ZOFRAN ® Ondansetron

ZOFRAN ® is a drug based on Ondansetron hydrochloride.

THERAPEUTIC GROUP: Antiemetics - Antinausea - antagonists of serotonin.

IndicationsAction mechanismStudies and clinical effectiveness Usage and dosage instructionsWarnings Pregnancy and lactationInteractionsContraindicationsUndesirable effects

Indications ZOFRAN ® Ondansetron

ZOFRAN ® is used both in adults and in children over 2 years of age, for the control of nausea and vomiting induced by chemotherapy, radiotherapy and surgery.

Mechanism of action ZOFRAN ® Ondansetron

The oral intake of ondansetron is followed by a rapid gastro-intestinal absorption, which guarantees the achievement of maximum plasma concentrations after about 90 minutes from the administration.

The active principle undergoes a broad first-pass metabolism to the liver level, to be subsequently distributed through the blood, over 70% bound to plasma proteins.

The formulation in suppositories instead, guarantees a maximum plasma peak within 15-60 minutes, with a total bioavailability of the drug of about 60%.

Studies on the pharmacokinetics of ZOFRAN ® have shown that absorption can be achieved more quickly in females, while elimination occurs more slowly, which occurs mainly via the bile following a hepatic metabolism supported by cytochromial enzymes.

The antiemetic action guaranteed by this medicine is essentially due to the ability of ondansetron to act at the level of the serotonin 5HT3 receptors involved in the genesis of vomiting.

Although the biological activity of this active ingredient has not yet been fully characterized, it is believed that the drug can act in two different ways: the first, which takes the form of the inhibition of the serotoninergic receptors of the gastro-intestinal tract, responsible for the activation of vagal afferent pathways useful in the onset of nausea and vomiting, and the second which is expressed through the inhibition of 5HT3i receptors expressed at the central level.

This particular mode of action makes ondansetron, particularly useful in the treatment of nausea and vomiting induced by chemo and radiotherapy, often characterized by a significant increase in the secretion of serotonin at the gastro-intestinal level.

Studies carried out and clinical efficacy

1. ONDANSETRON AND THERAPY COMBINED IN THE POST-OPERATIVE NAUSEA

Post-operative nausea and vomiting are some of the symptoms that commonly follow surgery, and that significantly reduce patients' quality of life throughout their hospitalization. The correct approach to this problem should include a combination therapy that also includes serotonin receptor antagonists. The data show that combined therapy can be more effective and decisive than monotherapy.

2. ONDANSETRON AND NEW DRUGS

Despite ondansetron, it represents today the forefather of an important family of drugs used in the prevention of nausea and vomiting following chemotherapy. On the basis of this active principle, other important analogues have developed over time, which despite being able to reduce the sensation of nausea, improving the patients' quality of life, maintain the same antiemetic capacity as their predecessor ondansetron.

3.ONDANSETRON IN THE PRE-HOSPITAL EMERGENCY

Although ondansetron is known today, due to its anti-emetic properties, particularly evident in patients undergoing chemotherapy or surgery, this study shows that the aforementioned active ingredient can carry out an important anti-emetic effect even when used by paramedics in the treatment of nausea and undifferentiated vomiting.

Method of use and dosage

ZOFRAN ® 4 or 8 mg waved or overdose coated tablets; suppositories from 16mg of ondansetron; syrup from 4mg of ondansetron; injectable solutions of 2-8mg / 2ml of ondansetron:

the dosage usually used in the prevention of nausea and vomiting is that of 8 mg of active ingredient, taken 2 hours before the chemotherapy, radiotherapy or surgical treatment, regardless of the formulation.

In any case the correct formulation of the dosage, which can vary considerably depending on the extent of the therapy, the physical and physiological characteristics of the patient and his pathological picture must necessarily be established by the doctor.

Warnings ZOFRAN ® Ondansetron

The use of ZOFRAN ® should be avoided, or monitored with particular care in patients who have experienced hypersensitivity reactions to other 5HT3 receptor antagonists, or suffering from intestinal obstruction, given the ability of the active ingredients to slow the rate of intestinal transit.

In the various formulations, lactose, sorbitol and sources of phenylalanine may be present, therefore it would be advisable to carefully control the excipients in order to avoid unpleasant side reactions in patients suffering respectively from galactose / glucose malabsorption or lactase enzyme deficiency, hereditary fructose intolerance and phenylketonuria.

The possible sedative activity of the drug could reduce the patient's perceptive abilities.

PREGNANCY AND BREASTFEEDING

Despite several studies conducted on animal models, they have shown the absence of side effects on the health of the fetus and the mother, following the intake of ondansetron in pregnancy, the absence of significant human clinical trials does not allow to establish the safety profile of ZOFRAN ® when taken during pregnancy.

Therefore it is advisable to avoid taking this drug during the entire period of pregnancy and subsequent breastfeeding, given the presence of the active ingredient in breast milk.

Interactions

At the moment there is no particularly significant pharmacokinetic experimental evidence relating to the possible consequent interactions of ondansetron with other active ingredients.

The hepatic metabolism of the active principle, supported by different enzymes, allows even in the presence of specific inhibitors, to keep this process active, without serious repercussions on the pharmacokinetic and pharmacodynamic properties of the active principle.

Contraindications ZOFRAN ® Ondansetron

ZOFRAN ® is contraindicated in patients with known hypersensitivity to one of its components, in the case of phenylketonuria, given the presence of sources of phenylalanine, and during the period of pregnancy and lactation.

Undesirable effects - Side effects

Experimental data and post-marketing monitoring showed some fairly common side effects following the intake of ZOFRAN ® such as: headache, feeling of heat and flushing, constipation and a burning sensation at the injection site.

Cases of extrapyramidal reactions, arrhythmias, hypotension, increased transaminases and bradycardia were rarer.