Dopaminergic drugs: pharmacological and therapeutic aspects / Drogas dopaminergicas: aspectos farmacológicos y terapéuticos

RESUMO

It has been widely established that dopamine and its agonists exect an import role in the regulation of the cardiovascular, renal hormonal systems, acting through adrenergic and beta-adrenergic systems. There are several DA-2 agonists such as bromocriptine pergolide, lisuride, and largotrile, which belong to the ergolin family and act both at central and peropheral levels-inhibiting norepinephrine release, which produces a decrease of arterial pressure and, in some cases, such as with bromocriptine and pergolide, a decrease in the heart rate. From a therapeutic viewpoint, the above mentioned DA-2 agonists are widely used for treating Parkinso's disease; these agonists act at the level of DA-2 receptors located in the nigrostriatal system. Bromocriptine and the other mentioned agonists DA-2 are used in the treatment of hyperprolatinemia and in pivitary tumors, since they decrease prolactin secretion and reduce the size of the tumor acting through inhibitory DA-2 receptors located in the tuberoinfuldibolar system. Similarly, there are Also DA-1 agonists such fenoldopam (selective) and piribedil non selective) which activate peripheral receptors, producing, a reduction of peripheral resistance and renal vascular resistance and an renal vascular resistance and an increase of renal blood flow. All these effects produce a decrease in arterial pressure and a reflex hearth rate increase. Fenoldopam in used in the treatment of arterial hypertensión, renal failure and heart failure. This agonist exerts its action at the level of the DA-1 receptors located in peripheral and renal resistance vessels (which leads to an increase use in renal blood flow and a decrease pressure). Among the selecttive antagonists of DA-2 receptors, we can mention metoclopramide and domperidone. Both antagonists produce a decrease in the hypotensor response of treatment of schizophrenia; it acts by activating DA-1 and DA-4 recepts located at the hypothalamus, olfactory bulb, and frontal cortex