High risk drugs Flashcards
What is the target plasma concentration of phenytoin?
10-20mg/L
(or 40-80micromol/L)
What are the signs of toxicity with phenytoin overdose?
Nystagmus, dipoplia, slurred speech, confusion, hyperglycaemia
What are cautions associated with phenytoin?
Enteral feeds - interrupt feed for 2 hours before and after dose.
HLA allele - presence of allele can increase risk of SJS
Which side-effect is a sign to discontinue phenytoin?
A rash developing. Reintroduce phenytoin cautiously if rash was mild (Measles-like), but discontinue immediately if there is reccurent rash.
What are the signs and symptoms of SJS?
headache, joint pain and cough can precede the rash.
rash looks like a target - dark/purple centre, surrounded by lighter area
blistering and peeling skin
(FYI: SJS is also commonly called toxic epidermal necrolysis)
What is the target plasma concentration of carbamazepine?
4-12mg/L measured after 1-2 weeks
What symptoms should patients be advised to look out for when on carbamazepine?
fever, rash, mouth ulcers, bruising, or bleeding develop - seek immediate medical attention
Blurred, yellow vision is a sign of toxicity with which drug?
Digoxin
What is the target plasma concentrations of theophylline and when do you measure it?
10-20mg/L - achieves satisfactory bronchodilation.
Measure 5 days after starting oral treatment, and at least 3 days after dose adjustments.
Collect blood sample 4-6 hours after oral dose of MR tablets (only form available)
What signs and symptoms occur in theophylline toxicity?
Vomiting (severe and intractable), dilated pupils, sinus tachycardia, hyperglycaemia.
Convulsions, arrythmias (severe hypokalaemia) and haematemesis - in severe overdoses
What sorts of thing decrease plasma-theophylline concentrations?
Smoking
Alcohol consuption
How do you perform TDM for lithium?
What are the general target levels?
plasma-conc should be measured 12 hours post-dose.
Target = 0.4-1mmol/L (lower end of the range should be achieved for maintenance and elderly)
What is the higher target of lithium that is sometimes required? When should it be used?
target 0.8–1 mmol/litre - for patients who have relapsed or have acute episodes of mania
[SPC states 0.8-1.2mmol/L; should never exceed 1.5mmol/L]
Which chemotherapy drugs are most associated with oral mucositis?
Methotrexate
Fuorouracil
Anthracyclines
Which cytotoxics are NOT associated with bone marrow suppression?
Vincristine
Bleomycin
Which chemotherapy agents are highly emetogenic ? (name 3 drugs)
cisplatin
dacarbazine
cyclophosphamide
Which 3 medications are used for prevention of acute N&V in patients at high risk of emesis?
dexamethasone + aprepitant + 5HT3-receptor antagonist (ondansetron)
Name examples of anthracyclines?
daunorubicin
doxorubicin
epirubicin
idarubicin
Which cytotoxics are most associated with cardiotoxic effects?
Anthracyclines - dose-related, cumulative, and potentially life-threatening cardiotoxic side-effects
What colour do the anthracyclines (e.g. doxorubicin, idarubicin) change urine to?
Pink or red for upto 48 hours after treatment
What are key interactions of methotrexate?
All PPIs - decrease clearance of mtx
Trimethoprim - increase risk of haematological s/e
Penicillin antibiotics - increase the risk of toxicity
Live vaccines - increased risk of infections
Which medications can affect the release of mesalazine GR or MR tablets?
medications which lower the stool pH e.g. lactulose
This prevents the release of mesalazine
Which electrolyte imbalances increases the risk of digoxin toxicity?
hypokalaemia
hypomagneseamia
hypercalcaemia
What are target serum digoxin levels?
0.7-2nanograms/mL
What levels indicate high chance of digoxin toxicity if patient also presents with symptoms?
Which levels indicate definite toxicity?
1.5-3ng/ml - high likelihood of toxicity
great than 3ng/ml - definite toxicity
Advice for methotrexate missed doses?
1-2 days since missed dose - take ASAP
more than 3 days since missed dose - skip dose
What are the baseline monitoring requirments for amiodarone?
Which tests need to repeated and how frequently?
Chest X-ray (prior to starting)
LFTs and TFTs (prior and 6 monthly)
Electrolytes (especially potassium prior to starting)
eye tests
What adjustments may need to be made to warfarin during COVID infection?
Reduced doses (monitor INR)
Acute illness can exaggerate effects of warfarin.
What side-effects can amiodarone cause (list 4)
Corneal microdeposits
Impaired thyroid function
Hepatotoxicity
Pulmonary toxicity
