Population pharmacokinetics of ramosetron

Ondansetron for Low Anterior Resection Syndrome (LARS): A Double-Blind, Placebo-Controlled, Cross-Over, Randomized Study

OBJECTIVE

The aim of the study was to examine the efficacity and safety of ondansetron, a serotonin receptor antagonist, to treat patients with low anterior resection syndrome (LARS).

BACKGROUND

LARS after rectal resection is common and debilitating. Current management strategies include behavioral and dietary modifications, physiotherapy, antidiarrheal drugs, enemas, and neuromodulation, but the results are not always satisfactory.

METHODS

This is a randomized, multicentric, double-blinded, placebo-controlled, and cross-over study. Patients with LARS (LARS score >20) no longer than 2 years after rectal resection were randomized to receive either 4 weeks of ondansetron followed by 4 weeks of placebo (O-P group) or 4 weeks of placebo followed by 4 weeks of ondansetron (P-O group). The primary endpoint was LARS severity measured using the LARS score; secondary endpoints were incontinence (Vaizey score) and irritable bowel syndrome quality of life (IBS-QoL questionnaire). Patients' scores and questionnaires were completed at baseline and after each 4-week treatment period.

RESULTS

Of 46 randomized patients, 38 were included in the analysis. From baseline to the end of the first period, in the O-P group, the mean (SD) LARS score decreased by 25% [from 36.6 (5.6) to 27.3 (11.5)] and the proportion of patients with major LARS (score >30) went from 15/17 (88%) to 7/17 (41%), ( P =0.001). In the P-O group, the mean (SD) LARS score decreased by 12% [from 37 (4.8) to 32.6 (9.1)], and the proportion of major LARS went from 19/21 (90%) to 16/21 (76%). After crossover, LARS scores deteriorated again in the O-P group receiving placebo, but further improved in the P-O group receiving ondansetron. Mean Vaizey scores and IBS QoL scores followed a similar pattern.

CONCLUSIONS

Ondansetron is a safe and simple treatment that appears to improve both symptoms and QoL in LARS patients.

The preventive effect of 5-hydroxytryptamine-3 receptor antagonist on blood pressure reduction and postoperative nausea and vomiting during general anesthesia induction: A double-blinded, randomized controlled trial

STUDY OBJECTIVE

Administering a 5-hydroxytryptamine-3 receptor (5-HT3) at anesthesia induction may aid in achieving hemodynamic stability during general anesthesia induced using opioids. Therefore, we aimed to evaluate the effect of ramosetron, a 5-HT3 antagonist, administered on hypotension at the induction of total intravenous anesthesia (TIVA) with propofol and remifentanil. Additionally, we aimed to compare the impact of ramosetron administration at anesthesia induction versus that at the end of the surgery on postoperative nausea and vomiting (PONV).

DESIGN

Patients were randomly allocated to the Induction group (administration of ramosetron [0.3 mg/5 ml] at anesthesia induction and normal saline [5 ml] at the end of the surgery) or End group (administration of normal saline [5 ml] at anesthesia induction and ramosetron [0.3 mg/5 ml] at the end of the surgery). Hemodynamic status, PONV, and postoperative pain were assessed.

SETTING

Operating room, post-anesthetic care unit, and general ward.

PATIENTS

In total, 176 non-smoking patients without any past medical history undergoing laparoscopic gynecological surgeries under TIVA were included in the study.

MEASUREMENTS

Blood pressure (BP), heart rate, PONV, visual analog scale (VAS).

MAIN RESULTS

The Induction group exhibited significantly higher BP at anesthesia induction and required significantly lower doses of phenylephrine and ephedrine during anesthesia than the End group had. However, PONV and postoperative pain were similar between the two groups.

CONCLUSIONS

Administering ramosetron at anesthesia induction resulted in significantly better hemodynamic stability with significantly lesser requirement of phenylephrine and ephedrine than administering at the end of the surgery did. Therefore, we recommend ramosetron administration at anesthesia induction rather than at the end of the surgery to prevent PONV and the decrease in the mean BP during TIVA with propofol and remifentanil.

Utilization of data below the analytical limit of quantitation in pharmacokinetic analysis and modeling: promoting interdisciplinary debate

Traditionally, bioanalytical laboratories do not report actual concentrations for samples with results below the LOQ (BLQ) in pharmacokinetic studies. BLQ values are outside the method calibration range established during validation and no data are available to support the reliability of these values. However, ignoring BLQ data can contribute to bias and imprecision in model-based pharmacokinetic analyses. From this perspective, routine use of BLQ data would be advantageous. We would like to initiate an interdisciplinary debate on this important topic by summarizing the current concepts and use of BLQ data by regulators, pharmacometricians and bioanalysts. Through introducing the limit of detection and evaluating its variability, BLQ data could be released and utilized appropriately for pharmacokinetic research.

Effect of the allelic variants of ABCB1, CYP2D6 and HTR3B on response of ramosetron to prevent chemotherapy-induced nausea and vomiting in Korean cancer patients

AIM

Despite appropriate use of antiemetics including 5-hydroxytryptamine type 3 (5-HT₃ ) receptor antagonists, chemotherapy-induced nausea and vomiting (CINV) is still an unsolved problem in patients with anticancer drugs. We examined whether the variants of ABCB1, CYP2D6 and HTR3B affect efficacy of ramosetron, a selective 5-HT₃ receptor antagonist in a dose escalation clinical trial.

METHODS

We conducted a clinical trial on patients who underwent FOLFOX combination chemotherapy. The participants were randomized into three groups of ramosetron: 0.3 mg (standard dose), 0.45 mg and 0.6 mg. Rhodes index of nausea, vomiting and retching were measured at 1, 6 h, day 1, day 2 and day 7 after the administration of ramosetron as a clinical parameter of CINV and polymorphism was analyzed from genomic DNA.

RESULTS

There was a dose-dependent decrease in the nausea and vomiting scores at day 1 and day 2, not statistically significant. The Rhodes index of nausea, vomiting and retching score at day 1 in participants with HTR3B-100_-102delAAG deletion variants was significantly higher than wild type participants, regardless of dosages. However, the polymorphisms including ABCB1, CYP2D6 and other HTR3B genes did not affect response to ramosetron after chemotherapy.

CONCLUSION

These results suggest that the -AAG deletion variant of the 5-HT_3B receptor gene may contribute to variability in response to antiemetic therapy for CINV regardless of dose escalation. These results suggest that carrying a -100_-102delAAG variant of 5-HT₃ gene should be supported by alternate or additive antiemetics in addition to 5-HT₃ antagonists to control acute emesis.

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.