Niacin
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Niacin (nicotinic acid, vitamin B3)
Niaspan (ER, Rx), Niacor (IR, Rx); huge OTC presence
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Summary
Classes
Common uses
Hyperlipidemia (HDL raising, triglyceride lowering — though clinical outcome benefit not demonstrated in modern trials)0, Pellagra (vitamin B3 deficiency)0, Hyperphosphatemia in CKD (off-label, modest)0
Pharmacy
Starting dose
Niaspan ER 500 mg PO at bedtime, titrate weekly to 1-2 g/d; flushing-protective aspirin 30-60 minutes before dose; pellagra replacement 100-500 mg/d
Preparations
OTC IR niacin 50-500 mg tablets; Niaspan ER 500, 750, 1000 mg tablets; "no-flush" niacin (inositol hexaniacinate, lacks evidence)
US FDA Max
2 g/d (Niaspan); higher off-label use historical
Pharmacology
Routes
Oral
Onset
Lipid changes 4-8 weeks
Duration
24 hours
Half-life
~1 hour (IR niacin); ER formulations extend functional duration[1]
Bioavailability
High (oral; food enhances)[1]
Pregnancy
Pharmacologic doses generally avoided in pregnancy; vitamin doses fine.[citation needed]
Legal status
OTC (low-dose, dietary supplement) and Rx-only (Niaspan ER) in US
Purported mechanism
Niacin in pharmacologic doses binds the GPR109A (HCA2) receptor on adipocytes, inhibiting hormone-sensitive lipase and decreasing free fatty acid release; the consequent reduction in hepatic substrate for VLDL synthesis lowers triglycerides and LDL, while a separate mechanism raises HDL.0 The AIM-HIGH (2011) and HPS2-THRIVE (2014) trials showed that adding niacin to statin therapy does not reduce cardiovascular events despite lipid changes, substantially reducing its modern use. Flushing (GPR109A-mediated PGD2 release in skin) is the universal adverse effect; aspirin pretreatment and ER formulations reduce but do not eliminate it[1].
References
edit- ↑ 1.0 1.1 1.2 FDA Prescribing Information, Niaspan (niacin ER), AbbVie, current revision. https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/020381s057lbl.pdf