Sulpiride, dopaminergic effects

Die specificity of the dopamine receptor was further studied with a series of dopaminergic antagonists of well known pharmacological activity. The 30-40% inhibitory effect of 10 nM dopamine was completely reversed by the addition of increasing concentrations of the potent neuroleptics (+)butaclamol (Kp = 1.5 nM) and (-)sulpiride (Kp = 0.5 nM) while their pharmacologically weak enantiomers (-)butaclamol and (+)sulpiride were 86 and 167 times less potent, respectively. The neuroleptics spiroperidol, thioproperazine, domperidone, haloperidol, fluphenazine and pimozide completely reversed the inhibitory effect of dopamine at low Kp values ranging from 0.02 to 0.8 nM (41). 

SK F 85174 was chosen for more detailed study (31). In anesthetized dogs, tachycardia Induced by cardiac accelerator nerve stimulation was inhibited by intravenous SK F 85174 (EDjg, 42 Ug/kg) which effect was antagonized by metoclopramide and 1-sulpiride. In anesthetized rats (normotensive, spontaneously hypertensive, DOCA-salt hypertensive) SK F 85174 decreased both blood pressure and heart rate. The results suggested that SK F 85174 has presynaptic dopaminergic activity and may be useful in the treatment of angina and hypertension (31). 

In a few cases, marked extrapyramidal side-effects (akathisia, dystonia, and parkinsonism) have been reported with flupbenazine, perphenazine, sulpiride, and thiothixene when fluoxetine is added to the regimen. The mechanism is speculated to be the result of fluoxetine-induced further suppression of dopaminergic activity in the nigrostriatal pathways (serotonergic stimulation leads to decreased dopamine release), in addition to increases in their plasma concentration. Fluoxetine has been shown to increase haloperidol serum levels by about 20%, presumably via inhibition of cytochrome P450 enzymes. Fluoxetine can increase the risk of seizure induction when added to clozapine due to an increase in clozapine serum levels, or by additive effects. Concomitant treatment with fluoxetine and risperidone is associated with a mean 4-fold increase in the plasma concentration of risperidone. ... 

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