III.2. Its active ingredient, domperidone Leisguard速 active substance is domperidone (Figure 8), a benzimidazole derivative which acts through specific blockade of dopamine D2 receptors in the periphery. Figure 8. Chemical structure of domperidone (5-chloro-1-(1 - [3 - (2-oxo-2 ,3-dihydro-1H-benzo [d] imidazol-1yl) propyl] piperidin-4-yl) - 1H-benzo [d] imidazol-2 (3H)-one).
Unlike other molecules that act likewise, domperidone practically does not cross the blood brain barrier, that is why not attributed any extra-pyramidal side effects (Reyntjens et al., 1978; Rooyen et al., 1981; Kohli et al ., 1983). This feature, together with the results of toxicological studies conducted during the development of Leisguard速, supported a wide margin of safety. Domperidone has been used extensively in humans and in dogs like gastrokinetic and antiemetic agent, with both activities due to the blockade of D2 dopamine receptors at the level of vomiting center integrated in the medulla and upper digestive tract level, respectively (Brodgen et al., 1982; Reyntjens et al., 1982, Prakash et al., 1998, Takahashi et al., 1991; Johnson, 1992; Barone, 1999; Washabu Hall, 2000). Less known is its endocrine hyperprolactinemia activity derived from the blockade of D2
dopamine
receptors
at
the
level
of
the
pituitary
gland.
This blocking involves the acute release of prolactin accumulated in the pituitary gland which leads to a transient peak of a few hours in blood levels of this hormone (Kato et al., 1980, Fujino et al., 1980). Numerous studies show that prolactin, in addition to participate in the hormonal regulation of reproductive function, also has a key role in the development and function 13