Newer dopamine receptor agonists such as quinagolide and Cabergoline are shown to effectively inhibit prolactin secretion with improved efficacy over Bromocriptine. These drugs are effective in patients who are intolerant or resistant to Bromocriptine. Quinagolide exists as a racemate and its relevant clinical activity is mediated predominantly by the (-) enantiomer. It is typically present in the hydrochloride salt form and is marketed as oral tablets. Quinagolide is a non-ergot-derived selective dopamine D2 receptor agonist used for the treatment of elevated levels of prolactin or hyperprolactinaemia. Quinagolide achieves long-lasting reduction in prolactin levels in a dose-proportional effect via selectively targeting D2 receptors as an agonist. It potently suppresses both basal and stimulated serum prolactin levels by exerting a strong inhibitory effect on the secretion of the anterior pituitary hormone prolactin. Prolactin secretion from the lactotroph cells present in the anterior pituitary gland is under tonic inhibitory control mediated by dopaminergic signalling via D2 receptors. Quinagolide selectively binds to D2 receptors expressed on the surface of lactotroph cells with high affinity which results in reduced adenylyl cyclase activity, reduced intracellular cyclic adenosine monophosphate and inhibited prolactin secretion. It also binds to D1 receptors but with low affinity and little clinical relevance.

Quinagolide Mechanism of Action Pathway References