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# Nicotinic acid and derivatives

Niacin (vitamin B3) at lipid-lowering doses: it lowers triglycerides and LDL and raises HDL, but flushing limits its use and it is now rarely chosen.

Updated 2026-11-01

## What they are

Nicotinic acid (niacin) and related compounds such as acipimox. At doses far above vitamin needs they act as lipid-modifying drugs.

## Mechanism of action

Niacin activates a Gi-coupled receptor (GPR109A, also called HCA2) on adipocytes, lowering cAMP and hormone-sensitive lipase activity, so fewer free fatty acids reach the liver. In the liver it reduces triglyceride synthesis, increases apo B degradation and lowers VLDL and LDL output; it also raises HDL. The same receptor on skin immune cells releases prostaglandins, which cause flushing.

Target: Niacin receptor HCA2 (GPR109A), a Gi-coupled receptor

## Key points

- Classic adverse effect: prostaglandin-mediated flushing and itching; aspirin taken beforehand reduces it.
- Raises glucose (insulin resistance) and uric acid (can trigger gout).
- Hepatotoxicity, especially when an immediate-release product is replaced by a sustained-release one.
- Adding niacin to a statin did not lower cardiovascular events in large trials, so it is now rarely used.
- At vitamin doses it treats pellagra (dermatitis, diarrhea, dementia).

## Drugs in this class

- [**Nicotinic acid (niacin)** Vitamin B3 used at high doses to lower triglycerides and LDL and raise HDL. Flushing, high glucose and liver effects… Niacin receptor HCA2 (GPR109A)](https://durgical.com/en/pharmacology/nicotinic-acid/)

## Others in the class

- acipimox
- nicotinamide (vitamin B3, no lipid effect)

## Test yourself

Think of the answer, then tap the question to see it.

## What causes niacin flushing and how is it reduced?

Prostaglandin release in the skin through the niacin receptor; aspirin before the dose reduces it, as does slow dose escalation.

## Which two metabolic laboratory values rise on niacin?

Glucose (insulin resistance) and uric acid (gout risk).

## Which niacin switch carries a risk of severe liver toxicity?

Replacing immediate-release niacin with a sustained-release product at the same dose.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [DailyMed - NIACIN tablet, extended release](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=6e604319-e164-4056-ab80-b78b98c519c7) (DailyMed (U.S. National Library of Medicine), 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 37 (McGraw Hill, 2023); [Cryo-EM structure of niacin bound human hydroxy-carboxylic acid receptor 2 (Local refinement)](https://www.rcsb.org/structure/8K5B) (RCSB Protein Data Bank, 2023).

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