Mechanism of Action

The a-antagonism produced by prazosin and the other quinazoline derivatives is of the equilibrium-competitive type. The drugs are selective for a1-adrenoceptors, so that at usual therapeutic concentrations there is little or negligible antagonism of a2-adrenoceptors. However, selectivity is only relative and can be lost with high drug concentrations. While most of the pharmacological effects of prazosin are directly attributable to a1-antago-nism, at high doses the drug can cause vasodilation by a direct effect on smooth muscle independent of a-recep-tors. This action appears to be related to an inhibition of phosphodiesterases that results in an enhancement of intracellular levels of cyclic nucleotides.

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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