Antiemetics Flashcards
Raglan( metocloropromide): Antiemetic
MOA: It is a dopamine receptor antagonist, stimulates the motility of upper GI tract, and decreases reflux into esophagus. Increases treshhold in chemoreceptor trigger zone
Dosage: 5mg/ml
onset: 1-3 min, half life: 4-6 hours
Metabolism: by liver, excreted in unirine, 30% protein bound
Zofran (Ondansetron): Antiemetic
Ondansetron (INN), originally marketed under the brand name Zofran, is a serotonin 5-HT3 receptor antagonist used to prevent nausea and vomiting caused by cancer chemotherapy, radiation therapy, and surgery.Blocks serotonin both peripherally on vagal nerve terminals and centrally in chemoreceptor trigger zone ( CTZ is an area of medulla that receives input from blood- born hormones and drugs and communicate with vomiting centers to cause vomiting, neurotransmitter a that control nausea are serotonine, dopamine, acetylcholine histamine and substance P.
It has little effect on vomiting caused by motion sickness,[1][2] and does not have any effect on dopamine receptors or muscarinic receptors[2]
Dosage: 4mg comes in 2mg/ ml vial —> 2cc
Onset: , half life: 4 hours
Metabolism: by liver excreted by kidney
Protein binding: 70-75%
Note: all serotonin receptor antagonists prolong Q-T interval
Decadron (Dexamethasone): long acting gluccocorticoids, antiemetic
MOA: Long acting glucocorticoid that inhibits accumulation of inflammatory cells at inflammation site, blocks immune response
It it produced in adrenal medulla
Used as: antiemetic or anti-inflammatory
Dose: antiemetic: 4 mg, no benefit at 8 mg
Anti inflammatory: 5-10 mg but it comes as 4-8 —-> 4-8 mg
Dose is 0.25 to 0.5 mg/ kg for anti inflammatory
0.15 mg/kg up to 4 mg nausea and vomiting
Comes in: 4mg/ ml
Side effects: hypoglycemia, a vascular necrosis of femoral head ( not single dose effect)
Serotonin
Serotonin /ˌsɛrəˈtoʊnɨn/ or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Biochemically derived from tryptophan, serotonin is primarily found in the gastrointestinal tract (GI tract), platelets, and the central nervous system (CNS) of animals, including humans. It is popularly thought to be a contributor to feelings of well-being and happiness.[6]
Approximately 90% of the human body’s total serotonin is located in the enterochromaffin cells in the GI tract, where it is used to regulate intestinal movements.[7][8] The remainder is synthesized in serotonergic neurons of the CNS, where it has various functions. These include the regulation of mood, appetite, and sleep. Serotonin also has some cognitive functions, including memory and learning. Modulation of serotonin at synapses is thought to be a major action of severSerotonin secreted from the enterochromaffin cells eventually finds its way out of tissues into the blood. There, it is actively taken up by blood platelets, which store it. When the platelets bind to a clot, they release serotonin, where it serves as a vasoconstrictor and helps to regulate hemostasis and blood clotting. Serotonin also is a growth factor for some types of cells, which may give it a role in wound healing.
Serotonin is metabolized mainly to 5-HIAA, chiefly by the liver. Metabolism involves first oxidation by monoamine oxidase to the corresponding aldehyde. This is followed by oxidation by aldehyde dehydrogenase to 5-HIAA, the indole acetic acid derivative. The latter is then excreted by the kidneys
In the digestive tract (emetic)
The gut is surrounded by enterochromaffin cells, which release serotonin in response to food in the lumen. This makes the gut contract around the food. Platelets in the veins draining the gut collect excess serotonin.
If irritants are present in the food, the enterochromaffin cells release more serotonin to make the gut move faster, i.e., to cause diarrhea, so the gut is emptied of the noxious substance. If serotonin is released in the blood faster than the platelets can absorb it, the level of free serotonin in the blood is increased. This activates 5HT3 receptors in the chemoreceptor trigger zone that stimulate vomiting.[27] The enterochromaffin cells not only react to bad food but are also very sensitive to irradiation and cancer chemotherapy. Drugs that block 5HT3 are very effective in controlling the nausea and vomiting produced by cancer treatment, and are considered the gold standard for this purpose.[28]
What is the side effect Zofran?!
Q-T interval prolongation
Droperidol
- Antidopaminergic drug( drug that blocks dopamine receptor) used as antiemetic and antipsychotic
Adverse effect: QT prolongation and torsade de pointes
