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Cobalt Chromium Toxicity

How does Zofran work?

  • Zofran (Ondansetron) is a serotonin 5-HT3 receptor antagonist. So, what does this mean? Why is this important?
  • What is Serotonin?
    • Serotonin, or 5-hydroxytryptamine (5-HT), is a neurotransmitter.
    • Neurotransmitters are chemicals transmitting signals between nerve cells (neurons) in the brain to relay messages. Each nerve cell has receptor sites for neurotransmitters. You can think of neurotransmitters as “keys” and receptors as “locks”. Each receptor is designed to bind only to a certain neurotransmitter. When a neurotransmitter (key) binds to the receptor site (lock) it sends a signal. If enough neurotransmitters bind to receptors, it transmits a message (i.e. it tells your body to perform a specific action).



  • Where is Serotonin found?
    • Gastrointestinal (GI) tract, blood, and central nervous system (CNS): brain and spinal cord.
  • What are Serotonin’s functions?
    •  Plays a role in regulating mood, appetite, and sleep
  • What are 5-HT3 receptors?
    • All cells in your body have thousands of locations on their surface called receptor sites. Receptor sites “locks” are regions responding to particular neurotransmitters “keys”.  The 5-HT3 receptors are the respective locks to the serotonin (5-HT) key.
  • Where are 5-HT3 receptors found?
    • They are found in similar places as serotonin.
      • Central Nervous System (CNS): nausea and vomiting center in the brain
      • Peripheral Nervous System (PNS): Gastrointestinal (GI) Tract
  • What happens when the serotonin (key) enters the 5-HT3 receptor (lock)?
    • The 5-HT3 receptors “locks” are activated when the level of Serotonin (5-hydroxytryptamine or 5-HT) “key” in the blood is increased. The 5-HT3 receptors are located in the nausea and vomiting center of the brain. So, when serotonin finally fits into the 5-HT3 receptor, it sends a signal to the nausea and vomiting center of the brain, and this message subsequently induces nausea and vomiting.
  • What is an antagonist?
    • A receptor antagonist blocks neurotransmitters “keys” from occupying the receptor sites “locks”. Zofran is part of a class of drugs acting as receptor antagonists, specifically at the 5-HT3 receptor. The serotonin 5-HT3 receptor antagonists suppress vomiting and nausea by stopping serotonin binding to the 5-HT3 receptors (i.e. the serotonin (5-HT) “key” is blocked from fitting into the 5-HT3 receptor “lock”).

In a nutshell, Zofran (receptor antagonist) stops serotonin (the key) from binding to the receptors (the locks) which prevents nausea and vomiting.

What are adverse side effects of Zofran? Some potential negative side effects include:

  • QT Prolongation- A prolonged QT interval is a lengthening of the time between the start of the Q wave and end of the T wave in the heart’s electrical activity. As a result, your cardiac muscle takes longer than normal to recharge between beats, disturbing the heart’s normal electrical cycle or impulses. This may lead to fatal ventricular defibrillations and ventricular arrhythmias such as torsades de pointes, a potentially fatal heart rhythm resulting in sudden death.
  • Serotonin Syndrome- Serotonin syndrome can occur when there is an excess of serotonin in your body. Zofran inhibits serotonin, or 5-HT, from binding to the 5-HT3 receptors. As a result, too much serotonin can accumulate causing serious to life-threatening injuries.

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