Pharmacological Agents Affecting Emesis : A Review (Part II)

Part I of this article reviewed the pathophysiology of emesis, and its pharmacological treatment. Drug-induced vomiting was also discussed. In the second part of the review, other common causes of vomiting are considered.The basis of the use of antiemetics in morning sickness and migraine is still obscure; for the latter, serotonin 5-HT₁ receptor agonists, 5-HT₃ receptor antagonists and dopamine D₂ receptor antagonists are effective. For motion sickness, control can be achieved with various antagonists of muscarinic or histamine H₁-receptors. Centrally active adrenoceptor agonists in combination with a muscarinic antagonist or H₁-receptor antagonist may offer better control of motion sickness and its associated symptoms than either antagonist alone; based on clinical studies, post-operative vomiting after opiate administration appears to be controlled by blocking dopamine D₂, histamine H₁-or muscarinic receptors.Radiation therapy appears to be similar to cytotoxic therapy in that the mediators produced or released by radiation activate both peripheral and central sites involved in the vomiting reflex. Blockade of dopamine D₂ and 5-HT₃ receptors may be effective.