Antiemetics, Laxatives and Anti-motility Flashcards
Cyclizine acts on which receptors and is indicated in what forms of nausea?
- acts on H1 and muscarinic receptors
- motion sickness, vertigo, surgery, cerebellar and brain disease induced nausea
2 CI for cyclizine use
NB: one is due to cyclizine is an antimuscarinic and there are antagonised by prokinetic cholinergic meds
CI: CONCURRENT METOCLOPRAMIDE / DOMPERIDONE USE
CI: TACHYARRYTHMIAS
Cyclizine, 2 SEs
NB: avoid in hepatic encephalopathy (-> drowsy) and BPH (risk of retention)
- drowsiness
- dry mouth
- tremor, flushing, tachycardia
Metoclopramide acts on D2 and 5H4 receptors, what type of action does it have? And when is this antiemetic indicated(give 2)?
- a prokinetic and inhibits sensing in the CTZ
- for N&V due to reduced gut motility
- e.g. post-abdo radiotherapy, chemo, distension/delayed gastric emptying, surgery, partial bowel obstruction
When is Metoclopramide contraindicated? Give 2CI:
CI: CONCURRENT CYCLIZINE USE CI: PARKINSON'S DISEASE CI: EXTRA-PYRAMIDAL SYMPTOMS CI: TOTAL BOWEL OBSTRUCTION and PERFORATION CI: LONG QT CI: EPILEPSY
Give 2 SEs of the prokinetic metoclopramide:
- colic
- extrapyramidal SEs
- long QT
Haloperidol is a 1st generation, typical antipsychotic that acts on which receptor? Helping nausea of what origin/cause?
- D2 receptors
- chemoreceptor triggered nausea
The gen 1 Haloperidol acts on -D2 receptors and helps -chemoreceptor triggered nausea, hence suggest 3 indications for it’s use:
- electrolyte disturbance (–>nausea)
- uraemia (“”)
- hormones (“”)
- opioid induced nausea
- chemo induced
- anaesthesia related “”
Give 2 CI for use of Haloperidol as an anti-emetic:
CI: PARKINSON’S DISEASE
CI: LONG QT
CI: EPILEPS
Based on the following, give 3 SEs from use of Haloperidol as an anti-emetic:
CI: PARKINSON’S DISEASE
CI: LONG QT
CI: EPILEPSY
SE: sedation, extrapyramidal SES, lower seizure threshold, prolonged QT
Levomepromazine is a broad spectrum antiemetic (acts on D2, H1, M,5TH2/3R…) , suggest 2 CIs and 2SEs
CI: PARKINSON’S DISEASE
CI: LONG QT
CI: EPILEPSY
SE: sedation, extrapyramidal SEs, lower seizure threshold, prolonged QT
Ondansetron acts on what receptor and works best for what kind of nausea? give 1 CI:
-5HT3
-Chemo related
CI: CONSTIPATION
CI: LONG QT
Suggest 4 medications or classes that may cause/contribute to constipation:
- opioids
- diuretics
- antimuscarinics e.g. TCAs
- ondansetron
- ocreotide
- ferrous sulphate
What classes of laxatives require pt to drink a lot of water? give an example of this class
-osmotic laxatives e.g. laxido/Movicol
How do stimulant laxatives work? Give 2 e.gs of this class. And 1 SE
- stimulate peristalsis
- transformed by bacteria in colon to active derivatives
- SE: can cause cramps
- e.g. Senna, Bisacodyl
Docusate reduces surface tension of stool, so improves water penetration, what class is it? 1 SE
- Surfactant laxative (stool softener)
- SE: cramps, diarrhoea
Osmotic Laxatives are not absorbed by the gut, how do they act, give 1 e.g, a non-constipation related use and a SE
- they retain water in the gut by osmosis
- the stool is softer and extra vol stimulates peristalsis
- lactulose, macrogol
- use: liver failure (reduces NH3)
- -SE: abdo distention, cramps, flatulence, nausea
What rouge class of laxatives are used for laxative refractory opioid induced constipation (mainly in pall. care)
-peripheral opioid antagonists e.g. methylnaltrexone (SC) or naloxagol (oral)
Bran powder and Ispaghula are examples of what class of laxative?
give 1 risk if not with enough water
and 2 SEs
- Bulk forming laxatives
- risk of obstruction
- SE: bloating and flatulence
PR intervention is used to treat what type of constipation?
- what are the main 2 modes of intervention
- what action can they have?
- for faecal impaction
- suppository e.g. glycerin/bisacodyl or enema e.g. phosphate
- can be softener/stimulant/(lubricant)
Name a medication that is used to symptomatically treat diarrhoea (e.g. in context of IBS/gastroenteritis), what class of drugs is used, that act how?
- loperamide
- codeine phosphate (+provides analgesia at same time)
- these are opiods
- agonist of mu receptors in gut, slows transit, increases anal tone
The opioid Loperamide doesn’t penetrate the CNS, it is an agonist of mu receptors in the gut, name 2 SEs based on it’s MOA in treating diarrhoea
-GI effects of constipation, abdominal cramping and flatulence
Loperamide is an antimotility opioid drug used to treat diarrhoea, when should it’s use be avoided? Suggest 2
Clue: inhibition of peristalsis increases risks of complications in these cases
- in acute ulcerative colitis (increased risk of megacolon/perforation)
- in c. diff colitis
- in dysentery (bloody diarrhoea) may signify bacterial infection e.g. E.coli
Loperamide is an antimotility opioid drug used to treat diarrhoea, why is it avoided:
-in dysentery (bloody diarrhoea) which may signify bacterial infection
What is the risk? And which bacterial infection is this most likely to occur in?
- Certain strands of E.coli (O157:H7) can cause Haemolytic Uremic Syndrome (HUS)
- Antimotility drugs increases the risk of HUS
Why would you hesitate to prescribe an antimotility drug (e.g. Loperamide) in a pt that develops diarrhoea while in hospital (pt may be frustrated they can’t get a medication they would be able to buy from chemist at home)
- because of the risks of inhibiting peristalsis in c.diff colitis context
- first wait until aetiology clearer (e.g. w PCR/c.diff toxin test)
Suggest 2 SEs of the anti-motility agent loperamide.
NB: this opiod angonist has no penetrance into CNS, acts only in gut
- constipation
- abdominal cramping
- flatulence
What are the 2 situations Loperamide anti-diarrhoeal use should be avoided due to the inhibition of peristalsis increasing risks of complications?
- in acute UC (increased risk of megacolon and perforation)
- in C. diff colitis
