Ondansetron is a selective antagonist of thedianabol results receptors (serotonin). Cytostatic drugs for chemotherapy and radiotherapy may cause an increase in the level of serotonin, which by activation of vagal afferent fibers containing 5-NTZ – receptors cause a gag reflex. Selectively blocking serotonin receptors 5 NTRP neurons of the central and peripheral nervous system, the end n.vagus in the gut and in the centers of the central nervous system (mainly the bottom of the IV ventricle), governing the implementation of the gag reflex.
Does not disturb the coordination of movements, it does not cause sedation and reduce efficiency. It has anxiolytic activity. Does not modify the concentration of prolactin in plasma.
Ondansetron completely absorbed from the gastrointestinal tract after oral administration and undergoes first pass metabolism through the liver. The time to maximum concentration (TCmax) ondansetron plasma levels achieved after about 1.5 hours after ingestion. Bioavailability increases slightly while eating, but does not change when taking antacids. In unaltered with urine output of less than 5% of the administered dose. Ondansetron pharmacokinetic parameters do not change during its repeated reception. In patients with moderate renal impairment (creatinine clearance of 15-60 ml / min) as a reduced systemic clearance and volume of distribution of ondansetron, the result is a small and clinically insignificant increase in T1 / 2 (to 5.4 hr). The pharmacokinetics of ondansetron virtually unchanged in patients with severe renal impairment who are on chronic hemodialysis. Patients with severe hepatic dysfunction dramatically reduced systemic clearance of ondansetron, thereby increasing its half-life period (up to 15-32 h), and oral bioavailability reaches 100% due to decreased first-pass metabolism.
- prevention and relief of nausea and vomiting induced by cytotoxic chemotherapy or radiotherapy;
- prevention and relief of nausea and vomiting in postoperative period.Contraindications
- Hypersensitivity to ondansetron or to other components of the drug;
- Pregnancy and lactation;
- Children up to age 12 years (for a given dosage).
- Dosage and administration of cytostatic therapy . The choice of dosage regimen is determined by the severity of the action carried out by emetogenic anticancer therapy for adult daily dose usually is 8-24 mg. In moderate emetogenic chemotherapy or radiotherapy: Adults and children over 12 years: 8 mg orally 1 . -2 hours prior to the primary therapy, then another 8 mg 12 hours later data on the use of radiotherapy in children under 12 years are not available. when dianabol results vysokoemetogennoy chemotherapy: The recommended dose for adults (on the application of data in children are not available) is 24 mg at the same time dexamethasone orally at a dose of 12 mg for 1-2 hours prior to chemotherapy. for the prevention or late emesis occurring long after 24 hours should continue receiving ondansetron 8 mg twice a day for 5 days. The prevention of postoperative nausea and vomiting Adults prescribed 16 mg orally 1 hour prior to the start of general anesthesia. Children for the prevention and treatment of post-operative nausea and vomiting ondansetron applies only parenterally. elderly patients dosage change is required. Patients with renal dysfunction Change the usual daily dose and frequency of dosing is required.Patients with hepatic impairment The daily dose of ondansetron should not exceed 8 mg per day. Patients with slow metabolism of sparteine / debrisokvina. Correction of daily dosage or frequency of administration of ondansetron are required.
Side effects: Allergic reactions: urticaria, bronchospasm, laryngospasm, angioedema, anaphylaxis. From the digestive system: hiccups, dry mouth, diarrhea, constipation, sometimes asymptomatic transient increase in serum transaminases. Cardio-vascular system: pain in chest, in some cases with ST segment depression, arrhythmia, bradycardia, decreased blood pressure. from the nervous system:headache, dizziness, spontaneous movement disorders and seizures. The other: “tide” of blood to the face, burning sensation, temporary violation of sharpness view rare – hypokalemia, hypercreatininemia.
In case of suspected overdose symptomatic therapy is shown. A specific antidote is not known. In case of overdose of ondansetron is not recommended the use of ipecac, as it is unlikely that this drug will be effective during the antiemetic action of ondansetron.
Interactions with other drugs
Because ondansetron is metabolized by the enzyme system (cytochrome P450) of the liver, caution is required when used together:
- P450 enzyme-inducers (of CYP2D6 and CYP3A) – barbiturates, carbamazepine, carisoprodol, glutetimid, griseofulvin, dinitrogen oxide, papaverine, phenylbutazone, phenytoin (probably other hydantoins), rifampicin, tolbutamide;
- with inhibitors of P450 enzymes (CYP2D6 and CYP3A) – allopurinol, macrolide antibiotics, antidepressants (inhibitors of monoamine oxidase (MAO)), chloramphenicol, cimetidine, estrogensoderzhaschie oral contraceptives, diltiazem, disulfiram, valproic acid and salts thereof, erythromycin, fluconazole, fluoroquinolones, isoniazid, ketoconazole, lovastatin, metronidazole, omeprazole, propranolol, quinidine, quinine, verapamil).
Special studies showed that ondansetron does not interact with alcohol, temazepam, furosemide, tramadol and propofol (Diprivan).Cautions
Patients who had previous allergic reactions to other selective blockers dianabol resultsreceptors, have an increased risk of their development against the backdrop of ondansetron.
Ondansetron may inhibit the motility of the colon, and therefore, his appointment to patients with signs of intestinal obstruction requires regular monitoring.
Due to the presence of lactose, patients with rare hereditary disorders such as galactose intolerance, lactose deficiency or glucose-galactose malabsorption should not take the drug.