Nausea and Vomiting: Case Study

what are the causes of nausea and emesis?

- medications - commonly chemotherapy, SSRIs, D2RA's for parkinsons

- migranes

- stress and anxiety

- pregnancy, commonly 1st trimester

- infections - bacterial, meningitis, food, UTIs

- motion sickness

- medical conditions

- obstructions and drugs that decrease peristalsis

what are the complications of nausea and emesis?

- dehydration: concern for younger and older patients

- electrolyte imbalances - due to constant vomiting, decreases acid and Na

- malnutrition - concerning in children

- aspirational pneumonia - vomit could get into the lungs - that's why before surgery it is important to be nil by mouth

- oesophegal tear - by vomiting lots

what is the treatment approach to nausea and vomiting?

- cannot JUST give any anti-emetic, it is important to IDENTIFY THE CAUSE

- underlying cause of vomiting may be serious and may also be treat

therefore, important to consider:

- onset of symptoms

- precipitating factors

- current medical conditions

- medications

if an anti-emetic is indicated, the drug is chosen according to the aetiology (cause) of the vomiting

what is motion sickness?

disagreement between visual perceived movement and movement detected by the vestibular system

prevention is better than the cure

what antiemetics do not have activity against motion sickness?

- domperidone - works centrally

- metoclopramide

- 5HT3 receptor antagonists

- NK1 receptor antagonists

- phenothiazines

what are the types of drugs that are treatment options for motion sickness? and the names?

anti-cholinergic drugs and anti histamines - drowsy only (that cross the BBB) effectively prevent and treat

- hyoscine most commonly used

- promethazine

- cyclizine

- cinnarizine (antihistamine)

what is the chemical structure considerations of hyoscine?

- hyoscine is a natural product

- there are two structures, hydrobromide and butylbromide

- butylbromide is a salt, therefore doesn't cross BBB, so not used for motion sickness

- however hydrobromide is used, in the mcg range

how do anticholinergic drugs work?

acetylcholine receptors (nicotinic and muscarinic) are blocked which prevents muscarinic neurotransmission

what are the side effects of anticholinergic drugs?

- drowsiness

- blurred vision

- dry mouth

- constipation

- urinary retention

these occur quickly

what are the long term side effects generally associated with anticholinergic drugs?

- it effects acetylcholine - which is important for memory

- therefore can cause dementia risk

- dementia drugs increase acetylcholine transmission

this risk is not really associated with hyoscine

what are the different types of CINV?

- acute - within 24hr

- delayed - 2-5 days after treatment

- anticipatory - body links feeling sick from chemotherapy to sights and smells

what are the factors affecting CINV?

- type of chemotherapy regimen

- patient based factors

- genotypic factors

- different agents have different risks of emesis

what are the indications of metoclopramide?

GORD, CINV, diabetic gastroparesis

what are the main risks of a high dose of metoclopramide?

D2RA's in large doses can cause extrapyramidal disorders

- akathisia - drug induced movement disorder (inability to stay still)

- tremor - pell-rolling, shaking or trembling movements

- dystonia - painful muscle spasms

- tardive dyskinesia - involuntary jaw movement, it is irreversable

largest risk in adults over 18

what are the drugs used for CINV? what is their class?

- ondansetron and palonosetron (SSRAs) selective seretonin receptor antagonists

- aprepitant (NK1 receptor antagonist)

- dexamethasone (corticosteroid)

- metoclopramide (D2RA)

these are usually prescribed in combinations to target different places of N&E pathways

some are given when inpatient, and some for afterwards

what are the pharmacogenetic considerations of Ondansetron?

- CYP which metabolises Ondansetron works different person to person, so some metabolise it well and some don't

- for those with lazy CYP2D6, ondansetron works well as it sticks around

what are the risk factors of PONV?

- female sex

- non smoking status

- use of post-operative opiods

- previous history of PONV or motion sickness

what are the complications of PONV?

- increased hospital stay

- stress on surgical closure (stitches)

- aspirational pneumonitis

what is the management framework of PONV? why is this in place? how does it link to risk factors?

1. zero risk factors - debatable, some recommend giving 1-2 antiemetics

2. one or two risk factors - give 2 antiemetics in combination

3. more than two risk factors - give 3 or 4 antiemetics in combination

what are examples of medicine classes that can be taken for PONV?

5HT3 antagonists, antihistamines, corticosteroids, anticholinergics, NK1 receptor antagonists, D2 receptor antagonists

what is palliative care?

specialized medical care that focuses on providing relief from pain and other symptoms of a serious illness

what are causes of nausea and vomiting in palliative care? what drug class are usually used to treat each?

- chemicals (drugs) - D2 antiemetics

- gastric stasis - (metoclopramide) D2 and prokinetics

- bowel obstruction - D2 antagonist

- raised intracranial pressure - antimuscarinic

- psychological factors - anxiety relief drug

- unknown cause - D2RA BUT ONLY IN PALLIATIVE CARE

usually absorbed poorly by the oral route