Flushing with niacin is reduced by all Except

Prostaglandin-mediated flushing due to binding of the vitamin to a G protein-coupled receptor has been observed at daily nicotinic acid doses as low as 30 mg taken as a supplement or as therapy for dyslipidemia. There is no evidence of toxicity from niacin that is derived from food sources. Flushing always stas in the face and may be accompanied by skin dryness, itching, paresthesia, and headache. Flushing is subject to tachyphylaxis and often improves with time; premedication with aspirin may allete these symptoms. Nausea, vomiting, and abdominal pain also occur at similar doses of niacin. Hepatic toxicity is the most serious toxic reaction caused by sustained-release niacin and may present as jaundice with elevated aspaate aminotransferase (AST) and alanine aminotransferase (ALT) levels. A few cases of fulminant hepatitis requiring liver transplantation have been repoed at doses of 3-9 g/d. Other toxic reactions include glucose intolerance, hyperuricemia, macular edema, and macular cysts . The combination of nicotinic acid preparations for dyslipidemia with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors may increase the risk of rhabdomyolysis. The upper limit for daily niacin intake has been set at 35 mg. However, this upper limit does not peain to the therapeutic use of niacin. Ref Harrison's internal medicine 20e p2312