Metoclopramide antiemetic properties

Metoclopramide is used for its antiemetic properties in patients with diabetic gastroparesis and with dexamethasone for prophylaxis of delayed nausea and vomiting associated with chemotherapy administration. 

B. Two medicines, ipecac and apomorphine, induce vomiting. Metoclopramide is a prokinetic with antiemetic properties and therefore would have the opposite of the desired effect. Morphine is an opioid with analgesic and sedating properties. Promethazine and ondansetron are also antiemetics, not emetics. 

Metoclopramide has antiemetic properties because it Accelerates gastric emptying time... 

A number of ANALGESICS can be used to offset the pain of the attack, including aspirin, codeine and paracetamol, and these are often incorporated into compound preparations together with a variety of other drugs and drug types, e.g. caffeine, buclizine, doxylamine, isometheptene, pizotifen. Sometimes drugs with antinauseant or ANTIEMETIC properties are included, e.g. cyclizine and metoclopramide. 

The antiemetic properties of metoclopramide appear to be a result of its antagonism of central and peripheral dopamine receptors. Dopamine produces nausea and vomiting by stimulation of the medullary chemoreceptor trigger zone (CTZ), and metoclopramide blocks stimulation of the CTZ by agents like levodopa or apomorphine that are known to increase dopamine levels or to possess dopaminelike effects. Metoclopramide also inhibits the central and peripheral effects of apomorphine and abolishes the slowing of gastric emptying caused by apomorphine. 

Most of the antiemetic clinical trials in the last decade have involved metoclopramide (1) either as a single agent or in combination with other drugs. Similarly, most of the chemical modification studies have been designed to optimize antiemetic and/or gastroprokinetic properties of metoclopramide and to eliminate undesirable CNS side-effects which are the consequence of its dopamine D2 receptor blockade [1-3]. 

Recently, several 5-HT3 antagonists have been identified and found to be effective as antiemetics in animals (Table 7.2). These compounds as a class have been proven to be free of D2-dopamine blocking properties which are responsible for dystonic side-effects seen with metoclopramide. 

---