Drugs for disorders of the bowel 2 Flashcards
D2 receptor antagonists is not indicated for what?
Vomiting because of motion sickness/labyrinth disturbances
Which drugs that are prefered because they will not cross what?
Hydrophilic drugs prefered because will not cross BBB
D2 receptor antagonists will block what?
Will not block extrapyramidal D2 receptors: dyskinesia and restlessness
Dopamine inhibits what?
Dopamine inhibits prolactin, its blockage may cause breast tenderness, galactorrhoea, amenorrhea
List 2 drugs that are D2 receptor antagonists that cross BBB
- Metoclopramide
- Prochlorperazine
Explain the usage of Metoclopramide
Metoclopramide (EML): radiation therapy, postoperative vomiting, drug related N/V. Empties the stomach, relaxes the pylorus
Adverse effects of Metoclopramide
AE: extrapyramidal symptoms,
slight sedation, constipation
Explain the usage of prochloperazine
Prochlorperazine : radiation therapy, oncotherapy, avail as suppositories.
Adverse effects for Prochloperazine
AE: jaundice
List the drug that does not cross the BBB under D2 receptor antagonists
Do not cross BBB
* Domperidone: Similar to metoclopramide without crossing BBB
The histamine and muscurinic receptor antagonist is used for what?
Used for all types of vomiting esp motion sickness, nausea from labyrinth disturbances
The histamine and muscuranic receptor antagonists crosses BBB and go to which centeres
Cross BBB = vomiting centre & chemoreceptor trigger zone (CTZ)
Anticholinergic side-effects
Promethazine is used for what?
Promethazine – sedative anithistamine – treat motion sickness & vertigo AE: Strong anticholinergic effect ,Strong sedative effect
Cyclizine is used fr what?
Cyclizine – also paediatric suppositories for over 6 years – treat motion sickness
Cinnarizine is used for what?
Cinnarizine - treat motion sickness, vertigo, vestibular disorders
List 4 examples for 5-HT3 antagonists
Examples:
* Dolasetron
* Granisetron
* Ondansetron
* Palonosetron
The 5-HT3 antagonists
1. Work on which zone
2. treat what?
3. Caution?
- Selective antagonists of 5HT receptors in chemoreceptor trigger zone (CTZ) & GIT
- N/V caused by chemotherapeutic drugs, radiation therapy
- Caution in cardiac disease- ECG abnormalities
what is hyperemesis gravidarum
Severe type of vomiting during pregnancy
When the preganant patient is hyperemesis gravidarum what to do?
Hyperemesis gravidarum (severe type of vomiting during pregnancy)
* Admission to hospital
* IV hydration with electrolytes and thiamine
* Parenteral antiemetics:
* IM prochlorperazine
* IV metoclopramide
* Ondansetron for pregnancies over 12 weeks if vomiting does not resolve
* Exclude organic causes: thyrotoxicosis, UTI, gestational trophoblastic disease
LIST THE SPECIAL SITUATIONS
Post-operative N&V -5HT₃ antagonists (ondansetron)
Pre-operatively N&V -antimuscarinics are used to inhibit salivation and excessive respiratory
secretions during anaesthesia), 5HT₃ antagonists combined with dexamethasone
Chemotherapy-induced N&V – phenothiazides (prochlorperazine) , metoclopramide use limited by
SE.
Highly emetogenic agents (cisplatin), disrupt gastric mucosa and initiate release of 5HT from
entrochromaffin cells, which stimulate 5HT₃ receptors in afferent vagal endings and trigger the
emetic reflex – use 5HT₃ antagonists (with other drugs); cannabinoids (nabilone) used when
conventional antiemetics are not effective – recommended for hospital setting
Radiotherapy-induced N&V – 5HT₃ antagonists (e.g ondansetron).
Migraine- metoclopramide , domperidone (prokinetics)
Drug-associated N&V – phenothiazides (prochlorperazine)
Palliative care-associated N&V – use domperidome
Special situations
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Explain the neurokinin 1 receptor antagonists usage
Aprepitant
Adjunct to other antiemetics for prevention of acute or delayed N&V
due to highly emetogenic chemotherapy
