Drug Interactions Flashcards
carbazepaine and contraceptives?
carbamezapine reduces contraceptive efficacy
levonogestrel and antiepiletics?
reduces seizure threshold
ssris reduce or increase inr?
increase
ssris and doacs?
Selective serotonin reuptake inhibitors (SSRIs) and direct oral anticoagulants (DOACs) can increase the risk of major bleeding, especially in the first month of taking both medications.
ssri and nsaids?
increase risk of bleeding
warfarin and nsaids
increase risk of bleeding
St John’s Wart and ssri
serotonin syndrome
St John’s Wart and warfarin
St John’s wort decreases the anticoagulant effect of Warfarin. Manufacturer advises avoid.
st johns wart and doac
St John’s wort is predicted to decrease the exposure to Apixaban.
enteral feeding and warfarin?
contains vit k - decreases inr
cranberry juice and warfarin?
Cranberry juice.
- Enhances anticoagulant effect. Avoid.
meropenem and sodium valproate
meropenem and sodium valproate reduces sodium valproate by 60-100%
iron tablets levo ?
4hours apart. Also iron tablets with any other medications ie antibiotics like doxy are usually avoided together as it reduces absoprtion of the antibiotic
ssri and triptans?
HEALTHPATHWAYS SAYS : Can be safely used in combination with selective serotonin reuptake inhibitors (SSRIs) and serotonin and norepinephrine reuptake inhibitors (SNRIs), but still counsel about the symptoms of serotonin toxicity (e.g. agitation, muscle twitching or rigidity, sweating, diarrhoea) however this is exceedingly rare.
simvastatin important interactions. Do all these drug interactions apply for atorvastatin?
- clarithromycin and erythromycin - increases exposure to simvastatin
- colchicine - rhabdomyolsis
- deltaparin/fragmin and enoxiparin
- Diltiazem and verapmil
- all the conazoles (fungal)
yes. therefore if you have a man with gout flare up you HAVE TO TELL THEM TO STOP THEIR STATIN!
drug inducers?
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Carbamezapine
Rifampicin
Alcohol chronically
Phenytoin (affects Warfarin and Digoxin for this reason)
Grusefulvin
Phenobarbital
Smoking and St John’s wart
Enzyme inhibitors
S
I
C
K
F
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C
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C
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SICKFACES.COM INHIBIT ME
Sodium valproate
Isonazid
Ciprofloxacin
Ketaconazole
Fluconazole
Alcohol acutely and AMIODARONE
Chloramphenicol
Erythromcyin
Sulphonamides
Clarithromycin
Omeprazole
Metronidazole (for 48hr afterwards too)
Clopidogrel and omeprazole SHOULD NOT BE prescribed together why?
omeprazole reduces the effectivenesss of clopidogrel
(inhibitor)
patient on lithium but has HTN. What is the most appropriate medication to start?
Amlodipine
Ramipril
Losartan
Bendroflumethiazide
Doxazosin
amlodipine. ACE-I and ARBs cause lithium toxicity and are advised against.
warfarin interactions
Amiodarone
Antibiotics (e.g. azithromycin, cephalosporins, tetracyclines, tigecycline, trimethoprim)
Antibiotics (e.g. macrolides, METRONIDAZOLE (INCREASES INR), quinolones, sulfonamides)
Rifamycins
Antidepressants (e.g. SSRIS, venlafaxine, mirtazepine)
Antiepileptics (e.g.
carbamazepine, phenytoin, phenobarbitone)
Antifungals - imidazole (e.g. econazole, miconazole, ketoconazole)
Antifungals - triazole (e.g. fluconazole, itraconazole, (voriconazole)
Proton pump inhibitors (e.g. esomeprazole, omeprazole, pantoprazole)
Statins (e.g. fluvastatin, simvastatin, rosuvastatin)
Thyroid hormones (e.g. levothyroxine)
why SSRI + tramadol have risk of serotonin syndrome?
Tramadol is a synthetic opioid analgesic that binds weakly to opioid receptors. It’s structurally related to codeine and morphine, but is about 1/10th as potent as morphine. BUT ALSO….
It’s an SNRI
Tramadol inhibits the reuptake of serotonin and norepinephrine, which are neurotransmitters that regulate mood, sleep, memory, and more. Tramadol’s effects on these neurotransmitters are similar to other SNRIs, such as duloxetine and venlafaxine.
drugs that interact with digoxin
Amiodarone, quinidine, dronedarone (antiarrhythmics)
Verapamil, diltiazem (calcium channel blockers)
Erythromycin, clarithromycin (macrolide antibiotics)
Cyclosporine, tacrolimus (immunosuppressants)
Furosemide, hydrochlorothiazide (diuretics)
Ketoconazole (antifungal)
Metronidazole (antibiotic)
Ritonavir (HIV protease inhibitor)
Metformin and contrast
BNF “There is no need to stop metformin hydrochloride after contrast medium in patients missing only one meal or who have an eGFR greater than 60 mL/minute/1.73m2. If contrast medium is to be used, and eGFR is less than 60 mL/minute/1.73m2, metformin should be omitted on the day of the procedure and for the following 48 hours”
do you ever have to be careful prescribing vitamin D? and if so, with what medications?
generally no, but definitely with digoxin (^ toxicity risk as it can increase risk of hypercalcemia) and thiazides (which also increase risk of hypercalcemia)
