Nicotinamide is a water-soluble isotype of vitamin B3 that occurs naturally in meats, dairy products, legumes, beans, nuts, seeds, green leafy vegetables, yeast, coffee, and tea.1 Nicotinamide is converted into coenzymes that are essential for metabolic processes and DNA repair mechanisms. It is commonly used in dermatology, with a recent interest as a chemopreventive agent against non-melanoma skin cancers.
Non-Melanoma Skin Cancer
Several in-human studies have evaluated the effects of oral nicotinamide on actinic keratoses (AKs) and non-melanoma skin cancers.
Two phase 2 double-blind studies randomly assigned 88 patients with at least 4 palpable AKs to receive 500 mg of nicotinamide or placebo either once or twice daily.2 There was a 29% (95% CI, 11-44; P = .005) and 35% (95% CI, 18-48; P = .0006) relative decrease in the number of AKs with once- or twice-daily nicotinamide, respectively, compared with placebo at 4 months.
A majority of the enrolled patients had a prior non-melanoma skin cancer, and nicotinamide resulted in significantly lower risk of new skin cancers compared with placebo (odds ratio [OR], 0.14; 95% CI, 0.03-0.73; P = .010). There were no reported adverse effects except nausea in one patient.
A randomized controlled study of 38 transplant recipients with AKs found that 500 mg of nicotinamide once daily reduced the size of AKs and prevented the development of new AKs compared with placebo.3 Another study found that 500 mg of nicotinamide twice daily resulted in a nonsignificant 16% reduction in AKs compared with placebo (95% CI, -7 to 34; P = 0.15) and a nonsignificant trend toward a decrease in new non-melanoma skin cancers (4.2 vs 2.7; rate ratio, 0.65; 95% CI, 0.3-1.6).4
A larger, phase 3 trial also showed that nicotinamide reduced the rate of new AKs and non-melanoma skin cancers.5 The trial randomly assigned 386 patients who had at least 2 non-melanoma skin cancers within the preceding 5 years to receive 500 mg of nicotinamide twice daily or placebo for 1 year.
Nicotinamide use resulted in a 23% reduction in the rate of new non-melanoma skin cancers compared with placebo at 1 year (95% CI, 4-38; P = .02), including a 20% reduction in basal cell carcinomas (95% CI, -6 to 39; P = 0.12) and a 30% reduction in squamous cell carcinomas (95% CI, 0-51; P = .05). The number of AKs also decreased with nicotinamide at 3 (P = .01), 6 (P < .001), 9 (P < .001), and 12 months (P = .001) compared with placebo. There was no significant difference in adverse events between the 2 groups.