5-hydroxytryptamine type-3 receptor antagonists for chemotherapy-induced and radiotherapy-induced nausea and emesis: can we safely reduce the dose of administered agents?

Enhanced field-amplified sample injection by mobility decrease in capillary electrophoresis for the analysis of trace enantiomeric impurities in palonosetron injection

Palonosetron hydrochloride [PALO (3aS, 2S)] is a highly selective second generation 5-HT3 receptor antagonist with two asymmetric carbon atoms in molecular structure. For chiral drugs, detection of the enantiomeric impurity is critical for drug safety and efficacy, because the undesired enantiomer can cause adverse effects or reduce the drug's therapeutic effect. In this work, the mechanism of online preconcentration in the analysis of PALO injection using micellar electrokinetic chromatography (MEKC) with bile salt sodium taurocholate (STC) as chiral selector was studied, based on the background difference between sample solution and background electrolyte (BGE). In addition to the field amplified sample stacking due to the conductivity difference between the sample plug and BGE, the disassociation of protonated solutes with positive charge caused by the pH increase and the distribution of solutes into STC micelles with negative charge result in a significant decrease in effective mobility, when they enter the BGE. This, combined with a reduction in field strength, causes the solutes slow down quickly and stack at the interface between sample plug and BGE. However, achieving the analysis of all three possible enantiomeric impurities in hydrodynamic injection mode is challenging due to poor separation. This is caused by the long effective capillary length consumed during online preconcentration and the wide solute band eventually focused if enough sample solution is injected. This issue was resolved by using electrokinetic injection mode, where solutes are driven into the capillary by both electric field and electroosmotic flow and stack at the interface meanwhile. As a result, a sufficient amount of solutes can be injected in a shorter sample plug compared to hydrodynamic injection mode. The method achieved a limit of detection of 0.014 μg mL-1 and a limit of quantification of approximately 0.05 μg mL-1 for enantiomeric impurities, without compromising the separation. Those are 0.03 % and 0.10 % of the content of main ingredient, respectively, representing nearly a ten-fold improvement in sensitivity over our previous works. Other quantitative data include a linear range of 0.05-0.50 μg mL-1, a coefficient of determination (R2) of 0.993-0.998, a spike recovery of 96.1-100.6 %, and a precision (RSD) of 2.2 % and 3.6 % for the intra-day and inter-day analysis, respectively. For the first time, the identification and quantification of trace amount of enantiomeric impurity in real sample of PALO drug was successfully achieved using MEKC with bile salt as chiral selector.

Comparison of the Performance of Different Bile Salts in Enantioselective Separation of Palonosetron Stereoisomers by Micellar Electrokinetic Chromatography

Bile salts are a category of natural chiral surfactants which have ever been used as the surfactant and chiral selector for the separation of many chiral compounds by micellar electrokinetic chromatography (MEKC). In our previous works, the application of sodium cholate (SC) in the separation of four stereoisomers of palonosetron (PALO) by MEKC has been studied systematically. In this work, the parameters of other bile salts, including sodium taurocholate (STC), sodium deoxycholate (SDC), and sodium taurodeoxycholate (STDC) in the separation of PALO stereoisomers by MEKC were measured and compared with SC. It was found that all of four bile salts provide chiral recognition for both pairs of enantiomers, as well as achiral selectivity for diastereomers of different degrees. The structure of steroidal ring of bile salts has a greater impact on the separation than the structure of the side chain. The varying separation results by different bile salts were elucidated based on the measured parameters. A model to describe the contributions of the mobility difference of solutes in the aqueous phase and the selectivity of micelles to the chiral and achiral separation of stereoisomers was introduced. Additionally, a new approach to measure the mobility of micelles without enough solubility for hydrophobic markers was proposed, which is necessary for the calculation of separation parameters in MEKC. Under the guidance of derived equations, the separation by SDC and STDC was significantly improved by using lower surfactant concentrations. The complete separation of four stereoisomers was achieved in less than 3.5 min by using 4.0 mM of SDC. In addition, 30.0 mM of STC also provided the complete resolution of four stereoisomers due to the balance of different separation mechanisms. Its applicability for the analysis of a small amount of enantiomeric impurities in the presence of a high concentration of the effective ingredient was validated by a real sample.

Differential pharmacology and clinical utility of rolapitant in chemotherapy-induced nausea and vomiting

Chemotherapy-induced nausea and vomiting (CINV) is a debilitating side effect of many cytotoxic chemotherapy regimens. CINV typically manifests during two well-defined time periods (acute and delayed phases). The acute phase is the first 24 hours after chemotherapy and is largely managed with 5-hydroxytryptamine 3 receptor antagonists. The delayed phase, a 5-day at-risk period during which patients are not often in direct contact with their health care provider, remains a significant unmet medical need. Neurokinin-1 (NK-1) receptor antagonists have demonstrated protection against acute and delayed CINV in patients treated with highly emetogenic chemotherapy and moderately emetogenic chemotherapy when used in combination with a 5-hydroxytryptamine 3 receptor antagonist and dexamethasone. Furthermore, recent data indicate that this protection is maintained over multiple treatment cycles. Rolapitant, a selective and long-acting NK-1 receptor antagonist, is approved as oral formulation for the prevention of delayed CINV in adults. This review discusses the differential pharmacology and clinical utility of rolapitant in preventing CINV compared with other NK-1 receptor antagonists.

Reappraisal of the role of dolasetron in prevention and treatment of nausea and vomiting associated with surgery or chemotherapy

Chemotherapy-induced nausea and vomiting and postoperative nausea and vomiting are one of the most frequent but also very concerning consequences for patients undergoing chemotherapy or surgical procedures under general anesthesia. There are a variety of mechanisms involved in the activation of nausea and vomiting. Serotonin, a ubiquitous central and peripheral neurotransmitter, is thought to be the predominant mediator of the perception of nausea and triggering of the vomiting response in both the brain and the periphery via the 5-hydroxytryptamine type 3 (5-HT₃) receptor pathways. 5-HT₃ receptor antagonists disrupt this pathway, largely at the level of the vagal afferent pathways, to decrease nausea and vomiting. This review will focus on dolasetron, an older but sill commonly used 5-HT₃ receptor antagonist and its multimodal mechanism of action, safety and tolerability, patient considerations, and a review of the current literature on its use to combat both chemotherapy-induced and postoperative nausea and vomiting in these two important patient populations.

Chemotherapy outpatients' unplanned presentations to hospital: a retrospective study

GOAL OF WORK

This descriptive, retrospective study sought to identify the nature and magnitude of chemotherapy outpatients' unplanned presentations and admissions to the emergency department and/or cancer centre at a large metropolitan tertiary hospital, and to explore the antecedents to those presentations.

PATIENTS AND METHODS

Retrospective data were collected for outpatients who made an unplanned presentation to a large metropolitan hospital in Sydney, Australia between October 1, 2006 and September 30, 2007. Detailed information was collected for those who had received cytotoxic chemotherapy at the hospital's cancer centre within the 6 months prior to the unplanned presentation to hospital. Demographic and explanatory variables were identified, including: reasons for presentation, cancer diagnosis, chemotherapy regimens, and position in the chemotherapy trajectory.

MAIN RESULTS

The Cancer Institute NSW figures indicate that each year approximately 518 outpatients are treated with chemotherapy at the participating cancer centre. During the study period, 316 cancer outpatients made 469 unplanned presentations to either the Cancer Centre or the hospital emergency department. Of those outpatients presented, 233 (73.7%) had received chemotherapy in the previous 6 months and made a total of 363 presentations. Of these 363 presentations, 253 (69.7%) occurred within 4 weeks of receiving chemotherapy. The majority of presentations by those who had received chemotherapy in the previous 6 months resulted in hospital admission (87.6%) for a median length of stay of 5 days. The most frequent presentation symptoms were nausea and/or vomiting (45.2%), pain (27%), fever and/or febrile neutropenia (23.4%), shortness of breath (19.3%), dehydration (12.1%), anaemia (8.8%), fatigue (8.8%), diarrhoea (8.8%), and anxiety and/or depression (5.5%).

CONCLUSIONS

Chemotherapy outpatients have significant unmet needs following treatment, indicating an urgent need for improved continuity of care and better integration of primary and tertiary health care services.

Polymorphism of human cytochrome P450 enzymes and its clinical impact

Pharmacogenetics is the study of how interindividual variations in the DNA sequence of specific genes affect drug response. This article highlights current pharmacogenetic knowledge on important human drug-metabolizing cytochrome P450s (CYPs) to understand the large interindividual variability in drug clearance and responses in clinical practice. The human CYP superfamily contains 57 functional genes and 58 pseudogenes, with members of the 1, 2, and 3 families playing an important role in the metabolism of therapeutic drugs, other xenobiotics, and some endogenous compounds. Polymorphisms in the CYP family may have had the most impact on the fate of therapeutic drugs. CYP2D6, 2C19, and 2C9 polymorphisms account for the most frequent variations in phase I metabolism of drugs, since almost 80% of drugs in use today are metabolized by these enzymes. Approximately 5-14% of Caucasians, 0-5% Africans, and 0-1% of Asians lack CYP2D6 activity, and these individuals are known as poor metabolizers. CYP2C9 is another clinically significant enzyme that demonstrates multiple genetic variants with a potentially functional impact on the efficacy and adverse effects of drugs that are mainly eliminated by this enzyme. Studies into the CYP2C9 polymorphism have highlighted the importance of the CYP2C9*2 and *3 alleles. Extensive polymorphism also occurs in other CYP genes, such as CYP1A1, 2A6, 2A13, 2C8, 3A4, and 3A5. Since several of these CYPs (e.g., CYP1A1 and 1A2) play a role in the bioactivation of many procarcinogens, polymorphisms of these enzymes may contribute to the variable susceptibility to carcinogenesis. The distribution of the common variant alleles of CYP genes varies among different ethnic populations. Pharmacogenetics has the potential to achieve optimal quality use of medicines, and to improve the efficacy and safety of both prospective and currently available drugs. Further studies are warranted to explore the gene-dose, gene-concentration, and gene-response relationships for these important drug-metabolizing CYPs.

Mirtazapine improves sleep and lowers anxiety and depression in cancer patients: superiority over imipramine

GOALS OF THE WORK

This study aimed to compare the effectiveness of mirtazapine and imipramine on not only the distressing symptoms of cancer patients such as pain, nausea, vomiting, appetite loss, and sleep disturbances but also depressive and anxiety symptoms.

MATERIALS AND METHODS

Fifty-three patients with cancer who were diagnosed with major depressive disorder, anxiety disorder, or adjustment disorder were included. Twenty patients on mirtazapine, 13 patients on imipramine, and 20 patients in the control group without medication were interviewed during three visits (baseline, third week, and sixth week). Pain, nausea, vomiting, appetite loss, and sleep disturbances were evaluated with self-assessment single-symptom scales during each visit. The patients were also asked to complete the Hospital Anxiety Depression Scale (HADS) during each visit.

MAIN RESULTS

There were no significant differences among the three visits in the mirtazapine, imipramine, or control groups in terms of pain, nausea, vomiting, or appetite loss. For the initial, middle, and late insomnia, only the mirtazapine group showed improvements (p = 0.001, p = 0.001, p = 0.003). There were also significant differences in the mean total (p = 0.03), anxiety (p = 0.003), and depression (p = 0.025) scores of HADS among the three visits for patients taking mirtazapine. There were no significant differences for HADS scores from the baseline to the end point for patients taking imipramine or control group patients.

CONCLUSION

Our findings suggest that mirtazapine is effective for resolving insomnia as well as anxiety and depressive symptoms in cancer patients. However, more systematic research, such as placebo-controlled studies, is needed.

Enantioseparation of palonosetron hydrochloride by micellar electrokinetic chromatography with sodium cholate as chiral selector

The enantioseparation of four stereoisomers of palonosetron hydrochloride by micellar electrokinetic chromatography using sodium cholate as chiral surfactant was described. Sodium cholate was shown to be effective in separating palonosetron hydrochloride stereoisomers. For method optimization, several parameters such as sodium cholate concentration, buffer pH and concentration, the types and concentration of organic modifiers and applied voltage, on the enantioseparation were evaluated and the optimum conditions were obtained as follows: 30 mM borate buffer (pH 9.40) containing 70 mM sodium cholate and 20% (v/v) methanol with an applied voltage of 20 kV. Under these conditions, baseline separation of palonosetron hydrochloride stereoisomers was achieved within 18 min.

A randomized blinded study of the incidence of postoperative nausea and vomiting in women after major gynecologic laparoscopic surgery

STUDY OBJECTIVE

To estimate the incidence of postoperative nausea and vomiting (PONV) in women undergoing major gynecologic laparoscopic surgery with an expected surgical duration exceeding 1 hour and anticipated overnight hospitalization.

DESIGN

Randomized, double-blind, placebo-controlled study.

SETTING

This study was set at a university hospital.

PATIENTS

One hundred forty female patients with an American Society of Anesthesiology (ASA) physical status I or II and scheduled for gynecologic inpatient laparoscopic surgery.

INTERVENTIONS

Patients were randomly assigned to receive 1 mg granisetron (Group A, n=70), or saline solution (Group B, n=70) intravenously after induction of general anesthesia.

MEASUREMENTS AND MAIN RESULTS

The endpoints were evaluated by the following parameters: the incidence of PONV, episodes of nausea, retching, vomiting, rescue antiemetics, and complete response. Patients were closely observed for 24 hours after administration of the study drug. The two groups were generally well balanced in terms of demographic variables. The surgical period was longer in the granisetron group compared with the saline solution group. The total incidence of PONV was 41/70 (59%) in patients who underwent inpatient gynecologic laparoscopic surgery when no prophylactic antiemetic was given. Administration of granisetron decreased the incidence of PONV (29/70 [41%] vs 41/70 [59%], p<.05), the incidence of vomiting (18/70 [26%] vs 31/70 [44%], p<.05), and the proportions of patients requiring rescue antiemetics (14/70 [20%] vs 47/70 [67%], p<.01), but these results were not comparable to other studies.

CONCLUSION

A long surgical period may have great impact on the PONV in women who undergo gynecologic laparoscopic surgery, which implies the need for skilled gynecologic laparoscopists.

Management of chemotherapy-induced nausea and vomiting

Chemotherapy-induced nausea and vomiting are symptoms that cause major concern to oncology patients. This article explores the types of nausea and vomiting in the context of chemotherapy, and discusses their pathogenesis and management.