Losartan carboxaldehyde is an intermediate aldehyde metabolite of the angiotensin II type 1 receptor antagonist, losartan . It does not block angiotensin receptors, but instead inhibits endothelial cyclooxygenase (COX)-2 expression, thereby exerting anti-inflammatory actions. At 1 μM in vitro, losartan carboxaldehyde has also been shown to block the upregulation of intercellular adhesion molecule (ICAM)-1 mRNA and COX-dependent generation of thromboxane A2 and prostaglandin F2α . Losartan carboxaldehyde can also act as a partial agonist (EC50 = 17.1 μM) of the insulin-sensitizing peroxisome proliferator-activated receptor γ in vitro.
