PD 109488 is a metabolite of quinapril. PD 109488, otherwise known as Quinapril Diketopiperazine, is a derivative of Quinapril that acts as an ACE inhibitor. Inhibition of ACE prevents the conversion of signaling peptide angiotensin I into angiotensin II, which acts as a potent vasoconstrictor. Reduced levels of angiotensin II also reduces the amount of aldosterone that is expressed due to RAAS signaling.

Providing storage is as stated on the product vial and the vial is kept tightly sealed, the product can be stored for up to 24 months.
Wherever possible, you should prepare and use solutions on the same day. However, if you need to make up stock solutions in advance, we recommend that you store the solution as aliquots in tightly sealed vials at -20°C. Generally, these will be useable for up to one month. Before use, and prior to opening the vial we recommend that you allow your product to equilibrate to room temperature for at least 1 hour.