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

Genome-Wide Association Study Identifies Novel Candidate Variants Associated with Postoperative Nausea and Vomiting

Considerable individual differences are widely observed in the incidence of postoperative nausea and vomiting (PONV). We conducted a genome-wide association study (GWAS) to identify potential candidate single-nucleotide polymorphisms (SNPs) that contribute to PONV by utilizing whole-genome genotyping arrays with more than 950,000 markers. The subjects were 806 patients who provided written informed consent and underwent elective surgery under general anesthesia with propofol or desflurane. The GWAS showed that two SNPs, rs2776262 and rs140703637, in the LOC100506403 and CNTN5 gene regions, respectively, were significantly associated with the frequency of nausea. In another GWAS conducted only on patients who received propofol, rs7212072 and rs12444143 SNPs in the SHISA6 and RBFOX1 gene regions, respectively, were significantly associated with the frequency of nausea as well as the rs2776262 SNP, and the rs45574836 and rs1752136 SNPs in the ATP8B3 and LOC105370198 gene regions, respectively, were significantly associated with vomiting. Among these SNPs, clinical and SNP data were available for the rs45574836 SNP in independent subjects who underwent laparoscopic gynecological surgery, and the association was replicated in these subjects. These results indicate that these SNPs could serve as markers that predict the vulnerability to PONV. Our findings may provide valuable information for achieving satisfactory prophylactic treatment for PONV.

Drugs for preventing postoperative nausea and vomiting in adults after general anaesthesia: a network meta-analysis

BACKGROUND

Postoperative nausea and vomiting (PONV) is a common adverse effect of anaesthesia and surgery. Up to 80% of patients may be affected. These outcomes are a major cause of patient dissatisfaction and may lead to prolonged hospital stay and higher costs of care along with more severe complications. Many antiemetic drugs are available for prophylaxis. They have various mechanisms of action and side effects, but there is still uncertainty about which drugs are most effective with the fewest side effects.

OBJECTIVES

• To compare the efficacy and safety of different prophylactic pharmacologic interventions (antiemetic drugs) against no treatment, against placebo, or against each other (as monotherapy or combination prophylaxis) for prevention of postoperative nausea and vomiting in adults undergoing any type of surgery under general anaesthesia • To generate a clinically useful ranking of antiemetic drugs (monotherapy and combination prophylaxis) based on efficacy and safety • To identify the best dose or dose range of antiemetic drugs in terms of efficacy and safety SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP), ClinicalTrials.gov, and reference lists of relevant systematic reviews. The first search was performed in November 2017 and was updated in April 2020. In the update of the search, 39 eligible studies were found that were not included in the analysis (listed as awaiting classification).

SELECTION CRITERIA

Randomized controlled trials (RCTs) comparing effectiveness or side effects of single antiemetic drugs in any dose or combination against each other or against an inactive control in adults undergoing any type of surgery under general anaesthesia. All antiemetic drugs belonged to one of the following substance classes: 5-HT₃ receptor antagonists, D₂ receptor antagonists, NK₁ receptor antagonists, corticosteroids, antihistamines, and anticholinergics. No language restrictions were applied. Abstract publications were excluded.

DATA COLLECTION AND ANALYSIS

A review team of 11 authors independently assessed trials for inclusion and risk of bias and subsequently extracted data. We performed pair-wise meta-analyses for drugs of direct interest (amisulpride, aprepitant, casopitant, dexamethasone, dimenhydrinate, dolasetron, droperidol, fosaprepitant, granisetron, haloperidol, meclizine, methylprednisolone, metoclopramide, ondansetron, palonosetron, perphenazine, promethazine, ramosetron, rolapitant, scopolamine, and tropisetron) compared to placebo (inactive control). We performed network meta-analyses (NMAs) to estimate the relative effects and ranking (with placebo as reference) of all available single drugs and combinations. Primary outcomes were vomiting within 24 hours postoperatively, serious adverse events (SAEs), and any adverse event (AE). Secondary outcomes were drug class-specific side effects (e.g. headache), mortality, early and late vomiting, nausea, and complete response. We performed subgroup network meta-analysis with dose of drugs as a moderator variable using dose ranges based on previous consensus recommendations. We assessed certainty of evidence of NMA treatment effects for all primary outcomes and drug class-specific side effects according to GRADE (CINeMA, Confidence in Network Meta-Analysis). We restricted GRADE assessment to single drugs of direct interest compared to placebo.

MAIN RESULTS

We included 585 studies (97,516 randomized participants). Most of these studies were small (median sample size of 100); they were published between 1965 and 2017 and were primarily conducted in Asia (51%), Europe (25%), and North America (16%). Mean age of the overall population was 42 years. Most participants were women (83%), had American Society of Anesthesiologists (ASA) physical status I and II (70%), received perioperative opioids (88%), and underwent gynaecologic (32%) or gastrointestinal surgery (19%) under general anaesthesia using volatile anaesthetics (88%). In this review, 44 single drugs and 51 drug combinations were compared. Most studies investigated only single drugs (72%) and included an inactive control arm (66%). The three most investigated single drugs in this review were ondansetron (246 studies), dexamethasone (120 studies), and droperidol (97 studies). Almost all studies (89%) reported at least one efficacy outcome relevant for this review. However, only 56% reported at least one relevant safety outcome. Altogether, 157 studies (27%) were assessed as having overall low risk of bias, 101 studies (17%) overall high risk of bias, and 327 studies (56%) overall unclear risk of bias. Vomiting within 24 hours postoperatively Relative effects from NMA for vomiting within 24 hours (282 RCTs, 50,812 participants, 28 single drugs, and 36 drug combinations) suggest that 29 out of 36 drug combinations and 10 out of 28 single drugs showed a clinically important benefit (defined as the upper end of the 95% confidence interval (CI) below a risk ratio (RR) of 0.8) compared to placebo. Combinations of drugs were generally more effective than single drugs in preventing vomiting. However, single NK₁ receptor antagonists showed treatment effects similar to most of the drug combinations. High-certainty evidence suggests that the following single drugs reduce vomiting (ordered by decreasing efficacy): aprepitant (RR 0.26, 95% CI 0.18 to 0.38, high certainty, rank 3/28 of single drugs); ramosetron (RR 0.44, 95% CI 0.32 to 0.59, high certainty, rank 5/28); granisetron (RR 0.45, 95% CI 0.38 to 0.54, high certainty, rank 6/28); dexamethasone (RR 0.51, 95% CI 0.44 to 0.57, high certainty, rank 8/28); and ondansetron (RR 0.55, 95% CI 0.51 to 0.60, high certainty, rank 13/28). Moderate-certainty evidence suggests that the following single drugs probably reduce vomiting: fosaprepitant (RR 0.06, 95% CI 0.02 to 0.21, moderate certainty, rank 1/28) and droperidol (RR 0.61, 95% CI 0.54 to 0.69, moderate certainty, rank 20/28). Recommended and high doses of granisetron, dexamethasone, ondansetron, and droperidol showed clinically important benefit, but low doses showed no clinically important benefit. Aprepitant was used mainly at high doses, ramosetron at recommended doses, and fosaprepitant at doses of 150 mg (with no dose recommendation available). Frequency of SAEs Twenty-eight RCTs were included in the NMA for SAEs (10,766 participants, 13 single drugs, and eight drug combinations). The certainty of evidence for SAEs when using one of the best and most reliable anti-vomiting drugs (aprepitant, ramosetron, granisetron, dexamethasone, ondansetron, and droperidol compared to placebo) ranged from very low to low. Droperidol (RR 0.88, 95% CI 0.08 to 9.71, low certainty, rank 6/13) may reduce SAEs. We are uncertain about the effects of aprepitant (RR 1.39, 95% CI 0.26 to 7.36, very low certainty, rank 11/13), ramosetron (RR 0.89, 95% CI 0.05 to 15.74, very low certainty, rank 7/13), granisetron (RR 1.21, 95% CI 0.11 to 13.15, very low certainty, rank 10/13), dexamethasone (RR 1.16, 95% CI 0.28 to 4.85, very low certainty, rank 9/13), and ondansetron (RR 1.62, 95% CI 0.32 to 8.10, very low certainty, rank 12/13). No studies reporting SAEs were available for fosaprepitant. Frequency of any AE Sixty-one RCTs were included in the NMA for any AE (19,423 participants, 15 single drugs, and 11 drug combinations). The certainty of evidence for any AE when using one of the best and most reliable anti-vomiting drugs (aprepitant, ramosetron, granisetron, dexamethasone, ondansetron, and droperidol compared to placebo) ranged from very low to moderate. Granisetron (RR 0.92, 95% CI 0.80 to 1.05, moderate certainty, rank 7/15) probably has no or little effect on any AE. Dexamethasone (RR 0.77, 95% CI 0.55 to 1.08, low certainty, rank 2/15) and droperidol (RR 0.89, 95% CI 0.81 to 0.98, low certainty, rank 6/15) may reduce any AE. Ondansetron (RR 0.95, 95% CI 0.88 to 1.01, low certainty, rank 9/15) may have little or no effect on any AE. We are uncertain about the effects of aprepitant (RR 0.87, 95% CI 0.78 to 0.97, very low certainty, rank 3/15) and ramosetron (RR 1.00, 95% CI 0.65 to 1.54, very low certainty, rank 11/15) on any AE. No studies reporting any AE were available for fosaprepitant. Class-specific side effects For class-specific side effects (headache, constipation, wound infection, extrapyramidal symptoms, sedation, arrhythmia, and QT prolongation) of relevant substances, the certainty of evidence for the best and most reliable anti-vomiting drugs mostly ranged from very low to low. Exceptions were that ondansetron probably increases headache (RR 1.16, 95% CI 1.06 to 1.28, moderate certainty, rank 18/23) and probably reduces sedation (RR 0.87, 95% CI 0.79 to 0.96, moderate certainty, rank 5/24) compared to placebo. The latter effect is limited to recommended and high doses of ondansetron. Droperidol probably reduces headache (RR 0.76, 95% CI 0.67 to 0.86, moderate certainty, rank 5/23) compared to placebo. We have high-certainty evidence that dexamethasone (RR 1.00, 95% CI 0.91 to 1.09, high certainty, rank 16/24) has no effect on sedation compared to placebo. No studies assessed substance class-specific side effects for fosaprepitant. Direction and magnitude of network effect estimates together with level of evidence certainty are graphically summarized for all pre-defined GRADE-relevant outcomes and all drugs of direct interest compared to placebo in http://doi.org/10.5281/zenodo.4066353.

AUTHORS' CONCLUSIONS

We found high-certainty evidence that five single drugs (aprepitant, ramosetron, granisetron, dexamethasone, and ondansetron) reduce vomiting, and moderate-certainty evidence that two other single drugs (fosaprepitant and droperidol) probably reduce vomiting, compared to placebo. Four of the six substance classes (5-HT₃ receptor antagonists, D₂ receptor antagonists, NK₁ receptor antagonists, and corticosteroids) were thus represented by at least one drug with important benefit for prevention of vomiting. Combinations of drugs were generally more effective than the corresponding single drugs in preventing vomiting. NK₁ receptor antagonists were the most effective drug class and had comparable efficacy to most of the drug combinations. 5-HT₃ receptor antagonists were the best studied substance class. For most of the single drugs of direct interest, we found only very low to low certainty evidence for safety outcomes such as occurrence of SAEs, any AE, and substance class-specific side effects. Recommended and high doses of granisetron, dexamethasone, ondansetron, and droperidol were more effective than low doses for prevention of vomiting. Dose dependency of side effects was rarely found due to the limited number of studies, except for the less sedating effect of recommended and high doses of ondansetron. The results of the review are transferable mainly to patients at higher risk of nausea and vomiting (i.e. healthy women undergoing inhalational anaesthesia and receiving perioperative opioids). Overall study quality was limited, but certainty assessments of effect estimates consider this limitation. No further efficacy studies are needed as there is evidence of moderate to high certainty for seven single drugs with relevant benefit for prevention of vomiting. However, additional studies are needed to investigate potential side effects of these drugs and to examine higher-risk patient populations (e.g. individuals with diabetes and heart disease).

CHRM3 rs2165870 Polymorphism Correlates with Postoperative Nausea and Vomiting Incidence and the Efficacy of Ondansetron in a Chinese Han Population

Background

Previous GWAS studies have shown that there is a relationship between M3 muscarinic acetylcholine receptor (CHRM3) rs2165870 polymorphism and postoperative nausea and vomiting (PONV) incidence. However, no Chinese studies have addressed this issue.

Methods

To explore the relationship between CHRM3 rs2165870 polymorphism and PONV incidence in a Chinese Han population, we enrolled 512 patients receiving elective surgery in this study. CHRM3 rs2165870 polymorphism was genotyped using PCR-RFLP method.

Results

We found that AA genotype or A allele of CHRM3 rs2165870 polymorphism elevated the risk of PONV (AA versus GG; OR, 2.88; 95% CI, 1.51-5.47; P = 0.001; A versus G; OR, 1.39; 95% CI, 1.07-1.81; P = 0.013). In addition, CHRM3 rs2165870 polymorphism was related to the risk of PONV among the males, smokers, and those individuals with Apfel Score 3-4 or ASA classification 2-3. Last, we assessed the effects of CHRM3 rs2165870 polymorphism on the treatment efficacy of ondansetron for PONV. Data uncovered that 103 of 209 patients (49.3%) showed response to ondansetron treatment for PONV. The PONV incidence was significantly higher in AA genotype carriers compared with GG genotype carriers during the first 2 h after surgery, but not from 2 to 24 h after surgery.

Conclusion

To sum up, this study reveals that CHRM3 rs2165870 polymorphism is related to the incidence of PONV and treatment effects of ondansetron for preventing PONV in this Chinese Han population.

Genetic variability in postoperative nausea and vomiting: A systematic review

BACKGROUND

Postoperative nausea and vomiting (PONV) is the most frequent side effect following anaesthesia. Predisposition to developing PONV is multifactorial with patient risk factors and anaesthetic techniques both being contributory. However, there is also a genetic susceptibility to PONV, and several studies have aimed to identify polymorphisms contributing to a genetic PONV risk.

OBJECTIVE

We summarised previous published studies investigating genetic contribution to PONV risk.

DESIGN

Systematic review without meta-analysis.

DATA SOURCE

We searched MEDLINE until June 2019.

ELIGIBILITY CRITERIA

Articles were chosen for review when PONV and polymorphisms were included. Exclusion criteria were reviews/meta-analysis/comments, articles not in the English language, nonappropriate content (e.g. PONV not as primary aim of the study, study investigated opioid-induced nausea) or if articles were pharmacogenetic studies addressing treatment of PONV.

RESULTS

A total of 59 studies were screened and 14 articles were reviewed including one genome-wide association study (GWAS). Seven studies were performed in East Asians, and seven in Caucasians. Seventeen polymorphisms have been positively associated with PONV in at least one study. Allele frequency of the investigated polymorphisms differs widely between the ethnicities. Furthermore, the anaesthesia regimen and the postoperative time point at which the association with PONV was reported were quite different. Only two polymorphisms, the CHRM3 rs2165870 and the KCNB2 rs349358 (both first associated with PONV in a GWAS), have been significantly associated with PONV incidence in Caucasians in independent studies.

CONCLUSION

There is a genetic susceptibility to the development of PONV. Two single nucleotide polymorphisms (SNPs), the CHRM3 rs2165870 and the KCNB2 rs349358 SNP, seem to have a major influence on PONV incidence, at least in Caucasians. Both SNPs were primarily identified in a GWAS and this association may lead to a better understanding of the disease aetiology. Further high-quality studies are needed to reveal more insights in genetic PONV susceptibility, particularly so in non-Caucasian ethnicities.

Pharmacogenetics of Postoperative Nausea and Vomiting

Postoperative nausea and vomiting (PONV) remains one of the most common adverse effects of anesthesia, affecting up to 80% of high-risk patients within 24 hours after surgery. Patient-related factors, surgical procedure, and perioperative medications such as opioids determine a patient's risk for PONV. To prevent and manage PONV, ondansetron, a 5-hydroxytryptamine type 3 (5-HT₃) receptor antagonist, is frequently administered. Ondansetron is metabolized predominantly by hepatic cytochrome P450 (CYP2D6) enzymes, encoded by the CYP2D6 gene, whereas most of the effects of opioids are exerted at the opioid mu-1 receptor, encoded by the OPRM1 gene. Genetic polymorphisms of the CYP2D6 and OPRM1 genes may have a role in interindividual variation in the occurrence of PONV. Specifically, the occurrence of the G-allele produced by the OPRM1 A118G appears to be protective against PONV, whereas CYP2D6 ultrarapid metabolism increases the risk for PONV. The Clinical Pharmacogenetics Implementation Consortium guidelines provide CYP2D6-guided therapeutic recommendations for ondansetron. However, further studies are needed to investigate the role of genetic polymorphism in the occurrence of PONV and response to antiemetics.

Genetic Factors Associated with Postoperative Nausea and Vomiting: a Systematic Review

BACKGROUND

In previous studies, there seems to be a relationship between different genetic polymorphisms and postoperative nausea and vomiting (PONV). We perform a systematic review of the current literature about the relationship between genetic polymorphisms and the presence of PONV.

METHODS

Two bibliographic searches were carried out in three databases (PubMed, Web of Science, and Scopus) of studies, preferably prospective, about PONV following abdominal surgery. It was completed with a backward citation searching. A total of 73 articles were found of which 6 were selected after their critical lecture using CASPe network criteria. Relative frequency and relative risk were taken in each study according to the polymorphism.

RESULTS

Studies about 5-HT3B gene receptor polymorphisms, ABCB1 transporter, and dopamine D2 receptor showed a significant association with the presence of PONV (p = 0.02, 0.01, and 0.034 respectively). In relation to cytochrome P-450 2D6 (CYP2D6) polymorphisms, two of the three analysed articles showed a significant association with postoperative vomiting (p = 0.007).

CONCLUSION

Genetic polymorphisms could play an important role in PONV. The AAG deletion in both alleles of the 5-HT3B receptor gene, the Taq IA polymorphism of the dopamine D2 receptor, and the presence of three or more functional alleles of CYP2D6 seem to be related with a higher incidence of PONV, especially in the first 24 h after surgery. The 2677TT and 3435TT genotypes of the ABCB1 transporter could reduce the PONV due to their association with a greater effectiveness of ondansetron. However, new quality studies are needed to consider this relationship.

Comparative Pharmacology and Guide to the Use of the Serotonin 5-HT3 Receptor Antagonists for Postoperative Nausea and Vomiting

Since the introduction of the serotonin 5-hydroxy tryptamine 3 (5-HT₃) receptor antagonists in the early 1990s, the incidence of postoperative nausea and vomiting (PONV) and post-discharge nausea and vomiting (PDNV) has decreased, yet continues to be a problem for the surgical patient. The clinical application of the 5-HT₃ receptor antagonists has helped define the approach and role of these antiemetics in the prevention and treatment of PONV and PDNV. Pharmacological and clinical differences exist among these medications resulting in corresponding differences in effectiveness, safety, optimal dosage, time of administration, and use as combination and rescue antiemetic therapy. The clinical application of the 5-HT₃ receptor antagonist antiemetics has improved the prevention and treatment of PONV and PDNV. The most recent consensus guidelines for PONV published in 2014 outline the use of these antiemetics. The 5-HT₃ receptor antagonists play an important role to help prevent PONV and PDNV in perioperative care pathways such as Enhanced Recovery After Surgery (ERAS). Comparisons and guidelines for use of the 5-HT₃ receptor antagonists in relation to the risk for PONV and PDNV are reviewed.

Pharmacogenomics and pharmacogenetics for the intensive care unit: a narrative review

PURPOSE

Knowledge of how alterations in pharmacogenomics and pharmacogenetics may affect drug therapy in the intensive care unit (ICU) has received little study. We review the clinically relevant application of pharmacogenetics and pharmacogenomics to drugs and conditions encountered in the ICU.

SOURCE

We selected relevant literature to illustrate the important concepts contained within.

PRINCIPAL FINDINGS

Two main approaches have been used to identify genetic abnormalities - the candidate gene approach and the genome-wide approach. Genetic variability in response to drugs may occur as a result of alterations of drug-metabolizing (cytochrome P [CYP]) enzymes, receptors, and transport proteins leading to enhancement or delay in the therapeutic response. Of relevance to the ICU, genetic variation in CYP-450 isoenzymes results in altered effects of midazolam, fentanyl, morphine, codeine, phenytoin, clopidogrel, warfarin, carvedilol, metoprolol, HMG-CoA reductase inhibitors, calcineurin inhibitors, non-steroidal anti-inflammatory agents, proton pump inhibitors, and ondansetron. Changes in cholinesterase enzyme function may affect the disposition of succinylcholine, benzylisoquinoline muscle relaxants, remifentanil, and hydralazine. Genetic variation in transport proteins leads to differences in the response to opioids and clopidogrel. Polymorphisms in drug receptors result in altered effects of β-blockers, catecholamines, antipsychotic agents, and opioids. Genetic variation also contributes to the diversity and incidence of diseases and conditions such as sepsis, malignant hyperthermia, drug-induced hypersensitivity reactions, cardiac channelopathies, thromboembolic disease, and congestive heart failure.

CONCLUSION

Application of pharmacogenetics and pharmacogenomics has seen improvements in drug therapy. Ongoing study and incorporation of these concepts into clinical decision making in the ICU has the potential to affect patient outcomes.

Population pharmacokinetics and prophylactic anti-emetic efficacy of ramosetron in surgical patients

AIMS

This study characterized the pharmacokinetics of ramosetron and compared prophylactic anti-emetic efficacy with that of ondansetron in a large population.

METHODS

Fifty-eight patients consented to the pharmacokinetic analysis and were assigned randomly to receive 0.3, 0.45 or 0.6 mg ramosetron after induction of anaesthesia. Blood samples were acquired at preset intervals. Non-compartmental and population pharmacokinetic analyses were performed. In total, 1102 patients consented to the evaluation of prophylactic anti-emetic efficacy and were allocated randomly to receive 0.3 mg ramosetron or 4 mg ondansetron at the end of surgery. An additional 16 mg ondansetron were mixed in the intravenous patient-controlled analgesia pump of the ondansetron group. Post-operative nausea and vomiting (PONV) were evaluated 6, 24 and 48 h post-operatively using the Rhodes index of nausea, vomiting and retching (RINVR). Administration of rescue anti-emetics and adverse events were evaluated.

RESULTS

The pharmacokinetic parameter estimates were V1 (l) = 5.12, V2 (l) = 108, CL (l⋅min(-1) ) = 0.08 + (59⋅age(-1) ) × 0.09, Q (l⋅min(-1) ) = 1.42. The incidences of PONV in the ramosetron and ondansetron groups were 77 (13.9%) and 113 (20.6%) and 44 (7.9%) and 66 (12.0%) at 24 and 48 h post-operatively, respectively (P = 0.004, 0.030). RINVR was significantly lower in the ramosetron than the ondansetron group 24 and 48 h post-operatively (P = 0.003, 0.025). Use of rescue anti-emetics and incidence of adverse events were comparable.

CONCLUSIONS

A two compartment mammillary model was used to describe ramosetron pharmacokinetics. Prophylactic anti-emetic efficacy of ramosetron was significantly better 24 and 48 h post-operatively than that of ondansetron, particularly when the Apfel score was ≥ 3.

Genetic factors associated with pharmacotherapy and background sensitivity to postoperative and chemotherapy-induced nausea and vomiting

Postoperative nausea and vomiting (PONV) continues to be a most common complication of surgery and anesthesia. It has been suggested that the inherited factors may play a significant role in the background sensitivity to both PONV and also chemotherapy-induced nausea and vomiting (CINV), including resistance to antiemetic prophylaxis and/or therapy. This notion could be best exemplified by occurrence of PONV in several generations of families and concordance of PONV in monozygotic twins. The most frequently addressed issue in the research on genomic background of PONV/CINV relates to the inherited resistance to the antiemetic treatment (pharmacogenomics), and in lesser degree to their genomic background. The most common group of antiemetics consists of 5HT3 receptor antagonists, and this group was an initial target of pharmacogenomic research. Most research approaches have been based on the investigation of polymorphic variations in the target for the antiemetic 5HT3 receptor antagonists, i.e., serotonin receptor subunits A and B (HTR3A and HTR3B). The other area of pharmacogenomic investigations includes metabolic pathways of 5HT3 antagonists, in particular polymorphic variants of the CYP450 2D6 isoform (CYP2D6) because most of them are metabolized in various degrees by the CYP2D6 system. The results of targeted genomic association studies indicate that other genes are also associated with PONV and CINV, including OPRM1, and ABCB1. In addition, genes such as DRD2 and CHRM3 genes have recently been associated with PONV. The new genome-wide association studies seem also to indicate that the background genomic sensitivity to PONV and CINV might be multifactorial and include several genomic pathways.

The association of CYP2D6 genotype and postoperative nausea and vomiting in orthopedic trauma patients

The CYP2D6 gene encodes for an enzyme that is involved in the metabolism of more than 25% of all medications, including many opioids and antiemetics. It may contribute to the risk of postoperative nausea and vomiting (PONV), a common surgical complication. However, little research has been conducted in this area. The purpose of this study was to explore the association of CYP2D6 genotypes with PONV in adult surgical trauma patients. Data from 112 patients (28% female) with single extremity fractures, aged 18-70 years, were analyzed. PONV was defined as present if patients reported nausea, were observed vomiting, or received medication for PONV. Saliva samples collected for DNA extraction and Taqman(®) allele discrimination and quantitative real time polymerase chain reaction (qRT-PCR) were used to collect genotype data that were then used to assign CYP2D6 phenotype classification. The incidence of PONV was 38% in the postanesthesia care unit and increased to 50% when assessed at 48 hr. CYP2D6 classification results were 7 (6%) poor metabolizers, 34 (30%) intermediate metabolizers, and 71 (63%) extensive metabolizers. No ultrarapid metabolizers were identified. Patients who were classified as poor metabolizers had less PONV and higher pain scores. Gender and history of PONV, but not smoking, were also significant risk factors. Findings suggest variability in CYP2D6 impacts susceptibility to PONV.

A network meta-analysis on the efficacy of serotonin type 3 receptor antagonists used in adults during the first 24 hours for postoperative nausea and vomiting prophylaxis

BACKGROUND

The serotonin type 3 receptor antagonists (5-HT(3) antagonists) ondansetron, granisetron, tropisetron, and dolasetron are potential prophylactic agents for patients with mild to moderate risk of postoperative nausea and vomiting (PONV). A few trials have been conducted to compare the efficacy among 2 to 3 of these 4 agents. However, the comparative efficacy of all four 5-HT(3) antagonists has not yet been quantitatively investigated.

OBJECTIVE

The goal of this study was to investigate whether the 5-HT(3) antagonists--ondansetron, granisetron, tropisetron, and dolasetron-differ in efficacy when used for the prevention of PONV.

METHODS

PubMed and the Cochrane Library were searched for randomized controlled, double-blind studies measuring efficacy in terms of PONV prophylaxis. A Bayesian meta-analysis was conducted using published studies of 5-HT(3) antagonists for PONV prophylaxis. The odds of patients with no PONV and postoperative vomiting (POV) within each study arm 24 hours after surgery were the primary indices of drug efficacy. Data were extracted and analyzed via indirect comparisons using random effects Bayesian models in WinBUGS version 1.4.3.

RESULTS

A total of 85 studies were identified, representing 15,269 patients. The results indicate that granisetron was significantly better than ondansetron (odds ratio [OR] = 1.53 [95% credible interval (CI), 1.15-2.00]) and dolasetron (OR = 1.67 [95% CI, 1.12-2.38]) in preventing PONV. Four antiemetic drugs had comparable efficacy in terms of preventing POV: granisetron showed similar efficacy compared with ondansetron (OR = 1.49 [95% CI, 0.90-2.43]), tropisetron (OR = 1.69 [95% CI, 0.92-3.13]), and dolasetron (OR = 1.32 [95% CI, 0.71-2.38]). Ondansetron exhibited comparable efficacy compared with tropisetron (OR = 1.14 [95% CI, 0.66-1.96]) and dolasetron (OR = 0.88 [95% CI, 0.51-1.47]). Tropisetron and dolasetron were also similar in efficacy (OR = 0.78 [95% CI, 0.40-1.45]). All 5-HT(3) antagonists were statistically significantly better at preventing PONV or POV than placebo.

CONCLUSIONS

With respect to PONV prophylaxis, granisetron was significantly better than ondansetron and dolasetron; ondansetron, tropisetron, and dolasetron exhibited similar efficacy. With respect to POV prophylaxis, ondansetron, granisetron, tropisetron, and dolasetron seemed to have comparable efficacy.

5 HT(3)-receptor antagonists and cardiac repolarization time in patients expressing a novel genetic target associated with baseline QTc interval abnormalities

STUDY OBJECTIVE

To investigate whether a common single nucleotide polymorphism (SNP), rs10494366, is associated with significant prolongation of the QTc interval following administration of 5-HT(3)-receptor antagonists in the perioperative setting.

DESIGN

Post-hoc analysis of deoxyribonucleic acid (DNA) samples and electrocardiographic (ECG) data from an established perioperative genomics database.

SETTING

University teaching hospital.

MEASUREMENTS

DNA samples of 132 ASA physical status 1, 2, and 3 patients were obtained from an established genomic database of surgical patients who had received either granisetron or dolasetron as part of their general anesthesia plan. ECG recordings were collected on all subjects before administration of antiemetic medication, then 10 minutes after drug injection. DNA analysis was performed using TaqMan real-time PCR genotyping assay. Results from the TaqMan real-time PCR assay were used to calculate relative frequencies of the T (major) and G (minor) alleles, in addition to calculating the genotype frequencies. QTc intervals were calculated according to Bazett's formula.

RESULTS

Relative frequencies for T and G alleles were 0.63 and 0.37, respectively. The relative frequencies of the pertinent genotypes were TT 39.4%, TG 46.9%, and GG 13.7%. No significant difference was noted in QTc interval pre-antiemetic or post-antiemetic drug administration for the homozygous carriers of the minor allele GG (P = 0.059), but a significant difference was seen in the pre-drug and post-drug QTc intervals in the heterozygous and homozygous carriers of the major allele TG and TT (P = 0.003 and P = 0.017, respectively). Compared with homozygous carriers of the minor allele, absolute risk increase for QTc interval prolongation after antiemetic administration was 0.08 and 0.15 in heterozygous and homozygous carriers of the major allele, respectively.

CONCLUSION

Homozygous and heterozygous carrier status for the major SNP, rs10494366 allele (T), in intron 1 of the human NOSA1P gene may be associated with an increased risk of QTc interval prolongation following administration of 5-HT(3)-receptor antagonists in the perioperative setting, when compared with homozygotes for the minor (G) allele.

Antiemetic prophylaxis in thyroid surgery: a randomized, double-blind comparison of three 5-HT3 agents

PURPOSE

The aim of this double-blind randomized study was to compare the antiemetic efficacy of three 5-hydroxytryptamine type 3 antagonists in terms of the incidence and intensity of postoperative nausea and vomiting (PONV) in a homogenous group of female patients undergoing thyroidectomy.

METHODS

The study cohort consisted of 203 American Society of Anesthesiologists PS I-II female patients randomized into four groups to receive at induction of anesthesia an intravenous (IV) bolus of 5 ml solution of one of the following: normal saline (placebo), granisetron 3 mg, ondansetron 4 mg, or tropisetron 5 mg. Nausea and vomiting were evaluated at five time points: during the first hour in the postanesthesia care unit (PACU) and 6, 12, 18, and 24 h postoperatively. Nausea intensity was measured using a visual analogue scale score (0-10).

RESULTS

Patients in the placebo group displayed a high incidence of nausea in the PACU and at 6, 12, and 18 h postoperatively (44, 60, 50, and 34%, respectively) and of vomiting (26, 42, 30 and 10%). The administration of granisetron reduced significantly the incidence of nausea at 6, 12, and 18 h (26, 18, and 2%, respectively) and vomiting at 6 and 12 h (10 and 6%, respectively). Ondansetron reduced significantly the incidence of nausea and vomiting only at 6 h postoperatively (28 and 12%, respectively). The administration of tropisetron did not affect the incidence of PONV compared to placebo.

CONCLUSION

Among the female patients of this study undergoing thyroid surgery, granisetron 3 mg provided the best prophylaxis from PONV. Ondansetron 4 mg was equally effective, but its action lasted only 6 h, whereas tropisetron 5 mg was found ineffective.

A review of granisetron, 5-hydroxytryptamine3 receptor antagonists, and other antiemetics

Nausea and vomiting are 2 of the most upsetting adverse reactions of chemotherapy. Current guidelines propose 5-hydroxytryptamine3 (5-HT3) receptor antagonists as a pharmacologic intervention for acute and delayed nausea and vomiting [chemotherapy-induced nausea and vomiting (CINV)] associated with moderately and highly emetogenic chemotherapy. Meanwhile, both postoperative nausea and vomiting (PONV) and postdischarge nausea and vomiting are challenging situations after surgeries and procedures. Prophylactic and therapeutic combinations of antiemetics are recommended in patients at high risk of suffering from PONV and postdischarge nausea and vomiting. Granisetron (Kytril) is a selective 5-HT3 receptor antagonist that does not induce or inhibit the hepatic cytochrome P-450 system in vitro. There are also 4 other antagonists of 5-HT3 receptor (dolasetron, ondansetron, palonosetron, and tropisetron) being metabolized via the CYP2D6 and are subject to potential genetic polymorphism. The launch of a new class of antiemetics, the substance P/neurokinin1 receptor antagonists, was attributed to the scientific update on the central generator responsible for emesis and role of substance P. There has been mounting interest in exploring integrative medicine, either acupuncture or acustimulation of P6 (Nei-Kuwan), to complement the western medicine for prevention and management of nausea and vomiting. The potential application of cannabinoids, either alone or in combination with other agents of different mechanism, could contribute further to improve outcome in CINV. Implementation of future treatment guidelines for more effective management of CINV and PONV could certainly improve the efficacy and outcome of cancer and postoperative care.

Effects of OCT1 polymorphisms on the cellular uptake, plasma concentrations and efficacy of the 5-HT(3) antagonists tropisetron and ondansetron

After uptake into liver cells, the antiemetic drugs tropisetron and ondansetron undergo metabolic inactivation by cytochrome P450 2D6 (CYP2D6). We investigated whether the hepatic organic cation transporter 1 (OCT1; SLC22A1) mediates cellular uptake and whether common OCT1 loss-of-function polymorphisms affect pharmacokinetics and efficacy of both drugs. Both tropisetron and ondansetron inhibited ASP(+) uptake in OCT1-overexpressing HEK293 cells. Overexpression of wild-type, but not OCT1 loss-of-function variants, significantly increased tropisetron uptake. Correspondingly, patients with two loss-of-function OCT1 alleles had higher tropisetron plasma concentrations (n=59, P<0.04) and higher clinical efficacy (n=91, P=0.009) compared with carriers of fully active OCT1. Overexpression of OCT1 did not increase ondansetron uptake. Nevertheless, OCT1 genotypes correlated with pharmacokinetics (n=45, P<0.05) and clinical efficacy (n=222, P<0.02) of ondansetron, the effect size of OCT1 genotypes on pharmacokinetics and efficacy was greater for tropisetron than for ondansetron. In conclusion, in addition to the known effects of CYP2D6, OCT1 deficiency may increase efficacy of tropisetron and potentially of ondansetron by limiting their hepatic uptake.

Perioperative genomic profiles using structure-specific oligonucleotide probes

OBJECTIVES

Many complications in the perioperative interval are associated with genetic susceptibilities that may be unknown in advance of surgery and anesthesia, including drug toxicity and inefficacy, thrombosis, prolonged neuromuscular blockade, organ failure and sepsis. The aims of this study were to design and validate the first genetic testing platform and panel designed for use in perioperative care, to establish allele frequencies in a target population, and to determine the number of mutant alleles per patient undergoing surgery. DESIGN/SETTING/PARTICIPANTS AND METHODS: One hundred fifty patients at Marshfield Clinic, Marshfield, Wisconsin, 100 patients at the Medical College of Wisconsin Zablocki Veteran's Administration Medical Center, Milwaukee, Wisconsin, and 200 patients at the University of Wisconsin Hospitals and Clinics, Madison, Wisconsin undergoing surgery and anesthesia were tested for 48 polymorphisms in 22 genes including ABC, BChE, ACE, CYP2C9, CYP2C19, CYP2D6, CYP3A4, CYP3A5, beta2AR, TPMT, F2, F5, F7, MTHFR, TNFalpha, TNFbeta, CCR5, ApoE, HBB, MYH7, ABO and Gender (PRKY, PFKFB1). Using structure-specific cleavage of oligonucleotide probes (Invader, Third Wave Technologies, Inc., Madison, WI), 96-well plates were configured so that each well contained reagents for detection of both the wild type and mutant alleles at each locus.

RESULTS

There were 21,600 genotypes confirmed in duplicate. After withdrawal of polymorphisms in non-pathogenic genes (i.e., the ABO blood group and gender-specific alleles), 376 of 450 patients were found to be homozygous for mutant alleles at one or more loci. Modes of two mutant homozygous loci and 10 mutant alleles in aggregate (i.e., the sum of homozygous and heterozygous mutant polymorphisms) were observed per patient.

CONCLUSIONS

Significant genetic heterogeneity that may not be accounted for by taking a family medical history, or by obtaining routine laboratory test results, is present in most patients presenting for surgery and may be detected using a newly developed genotyping platform.

PhRMA white paper on ADME pharmacogenomics

Pharmacogenomic (PGx) research on the absorption, distribution, metabolism, and excretion (ADME) properties of drugs has begun to have impact for both drug development and utilization. To provide a cross-industry perspective on the utility of ADME PGx, the Pharmaceutical Research and Manufacturers of America (PhRMA) conducted a survey of major pharmaceutical companies on their PGx practices and applications during 2003-2005. This white paper summarizes and interprets the results of the survey, highlights the contributions and applications of PGx by industrial scientists as reflected by original research publications, and discusses changes in drug labels that improve drug utilization by inclusion of PGx information. In addition, the paper includes a brief review on the clinically relevant genetic variants of drug-metabolizing enzymes and transporters most relevant to the pharmaceutical industry.

Recent advances, trends and economic considerations in the risk assessment, prevention and treatment of postoperative nausea and vomiting

During the last two decades there have been considerable achievements regarding the management of postoperative nausea and vomiting (PONV). Due to the importance of these symptoms in the aim to streamline clinical processes and to improve patient satisfaction, the debate on the best strategies and also research that focuses on PONV continues. This review summarises the recent developments with respect to the management of PONV. Following a brief review on what is already known on the risk assessment, prevention and treatment of PONV, newer trends in the pharmacological prevention (dexamethasone, neurokinin-1 antagonists, multimodal prevention) will be discussed as well as new insights regarding the value of algorithms for the prevention of PONV. Further, pharmacogenetically based algorithms (according to the metaboliser status) as well as new treatment strategies (dexamethasone, multimodal treatment) will be covered. No drug so far can achieve a reduction of PONV of more than one third. Furthermore, all clinical studies consistently demonstrated that a combination treatment has a simple additive effect without any relevant interaction between different drugs or classes of drugs. The relative reduction of approximately 30% can also be expected from dexamethasone and it is likely that the substances presently in development and in an early clinical use (e.g., neurokinin-1 antagonists) will not represent the new panacea. However, they will probably replenish the existing antiemetic portfolio to better cope with high risk patients. Stratified prevention using pharmacogenetic knowledge is still in the early stages. Algorithms need to be customized to the local settings in order to prove efficient. Treatment remains a most important pillar and there is evidence that the principles of combining antiemetics to prolong effects and improve protection can be similarly applied to treatment. Recent developments in the area of PONV are more related to implementing the already existing evidence than based on the introduction of new molecules. New molecules replenish the pharmacological antiemetic portfolio, which is needed due to the limited efficacy of any single agent available so far. The new neurokinin-1 receptor antagonist, aprepitant, and the long lasting 5-HT(3) receptor antagonist palonosetron are the latest developments in this context. Treatment is most important and can also be regarded as a secondary prevention. Due to limited efficacy of single treatment interventions, combination therapy may gain more widespread use in the future.

Pharmacology, pharmacogenetics, and clinical efficacy of 5-hydroxytryptamine type 3 receptor antagonists for postoperative nausea and vomiting

PURPOSE OF REVIEW

The use of selective 5-hydroxytryptamine type 3 receptor antagonists has improved the management of postoperative nausea and vomiting, but has not completely eliminated it. In this article, we discuss the pharmacology of 5-hydroxytryptamine type 3 receptor antagonists and the impact of pharmacogenetics on postoperative nausea and vomiting.

RECENT FINDINGS

Dolasetron, granisetron, ondansetron, palonosetron, and tropisetron have similar mechanisms of action but different pharmacokinetic and pharmacodynamic properties. Genetic polymorphism in the cytochrome P450 mono-oxygenase system, drug efflux transporter adenosine triphosphate-binding cassette subfamily B member 1 and 5-hydroxytryptamine type 3 receptor subunits also contribute to the interindividual variation in response to different 5-hydroxytryptamine type 3 receptor antagonists. These differences account for differences in the duration of action and clinical efficacy of these agents.

SUMMARY

Pharmacogenetics testing in patients may help differentiate responders to 5-hydroxytryptamine type 3 receptor antagonists from non-responders and allow the anesthesiologist to individualize antiemetic therapy. The cost-effectiveness of such screening in postoperative nausea and vomiting management has, however, not been evaluated. Given the multifactorial nature of postoperative nausea and vomiting, a multimodal approach to reduce or eliminate risk factors will be most successful in its management.

Pharmacogenetics, drug-metabolizing enzymes, and clinical practice

The application of pharmacogenetics holds great promise for individualized therapy. However, it has little clinical reality at present, despite many claims. The main problem is that the evidence base supporting genetic testing before therapy is weak. The pharmacology of the drugs subject to inherited variability in metabolism is often complex. Few have simple or single pathways of elimination. Some have active metabolites or enantiomers with different activities and pathways of elimination. Drug dosing is likely to be influenced only if the aggregate molar activity of all active moieties at the site of action is predictably affected by genotype or phenotype. Variation in drug concentration must be significant enough to provide "signal" over and above normal variation, and there must be a genuine concentration-effect relationship. The therapeutic index of the drug will also influence test utility. After considering all of these factors, the benefits of prospective testing need to be weighed against the costs and against other endpoints of effect. It is not surprising that few drugs satisfy these requirements. Drugs (and enzymes) for which there is a reasonable evidence base supporting genotyping or phenotyping include suxamethonium/mivacurium (butyrylcholinesterase), and azathioprine/6-mercaptopurine (thiopurine methyltransferase). Drugs for which there is a potential case for prospective testing include warfarin (CYP2C9), perhexiline (CYP2D6), and perhaps the proton pump inhibitors (CYP2C19). No other drugs have an evidence base that is sufficient to justify prospective testing at present, although some warrant further evaluation. In this review we summarize the current evidence base for pharmacogenetics in relation to drug-metabolizing enzymes.