Purchase in USA

Purchase in USA of vitamins B3 and C in mega sizes and of sustained release

With sustained release or time release ie. slow release is generally required only half the dose.

Niacin (nikotinsyre).
Niacin can cause the tingling of the skin (flush) and redness as histamine is released and the capillaries expand. The effect is reduced by the use of slow release niacin, and also by frequent use, so that the histamine stores do not become large. Since niacin provides a more effective sleep, it is a good idea to ingest just before bedtime. The flush can be moderated by aspirin (one tablet before each dose of niacin) for a few days, antihistamines (eg, vitamin C) or sedatives. If niacin cannot be tolerated, “inositol niacinate” is another and slightly weaker version of vitamin B3 an option.
Now Foods, Niacin, 500 mg, 250 Tablets 
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Niacinamid. Dose as niacin. These tablets are 3 times larger than the others. Used by Dr. Kaufman for Arthritis. Not for Cholesterol Control and Raynaud’s disease.
Source Naturals, Niacinamide, B-3, Timed Release, 1,500 mg, 100 Tablets 
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Inositol Hexanicotinate. Dose as niacin. Not for Raynaud’s disease.
Natrol, Niacin, Time Release, 500 mg, 100 Tablets
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C-vitamin. The beneficial sustained release version with Rose Hips.
Now Foods, Vitamin C, 1000 mg, 250 Tablets. 
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