Prazosin-d8 is intended for use as an internal standard for the quantification of prazosin by GC- or LC-MS. Prazosin is an antagonist of α1-adrenergic receptors (α1-ARs).1,2 It selectively binds to α1-ARs with Ki values of 0.2, 0.25, and 0.32 nM for the human recombinant α1A-, α1B-, and α1D-ARs, respectively, over α2-ARs (Kis = 340 and 3.7 nM in α2A-AR-expressing HT-29 cells and α2B-AR-expressing NG108 cells, respectively).3,4 It also binds to melatonin receptor 3 (MT3) in hamster brain membranes (IC50 = 7.8 nM).5 Prazosin inhibits peripheral and central postsynaptic α1-ARs with IC50 values of 0.20 and 1.7 nM in isolated dog aorta and rat brain, respectively.1 It decreases diastolic blood pressure in normal, renal hypertensive, and spontaneously hypertensive rats when administered at a dose of 1 mg/kg.6 Prazosin (1.5 mg/kg) increases the number of entries and percentage of time spent in the open arms of the elevated plus maze, indicating anxiolytic-like activity, in alcohol-consuming rats and also reduces alcohol intake and alcohol-seeking behavior in alcohol-preferring rats.7,8

|1. Nagatomo, T., Tsuchihashi, H., Sasaki, S., et al. Displacement by α-adrenergic agonists and antagonists of 3H-prazosin bound to the α-adrenoceptors of the dog aorta and the rat brain. Japan J. Pharmacol. 37(2), 181-187 (1985).|2. Kristek, F., and Koprdova, R. Long-term effect of prazosin administration on blood pressure, heart and structure of coronary artery of young spontaneously hypertensive rats. J. Physiol. Pharmacol. 62(3), 295-301 (2011).|3. Leiker, A.J., DeGraff, W., Choudhuri, R., et al. Radiation enhancement of head and neck squamous cell carcinoma by the dual PI3K/mTOR inhibitor PF-05212384. Clin. Cancer Res. 21(12), 2792-2801 (2015).|4. Bylund, D.B., and Ray-Prenger, C. Alpha-2A and alpha-2B adrenergic receptor subtypes: Attenuation of cyclic AMP production in cell lines containing only one receptor subtype. J. Pharmacol. Exp. Ther. 251(2), 640-644 (1989).|5. Paul, P., Lahaye, C., Delagrange, P., et al. Characterization of 2-[125]iodomelatonin binding sites in Syrian hamster peripheral organs. J. Pharmacol. Exp. Ther. 290(1), 334-340 (1999).|6. Fernandes, M., Smith, I.S., Weder, A., et al. Prazosin in the treatment of hypertension. Clin. Sci. Mol. Med. Suppl. 48, 181s-184s (1975).|7. Verplaetse, T.L., Rasmussen, D.D., Froehlich, J.C., et al. Effects of prazosin, an α1-adrenergic receptor antagonist, on the seeking and intake of alcohol and sucrose in alcohol-preferring (P) rats. Alcohol Clin. Exp. Res. 36(5), 881-886 (2012).|8. Skelly, M.J., and Weiner, J.L. Chronic treatment with prazosin or duloxetine lessens concurrent anxiety-like behavior and alcohol intake: Evidence of disrupted noradrenergic signaling in anxiety-related alcohol use. Brain Behav. 4(4), 468-483 (2014).