IC5 Supportive and Palliative Care (Cancer therapy side effects) Flashcards
What is the most bothersome side effects of chemotherapy?
N&V
What are the 2 types of emesis pathways?
- Central pathway – CNS – predominantly delayed phase of CINV
- Chemotherapy triggers the vomiting centre (area postrema) in the medullae (brainstem) → send signals via the vagus nerve → releases substance P at the synapse which binds to and agonises NK1 receptors → inducing N&V
- Peripheral pathway – Gut – predominantly acute phase of CINV
- Chemotherapy triggers enterochromaffin cell of the GIT → releases serotonin which binds to and agonises the 5-HT3 receptors on the vagal afferent → inducing N&V
What are the types of CINV?
- Acute
- Usually starts within 1-2 hours after administration
- Peak intensity within 5-6 hours, resolution at 12-24 hours
- Delayed
- Peak onset 48-72 hours after chemotherapy, diminishing after 1-3 days
- Occurs in 50-90% (highly emetogenic regimens), 35-08% (moderately emetogenic regimens) of patients
- Breakthrough
- N&V occurring despite preventive therapy
- Anticipatory CINV
- fear for chemotherapy, when dr say that u need to go for chemo then they will have nausea and vomiting
- Conditioned response
- Associated with uncontrolled emesis prior chemotherapy
- Refractory CINV
- N&V occurring during subsequent cycles of chemotherapy when antiemetic prophylaxis or rescue therapy has failed in previous cycles
- time where u have to use agents that have less evidence in guidelines
What are the steps to take to manage CINV?
Step 1: Assess Emetic Risk Groups – IV drugs
Step 2: Assess Patient Risk Factors for CINV
Step 3: Select anti-emetic combination(s)
What is the percentage ranges for the different levels of emetogenic risk of the IV cancer drugs?
High emetic risk (91-100%)
Moderate emetic risk (31-90%)
Low emetic risk (10-30%)
What are some IV chemotherapy that have high emetogenic risk?
High emetic risk (91-100%)
- AC combination → chemo that contains anthracycline and cyclophosphamide
- Anthracycline e.g. doxorubicin and epirubicin
- cisplatin, carmustine
What are some IV chemotherapy that have moderate emetogenic risk?
Moderate emetic risk (31-90%)
- Daunorubicin
- carboplatin AUC<4
- Daunorubicin
What are some IV chemotherapy that have low emetogenic risk?
Low emetic risk (10-30%)
- 5-FU
- paclitaxel
What is the percentage ranges for the different levels of emeetogenic risk for Oral chemotherapy?
Minimal-low: 1-30%
Moderate-high: 31-100%
What are the risk factors for CINV?
Patient-related risk factors
- Younger age (<50 years old)
- Female gender
- History of low prior chronic alcohol intake (<1 glass of alcohol/day)
- History of previous chemotherapy induced emesis
- History of motion sickness
- History of emesis during past pregnancy
- Anxiety
What are the anti-emetic combinations for the different levels of emetogenic risks?
High emetogenic risk
- Acute antiemetics (Day 1): NK1, 5HT3, DEXA +/- Olanzapine
- Delayed antiemetics (Day 2 onwards): DEXA D2-4, Olanzapine D2-4 (if it was used)
Moderate emetogenic risk
- Acute antiemetic (Day 1): 5HT3, DEXA
- Delayed antiemetics (Day 2 onwards): DEXA D2-3
Low emetogenic risk
- Acute antiemetic (Day 1): 5HT3 or DEXA or DOPA
Minimal emetogenic risk
- NIL
What arethe anti-emetic medications present?
NK1 antagonist:
Aprepitant (Emend®)
PO 125mg OD Day 1, 80mg OD Day 2, Day 3
5HT3 antagonist:
IV/PO Ondansetron 8-16mg OD Day 1
IV/PO Granisetron 1mg OD Day 1
Combination NK1 + 5HT3 antagonist
Netupitant 300mg + Palonosetron 0.5mg (Akynzeo®)
PO 1 capsule OD Day 1
Dexamethasone
IV/PO 12mg OD Day 1, IV/PO 8mg OD Day 2 onwards
Dopamine antagonist
IV/ PO Metoclopramide 10mg OD-TDS
What is the place of therapy for Neurokinin-1 (NK1) antagonists?
What is the MOA?
What is the dosing?
What are the ADRs?
What are the DDIs?
Neurokinin-1 (NK-1) antagonists
- Strongest we have in the market to prevent CINV
Place in therapy:
- Prevents acute and delayed CINV
Mechanism of action (MOA):
- Binds to NK-1 receptors, which prevents substance P (nociceptive neurotransmitter) from binding.
- Attenuates/reduces vagal afferent signals and exert antiemetic effect
Dosing:
- Aprepitant (Emend®) 125 mg PO day 1, 80 mg PO days 2-3
- Netupitant 300mg (in combination with 5HT3 antagonist Palonosetron 0.5mg) (Akynzeo® 4-5 yrs ago) PO day 1
Common adverse effects:
- Low frequency of fatigue, weakness, nausea, hiccups
Drug Interactions:
- Steroids
- Warfarin
- Benzodiazepines (increase benzodiazepine concentrations due to reduced metabolism)
- Certain chemotherapy eg Ifosfamide (decreases metabolism of ifosfamide)
- Need to consider risk and benefits
What is the place of therapy for 5-HT3 (Serotonin) antagonists?
What is the MOA?
What is the dosing?
What are the ADRs?
What are the DDIs?
Serotonin (5HT-3) Antagonists
Place in therapy:
- Prevents acute CINV
MOA:
- Block 5HT-3 receptors peripherally in the gastrointestinal tract and centrally in the medulla
Examples:
- IV/PO Ondansetron
- IV/PO Granisetron (longer acting that ondansetron, but cost $$$ more)
- IV/PO Palonosetron (PO form available in combination with NK-1 antagonist Netupitant given on Day 1 of chemotherapy)
Dosing
- IV/PO Ondansetron 8-16mg OD Day 1, IV/PO Ondansetron 8mg BD Day 2 onwards (max 16mg/dose)
- IV/PO Granisetron 1mg OD Day 1, IV/PO Granisetron 1mg OM Day 2 onwards
Adverse events: Headache and constipation - occurring in 15% of patients. May cause QTc prolongation (black box warning)
- Cancer patients very scared cannot pass motion, so pharmacist will selectively not counsel on constipation, because they won’t take and if they don’t take they will vomit, unless they ask or if it’s great importance
- Consider if on meds that cause high risk of QTc prolongation e.g. fluoroquinolones, haloperidol, phenothiazines, SSRIs, TCA
What is the place of therapy for dexamethasone?
What is the MOA?
What is the dosing?
What are the ADRs?
What are the DDIs?
Dexamethasone
Place in therapy:
- Prevents acute and delayed CINV
MOA:
- Unknown
- May be partially due to its activity in the central nervous system
Dosing:
- IV/PO 12mg OD D1, IV/PO 8mg OD D2 onwards for highly emetogenic regimens
Adverse Effects
- Most common – transient elevations in glucose, insomnia, anxiety, and gastric upset
- Will counsel to take the night dose earlier
- Less common – psychosis, or reactivation of ulcers
- Psychosis is common especially amongst young patients, when they take they will become hyper and cranky then give parents a lot of problems
- Cause ulcers so should take after or with food
- If see that patients have previous gastric issues, it’s not wrong to give omeprazole (take before food) as gastric protection together with the steroids
What is the place of therapy for olanzapine?
What is the MOA?
What is the dosing?
What are the ADRs?
What are the DDIs?
Olanzapine (Atypical Antipsychotic)
Place in therapy: Prevents acute and delayed CINV
MOA
- Antagonist of multiple receptors involved in CINV
- Dopamine, Serotonin (5HT3), Histamine, Cholinergic
Dose: 5mg – 10mg OD , consider lower doses (2.5mg OD) for elderly
Adverse effects
- Fatigue, sedation, postural hypotension, anticholinergic side effects
- Don’t feel much since the dose is low
- Some older consultant don’t use olanzapine much since this drug came in in 2017 guidelines
- Impt to look at risk factors and risk of chemotherapy and then balance to make the best choice
What is the place of therapy for dopamine antagonists (metoclopramide)?
What is the MOA?
What is the dosing?
What are the ADRs?
What are the DDIs?
Dopamine Antagonists (Metoclopramide)
Place in therapy:
- Prevents acute CINV in low emetogenic regimens
- Useful for breakthrough CINV
MOA:
- Blockade of dopamine receptors in the chemoreceptor trigger zone; stimulation of cholinergic activity in the gut, increasing (forward) gut motility; and antagonism of peripheral serotonin receptors in the intestines.
Dosing:
- PO/IV Metoclopramide 10mg TDS PRN
Adverse events:
- Mild sedation and diarrhea, extrapyramidal reactions (e.g., dystonia, akathisia)
- Avoid prescribing Metoclopramide with Olanzapine – increase risk of extrapyramidal reactions (tardive dyskinesias, neuroleptic malignant syndrome)
- Metoclopramide has more CNS effect so it’s not sold as P-only compared to domperidone
What types of benzodiazepines are used for CINV?
What is the place of therapy for benzodiazepines?
What is the MOA?
What is the dosing?
What are the ADRs?
What are the DDIs?
Benzodiazepines
- Choose not long acting ones e.g. lorazepam, alprazolam
Place in therapy:
- Useful for anticipatory CINV
MOA:
- Binds to benzodiazepine receptors on the postsynaptic GABA neuron to enhance inhibitory effect of GABA
- Leads to sedation, reduction in anxiety, and possibly depression of the vomiting centre
- Used for those who are anxious about chemo due to perception
Dosing:
- PO alprazolam 0.5-1mg/PO lorazepam 0.5-2mg on the night before treatment and then 1-2 hours before chemotherapy begins (take twice)
Adverse events
- Drowsiness, dizziness, hypotension, anterograde amnesia, paradoxical reactions (hyperactive, aggressive behaviour)
- Caution in elderly (risk of falls, prescribe lowest effective dose)
What types of adjunctive agents are used for CINV?
What is the place of therapy for adjunctive agents?
What is the MOA?
What is the dosing?
What are the ADRs?
What are the DDIs?
Adjunctive Agents
Place in therapy:
- Not efficacious to be used upfront anti-emetic for acute or delayed CINV
- May be considered in refractory CINV
- Butyrophenones (haloperidol)
MOA: Block dopamine receptors in the chemoreceptor trigger zone
Usual dose: PO/IV 0.5-2mg q4-q6hr
Adverse events: Sedation, extrapyramidal symptoms are also seen
- Phenothiazines (prochlorperazine, chlorpromazine [usually used for giddiness], promethazine [usually used for cough])
MOA: Block dopamine receptors in the chemoreceptor trigger zone
Dosing: Prochlorperazine PO 10mg TDS/QDS PRN
Adverse events: Drowsiness, hypotension, akathisia, and dystonia, extrapyramidal symptoms
How to manage breakthrough CINV?
Breakthrough CINV
- General principle is to give an additional agent from a different drug class
-Block different pathways that can affect patients wrt CINV
E.g. oral route can’t work then IV route - Choice of agent should be based on assessment of the current prevention strategies used
- Consider use of several agents utilizing different mechanism of actions if necessary
- If PO route not feasible due to ongoing vomiting, consider IV route
- Hydration and fluid repletion for losses (e.g. ORS, 100plus)
- Reassess next cycle’s antiemetics to ensure anti-emetic regimen (better than the last one) is appropriate
What are the non-pharm management for CINV?
Non-Pharmacologicals for CINV
- Take small, frequent meals. Avoid heavy meals.
- Avoid greasy, spicy, very sweet or salty food and food with strong flavors or smells.
- Sip small amounts of fluid often instead of trying to drink a full glass at one time. (because can cause them to vomit too)
- Avoid caffeinated beverages.
- Avoid lying flat for 2 hours after eating.