Antiemetics in cancer chemotherapy: historical perspective and current state of the art

Brain penetration of aprepitant, a substance P receptor antagonist, in ferrets

The pharmacokinetics, metabolism, and brain penetration of the neurokinin 1 (NK1) receptor antagonist (substance P receptor antagonist), aprepitant (MK-0869), were examined in ferrets. This species exhibits human-type NK1receptor pharmacology and is of proven value in the identification of clinically useful drugs for the treatment of chemotherapy-induced nausea and vomiting in humans. After a single p.o. dose of aprepitant at 1 or 2 mg/kg, plasma levels of the compound were between approximately 200 and 270 ng/ml, 24 h after dosing. In the brain cortex, concentrations of aprepitant reached between approximately 80 and 150 ng/g of tissue 24 h after dosing. The predominant radioactive component present in the plasma and the brain of ferrets at 24 or 48 h after a single oral dose of [14C]aprepitant at 3 mg/kg was the parent compound itself. The slow plasma clearance of aprepitant ( approximately 1.5 ml/min/kg) and its abundance in ferret brain were in accord with its efficacy in blocking the retching and vomiting at 24 and 48 h postdose when ferrets were challenged with the emetic anticancer drug, cisplatin. When aprepitant and some of its metabolites were assessed for their in vitro binding affinity to the human NK1receptor, aprepitant demonstrated the highest affinity. Collectively, these data suggested that aprepitant, rather than its metabolites, was responsible, primarily, for the antiemetic activity of this compound in the male ferret.

The effect of electroacupuncture as an adjunct on cyclophosphamide-induced emesis in ferrets

The effect of electroacupuncture (EA) on cyclophosphamide-induced emesis in ferrets was studied at acupuncture point Neiguan (P6) with various electrical stimulation parameters (5-100 Hz, 1.5-3 V, 5-20 min, n=6/group). The combination therapy of EA (100 Hz, 1.5 V and 10 min) with the lower doses of ondansetron (0.04 mg/kg), droperidol (0.25 mg/kg) and metoclopramide (2.24 mg/kg) significantly reduced the total number of emetic episodes by 52%, 36% and 73%, respectively, as well as the number of emetic episodes in the first phase as compared to the sham acupuncture control (P<.01). These EA/drug combinations also showed a significant effect in preventing emesis as compared to either EA or drug alone (P<.05). The present study suggests that acupuncture may be useful as an adjunctive therapy in the treatment of chemotherapy-induced emesis.

The effect of single dose intravenous dexamethasone in tonsillectomy in children

A prospective, randomized, double-blinded, placebo-controlled clinical trial was conducted in 41 patients evaluating the effect of a single preoperative dose of intravenous dexamethasone on postoperative vomiting and pain in children undergoing elective tonsillectomy. Dexamethasone was found to significantly reduce the incidence of vomiting in the first 24 hours postoperatively (P = 0.02), the time to first intake of solids (P = 0.001), the need to administer a rescue antiemetic (P = 0.005) and intravenous fluid therapy requirements (P = 0.006) in the postoperative period. No significant difference was found between the dexamethasone and placebo groups in the time to first intake of fluids, pain scores or analgesic requirement postoperatively. These results indicate that dexamethasone substantially reduces morbidity after tonsillectomy in children.

Costs of treating and preventing nausea and vomiting in patients receiving chemotherapy

PURPOSE

To evaluate the effect of ondansetron availability on the costs of managing nausea and vomiting.

METHODS

We retrospectively assessed antiemetic costs (drug costs, nursing time, pharmacy time, physician's time, supplies, and facility "hotel" costs, in 1991 Canadian dollars) for all patients who received moderately or highly emetogenic chemotherapy from 6 months before to 6 months after ondansetron became commercially available in September 1991. We compared the costs for treating patients who received ondansetron versus those who received other antiemetic regimens, the costs for treating patients in the 6 months before versus the 6 months after ondansetron commercial availability, and the costs for treating patients in the first 4 months versus the last 4 months of the study period.

RESULTS

We found no cost differences for patients treated with ondansetron versus other antiemetic regimens. However, there was a significant reduction in emesis management costs for patients treated after versus before the availability of ondansetron: for patients treated in the last third versus first third of the study period, there was a decrease in cost per patient per month of treatment of $374 (95% confidence interval, $243 to $505). These savings were achieved through a reduction in hospital bed days and other costs associated with the prevention and more effective management of nausea and vomiting. At the same time, the number of patients who received emetogenic chemotherapy and their average age increased, presumably because of the better control of gastrointestinal toxicity.

CONCLUSION

Ondansetron availability has been associated with changes in the clinical management of cancer patients receiving chemotherapy and with overall cost savings compared with previously available antiemetic therapy.