are specific dietary deficiencies) or in disease states wherein there is excessive consumption of GLA metabolites. Source of eicosanoids From GLA, the body forms dihomo-γ-linolenic acid (DGLA). This is one of the body's three sources of eicosanoids (along with AA and EPA.) DGLA is the precursor of the prostaglandin PGH1, which in turn forms PGE1 and the thromboxane TXA1. Both PGE11 and TXA1 are anti-inflammatory; thromboxane TXA1, unlike its series-2 variant, induces vasodilation, and inhibits platelet consequently, TXA1 modulates (reduces) the pro-inflammatory properties of the thromboxane TXA2. PGE1 has a role in regulation of immune system function and is used as the medicine alprostadil. Unlike AA and EPA, DGLA cannot yield leukotrienes. However, it can inhibit the formation of pro-inflammatory leukotrienes from AA. Although GLA is an n−6 fatty acid, a type of acid that is, in general, pro-inflammatory, it has anti-inflammatory properties. (See discussion at Essential fatty acid interactions: The paradox of dietary GLA.) Topical use In 2002, the UK Medicines and Healthcare products Regulatory Agency withdrew marketing authorisations for evening primrose oil as an eczema remedy. Notes and references 5α-Reductase inhibitors Fatty acids Alkenoic acids