Antiemetics

Question 1

Antihistamines:
- examples
- mech
- indications
- contraind
- SE

Answer 1

Antihistamines:
- examples : cyclizine, promethazine
- mech : H1 antagonist
- indications: motion sickness, post op, preg, vertigo disorders
- contraind: cardiac oedema - cyclizine, people at risk of urinary retention, old people/children
- SE: drowsy, antichol (urin retention, constip, blurred vision), cardiac toxicity

Question 2

Phenothiazines:
- examples
- mech
- indications
- contraind
- SE

Answer 2

• examples : metoclopramide, prochlorperazine, levomepromazine, haloperidol, domperidone
• mech : dopamine antagonists (levo works at multiple rec sites not just dopamine)
• indications: chemo/radio induced, acute n+v, migraine, palliative, hypercalc (levo/halop), constip/ileus vomiting (metoclop)
• contraind: metoclop in bowel obstruct, parkinsons, cardiac disorders dopmperidone
• SE: acute dystonic reactions, constip, drowsy, dry mouth, urin retention, prolonged QT (levomep), galactorrhea

Question 3

5HT3 rec antagonists:
- examples
- indications
- contraind
- SE

Answer 3

• examples : ondanestron
• indications: chemo, post op, parkinsons, acute gastroenteritis
• contraind: anyone at risk of prolonged qt, t1 preg due to oral clefts
• SE: constip, prolonged QT, headache, abnormal sensation

Question 4

parkinsons
preg
menieres
motion sickness
post op
palliative

Answer 4

parkinsons: low dose domperidone, cyclizine, ondanestron
preg: promethazine, cyclizine
menieres: antihistamines, phenothiazines
motion sickness: hyoscine hydrobromide (antimusc)
post op: ondanestron,
palliative: levomepromazine

Question 5

PPIs
- examples
- mech action
- SE

Answer 5

PPIs
- examples: omeprazole, lansoprazole
- mech action: irrev block hkatpase of gastric parietal cells reducing acid formation
- SE: hyponat, hypomag, osteoporosis, microscopic colitis, inc risk c diff, can mask gastric cancer