(Here’s more on Vitamin B6 on this site:  https://www.integrative-archives.com/category/nutrition/vitamin-b6/)

Chang HY,et al.
Am J Clin Nutr. 2013 Dec;98(6):1440-9. doi: 10.3945/ajcn.113.064477. Epub 2013 Oct 23.

Abstract
BACKGROUND: A low circulating vitamin B-6 concentration, which is an independent risk factor for cardiovascular disease, is commonly seen in human inflammation.

OBJECTIVE: We investigated whether cyclooxygenase inhibitors alter vitamin B-6 metabolism.

DESIGN: To investigate whether subjects taking a cyclooxygenase inhibitor had an altered vitamin B-6 profile, we conducted a cross-sectional study that involved 150 rheumatoid arthritis patients, with and without cyclooxygenase inhibitor treatments. C57BL/6J mice and hyperlipidemic Syrian hamsters received drug regimens that reflected clinical nonsteroidal antiinflammatory drug (NSAID) uses in treating human inflammation. The impact of long-term physiologic use of selective and nonselective cyclooxygenase inhibitors on vitamin B-6 metabolism was systematically investigated in these independent in vivo models.

RESULTS: Patients who were taking cyclooxygenase inhibitors had lower circulating pyridoxal-5′-phosphate, especially those taking NSAIDs >6 mo. Long-term celecoxib and naproxen use reduced hepatic pyridoxal-5′-phosphate in mice. Nonselective cyclooxygenase inhibitor naproxen significantly decreased vitamin B-6 vitamers in the kidney.

CONCLUSIONS: To our knowledge, we show novel findings that long-term physiologic doses of cyclooxygenase inhibitor may impede the synthesis of the coenzymatically active form of vitamin B-6. Because the cause of vitamin B-6 depletion in inflammation remains unknown, this study provides a potential mechanism that could account for the poor vitamin B-6 status in human inflammation. Moreover, this study further raises concerns about the long-term clinical use of antiinflammatory NSAIDs in humans. Vitamin B-6 status should be carefully monitored in long-term NSAID users. Future randomized placebo-controlled studies are needed to determine the impacts of antiinflammatory cyclooxygenase inhibitor use on vitamin B-6 metabolism in humans.

PubMed Reference:  http://www.ncbi.nlm.nih.gov/m/pubmed/24153347/