Development of antiemetic therapy in cancer patients

Gender and anthropometrics of patients undergoing cisplatin-containing chemotherapy as determinants of acute emesis over repeat courses

Objective. To characterize the anthropometric and pharmacotherapeutic variables related to acute emesis over repeat courses of cisplatin-containing regimens (≥50 mg/m survival analysis.2) by means of survival analysis.

Methods. A prospective, cross-sectional non-controlled study was started to analyse acute vomiting in patients treated in a general hospital. The patients received an intravenous combination of drugs based on metoclopramide (two 3 mg/kg doses), diphenhydramine (20 mg) and dexamethasone (20 mg) as first choice antiemetic treatment. An intravenous regimen based on ondansetron (8 mg) and dexamethasone (20 mg) was given as an alternative regimen. Therapeutic failure was defined as the recording of one or more vomiting episodes on a self-evaluation sheet. Other variables included were chemotherapeutic regimen, antiemetic regimen, gender, age, weight and height. The statistical analysis was developed using the Cox proportional hazards model.

Results. Eighty-eight patients were finally included in the study, 16 women (18%) and 72 men (82%). The metoclopramide-based regimen was administered to 74 patients (84%) and the ondansetron-based regimen to 14 patients (15%). The univariate analysis showed that any variable included in the study was significant. The multivariate survival analysis retained three variables: height (hazard ratio 1.22), gender (hazard ratio 2.12) and weight (hazard ratio 1.44) of the patients. It is hypothesized that gender and anthropometrics of patients could represent differences in pharmacokinetic and/or pharmacodynamic behaviour of cisplatin and/or antiemetics. The potential role of these parameters in these drugs is discussed.

Conclusions. Emesis over repeat courses in cisplatin-containing regimens seems a function of the gender and anthropometrics of patients, irrespective of the antiemetic regimen and the emetogenicity of the cytostatics. Dosing individualization of cisplatin and/or antiemetics based on pharmacokinetic and/or pharmacodynamic parameters can be a valid tool to increase the effectiveness and safety of these drugs.

Metoclopramide-induced acute dystonic reaction: a case report

The aim of this case report is to draw attention to the frequent occurrence of metoclopramide-induced movement disorders. We report a case of an acute dystonic reaction to metoclopramide in a patient treated for hepatitis A. Metoclopramide can cause severe adverse events, such as an acute dystonic reaction, and should be used with caution in patients with infectious diseases.

Selective serotonin 5-HT3 receptor antagonists for postoperative nausea and vomiting: are they all the same?

Selective serotonin 5-HT(3) receptor antagonists have proven safe and effective for the management of postoperative nausea and vomiting. Dolasetron, granisetron, ondansetron and tropisetron selectively and competitively bind to 5-HT(3) receptors, blocking serotonin binding at vagal afferents in the gut and in the regions of the CNS involved in emesis, including the chemoreceptor trigger zone and the nucleus tractus solitarii. Despite their shared mechanism of action, 5-HT(3) receptor antagonists have different chemical structures and exhibit differences in receptor binding affinity, dose response and duration of effect. Furthermore, although dolasetron, granisetron, ondansetron and tropisetron are all extensively metabolised by the cytochrome P450 (CYP) system, different components of this system predominate in the metabolism of each of these agents. Hence, although these agents are considered equally effective in the overall population, their pharmacokinetic and pharmacodynamic differences may explain the variability in individual responses to these drugs. This review discusses the pharmacological profiles of dolasetron, granisetron, ondansetron and tropisetron, and the clinical implications of differences in their profiles.

Review article: the therapeutic potential of 5-HT3 receptor antagonists in the treatment of irritable bowel syndrome

There is evidence from studies, in both animals and humans, that 5-HT3 receptor blockade has potential value in the treatment of irritable bowel syndrome, particularly in those patients with diarrhoea-predominant bowel habits. New findings suggest that 5-HT3 receptors exist on gut afferent neurones and that their activation by locally released 5-HT leads to visceral nociceptive stimulation, in addition to increased neuronally-mediated motor and secretory activity. If this concept is validated, it will provide a rationale for the use of 5-HT3 receptor antagonists in patients with increased gut motility, reduced fluid absorption and low nociceptive thresholds leading to abdominal pain. Alosetron is a highly selective, potent 5-HT3 receptor antagonist which is well absorbed with a long pharmacodynamic half-life. Its ability to provide long-lasting blockade of 5-HT3 receptors throughout the body make it an ideal candidate within its class to evaluate the clinical hypothesis that sustained and ubiquitous 5-HT3 receptor blockade is of value in the treatment of IBS.

New perspectives in antiemetic treatment

Though antiemetic therapy has improved markedly in the past 15 years, patients still regard nausea and vomiting as two of the most distressing adverse events during chemotherapy. A major progress was the development of the serotonin3 (5-HT3) receptor antagonists. A possible antiemetic effect, achieved by interference with the "serotonergic system", is not restricted to antagonism at 5-HT3 receptors, however, but also includes agonism at 5-HT1A and 5-HT2 receptors, and serotonin synthesis inhibitors. The number of receptors thought to be involved in the emetic reflex has been augmented by neurokinin1 receptors with substance P as the preferred ligand. Animal studies have demonstrated a broad antiemetic profile of substance P antagonists. The somatostatin analogue octreotide has an antiemetic effect in patients with gastrointestinal obstruction, but has not been investigated against chemotherapy-induced emesis. The next few years will disclose, whether the efficacy and safety profiles of one or more of these drugs will make it clinically useful in the treatment of chemotherapy-induced nausea and vomiting.