Alpha blockers also called as alpha-adrenergic antagonists. These are the drugs that block the effect of sympathetic nerves by binding to alpha Adrenergic receptors.
Most of these drugs act as competitive antagonists to the binding of noradrenaline that is released by sympathetic nerves.
So they are called as sympatholytics.
1. NONEQUILIBRIUM TYPE
β-Haloalkylamines:
Phenoxybenzamine
2. EQUILIBRIUM TYPE (COMPETITIVE)
a. Nonselective
1. Ergot alkaloids:
Ergotamine
Ergotoxine
2. Hydrogenated ergot alkaloids:
Dihydroergotamine (DHE)
Dihydroergotoxine
3. Imidazolines:
Tolazoline
Phentolamine
4. Miscellaneous:
Chlorpromazine
Ketanserin
b. α1 Selective:
Prazosin
Terazosin
Doxazosin
Alfuzosin
Tamsulosin
c. α2 selective:
Yohimbine