Nausea and vomiting Flashcards
what is emesis/vomiting?
forceful expulsion of gastric contents controlled by the vomiting centre
what is the vomiting centre?
- located in the medulla
- input from area postrema/ chemoreceptor trigger zone
What does the act of vomiting cause?
LES relaxation
Respirations stops
Increased abdominal pressure
Contraction of diaphragm and abdominal muscles
Are emetics useful?
only in emergency situations after ingestion of a toxin
- No OTC emetics available
what are the receptors in the vomiting centre?
mACH, 5HT3
what are uses of anti-emetics?
Morning sickness
Motion sickness
Cytotoxic chemotherapy drugs
Radiation therapy
what are OTC anti-emetics?
For travel sickness
- Cinnarizine (anti-histamine H1)
- Promethazine (anti-histamine H1 and weak mACH antagonist)
what is hyoscine?
a mACH antagonist
what is ondasteron?
a 5-HT3 antagonist
- used to reduce nausea and vomiting during cancer treatment, post operative N&V
what is hyperemesis gravidum
- excessive nausea and vomiting during pregnancy
- no clear reason
- some say it’s hereditary
- treated with antiemetics, steroids, vitamins , iv fluids
what happens when binding to a receptor occurs?
receptor is activated by a change in its conformation and the biochemical communication is achieved to allow normal function
what is the strongest type of non-covalent bonds?
ionic
what is the mechanism of action of cinnarizine working in the H1 receptor?
- GPCR activated by histamine
- Has three points of interaction - Binds in a slightly different position due to lipophillic interaction
- stops the conformational change needed to activate histamine receptor
what is something that’s essential for activity?
pharmacophore
