Intravenous pharmacokinetics and absolute oral bioavailability of dolasetron in healthy volunteers: part 1

A review of dolasetron as management of nausea and vomiting in cancer patients

Objective. To systematically review the literature about the pharmacology, pharmacokinetics, efficacy, dosing, and adverse effects of dolasetron, and to define its role in the management of chemotherapy-and radiation-induced nausea and vomiting.

Data Synthesis. A MedLine search was conducted using 5-HT3-receptor antagonists, antiemetics, chemotherapy toxicity, dolasetron, emesis, nausea, and vomiting as search terms. Reference lists and bibliographies of pertinent articles were also identified and reviewed. Both preclinical and clinical literature were reviewed and analyzed.

Data Synthesis. Dolasetron is a serotonin type 3 (5-HT3)-receptor antagonist with potent antiemetic effects in the management of nausea and vomiting. Following administration, dolasetron is rapidly converted to hydrodolasetron, which is believed to be responsible for the drug's antiemetic activity. Results of multiple studies have demonstrated the efficacy of this agent in the prevention of chemotherapy-induced emesis, including that induced by cisplatin. As a single agent, dolasetron produces a complete response rate (RR) in 44% to 57% of patients treated with cisplatin (≥70 mg/m2) and in 59% to 80% of patients treated with moderately emetogenic chemotherapy, such as cyclophosphamide, methotrexate, and fluorouracil (CMF) therapy. When combined with dexamethasone, the RRs are increased. Dolasetron is well tolerated, with headache (24%) and diarrhea (12%) the most commonly reported adverse effects. The efficacy and safety of dolasetron are comparable to those observed with other 5-HT3-receptor antagonists. According to four recently published clinical practice guidelines for use of antiemetics, dolasetron is an appropriate first-line option for the prevention of nausea and vomiting due to moderately to highly emetogenic chemotherapy. Further clinical trials will determine the optimal dose and the role of this highly effective antiemetic agent for other purposes, such as treatment of delayed emesis and emesis resulting from radiation therapy and high-dose chemotherapy followed by bone marrow transplantation.

Optimization of sample pretreatment methods for simultaneous determination of dolasetron and hydrodolasetron in human plasma by HPLC-ESI-MS

A high-performance liquid chromatographic method coupled with electrospray mass spectrometry was developed for the simultaneous determination of dolasetron and its major metabolite, hydrodolasetron, in human plasma. A new sample pretreatment method, i.e., salt induced phase separation extraction (SIPSE), was proposed and compared with four other methods, i.e., albumin precipitation, liquid-liquid extraction, hydrophobic solvent-induced phase separation extraction and subzero-temperature induced phase separation extraction. Among these methods, SIPSE showed the highest extraction efficiency and the lowest matrix interferences. The extraction recoveries obtained from the SIPSE method were all more than 96% for dolasetron, hydrodolasetron and ondansetron (internal standard). The SIPSE method is also very fast and easy because protein precipitation, analyte extraction and sample cleanup are combined into one simple process by mixing acetonitrile with plasma and partitioning with 2 mol/L sodium carbonate aqueous solution. The correlation coefficients of the calibration curves were all more than 0.997, in the range of 7.9-4750.0 ng/mL and 4.8-2855.1 ng/mL for dolasetron and hydrodolasetron, respectively. The limits of quantification were 7.9 and 4.8 ng/mL for dolasetron and hydrodolasetron, respectively. The intra-day and inter-day repeatability were all less than 10%. The method was successfully applied to the pharmacokinetic study of dolasetron.

Treating nausea and vomiting in palliative care: a review

Nausea and vomiting are portrayed in the specialist palliative care literature as common and distressing symptoms affecting the majority of patients with advanced cancer and other life-limiting illnesses. However, recent surveys indicate that these symptoms may be less common and bothersome than has previously been reported. The standard palliative care approach to the assessment and treatment of nausea and vomiting is based on determining the cause and then relating this back to the "emetic pathway" before prescribing drugs such as dopamine antagonists, antihistamines, and anticholinergic agents which block neurotransmitters at different sites along the pathway. However, the evidence base for the effectiveness of this approach is meager, and may be in part because relevance of the neuropharmacology of the emetic pathway to palliative care patients is limited. Many palliative care patients are over the age of 65 years, making these agents difficult to use. Greater awareness of drug interactions and QT(c) prolongation are emerging concerns for all age groups. The selective serotonin receptor antagonists are the safest antiemetics, but are not used first-line in many countries because there is very little scientific rationale or clinical evidence to support their use outside the licensed indications. Cannabinoids may have an increasing role. Advances in interventional gastroenterology are increasing the options for nonpharmacological management. Despite these emerging issues, the approach to nausea and vomiting developed within palliative medicine over the past 40 years remains relevant. It advocates careful clinical evaluation of the symptom and the person suffering it, and an understanding of the clinical pharmacology of medicines that are available for palliating them.

Anti-emetic drugs in oncology: pharmacology and individualization by pharmacogenetics

OBJECTIVE

Nausea and vomiting are the most distressful side effects of cytotoxic drugs in cancer patients. Antiemetics are commonly used to reduce these side effects. However, the current antiemetic efficacy is about 70-80% in patients treated with highly-emetogenic cytotoxic drugs. One of the potential factors explaining this suboptimal response is variability in genes encoding enzymes and proteins which play a role in metabolism, transport and receptors related to antiemetic drugs. Aim of this review was to describe the pharmacology and pharmacogenetic concepts of of antiemetics in oncology.

METHOD

Pharmacogenetic and pharmacology studies of antiemetics in oncology published between January 1997 and February 2010 were searched in PubMed. Furthermore, related textbooks were also used for exploring the pharmacology of antiemetic drugs. The antiemetic drugs which were searched were the 5-hydroxytryptamine 3 receptor antagonists (5-HT3RAs), dopamine antagonists, corticosteroids, benzodiazepines, cannabinoids, antihistamines and neurokinin-1 antagonists.

RESULT

The 5-HT3RAs are widely used in highly emetogenic chemotherapy in combination with dexamethasone and a neurokinin-1 antagonist, especially in acute phase. However, the dopamine antagonists and benzodiazepines were found more appropriate for use in breakthrough and anticipatory symptoms or in preventing the delayed phase of chemotherapy induced nausea and vomiting. The use of cannabinoids and antihistamines need further investigation. Only six articles on pharmacogenetics of the 5-HT3RAs in highly emetogenic chemotherapy are published. Specifically, these studies investigated the association of the efficacy of 5-HT3RAs and variants in the multi drug resistance 1 (MDR1) gene, 5-HT3A,B and C receptor genes and CYP2D6 gene. The pharmacogenetic studies of the other antiemetics were not found in this review.

CONCLUSION

It is concluded that pharmacogenetic studies with antiemetics are sparse. It is too early to implement results of pharmacogenetic association studies of antiemetic drugs in clinical practice: confirmation of early findings is required.

Treatment of nausea and vomiting in terminally ill cancer patients

Nausea and vomiting is a common and distressing symptom complex in patients with far-advanced cancer, affecting up to 60% of individuals at some stage of their illness. The current approach to the palliative care of patients with nausea and vomiting is based on identifying the cause, understanding its pathophysiology and knowing the pharmacology of the drugs available for its amelioration. The following six main syndromes are identified: gastric stasis, biochemical, raised intracranial pressure, vestibular, mechanical bowel obstruction and ileus. A careful history, focused physical examination and appropriate investigations are needed to elucidate the syndrome and its cause, so that therapy is rational. Drugs are the mainstay of treatment in terminal cancer, and the main classes of antiemetic agents are prokinetics, dopamine antagonists, antihistamines, anticholinergics and serotonin antagonists. Dexamethasone and octreotide are also used, especially in bowel obstruction. Non-drug measures are important in relieving the associated distress. Patients should be able to die comfortably, without tubes. Despite decades of practice affirming this approach, the evidence base is weak and well designed studies are urgently needed.

Prevention of Postoperative Nausea and Vomiting with Granisetron and Dolasetron in Relation to CYP2D6 Genotype

We investigated the efficacy of granisetron and dolasetron in preventing postoperative nausea and vomiting. Because the metabolism of the various antiemetic 5-hydroxytryptamine type 3 (5-HT3) antagonists involves different isoforms of the hepatic cytochrome P450 system, we examined the relationship between the clinical efficacy of these drugs and polymorphic cytochrome P450 2D6 (CYP2D6) genotype. This prospective, randomized, double-blind study involved 150 adult patients with a moderate to high risk for postoperative nausea and vomiting. All subjects received dexamethasone at induction of anesthesia followed by either 12.5 mg of dolasetron or 1 mg of granisetron. We analyzed the number of complete responders (no vomiting or rescue medication) during the first 24 hours after surgery. CYP2D6 genotyping was performed using a TaqMan real-time polymerase chain reaction. A complete response was more frequent in the granisetron group (54.7%) compared with the dolasetron group (38.7%, P < 0.05). In subjects receiving dolasetron, carriers of the duplication of the CYP2D6 allele predicting ultrarapid metabolizer status had more frequent vomiting episodes (P < 0.05) than patients in the granisetron group. It is postulated that the difference in the antiemetic efficacy between two investigated 5-HT3 receptor antagonists may be associated with differences in the carrier status for the duplication of the CYP2D6 allele.

Antiemetics of the 5-hydroxytryptamine 3A antagonist class inhibit muscle nicotinic acetylcholine receptors

Antagonists of the serotonergic 5-hydroxytryptamine 3A receptor (5-HT(3A)R) and muscle nicotinic acetylcholine receptors (nAChR) are widely used in anesthesia practice. Both 5-HT(3A)R and nAChR are ligand-gated ion channels with known pharmacological overlap between some of their agonists and antagonists. We studied the actions of clinically used 5-HT(3A)R antagonist antiemetics and nondepolarizing muscle blockers on ionic currents elicited by the activation of mammalian 5-HT(3A)R and muscle nAChR, expressed in Xenopus laevis oocytes. Currents were recorded using a whole-cell two-electrode voltage clamp technique. Dolasetron, ondansetron, and granisetron reversibly inhibited 5-HT(3A)R function at nanomolar concentrations with 50% inhibitory concentrations (IC(50)) of 11.8, 6.4, and 0.2 nM; the rank order of inhibition correlated well with their clinical antiemetic potencies. The principal metabolite of dolasetron, hydrodolasetron, was 40 times more potent than the parent compound on 5-HT(3A)R (IC(50) = 0.29 nM). The potency of the nondepolarizing muscle blocker d-tubocurarine in blocking 5-HT(3A)R was similar to that of the antiemetics and significantly more than vecuronium and rapacuronium (IC(50) = 11.4 nM, 18.9 microM, 60.5 microM). Conversely, ondansetron, dolasetron, and granisetron also reversibly inhibited nAChR currents in a dose-dependent manner with IC(50)s of 14.2, 7.8, and 4.4 microM for the adult nAChR and 16.0, 18.6, and 13.9 microM for the embryonic nAChR. Again, hydrodolasetron showed significantly (10 times) more inhibitory potency on the adult nAChR than the parent compound dolasetron. These results indicate that drugs that target specific ligand-gated ion channels may also affect other ion channel types.

Timing of administration of dolasetron affects dose necessary to prevent postoperative nausea and vomiting

STUDY OBJECTIVE

To determine if the timing of administration affects the dose of dolasetron necessary to prevent postoperative nausea and vomiting (PONV).

DESIGN

Pooled data from 8 randomized, multicenter, double-blind, placebo-controlled studies with common endpoints.

SETTING

University hospital.

PATIENTS

A total of 4,587 ASA physical status I, II, and III patients, including 4,124 females undergoing primarily gynecologic procedures and 463 males undergoing various procedures (i.e., thyroidectomy or orthopedic, ophthalmologic, urologic, ENT, or laparoscopic surgery).

INTERVENTIONS

Balanced general anesthesia was used during all procedures. Patients received a dose of dolasetron either for prevention of PONV (25 or 50 mg IV at induction; 25, 50, 100, or 200 mg orally 1 to 2 hours pre-induction; or 12.5, 25, 50, or 100 mg IV at end of anesthesia) or for treatment of PONV (12.5, 25, 50, or 100 mg IV). One PONV prevention study had an ondansetron (comparator) group.

MEASUREMENTS

Outcome measures over a 24-hour study period included complete response (defined as no vomiting/retching and no need for rescue medication), percentage of patients without nausea [defined as nausea visual analog scale (VAS) score < 5 mm], and maximum nausea according to VAS score.

MAIN RESULTS

A 12.5-mg IV dose of dolasetron resulted in a complete response rate that was statistically significantly higher than placebo and comparable to higher dolasetron doses (25 mg to 100 mg IV) when administered either near the end of anesthesia for prevention of PONV or at the onset of symptoms for treatment of PONV. In contrast, when administered at induction of anesthesia, a statistically significant treatment response was observed with dolasetron 50 mg IV, but not at a lower dose.

CONCLUSIONS

When dosed near the end of anesthesia, a 12.5 mg IV dose of dolasetron was comparable to higher doses administered at or before induction of anesthesia.

Comparison of oral dolasetron and ondansetron in the prophylaxis of postoperative nausea and vomiting in children

BACKGROUND AND OBJECTIVE

In a randomized, placebo-controlled, double-blind trial, we compared the efficacy of oral dolasetron and ondansetron in preventing postoperative nausea and vomiting in children after various surgical operations.

METHODS

Children were assigned randomly to one of three groups (each contained 50 children) to receive dolasetron 1.8 mg kg(-1) or ondansetron 0.15 mg kg(-1) orally, or a placebo. All children received methylene blue capsules (10 mg) orally as an indicator before the induction of anaesthesia. Postoperatively, contamination of the mouth and the endotracheal tube by methylene blue was recorded, and postoperative nausea and vomiting was recorded for 0-1, 1-24 and 0-24 h. Metoclopramide (0.1 mg kg(-1)) intravenously was used as the rescue antiemetic.

RESULTS

In the 0-1 h period after operation, there were no differences between the groups. In the 1-24 h period, dolasetron was significantly better than placebo (nausea 8 versus 24%; vomiting 4 versus 20%; total nausea and vomiting scores 16 versus 48%). Over the 0-24 h period, both dolasetron and ondansetron were significantly better than placebo (nausea 16 versus 26 versus 40%), vomiting (8 versus 16 versus 30%), and total nausea and vomiting scores (32 versus 48 versus 78%). There were no significant differences between dolasetron and ondansetron. There was no important methylene blue contamination, and little use of rescue metoclopramide. There were no important adverse events.

CONCLUSIONS

Prophylactic oral dolasetron and ondansetron were effective in reducing postoperative nausea and vomiting in children.