Ebm Flashcards
How does grapefruit interact with amlodipine
Grapefruit increase hypotension
How does grapefruit interact with statins
Grapefruit increases muscle pain
How does excessive leafy green vegetables interact with warfarin
Excessive leafy green vegetables decrease INR
How does St John worts interact with contraceptives
St John worts increases metabolism of COC
Pharmacodynamic Interactions can be antagonist or synergistic
Which is the interaction between levodopa and risperidone
Antagonist
Pharmacodynamic Interactions can be antagonist or synergistic
Which is the interaction between propanolol and salbutamol
Antagonistic
Pharmacodynamic Interactions can be antagonist or synergistic
Which is the interaction between warfarin and DOACs
Synergistic
Pharmacodynamic Interactions can be antagonist or synergistic
Which is the interaction between anticoagulants and NSAIDs
Synergistic
Pharmacodynamic Interactions can be antagonist or synergistic
Which is the interaction between NSAIDs and Antiplatelet
Synergistic
Pharmacodynamic Interactions can be antagonist or synergistic
Which is the interaction between opioids and benzodiazepines
Synergistic
Respiratory depression
Describe the interaction between Ciprofloxacin and calcium supplements
And can you fix it
It is a pharmacokinetic interaction affecting absorption
It causes chelation
A 2 hour gap should be kept
Describe the interaction between phenytoin and albumin
It is a pharmacokinetic interaction affecting distribution
Phenytoin is protein bound so if a patient has hypoalbuminaemia, there’s more free drug resulting in toxicity
Can result in CKD, malnutrition, nephrotoxic syndrome
Describe an pharmacokinetic interaction that affects metabolism
Enzyme inducers and enzyme inhibitors
Give an example of an cyp2c9 inhibitor
Miconazole
What is sulphonylureas
Inducer or inhibitor?
CYP3A4 inducer
What is smoking
Inducer or inhibitor?
CYP3A4 inducer
What is carbamazepine
Inducer or inhibitor?
CYP3A4 inducer
What is rifampicin
Inducer or inhibitor?
CYP3A4 inducer
What is alcohol
Inducer or inhibitor?
CYP3A4 inducer
What is phenytoin
Inducer or inhibitor?
CYP3A4 inducer
What is Griseofulvin
Inducer or inhibitor?
CYP3A4 inducer
What is phenobarbital
Inducer or inhibitor?
CYP3A4 enzyme inducer
What is cimetidine
Inducer or inhibitor?
CYP3A4 inhibitors
What is Azoles
Inducer or inhibitor?
CYP3A4 inhibitors
What is antibiotics
Inducer or inhibitor?
CYP3A4 inhibitors
What is grapefruit
Inducer or inhibitor?
CYP3A4 inhibitors
What is omeprazole
Inducer or inhibitor?
CYP3A4 inhibitors
What is sodium Valporate
Inducer or inhibitor?
CYP3A4 inhibitors
Name a pharmacokinetic interaction that affecting elimination
Digoxin and verapamil
What are 5 ways in which drug interactions can be managed
- Switch one of the potentially interacting drugs
- Minimise the interaction by leaving 2-3 hours between the drugs
- Alter the dose of one of the drugs
- Increase monitoring
- Mitigate the risks e.g. providing GI Protection
DOACs are high risk drugs, what is their MOA
Direct selective reversible inhibitor of factor xa
DOACs are high risk drugs, which DOAC has side effects of a headache
Rivaroxaban
What are the 4 side effects associated with all DOACs
Anaemia
Haemorrhage
Nausea
Skin reactions
What are the contraindications of DOACs
A
A
H
R
G
R
Active bleeding
Anti-phospholipid syndrome
High risk malignancies
Recent brain and spine injury
GI ulcers
Recent surgeries
What is the MHRA warning for DOACs
Recognise signs and symptoms of bleeding
- bruising
- blood in stools or vomit
-Prolonged bleeding
-Gingival bleeding - coffee ground vomit
- Heavier menstrual cycle
Who must you never give DOACs to
People with antiphospholipid syndrome
Describe the diagnosis and treatment of VTE
- Look at the wells score, if 2 points or more than DVT is likely
- A proximal leg vein ultrasound should be done within 4 hours
> positive= DVT = start anticoagulant
> negative = do d-dimer test - If d-dimer test is positive = start anticoagulant
Describe the diagnosis and treatment of pulmonary embolism
- If wells score is more than 4
- Send patient to CT pulmonary angiogram, give interim anticoagulant while waiting
- If CTPA positive = diagnose PE
If CTPA negative = do proximal leg vein ultrasounds
When giving warfarin what must you do
Bridge with low molecular weight heparin
If a patient requires a DOAC but is renally impaired or has cancer, what would be appropriate
Apixaban
Rivaroxaban
For 5 days
What are the key interactions of DOACs
DOACs metabolised by CYP3A4 enzyme and transported by p-gp so inhibitors increase bleeding risk and inducers decrease conc of DOACs
Other anticoagulants
NSAIDs
SSRI, SNRI
Which NSAIDS have the greatest GI risk
THINK PKK
piroxicam, ketoprofen, ketoraolac
Which NSAIDS have an intermediate GI risk
There’s 4
indometacin
diclofenac
naproxen
high dose ibuprofen 2.4g od
How do you decrease the GI risk of NSAIDs
Taking one NSAID at a time
Do not use it in combination with aspirin or alcohol
Use selective COX 2 inhibitors
Which NSAIDS have the highest risk of heart attack and stroke
COX 2 inhibitors
Which NSAID is neutral and so has a lower thrombotic risk
Naproxen
Does low dose ibuprofen(1.2g or less daily) increase the risk of myocardial infarction
No, it does not increase MI risk
What is MHRA warning of NSAIDS
Not suitable for pregnancy after 20 weeks due to oligohydramnios and constriction of ductus arteriosus
What are the key interactions of NSAIDs
A
A
A
D
M
L
C
S
C
Anticoagulant
Alcohol
ACEi, ARBs
Diuretics
Methotrexate
Lithium
Corticosteroids
SSRIs
Cyclosporin
Chemotherapy agents are described as narrow therapeutic drugs. What does this mean
little difference between therapeutic dose and toxicity
What are the common side effects of chemotherapy agents
E
O
T
H
B
A
Extravasation of IV drugs
Oral mucositis
Tumour lysis syndrome
Hyperuricaemia
Bone marrow suppression
Alopecia
How do you prevent oral mucositis caused by fluorouracil, methotrexate and anthracyclines
Good oral hygiene
Sucking on ice chips
How do you prevent hyperuricaemia caused by chemotherapy
Give allopurinol or rasburicase
What are the key interactions of chemotherapy
Live vaccines e.g. nasal flu vaccine, typhoid, BCG, Varicella
Increased anticoagulant effect e.g. DOACs
CYP450 inducers and inhibitors
What are the MHRA warnings for Vinca Alkaloids
Should not be given via IV
What MHRA warning is associated with Doxorubicin
Formulations are not bioequivalent and can be fatal
What are the red flag symptoms associated with methotrexate
Sore throat
Rash
—> leukopenia, thrombocytopenia, increased infection risk
What is MHRA warning and advise associated with methotrexate
Patients should be advised to take it ONCE WEEKLY, not daily
Photosensitivity
Avoid exposure to UV light at 11am-3om
Use SPF 50 and wear protective clothing
Blood count and bone marrow suppression is a caution for methotrexate, what are the risk factors for this
How do you handle this caution
Risk factors are advanced age, renal impairment, using trimethoprim
Methotrexate should be withdrawn if WBC or platelet count is reduced significantly
GI toxicity is a caution for methotrexate, what are the risk factors for this
How do you handle this caution
Risk factors are stomatitis and diarrhoea
Withdrawal treatment
Photosensitivity is a caution for methotrexate, what are the risk factors for this
Those with psoriasis as it can worsen
Liver toxicity is a caution for methotrexate, what are the risk factors for this
How do you treat/prevent this
Risk factor = those with liver cirrhosis
Do LFT before starting to make sure liver function is normal
Pulmonary toxicity is a caution for methotrexate, what are the risk factors for this
How do you treat/prevent this
Risk factors = special concern in those with RA
Do X Rays and monitor for dyspnoea, cough, fever
Discontinue if pneumonia is suspected
What are the key interactions for methotrexate
N
A
T
L
NSAIDs
Antibiotics
Trimethoprim
Live vaccines
What are the common side effects of Valporate [4]
Nausea
Weight gain
Drowsiness
Hair loss
What are the 3 severe side effects associated with Valporate
Liver toxicity
Pancreatitis
Thrombocytopenia
What is the management of side effects caused by Valporate
Gradual withdrawal
What is MHRA warning and advice for sodium Valporate
Teratogenic and thrombocytenia
Advise
- men should use condoms even 3 months after treatment cessation
- sore throat is a side of thrombocytenia
- must given in its original packet
- not given to men under 55
- appropriate contraceptives = IUD, Depoprovera
- no sperm donation
- abrupt withdrawal —> status epilepticus
What monitoring is done for a patient on Valporate
LFT = at start and 6 months
FBC = Pre treatment and pre surgery
3 contradictions for Valporate
A
S
M
Acute porphyria
Severe hepatic dysfunction
Mitochondrial disorders
5 interactions with Valporate
Carbamazepine, phenytoin = enzyme inducers so reduce conc of Valporate
Increased exposure of lamotrigene
Alcohol and LMWH = increased hepatotoxicity
