shivers20 said:Merk has a drug called Laropiprant, it inhibits PGD2, reducing the amount flushing that occurs when taking niacin. In one study, the flavanoid quercetin was also used to reduce PGD2 levels in niacin flush.
http://www.ncbi.nlm.nih.gov/pubmed/18831918
There are two types of PGD2 receptors, DP1 and DP2 (DP2 is also known as 'GPR44' and 'CRTH2'). Laropiprant (Merck's drug) selectively blocks the PD1 receptor - Cotsarelis showed that the PD2 receptor (and not PD1) is involved in hair growth downregulation. BTW, niacin produces flushing via the PD1 receptor - the PD2 receptor is not involved in the flushing at all.
Setipiprant by Actelion blocks the right PGD2 receptor implicated in male pattern baldness (PD2). Right now, setipiprant is in phase 2/3 testing.