Module 3 - Antinausea medication Flashcards
What is Ondansetron used for, and how does it work?
Ondansetron (Zofran) is used for chemotherapy-induced nausea and vomiting (CINV) and to prevent nausea and vomiting caused by radiotherapy and anesthesia. It is also used off-label for other conditions like childhood viral gastritis and pregnancy-related morning sickness. Ondansetron works by blocking type 3 serotonin receptors (5-HT3 receptors) in the chemoreceptor trigger zone (CTZ) and on afferent vagal neurons in the upper GI tract.
What are the common side effects of Ondansetron?
The most common side effects of Ondansetron are headache, diarrhea, and dizziness.
What is a significant concern when using Ondansetron, and who should avoid it?
Ondansetron can prolong the QT interval, posing a risk for a potentially life-threatening dysrhythmia called torsades de pointes. It should not be given to patients with long QT syndrome and should be used cautiously in patients with electrolyte abnormalities, heart failure, or bradydysrhythmias, especially when they are taking other drugs that affect the QT interval.
How can Ondansetron’s effectiveness be enhanced, and what are its advantages compared to some other antiemetics?
Ondansetron can be even more effective when combined with dexamethasone. Unlike some antiemetic phenothiazines, Ondansetron does not cause extrapyramidal effects like akathisia and acute dystonia because it does not block dopamine receptors.
What is the therapeutic goal when using Ondansetron, and for what purposes is it typically prescribed?
The therapeutic goal of Ondansetron is to suppress nausea and vomiting caused by chemotherapy, radiation therapy, or anesthesia. It is commonly prescribed to alleviate these symptoms in patients undergoing such treatments.
What baseline data should be obtained before initiating Ondansetron therapy?
Before starting Ondansetron treatment, it is essential to obtain baseline data, including the measurement of QTc (corrected QT interval) levels and assessment of electrolyte levels.
What monitoring is recommended during prolonged use of Ondansetron?
During prolonged use of Ondansetron, it is advisable to periodically recheck QTc levels to monitor any potential changes or irregularities.
How should high-risk patients be identified when considering Ondansetron therapy, and what conditions require caution when using this medication?
High-risk patients for Ondansetron therapy should be identified, and caution is warranted in individuals with conditions such as electrolyte imbalances, heart failure, or bradydysrhythmias.
How can the therapeutic effects of Ondansetron be evaluated, and what should healthcare providers look for when assessing its efficacy?
To evaluate the therapeutic effects of Ondansetron, healthcare providers should assess for a decrease in or prevention of nausea and vomiting, as the primary goal of the medication is to alleviate these symptoms.
What measures should be taken to minimize adverse effects associated with Ondansetron, especially concerning cardiac risks?
To minimize adverse effects, Ondansetron should be avoided in patients with a prolonged QTc interval. Caution is also necessary when prescribing it to individuals taking other medications known to prolong QTc.
In which pharmacologic category does dimenhydrinate belong?
This medication belongs to the pharmacologic category of “Ethanolamine Derivative; Histamine H1 Antagonist; Histamine H1 Antagonist, First Generation.”
What are indications for use of dimenhydrinate
Nausea, vomiting and/or vertigo: Treatment and prevention of nausea, vomiting and/or vertigo associated with motion sickness, radiation sickness, postoperative recovery, use of other drugs, Ménière disease and other labyrinthine disturbances.
Mechanism of action for dimenhydrinate
Competes with histamine for H1-receptor sites on effector cells in the gastrointestinal tract, blood vessels, and respiratory tract; blocks chemoreceptor trigger zone, diminishes vestibular stimulation, and depresses labyrinthine function through its central anticholinergic activity
Adverse effects of dimenhydrinate
- Feeling dizzy, sleepy, tired, or weak
- Dry mouth, nose, or throat
- Thickening of mucus in nose or throat
- Feeling nervous and excitable
- Headache
- Decreased appetite
- Stomach pain
- Upset stomach
- Trouble sleeping
