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Site of emetic action of oral copper sulfate in dogs. (II) Importance of lower duodenum.

Sensitivities of the stomach and duodenum to oral copper sulfate emesis were compared in dogs. 1) Dogs equipped with a stainless stell cannula in the middle of the duodenum were challenged to the oral threshold emetic dose of copper sulfate administered by a gastric tube. When the cannulas were opened, the oral thresholds were not effective to elicit vomiting in the most cases (1/13). Fairly rapid and high rate recoveries of copper through the open cannula were noted. With the closed cannulas, the thresholds were highly effective (16/16). 2)In the dogs with a cannula at the upper part of the jejunum, the oral threshold doses were always effective whether the canula was opened (9/9) or closed (11/11). Recovery rates of copper from the cannula were usually poor. 3) The oral thresholds administered into the proximal end or the middle of the duodenum through a PVC tubing were equally effective. 4) Although copper sulfate might irritate the stomach and upper duodenum to evoke vomiting, these results suggested a higher sensitivity of the lower duodenum.

Administration, Oral↗

Studies for the emetic mechanisms of ipecac syrup (TJN-119) and its active components in ferrets: involvement of 5-hydroxytryptamine receptors.

Ipecac syrup, prepared from a galentical ipecac, contains the nauseant alkaloids cephaeline and emetine. The involvement of receptors and serotonin- and dopamine-metabolizing enzymes in the emesis induced by ipecac syrup and these components was investigated. 1) In ferrets, the selective 5-HT3-receptor antagonist ondansetron (0.5 mg/kg, p.o.) prevented each emesis induced by TJN-119 (0.5 mL/kg, p.o.), cephaeline (0.5 mg/kg, p.o.) and emetine (5.0 mg/kg, p.o.), but the intraperitoneal administration of the selective dopamine D2-receptor antagonist sulpiride failed to significantly suppress the TJN-119, cephaeline and emetine-induced emesis at a dose of 0.1 mg/kg that blocked apomorphine-induced emesis. 2) In the receptor binding assays, cephaeline and emetine had a distinct affinity to 5-HT4 receptor, but no or weak affinity to 5-HT1A, 5-HT3, nicotine, M3, beta1, NK1, and D2 receptors. 3) Cephaeline and emetine did not affect activities of metabolic enzymes of 5-HT and dopamine (MAO-A, MAO-B, tryptophan 5-hydroxylase and tyrosine hydroxylase) in vitro. These results suggest that 5-HT3 receptor plays an important role in the emetic action of TJN-119, cephaeline and emetine, and the 5-HT4 receptor may be involved in their mechanisms.

Animals↗

Application of packed capillary liquid chromatography/mass spectrometry with electrospray ionization to the study of the human biotransformation of the anti-emetic drug dolasetron.

Packed capillary liquid chromatography/mass spectrometry (LC/MS) using electrospray ionization (ESI) was used to study the human biotransformation of the anti-emetic drug dolasetron. Urine from subjects given a single 100 mg intravenous dose, containing 14C-labeled dolasetron (50 microCi), was de-salted and concentrated for LC/MS with minimal loss of radioactivity (97% recovery). Aliquots of the de-salted material were injected directly onto a C8 packed capillary column (25 cm x 0.32 mm i.d.) and eluted with an acetonitrile-water gradient, buffered with 1% acetic acid, at a flow rate of 2 microliters min-1. Five metabolites were detected by LC ESI-MS which, yielded molecular mass information but no fragmentation. The identity of each metabolite was confirmed in a subsequent analysis using product ion scans in conjunction with collisionally induced dissociation. Precursor ion scanning was also employed and did not reveal any new biotransformation products. In addition to defining the major routes of biotransformation, the data obtained were compared with a 14C radioprofile prepared in a separate experiment. Qualitative agreement in the two chromatographic profiles enabled the major clusters of radioactivity to be assigned to specific metabolites of dolasetron. An important observation in this comparison was that the signal obtained by ESI did not provide an accurate assessment of the quantity of each metabolite. This was especially true for acidic conjugates (i.e. glucuronides, sulfates), which in the case of dolasetron can exist as zwitterions (no net charge). The results demonstrate the power of packed capillary LC ESI-MS for use in drug biotransformation studies and suggest that caution should be exercised when interpreting relative metabolite abundances from ESI data in the absence of actual reference standards.

Antiemetics↗

Pharmacokinetics and bioavailability of the anti-emetic agent bromopride.

The pharmacokinetics of bromopride, an anti-emetic agent chemically related to metoclopramide, has been investigated in normal human subjects. After intravenous bolus doses of 10 mg, a one-compartment open model appeared adequate to describe the plasma drug concentration data. The systemic clearance of bromopride was 899 ml min-1 +/- 22 per cent CV, the volume of distribution was 2151 +/- 16 per cent CV, and the elimination half-life was 2.9 h +/- 21 per cent CV. Over a wide drug concentration range of up to 650 ng ml-1, bromopride was only 40 per cent bound to plasma proteins. The systemic availability of orally and intramuscularly administered solution doses of 20 mg of bromopride was 54 per cent and 78 per cent, respectively. Formulation of bromopride as the solid material in capsules delayed absorption but did not affect the extent of drug bioavailability. The pharmacokinetics of bromopride appeared similar to that of metoclopramide. No evidence for non-linear kinetics was found when bromopride was administered orally in the dose range 10-30 mg: after single oral doses of 10, 20, and 30 mg, peak mean plasma drug concentrations were 20 ng ml-1 +/- 32 per cent CV, 38 ng ml-1 +/- 16 per cent CV, and 64 ng ml-1 +/- 23 per cent CV, respectively.

Administration, Oral↗

The anti-emetic efficacy and tolerability of tropisetron in patients conditioned with high-dose chemotherapy (with and without total body irradiation) prior to bone marrow transplantation.

Nausea and vomiting are among the most distressing side-effects of chemoradiotherapy. Conditioning protocols for patients undergoing bone marrow transplantation consist of highly emetogenic high-dose chemotherapy with or without total body irradiation. Marked improvement in controlling emesis and nausea was achieved by the introduction of a new class of antiemetic drugs, the 5HT3 serotonin-receptor antagonists. Tropisetron is a highly potent, selective antagonist of 5HT3 receptors. Previous studies have used a single 5-mg dose i.v. of tropisetron to control nausea and vomiting in cancer patients. The present study was undertaken to evaluate the efficacy and safety of a single daily dose of tropisetron in controlling emesis in patients receiving high-dose chemotherapy (with or without total body irradiation) prior to bone marrow transplantation. The anti-emetic efficacy was investigated in a non-homogeneous cohort in a prospective and open study. Of 11 patients evaluated, 9 (81%) showed complete or major control, 1 (9%) minor control and 1 (9%) failed to respond. The most common adverse events reported during the study included diarrhea (46%) and headache (18%), no patients being withdrawn because of side-effects. Our data suggest that a single 5-mg i.v. dose of tropisetron is safe and effective in preventing chemotherapy-induced emesis in patients receiving bone marrow transplantation conditioning. A larger randomized study is warranted to confirm our preliminary results.

Adolescent↗

Reye syndrome or side-effects of anti-emetics?

By analysing two patients initially diagnosed as Reye syndrome evidence is given that in some patients considered as having Reye syndrome, the syndrome is an escalation of symptoms due to viral disease and to unrecognized drug-induced encephalopathy, mainly by anti-emetics. A detailed drug history, considering all medication--not exclusively aspirin--taken during the full course of the illness is essential to differentiate between Reye syndrome and drug-induced symptoms. In addition, a critical analysis is presented of the four main case-control surveys that have lead to the proposal that salicylates are primary causative agents of Reye syndrome. In these surveys, medications given during the prodromal illness were adequately recorded, but other drugs given after the onset of vomiting have been overlooked or deliberately excluded. New epidemiological studies are needed, recording all drugs given to the patients throughout the full course of their illness until the moment of admission, in order to elucidate the mystery of Reye syndrome.

Antiemetics↗

Optimal anti-emetic dose of granisetron for preventing postoperative nausea and vomiting.

In order to determine the optimal effective dose of granisetron for preventing postoperative nausea and vomiting, the drug was administered in doses of either 20, 40 or 60 micrograms.kg-1. The efficacy of granisetron was evaluated in a randomized, double-blind comparison with placebo in 100 patients undergoing general anaesthesia for major gynaecological surgery. The patients received a single dose of either granisetron or placebo (saline) iv immediately after recovery from anaesthesia. The effects were assessed during the 24 hr after recovery from anaesthesia by means of a nausea and vomiting score; 0 = no emetic symptoms, 1 = nausea, 2 = vomiting. The treatment groups were similar for patient characteristics, surgical procedures and anaesthetics administered. The mean scores were 0.7, 0.6, 0.2 and 0.2 after administration of placebo, granisetron 20, 40 and 60 micrograms.kg-1, respectively. Granisetron 40 micrograms.kg-1 was as effective as 60 micrograms.kg-1 and both resulted in reduction of the scores compared with placebo and granisetron 20 micrograms.kg-1 (P < 0.05). In conclusion, granisetron 40 micrograms.kg-1 is considered to be the appropriate dosage for preventing postoperative emesis after anaesthesia.

Adult↗

Additive anti-emetic efficacy of prophylactic ondansetron with droperidol in out-patient gynecological laparoscopy.

PURPOSE: To determine the efficacy of ondansetron and droperidol, alone and in combination, administered for prophylaxis of postoperative nausea and vomiting (PONV) in women undergoing general anesthesia for outpatient gynecological laparoscopy. METHODS: Following Institutional Ethics Board approval and patient consent, 160 female out- patients scheduled for laparoscopy were randomly allotted in a double-blind fashion to receive: i) saline (placebo), ii) 4 mg ondansetron, iii) 1.25 mg droperidol, or iv) 4 mg ondansetron and 1.25 mg droperidol combination intravenously on induction. Following a standardized general anesthesia, patients were interviewed and assessed for PONV at various times. RESULTS: During the first 24 hr after surgery, the incidence of PONV in the placebo group was 71%. This was reduced to 61% with droperidol alone (P = 0.334), to 46% with ondansetron alone (P = 0.027), and to 23% with the combination group (P<0.001). A statistically significant difference was observed between combination and droperidol (P<0.001) and between combination and ondansetron (P = 0.036). There were fewer requests for rescue medication from the combination group (7.7%) than from the ondansetron and placebo groups. CONCLUSION: The results of this study suggest that the combination of 4 mg ondansetron and 1.25 mg droperidol is more efficacious as a prophylactic anti-emetic than either agent alone during the 24 hr post-surgery. This additive effect may be due to the different mechanisms of action of ondansetron and droperidol.

Adolescent↗

Cisplatin-evoked induction of c-fos protein in the brainstem of the ferret: the effect of cervical vagotomy and the anti-emetic 5-HT3 receptor antagonist granisetron (BRL 43694).

We have monitored the expression of c-fos protein in the medulla oblongata of the ferret, using immunocytochemistry, to identify the brainstem pathways involved in the mediation of nausea and vomiting caused by the antineoplastic drug cisplatin. Cisplatin administration resulted in c-fos-like immunoreactivity (FLI) in the area postrema, the nucleus of the solitary tract, and in scattered cells within the ependymal lining of the fourth ventricle. Unilateral cervical vagotomy greatly reduced FLI in the ipsilateral nucleus of the solitary tract but did not significantly affect reactivity in the contralateral solitary tract nucleus or in the area postrema. Pretreatment of the animals with the 5-HT3 antagonist granisetron (BRL 43694) abolished the retching and vomiting caused by cisplatin and markedly reduced the cisplatin-evoked FLI in the nucleus of the solitary tract; treatment with this drug had no significant effect on cisplatin-evoked FLI in the area postrema. The results suggest that cisplatin induces c-fos gene expression in the nucleus of the solitary tract by an action involving vagal afferent pathways and also by a vagally independent, direct action on the area postrema. The anti-emetic 5-HT3 antagonist drug granisetron mimicked the effect of vagotomy on c-fos protein induction suggesting that it may act via 5-HT3 receptors known to be associated with vagal afferent terminals. The FLI seen in the area postrema was neither vagally dependent nor was it abolished by granisectron.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Central alpha-adrenoceptor subtypes involved in the emetic pathway in cats.

The intracerebroventricular (i.c.v.) injection of clonidine, xylazine, adrenaline and methoxamine elicited dose-dependent vomiting in cats in that order of potency. The vomiting induced by clonidine, xylazine and adrenaline was antagonized by i.c.v. yohimbine and phentolamine possessing alpha 2-adrenoceptor-blocking activity, but not by prazosin showing alpha 1-adrenoceptor-blocking activity. In contrast, methoxamine-induced vomiting was antagonized by prazosin, but not by yohimbine. The vomiting induced by xylazine and adrenaline was not prevented by i.c.v. 6-hydroxydopamine treatment, but was prevented by i.c.v. reserpine treatment. Ablation of the area postrema with some damage to extremely adjacent areas abolished the vomiting induced by each alpha-adrenoceptor agonist. These results indicate that both central alpha 1- and alpha 2-adrenoceptors are involved in the emetic pathway in cats, although alpha 2-adrenoceptors seem to have the main role. It is also suggested that monoamines, and in particular 5-hydroxytryptamine in the brain, are involved in the regulation of alpha-adrenoceptor-mediated vomiting.

Adrenergic alpha-Agonists↗

Absence of emetic effects of morphine and loperamide in Suncus murinus.

The house musk shrew Suncus murinus recently has been introduced for the study of emesis. We investigated the emetic effects of the opioids morphine (0.1-21.5 mg/kg i.p.) and loperamide (0.01-10 mg/kg i.p.) and found a complete lack of emetogenic potential. Nicotine, however, dose dependently induced vomiting in the Suncus with an ED50 of 8.8 mg/kg s.c. and a 100% incidence at 20 mg/kg. This drug-induced vomiting was reduced by morphine or loperamide: ED50 values obtained were 1.2 mg/kg i.p. for morphine and 0.7 mg/kg i.p. for loperamide. Naloxone (2 mg/kg s.c.) antagonised the inhibitory effect of morphine (2 mg/kg i.p.) or loperamide (10 mg/kg i.p.). Serotonin (20 mg/kg s.c.) had less reliable emetogenic potency than nicotine in the Suncus with incidences between 50 and 100%. However, the serotonin-induced vomiting was abolished by morphine and loperamide and this inhibition was antagonised by naloxone. These results suggest that systemically administered opioids are pure antiemetics in Suncus murinus in contrast to other animal models and man. Naloxone antagonism indicates that this antiemetic effect is mediated by opioid receptors.

Animals↗

Neural factors in acute emetic, cardiovascular, and respiratory effects of T-2 toxin in cats.

T-2 toxin, a trichothecene mycotoxin, was injected iv or ip in the single lethal dose of 2 mg/kg. Vomiting was elicited in normal and decerebrate cats with an average onset time of 26.6 min. Chronic ablation of the area postrema significantly delayed the emetic latency to 304 min. Polygraph recording revealed a steady decline in mean arterial blood pressure and pulse pressure to an extreme shock level resulting in death after 5 to 15 hr. Heart rate varied unremarkably throughout the course of circulatory failure, and the cardiac beat persisted after respiratory arrest. No protection against the lethal response was afforded by midbrain decerebration, area postrema ablation, section of the carotid sinus and vagus nerves, and high spinal cord transection supported with artificial ventilation. Effects of T-2 toxin on central and reflex control of breathing were evaluated through changes in VT/FACO2 and f/VT relationships generated by delivery of CO2 enriched gas for inhalation. Central CO2 responsiveness was well maintained under all tested neurological conditions up to the stage of terminal collapse with late decreases in delta VT/delta FACO2 gain and FACO2 setpoint. A toxin-induced progressive increase in resting frequency and an associated decrease in delta f/delta VT gain was found in unanesthetized decerebrate cats, though resting f did not change remarkably in the anesthetized brain-intact cats. In vagotomized brain-intact cats, the delta f/delta VT gain was sustained at zero. These findings indicate that T-2 toxin exercised minimal influence on the brain stem CO2-VT regulator but it caused an acceleration of the central respiratory oscillator after interruption of forebrain connections.

Animals↗

Emetic activity of the trichothecene 15-acetyldeoxynivalenol in swine.

The emetic activity of 15-acetyldeoxynivalenol (15-ADON), a deoxynivalenol (DON) precursor, was evaluated in swine over a dose range of 25-200 micrograms/kg body weight and found to be very similar to that of DON. The minimum effective oral doses for 15-ADON and DON were 75 and 50 micrograms/kg, respectively, with 3/15 of the 15-ADON- and 4/15 of the DON-treated pigs exhibiting emesis, over the total dose range. The minimum effective ip doses for 15-ADON and DON were also 75 and 50 micrograms/kg, respectively, with 9/15 pigs in each group exhibiting emesis, over the total dose range. For pigs receiving 15-ADON and DON ip, increased dosage was associated with decreased average time to vomition, increased duration of emesis and increased average number of vomitions.

Animals↗

Comparative analysis of 23S ribosomal RNA gene sequences of Bacillus anthracis and emetic Bacillus cereus determined by PCR-direct sequencing.

The primary structures of the 23S ribosomal RNA genes of Bacillus anthracis and an emetic strain of Bacillus cereus were determined by direct sequencing of enzymatically amplified chromosomal DNA. The 23S rRNA gene sequences of B. anthracis and B. cereus were found to be almost identical and showed only two differences (a single nucleotide change, and a single base insertion in B. cereus). The feasibility of using PCR-direct sequencing for the rapid sequence determination of large-subunit rRNA genes is demonstrated.

Bacillus anthracis↗

In vitro formulation optimization of intranasal galantamine leading to enhanced bioavailability and reduced emetic response in vivo.

The purpose of the current investigation was to optimize an intranasal (IN) galantamine (an acetylcholinesterase inhibitor used for treatment of Alzheimer's disease) formulation using an in vitro tissue model, to correlate those results to in vivo bioavailability, and to compare emetic response to oral dosing. A design-of-experiments (DOE) based formulation screening employing an in vitro tissue model of human nasal epithelium was used to assess drug permeability, tight junction modulation, and cellular toxicity. In vivo studies in rats compared pharmacokinetic (PK) profiles of different formulations dosed intranasally. Finally, studies in ferrets evaluated PK and gastrointestinal (GI) related side effects of oral compared to nasal dosage forms. Galantamine permeation was enhanced without increasing cytotoxicity. Pharmacokinetic testing in rats confirmed the improved drug bioavailability and demonstrated an in vitro-in vivo correlation. Compared to oral dosing, IN galantamine resulted in a dramatically lowered incidence of GI-related side effects, e.g., retching and emesis. These findings illustrate that IN delivery represents an attractive alternative to oral dosing for this important Alzheimer's disease therapeutic. To our knowledge, the data herein represent the first direct confirmation of reducing GI-related side effects for IN galantamine compared to oral dosing.

Administration, Intranasal↗

Reduction of postoperative emetic episodes and analgesic requirements with dexamethasone in patients scheduled for dental surgery.

STUDY OBJECTIVE: To evaluate the antiemetic and analgesic effects of dexamethasone for the first 24 hours postoperatively in patients scheduled for dental surgery. DESIGN: Prospective, randomized, double-blind, placebo-controlled study. SETTING: University hospital. PATIENTS: One hundred twenty ASA physical status I and II patients (45 men, 75 women; aged 17-48 years) undergoing general anesthesia for dental surgery. INTERVENTIONS: Patients received intravenously placebo or dexamethasone at 3 different doses (4, 8, or 16 mg) at the end of the surgical procedure. A standard general anesthetic technique, including sevoflurane and nitrous oxide in oxygen, was used. MEASUREMENT AND MAIN RESULTS: Emetic episodes and analgesic requirements were evaluated. The rate of patients who were emesis free (no nausea, retching, or vomiting) during 0 to 24 hours after anesthesia was 63% with dexamethasone 4 mg (P = NS), 83% with dexamethasone 8 mg (P < .05), and 90% with dexamethasone 16 mg (P < .05), compared to placebo (60%). The need for diclofenac sodium for intolerable pain was less in patients who had received dexamethasone 8 mg or dexamethasone 16 mg than in those who had received placebo or dexamethasone 4 mg (P < .05). No clinically important adverse events were observed in any group. CONCLUSIONS: Prophylactic dexamethasone 8 mg is effective for the prevention of nausea and vomiting after dental surgery and in the management of postoperative pain. Increasing the dose to 16 mg provides no further benefit.

Adult↗

Abdominal pain with rigidity secondary to the anti-emetic drug metoclopramide.

We report a case of abdominal pain with rigidity, mimicking an acute abdomen, caused by metoclopramide, a common anti-emetic drug. Extrapyramidal symptoms are commonly reported side-effects of this medication. They generally include involuntary movements of limbs, torticollis, oculogyric crisis, rhythmic protrusion of tongue, trismus, or dystonic reactions resembling tetanus, etc. Abdominal rigidity due to this medication, resembling an acute abdomen, has not been reported previously. This case report illustrates the importance of considering medication side-effects when evaluating a patient with abdominal pain and rigidity.

Abdomen, Acute↗