Zofran Over the Counter

Several debilitating conditions require specific procedures such as surgery to improve the quality of life of the patient and maybe even save their lives.

But often, such treatments cause side effects such as nausea and vomiting.

When a person undergoes cancer treatment, particularly chemotherapy (use of drugs to reduce the symptoms and stop the development of cancer), it is believed that a certain part of the brain commonly referred to as the vomiting center as well as certain parts of the esophagus, stomach, small intestine and large intestine get triggered and activate a reflex pathway that causes nausea and vomiting. These symptoms could occur immediately or develop over a period of time and can last from a few hours to many days.

The vomiting center of the brain consists of the chemoreceptor trigger zone (CTZ) located in the medulla oblongata. It is triggered by blood-borne drugs or hormones. It then communicates with the other parts of the gastrointestinal tract to initiate vomiting.

Generic Zofran Ondansetron

Zofran, also known as Ondansetron, is a medication which prevents nausea and vomiting associated with chemotherapy for cancer, radiation therapy or surgery. It can be administered orally, or injected into a muscle or vein. It was developed in the 1980s in Great Britain by GlaxoSmithKline and was first used medically in 1991.

When a person undergoes chemotherapy or radiation, a hormone called serotonin (5HT) is released in the gut. Serotonin acts on the 5HT3 receptors present in the gut which carry an impulse to the Chemoreceptor Trigger Zone in the brain which communicates with other parts of the vomiting center and sends an impulse to the gut causing the person to vomit. The active ingredient in Zofran acts on the 5HT3 receptors present in the gut and the brain and doesn’t allow the impulses to travel, thus preventing nausea and vomiting.

Though Ondansetron is a well-tolerated drug, it does have some side effects such as constipation, diarrhea, dizziness and headache. It has also been discovered to be ototoxic (harmful to auditory system). But its most serious complication is QT Prolongation which is a serious heart rhythm disorder that may be a factor for sudden death. This may occur in any patient with any formulation but the risk is most noticeable with the injectable (intravenous) form of the drug and increases with the dose. It is more risky for patients taking other medicines which prolong the QT interval and also for patients suffering from congenital long QT syndrome (delayed repolarization of heart after heartbeat), congestive heart failure, and/or bradycardia (slow heartbeat).

Difference Between Generic and Brand Name Zofran

Generic Zofran is called Ondansetron. In accordance with the rules stipulated by the FDA, there can be no difference between the generic and brand name variants of any drug with regards to essential properties like composition of active ingredient, efficacy, speed of action, speed of absorption, pharmacology, etc.

The only difference can be in the form, color or flavor of the oral tablet and the inactive ingredients which the active ingredient is paired with. These factors have no effect whatsoever on the efficacy of the active ingredient.

This stands true for all drugs including Zofran and its generic variant Ondansetron.

Ondansetron (Generic Zofran) dosage

Zofran over the counter is available in the following formats and dosages:

  • Tablets: 4mg, 8mg, 24mg.
  • Oral solution: 4mg/5ml.
  • Orally disintegrating tablets: 4mg, 8mg.
  • Injection: 2mg/ml.
  • Premixed injection: 32mg/50ml, 4mg/50ml.

The dosage and duration of treatment for various procedures for adults is given below:

  • Highly Emetogenic Cancer Chemotherapy: A single 24mg dose administered half an hour before the start of a single-day highly emetogenic cancer chemotherapy along with cisplatin (at least 50mg/m2).
  • Moderately Emetogenic Cancer Chemotherapy: An 8mg dose is to be administered 30 minutes before chemotherapy starts and a subsequent 8mg dose is to be given 8 hours after the first dose. After the completion of chemotherapy administer 8mg doses twice a day (every 12 hours) for 1 or 2 days.

In case the patient is undergoing radiotherapy, the following dosage and treatment duration recommendations should be considered.

  • In case of total body irradiation: 8mg administered 1 or 2 hours before the start of each fraction of radiotherapy each day.
  • For single high-dose fraction radiation to the abdomen: 8mg administered 1 or 2 hours before start of radiation therapy and subsequent 8mg doses every 8 hours after the first dose for 1 to 2 days after completion of radiotherapy.
  • For daily fractionated radiation to the abdomen: 8mg administered 1 or 2 hours before start of radiation with subsequent 8mg doses every 8 hours for every day that radiotherapy is given.

In cases when the patient is likely to suffer from nausea or vomiting during or after surgery, a 16mg dose should be administered 1 hour before induction of anesthesia.

Ondansetron (generic Zofran) dosage for moderately emetogenic cancer chemotherapy should be altered in younger patients. In children 4 to 11 years of age 4mg of Ondansetron is to be administered 30 minutes before the start of chemotherapy with subsequent 4mg doses 4 and 8 hours after the first dose. Then the patient should administer 4mg doses thrice a day for 1 to 2 days after completion of chemotherapy. In children 12 to 17 years of age 8mg should be administered 30 minutes before the start of chemotherapy with subsequent 8mg doses 4 and 8 hours after the first dose. That should be followed by 8mg doses thrice a day for 1 to 2 days after completion of chemotherapy.

In patients with severe hepatic impairment, it is not recommended to exceed a total daily dose of 8mg.

Difference between Ondansetron 8mg and Ondansetron 4mg

The only difference between Ondansetron 8 mg and Ondansetron 4 mg is the dosage of the active ingredient. Thus, in cases when an 8 mg dose is not available, a patient can be given two 4 mg doses.

Ondansetron overdose

Zofran overdose in adults is extremely rare, so there is not enough information on the symptoms associated with it. In one case, sudden blindness (amaurosis) for a time period of 2 to 3 minutes along with severe constipation was observed.

In pediatric patients, tachypnea, agitation, tachycardia, somnolence were reported, which are consistent with serotonin syndrome.

There is no specific antidote for Zofran overdose, but patients can be managed with appropriate supportive therapy.

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