determine whether guaifenesin is able to also increase analgesic activity in the non-steroid anti-inflammatory drugs ibuprofen [a non-selective NSAID], nimesulide [a ‘relatively’ COX-2 selective NSAID] and celecoxib [a COX-2 selective NSAID, meaning it inhibits the COX-2 inflammation enzyme].
In addition we investigated the influence of guaifenesin on plasma levels of nimesulide.
Methods: A model of visceral pain consisting of intraperitoneal injection of acetic acid (writhing test) was used. Levels of nimesulide in plasma were measured by HPLC. All drugs were given orally and tested in mice.
Results: Guaifenesin alone did not produce any antinociceptive effect.
Simultaneous administration of guaifenesin (200 mg/kg) and subanalgesic [less than pain relieving] doses of ibuprofen (10 and 30 mg/kg), nimesulide (10 and 20 mg/kg) or celecoxib (1 and 5 mg/kg) resulted in a significant antinociceptive effects.
The plasma levels of nimesulide were significantly higher in combination with guaifenesin at 30, 60 and 90 min after oral administration in comparison to nimesulide monotherapy.
Conclusion: The present results suggest that guaifenesin might enhance the analgesic activity of various non-steroidal anti-inflammatory drugs.
Source: Neuro Endocrinology Letters, 2009;30(3):352-6. PMID: 19855358, by Sliva J, Dolezal T, Sykora D, Vosmanska M, Krsiak M. Department of Pharmacology, 2nd & 3rd Faculties of Medicine, Charles University, Prague; Department of Analytical Chemistry, Faculty of Chemical Engineering, Prague, Czech Republic. [Email: firstname.lastname@example.org]