Ondansetron

Pharmacological properties

ondansetron is a potent, highly selective 5nt3- (serotonin) receptor antagonist. the drug prevents or eliminates nausea and vomiting caused by cytotoxic chemotherapy and / or radiation therapy, as well as postoperative nausea and vomiting. the mechanism of action of ondansetron is not fully understood. perhaps the drug blocks the occurrence of the vomiting reflex, exhibiting an antagonistic effect against 5nt3 receptors localized in neurons of both peripheral and central nervous systems. the drug does not reduce the psychomotor activity of the patient and does not have a sedative effect.

Pharmacokinetics With a / m introduction of C_max in blood plasma is reached within 10 minutes The volume of distribution after parenteral administration in adults is 140 liters. The main part of the administered dose can be metabolized in the liver. Less than 5% of the drug is excreted unchanged in urine. T_½ - about 3 hours (in elderly patients - 5 hours). Binding to blood plasma proteins - 70–76%.

In patients with moderate renal failure (creatinine clearance - 15–60 ml / min), both systemic clearance and the volume of ondansetron distribution decrease, resulting in a slight and clinically insignificant increase in T_½ the drug. The pharmacokinetics of ondansetron practically does not change in patients with severe renal failure who are on chronic hemodialysis. In individuals with severe chronic liver failure, the systemic clearance of ondansetron significantly decreases with an increase in T_½ (15–32 hours).

Indications

Nausea and vomiting caused by cytotoxic chemotherapy and radiation therapy. prevention and treatment of postoperative nausea and vomiting.

Application

Nausea and vomiting caused by chemotherapy and radiation therapy

The emetogenic potential of therapy for cancer varies depending on the dose and combination of chemotherapy and radiation therapy regimens. The choice of dosage regimen depends on the severity of the emetogenic effect.

Adults

Emetogenic chemotherapy and radiation therapy

The recommended intravenous or intramuscular dose of Emeton is 8 mg as a slow injection for at least 30 s, immediately before treatment.

For the prevention of delayed or prolonged vomiting after the first 24 hours, oral or rectal administration of the drug is recommended.

Highly chemogenic chemotherapy (e.g. high dose cisplatin)

Emeton can be prescribed as a single dose of 8 mg iv or im immediately before chemotherapy. Doses above 8 mg (up to 16 mg) can be used only in the form of an iv infusion of 50-100 ml of 0.9% sodium chloride solution or other appropriate solvent (see instructions for use); infusion should last at least 15 minutes. A single dose exceeding 16 mg cannot be used (see SPECIAL INSTRUCTIONS).

For highly emetogenic chemotherapy, Emeton ≤8 mg does not need to be diluted and can be administered by slow intravenous or intramuscular injection (for at least 30 s) immediately before chemotherapy followed by a double intravenous or intramuscular administration of 8 mg every 2 and 4 hours or continuous infusion of 1 mg / h for 24 hours.

The efficacy of Emeton in highly emetogenic chemotherapy can be enhanced by the additional single administration of 20 mg dexamethasone sodium phosphate before chemotherapy.

For the prevention of delayed or prolonged vomiting after the first 24 hours, oral or rectal administration of the drug is recommended.

Children and adolescents (ages 6 months to 17 years)

In pediatric practice, Emeton should be administered by iv infusion in 25-50 ml of 0.9% sodium chloride solution or other appropriate solvent (see instructions for use) for at least 15 minutes. The dose of the drug can be calculated by the surface area of ​​the body or body weight of the child.

Calculation of the dose according to the surface area of ​​the child’s body

Emeton should be administered immediately before chemotherapy by a single iv injection at a dose of 5 mg / m²iv dose should not exceed 8 mg.After 12 hours, you can start oral administration of the drug, which can last another 5 days. Do not exceed adult dose.

Calculation of the dose according to the body weight of the child

Emeton should be administered immediately before chemotherapy by a single intravenous injection at a dose of 0.15 mg / kg body weight. The iv dose should not exceed 8 mg. On the first day, you can enter two more iv doses with a 4-hour interval. After 12 hours, you can start oral administration of the drug, which can last another 5 days. Do not exceed adult dose.

Elderly patients

For patients over the age of 65, all doses for iv injection should be dissolved and administered within 15 minutes, with repeated use, the interval between injections should be at least 4 hours.

In patients aged 65 to 74 years, the initial dose of ondansetron is 8 or 16 mg, it is administered by iv infusion for 15 minutes, which can be continued with two doses of 8 mg for 15 minutes with an interval between infusions of at least 4 hours

In patients over the age of 75, the initial iv injection of ondansetron should not exceed 8 mg with an infusion for at least 15 minutes. After an initial dose of 8 mg, you can continue to use two doses of 8 mg, which are administered by infusion for 15 minutes with an interval between infusions of at least 4 hours.

Patients with kidney failure

There is no need to change the dosage regimen or route of administration of the drug to patients with impaired renal function.

Patients with liver failure

In patients with moderate and severe hepatic impairment, Emeton’s clearance is significantly reduced, and T_½ from blood serum - growing. For such patients, the maximum daily dose should not exceed 8 mg.

Patients with impaired spartein / debrisoquin metabolism

T_½ ondansetron in patients with impaired metabolism of spartein and debrisokvin does not change. In these patients, repeated administration leads to the same concentration of the drug as in patients with undisturbed metabolism. Therefore, a change in dosage or frequency of administration is not required.

Postoperative Nausea and Vomiting

Adults

For the prevention of postoperative nausea and vomiting, the recommended dose of Emeton is 4 mg in the form of a single i / m or a slow iv injection during administration to anesthesia.

For treatment of postoperative nausea and vomiting, the recommended single dose of Emeton is 4 mg in the form of a / m or a slow iv injection.

Children and adolescents (from 1 month to 17 years)

For the prevention and treatment of postoperative nausea and vomiting in children who are operated on under general anesthesia, Emeton can be administered at a dose of 0.1 mg / kg body weight (maximum - up to 4 mg) as a slow iv injection (at least 30 s ) before, during, after anesthesia or after surgery.

Elderly patients

The experience with Emeton for the prevention and treatment of postoperative nausea and vomiting in the elderly is limited, but Emeton is well tolerated by patients over the age of 65 who receive chemotherapy.

Patients with kidney failure

There is no need to change the dosage regimen or route of administration of the drug to patients with impaired renal function.

Patients with liver failure

In patients with moderate and severe hepatic impairment, Emeton’s clearance is significantly reduced, and T_½ from blood serum - growing. For such patients, the maximum daily dose should not exceed 8 mg.

Patients with impaired spartein / debrisoquin metabolism

T_½ ondansetron in individuals with impaired metabolism of spartein and debrisokvin does not change. In such patients, repeated administration leads to the same concentration of the drug as in patients with undisturbed metabolism. Therefore, a change in dosage or frequency of administration is not required.

Instructions for use

Ampoules with Emeton do not contain preservatives, and they must be used immediately after opening; the remaining solution is required to be destroyed.

Ampoules with Emeton cannot be autoclaved.

Compatible with other intravenous fluids

Solutions for iv infusion should be prepared immediately before infusion. However, it was found that the ondansetron solution remains stable for 7 days at room temperature (up to 25 ° C) in daylight or in the refrigerator when dissolved in such media: 0.9% sodium chloride solution, glucose solution 5 %, mannitol solution 10%, ringers solution, 0.3% potassium chloride solution and 0.9% sodium chloride solution, 0.3% potassium chloride solution and 5% glucose solution .

It has been established that ondansetron also maintains stability when using plastic and glass bottles. Ondansetron, diluted with 0.9% sodium chloride or 5% glucose, is known to remain stable in polypropylene syringes. It has also been proven that stability in polypropylene syringes is maintained when ondansetron is diluted with other recommended solutions.

If necessary, long-term storage of the drug, dissolution should be carried out in appropriate aseptic conditions.

Compatibility with other drugs

Emeton can be prescribed as an intravenous infusion at a rate of 1 mg / h. Through the Y-shaped injector, together with Emeton, at a concentration of ondansetron from 16 to 160 μg / ml (i.e. 8 mg / 500 ml or 8 mg / 50 ml, respectively), you can enter:

- cisplatin in a concentration of up to 0.48 mg / ml, for 1-8 hours;

- 5-fluorouracil in a concentration of up to 0.8 mg / ml (for example, 2.4 g in 3 l or 400 mg in 500 ml) at a rate of not more than 20 ml / h. Higher concentrations of 5-fluorouracil may precipitate ondansetron. The 5-fluorouracil infusion solution may contain up to 0.045% magnesium chloride in addition to other compatible excipients;

- carboplatin in a concentration of from 0.18 mg / ml to 9.9 mg / ml (for example, from 90 mg in 500 ml to 990 mg in 100 ml) for 10-60 minutes;

- etoposide in a concentration of from 0.14 mg / ml to 0.25 mg / ml (for example, from 72 mg in 500 ml to 250 mg in 1 l) for 30-60 minutes;

- ceftazidime in a dose of 250 mg to 2 g, diluted in water for injection (for example 2.5 ml per 250 mg or 10 ml per 2 g of ceftazidime) as a bolus injection for 5 min;

- cyclophosphamide in a dose of 100 mg to 1 g, diluted in water for injection (5 ml per 100 mg of cyclophosphamide), in the form of an intravenous bolus injection for 5 minutes;

- doxorubicin in a dose of 10 to 100 mg, diluted in water for injection (5 ml per 10 mg of doxorubicin), in the form of an intravenous bolus injection for 5 minutes;

- dexamethasone in a dose of 20 mg, in the form of a slow intravenous injection for 2–5 minutes (with the simultaneous administration of 8 mg or 16 mg of ondansetron dissolved in 50–100 ml of injection solution), for about 15 minutes. Since these drugs are compatible, they can be administered through a single dropper, while in the solution the concentration of dexamethasone phosphate (in the form of sodium salt) will be from 32 μg to 2.5 mg in 1 ml, and ondansetron from 8 μg to 1 mg in 1 ml.

Contraindications

The use of ondansetron is contraindicated in combination with apomorphine hydrochloride, since during their simultaneous use cases of severe arterial hypotension and loss of consciousness were noted. hypersensitivity to any component of the drug.

Side effects

Side effects, information about which is given below, are classified by organs and systems and by the frequency of occurrence. by frequency of occurrence is divided into the following categories: very often (≥1 / 10), often (≥1 / 100 and 1/10), infrequently (≥1 / 1000 and 1/100), rarely (≥1 / 10,000 and 1 / 1000), very rarely (1/10 000).

On the part of the immune system: immediate hypersensitivity reactions, sometimes severe, up to anaphylaxis.

From the nervous system: headache; convulsions, motor disturbances (including extrapyramidal reactions such as oculogyric crisis, dystonic reactions and dyskinesia without persistent clinical consequences); dizziness mainly during rapid iv administration of the drug.

From the side of the organ of vision: fleeting visual disturbances (blurred eyes), mainly with on / in the introduction; transient blindness, mainly during iv use. In most cases, blindness disappears within 20 minutes.

From the side of the heart: arrhythmia, chest pain (with or without ST segment depression), bradycardia; lengthening of the Q – T interval (including flutter / ventricular fibrillation (torsade de pointes).

From the vessels: sensation of warmth or hot flashes; hypotension.

From the respiratory system and organs of the chest cavity: hiccups.

From the digestive tract: constipation.

From the hepatobiliary system: asymptomatic increase in liver function indices. These cases are noted mainly in patients who are treated with chemotherapeutic drugs containing cisplatin.

On the part of the skin and subcutaneous tissue: toxic rashes, including toxic epidermal necrolysis.

General disorders: local reactions in the field of intravenous administration.

According to post-registration observation, such adverse reactions are known.

From the cardiovascular system: chest pain and discomfort, extrasystoles, tachycardia, including ventricular and supraventricular tachycardia, atrial fibrillation, palpitations, syncope, ECG changes.

Hypersensitivity reactions: anaphylactic reactions, angioedema, bronchospasm, anaphylactic shock, itching, skin rashes, urticaria.

From the nervous system: gait disturbance, chorea, myoclonus, restlessness, burning sensation, protrusion of the tongue, diplopia, paresthesia.

General disorders and local reactions: fever, pain, redness, burning at the injection site.

Other: hypokalemia.

special instructions

In the treatment of patients with manifestations of hypersensitivity to other selective 5nt3 receptor antagonists, hypersensitivity reactions were observed.

Ondansetron in a dose-dependent manner prolongs the Q – T interval (see PHARMACOLOGICAL PROPERTIES). Additionally, according to the post-marketing observation, there were reports of cases of ventricular flutter / fibrillation (torsade de pointes) when using ondansetron. The use of ondansetron in patients with congenital Q – T lengthening syndrome should be avoided. Ondansetron should be used with caution to treat patients who have or may develop Q-T prolongation, including patients with electrolyte imbalance, congestive heart failure, bradyarrhythmias, or patients who are being treated with other drugs that cause Q-T prolongation or impaired electrolyte balance. Before use, hypokalemia and hypomagnesemia should be corrected.

After the simultaneous use of ondansetron and other serotonergic drugs, a serotonin syndrome has been described (see INTERACTIONS). If combined treatment with ondansetron and other serotonergic drugs is clinically justified, appropriate monitoring of the patient’s health is recommended.

Since ondansetron weakens intestinal motility, careful monitoring of patients with signs of subacute bowel obstruction during the use of Emeton is necessary.

In patients undergoing surgery in the adenotonsillar region, the use of ondansetron for the prevention of nausea and vomiting can mask the occurrence of bleeding. Therefore, these patients are subject to careful monitoring after the use of ondansetron.

Use during pregnancy and lactation. Ondansetron is not used during these periods due to limited data on the safety of its use during pregnancy and lactation. Ondansetron is able to pass into breast milk. If the use of the drug is necessary, breast-feeding should be discontinued.

Children. The drug is prescribed for children from 6 months of age with chemotherapy and from 1 month of age to prevent treatment with postoperative nausea and vomiting.

The ability to influence the reaction rate when driving vehicles or working with other mechanisms. Ondansetron does not have a sedative effect, however, the profile of the side effects of the drug when driving vehicles or working with other mechanisms should be taken into account.

Interactions

Ondansetron does not accelerate or inhibit the metabolism of other drugs with simultaneous use. special studies have shown that ondansetron does not interact with alcohol, temazepam, furosemide, alfentanil, tramadol, morphine, lignocaine, thiopental or propofol.

Ondansetron is metabolized by various liver cytochrome P450 enzymes: CYP 3A4, CYP 2D6 and CYP 1A2. Due to the variety of ondansetron metabolism enzymes, inhibition or decrease in the activity of one of them (for example, CYP 2D6 genetic deficiency) under normal conditions is compensated by other enzymes and will not have an effect or influence on the total creatinine clearance will be insignificant.

With caution, ondansetron should be used with drugs that extend the Q – T interval and / or cause electrolyte imbalance (see SPECIAL INSTRUCTIONS).

Apomorphine

The use of ondasetron together with apomorphine hydrochloride is contraindicated, since there have been cases of severe hypotension and loss of consciousness during combined use.

Phenytoin, carbamazepine and rifampicin

In patients treated with potential CYP 3A4 inducers (e.g. phenytoin, carbamazepine and rifampicin), ondansetron clearance increases and its concentration in the blood decreases.

Serotonergic drugs (e.g., selective serotonin reuptake inhibitors and serotonin and norepinephrine reuptake inhibitors)

Serotonin syndrome (including changes in mental status, autonomic instability, and neuromuscular disorders) has been described after the simultaneous use of ondansetron and other serotonergic drugs, including selective serotonin reuptake inhibitors and serotonin and norepinephrine reuptake inhibitors (see SPECIFIC INSTRUCTIONS).

Tramadol

According to a small number of clinical studies, ondansetron may reduce the severity of the analgesic effect of tramadol.

The use of Emeton with other drugs that extend the Q – T interval can cause an additional lengthening of this interval. The combined use of Emeton with cardiotoxic drugs (e.g. anthracyclines) may increase the risk of arrhythmias (see SPECIAL INSTRUCTIONS).

Incompatibility. Ondansetron should not be mixed in the same syringe or infusion solution with other drugs, except as indicated in the APPLICATION section.

Overdose

Data on cases of overdose of ondansetron are insufficient. in most cases, the symptoms are similar to those described in patients who were given the drug at the recommended doses (see side effects).

Ondansetron lengthens the Q – T interval in a dose-dependent manner. In case of overdose, ECG monitoring is recommended.

Among the manifestations of an overdose, visual disturbances, severe constipation, hypotension, and vasovagal manifestations with transient grade II AV block were reported. In all cases, these phenomena completely disappeared.

There is no specific antidote, therefore, in cases of overdose, symptomatic and supportive therapy is necessary.

The use of Ipecac in an overdose of ondansetron is not recommended, since its effect cannot be manifested due to the antiemetic effect of ondansetron.

Storage conditions

In the original packaging at a temperature not exceeding 25 ˚s.