Antinauseants Flashcards
Drugs which cause nausea and vomiting
- Chemotherapy drugs
- Cholinergic agonists
- Dopaminergics
- Opioids
Key areas mediating N/V in BBB
- Emetic Center
- Nucleus Tractus Solitarius
Key areas mediating N/V outside the BBB
Chemoreceptor trigger zone
Serotonin and muscarinic receptors in the gut
Anti-nauseant categories
H1 antagonists Anti-muscarinic Serotonin antagonists Corticosteroids Neurokinin-1 antagonists D2 antagonists Cannabinoids
H1 antagonists example
Dimenhydrinate (Gravel)
Dimenhydrinate mechanism
Blocks receptors in the NTS and inner ear, inhibits stimulation of the emetic center
- also has anticholinergic effects (reduces peristalsis in the GI tract)
- For motion sickness, must allow 30 minutes to absorb
Dimenhydrinate side effects
- Drowsiness (help patients sleep)
- Anticholinergic effects: dry mouth
Routes of administration of Dimenhydrinate
Oral, Rectal, Parenteral
Muscarinic Antagonist example
Scopolamine
Scopolamine receptors
CNS: inner ear, NTS, CTZ
Gut: reduce peristalsis
- Can be used as a patch
Serotonin antagonist example
Ondansetron - key role in chemo-induced nausea and vomiting (CINV)
Serotonin receptors in
Gut: peristalsis, signal nausea
CNS: NTS, CTZ
Serotonin antagonists side effects
Constipation - related to reduced peristalsis
Corticosteroid example
Dexamethasone
Dexamethasone used to treatment and mechanism
- reserved for severe N/V
- useful in cases of raised intracranial pressure
- reduces inflammation
Corticosteroids side effects
Systemic corticosteroids have significant side effects so should be used short-term
Neurokinin antagonist example
Aprepitant
NK-1 receptors located in
emetic center and the CTZ
- blocking these inhibits N/V
- most commonly used in CINV
NK-1 antagonist side effects
Hiccups
Anorexia
Fatigue
Cannabinoids uses
- used for many years to treat nausea and vomiting
- also stimulate appetite
- reduces anxiety
Benzodiazepines uses
Address anxiety associated with N/V
Safe drugs used in pregnancy for morning sickness
Pyridoxine
Pyridoxine/Doxylamine
Dimenhydrinate
Doxylamine
- is and H1 receptor antagonist