Pathophysiology of cytotoxic drug-induced emesis: far from crystal-clear.

Both radiotherapy and chemotherapy for cancer are capable of causing severe nausea and vomiting, which formerly often interfered with the patient's compliance to treatment. The basic pathway and pharmacological mechanisms involved in this are still poorly understood. The recent discovery, however, that 5-HT3 receptor antagonists can prevent or greatly reduce chemotherapy-induced emesis led to a re-evaluation of the sequence of events occurring in the protective emetic reflex, which are reviewed in this paper. The vomiting centre co-ordinates the incoming and outgoing information, and is thought to be represented by complex interactions between different adjacent areas in the brainstem. Whether the main role in the emetic reflex arch is accomplished by either the central part (chemoreceptor trigger zone) or the peripheral part (gastro-intestinal tract) needs further confirmation A more important role, however, of the vagal nerve and the gastro-intestinal tract is generally accepted. The neurotransmitter serotonin (5-HT) appears to play a major role in chemotherapy-induced emesis via the 5-HT receptor. These indications could form the basis for further investigations into the involvement of other neurotransmitters, and the character of their interactions.