Nicotinamide: An Update and Review of Safety & Differences From Niacin

Reed Huber, BSc; Aaron Wong, MD, FRCPC

Disclosures

Skin Therapy Letter. 2020;25(5):7-11. 

In This Article

Adverse Effects and Potential Drug Interactions

Unlike other oral agents used for prevention of NMSC, such as systemic retinoids or chemotherapeutic agents in organ transplant recipients, nicotinamide has a much more favorable safety profile. Furthermore, nicotinamide is not associated with the undesirable side effects of its biochemical precursor niacin, such as skin flushing, pruritis, and xerosis.[18,19] In the two largest phase 3 studies involving nicotinamide, the ONTRAC study (n = 386) outlined above and the ENDIT study (n = 552) involving patients at risk of developing Type 1 diabetes mellitus, both showed that there was no difference in patient tolerability and laboratory adverse events between nicotinamide (1–3 g/day) and placebo.[12,20] Other reported adverse events of nicotinamide include thrombocytopenia and hepatotoxicity, however, the ONTRAC study showed no difference in platelet counts between nicotinamide versus placebo groups, and evidence of liver toxicity has only been reported at extremely high dosages of nicotinamide in excess of 3 g/day.[12,18] Nicotinamide is renally cleared and 1 study in patients with ESRD on dialysis receiving nicotinamide reported thrombocytopenia, though reassuringly all cases resolved upon cessation of nicotinamide.[21]

In summary, 1g daily of nicotinamide is well tolerated as highlighted by multiple reports of minimal if any adverse events.[12,14,15,21] Unlike niacin, nicotinamide does not cause flushing, and thrombocytopenia and hepatotoxicity are rare, isolated effects in patients receiving hemodialysis or at extremely high dosages in excess of 3 g per day.

Regarding potential drug interactions, Lexicomp reports both niacin and nicotinamide as potentially increasing the adverse effects of statins, with a risk rating to monitor therapy. Clinical trials involving statin-niacin combination therapy have not reported myopathy, however, there have been case reports of niacin in combination with specific statins associated with rhabdomyolysis and transaminase elevations.[22] Though, upon searching the Ovid MEDLINE database using the nicotinamide synonyms and medical subject heading for HMG-CoA reductase inhibitors, there were no adverse drug interactions cited between nicotinamide and statins. Thus, as with statin monotherapy, patients should be cautioned to report symptoms suggestive of myopathy and consideration should be given to monitoring creatinine kinase (CK) and transaminase levels.

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