Lesson 20: Vomiting Pathophysiology

A complex signaling cascade involving various brain regions and neurotransmitters that ultimately leads to the expulsion of stomach contents.

The medulla oblongata, specifically the 'vomit center', is responsible for coordinating the complex muscle contractions involved in vomiting.

The chemoreceptor trigger zone (CTZ) is a sensitive area in the brain that detects toxins, drugs, and other substances that can trigger vomiting.

Neurotransmitters like acetylcholine, histamine, serotonin, dopamine, and substance P play crucial roles in the vomiting process. They transmit signals between different brain regions involved in the vomiting reflex.

Drugs that block the actions of specific neurotransmitters involved in vomiting can help alleviate nausea and vomiting. They are categorized by the specific neurotransmitter they target.

H1 receptor antagonists like promethazine, dimenhydrinate, and betahistine work by blocking histamine receptors in the vestibular nuclei and the gastrointestinal tract.

Motion sickness is often treated with antihistamines that block H1 receptors in the vestibular nuclei, which plays a crucial role in balance and movement.

Drowsiness and sedation are common side effects of some antihistamines, especially older generations of drugs.

A type of medication that blocks the effects of histamine at H1 receptors. They are used to treat nausea and vomiting in pregnancy.

Vitamin B6, a first-line treatment for nausea and vomiting in pregnancy. It is often combined with other antihistamines like doxylamine.

A type of medication that blocks the effects of dopamine (D) receptors. It is used as an option if other antiemetics fail.

A type of medication that blocks the effects of serotonin at 5-HT3 receptors. It is another option for treating nausea and vomiting if other medications are unsuccessful.

A powerful antiemetic, commonly known as an antipsychotic, used to treat severe nausea and vomiting. It is typically given buccally or intramuscularly.

An immune modulator used intratympanically to treat vertigo in Meniere's disease. Its action suggests an autoimmune role in the disease.

A drug that blocks muscarinic receptors, used to prevent and treat motion sickness. Oral or intramuscular administration is reserved for short or intense motion exposure.

A medication that acts as a partial H1 agonist and an H3 antagonist. It is prescribed for preventing attacks of Meniere's disease.

These drugs block 5-HT3 receptors in the gastrointestinal tract and the chemoreceptor trigger zone (CTZ), preventing the activation of pathways that lead to nausea and vomiting.

Metoclopramide is a dopamine antagonist used for vomiting related to migraines, gastroesophageal reflux, and liver/gallbladder disorders.

Domperidone is a dopamine antagonist that doesn't reach the brain, making it safer for vomiting related to levodopa (Parkinson's) and cytotoxic treatments.

These antipsychotics (like chlorpromazine, prochlorperazine, and perphenazine) are effective antiemetics for severe nausea and vomiting from various causes, including chemotherapy, radiation therapy, and opioid use.

These drugs (like haloperidol and droperidol) are used for acute chemotherapy-induced vomiting but have limited use due to potential side effects.

Granisetron, Ondansetron, and Palonosetron are medications that belong to the class of 5-HT3 receptor antagonists.

Chemotherapy-induced nausea and vomiting, postoperative nausea and vomiting.

Vomiting is a complex process involving the brain, GI tract, and specific neurotransmitters. When triggered, it results in the expulsion of stomach contents through coordinated muscle contractions.

The Chemoreceptor Trigger Zone (CTZ) is a specialized area in the brain that is highly sensitive to toxins, drugs, and other harmful substances. When activated, it sends signals to the vomit center, triggering the vomiting reflex.

Neurotransmitters like acetylcholine, histamine, serotonin, dopamine, and substance P play key roles in vomiting by transmitting signals between different brain regions involved in the vomiting reflex.

Antiemetic drugs are medications designed to prevent or reduce nausea and vomiting. Different types of antiemetics work by targeting specific neurotransmitters involved in the vomiting process.

H1 receptor antagonists like promethazine or dimenhydrinate block histamine receptors in the vestibular nuclei and the GI tract, reducing motion sickness and nausea from stomach irritants.

5-HT3 receptor antagonists like ondansetron block serotonin receptors in the GI tract and the CTZ, preventing the activation of pathways leading to nausea and vomiting.

Dopamine antagonists like metoclopramide block dopamine receptors, playing a role in reducing nausea and vomiting connected to migraines, gastroesophageal reflux, and liver/gallbladder issues.

Antiemetic antipsychotics, such as prochlorperazine, are used to treat severe nausea and vomiting from causes like chemotherapy, radiation therapy, and opioid use, by targeting dopamine receptors.

Vitamin B6, also known as pyridoxine, is the first-line treatment for nausea and vomiting in pregnancy. It's often used in combination with other antihistamines like doxylamine.

H1 receptor antagonists are a class of medications that block the effects of histamine at H1 receptors, helping to alleviate nausea and vomiting.

Promethazine, dimenhydrinate, and betahistine are examples of H1 receptor antagonists used to treat nausea and vomiting.

Doxylamine is an H1 receptor antagonist often used in combination with pyridoxine (vitamin B6) for the treatment of nausea and vomiting in pregnancy.

Prochlorperazine is a powerful antiemetic, often classified as an antipsychotic, used to treat severe nausea and vomiting. It's typically administered buccally or intramuscularly.

Scopolamine (hyoscine) is a medication that blocks muscarinic receptors, used to prevent and treat motion sickness. Oral or intramuscular administration is typically reserved for short, intense motion exposure or individuals highly susceptible to motion sickness.

Betahistine is a medication that acts as a partial H1 agonist and an H3 antagonist. It's prescribed for preventing attacks of Meniere's disease.

Dexamethasone is an immune modulator used intratympanically to treat vertigo in Meniere's disease. It suggests an autoimmune role in the disease.

5-HT3 receptor antagonists block serotonin receptors in the GI tract and CTZ, preventing signals that cause nausea and vomiting.

Granisetron, Ondansetron, and Palonosetron are commonly used 5-HT3 antagonists.

Metoclopramide works by blocking dopamine receptors in the CTZ (central) and stimulating gut motility (peripheral).

Although effective, Metoclopramide can cause dyskinesia (involuntary movements) and stimulate prolactin, leading to menstrual issues.

Domperidone is a dopamine antagonist that doesn't cross the blood-brain barrier, meaning it's safer for nausea caused by Parkinson's medication.

Dopamine antagonists like Chlorpromazine, Prochlorperazine, and Perphenazine are powerful antiemetics for severe nausea.

Haloperidol and Droperidol are dopamine antagonists used for acute nausea from chemotherapy, but their use is limited due to side effects.

NK1 receptor antagonists work by blocking substance P receptors in the CTZ and vomiting center, thus inhibiting nausea.