Dolasetron antagonists

Bell shaped concentration-effect relationships (an Emax curve, followed by a decrease in effect when concentrations are further increased) have been observed for a number of drugs. Concerning serotonin 5-HT3 receptor antagonists, a decrease in effect was reported with increasing doses of tropisetron and dolasetron. This implies a bell shaped concentration-effect relationship, which may be due to the fact... 

Serotonin (S-HTj) antagonists dolasetron mesylate granisetron hydrochloride ondansetron... 

Alosetron is a 5-HT3 antagonist that has been approved for the treatment of patients with severe IBS with diarrhea (Figure 62-5). Four other 5-HT3 antagonists (ondansetron, granisetron, dolasetron, and palonosetron) have been approved for the prevention and treatment of nausea and vomiting (see Antiemetics) however, their efficacy in the treatment of IBS has not been determined. The differences between these 5-HT3 antagonists that determine their pharmacodynamic effects have not been well studied. 

Chemical structure of serotonin the 5-HT3 antagonists ondansetron, granisetron, dolasetron, and alosetron and the 5-HT4 partial agonist tegaserod. 

Ondansetron is one of a group of 5HT3-receptor antagonists currently available in the UK, which also includes granisetron, tropisetron, dolasetron and palonosetron. Dexamethasone is a corticosteroid. Ranitidine is a histamine-2 (H2)-receptor antagonist. 

FLECAINIDE ANTIEMETICS-5-HT3-ANTAGONISTS Risk of arrhythmias Additive effect Manufacturers recommend avoiding co-administration of flecainide with dolasetron. Caution with other 5-HT3-antagonists monitor ECG closely... 

MDL 73147EF) is a substituted quinolizinylindole, a selective (5-HT3) 5-hydroxytryptamine receptor antagonist. It shows ANTIEMETIC activity against chemotherapy-induced emesis, and also has antimigraine activity, dolasetron mesylate dolasetron. 

Selective Serotonin Antagonists for CINV Dolasetron (Anzemet) chemotherapy, 80 mg on days 2 and 3 1.8 mg/kg 30 min prior to chemotherapy IV Rx... 

The 5-HT -receptor antagonists are the most widely used drugs for chemotherapy-induced emesis. Ondansetron (zofran) is the prototypical drug in this class other agents include granisetron (kytril), dolasetron (anzemet), palonosetron (aloxi intravenous use only) and tropisetron (available in some countries but not in the U.S.). Differences among these agents relate mainly to their chemical structures, 5-HTj receptor affinities, and pharmacokinetic profiles (Table 37-8). 

Dolasetron and granisetron are 5-HT3 antagonists. Sumatriptan is a 5-HT,p agonist. Ranitidine is a histamine antagonist but blocks the H, receptor in the stomach and the heart, not H, receptors in smooth muscle. Epinephrine has a physiologic antagonist action that reverses histamine s effects on smooth muscle. The answer is (B). 

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