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Other pharmacy > Important Interactions > Flashcards

Important Interactions Flashcards

1
Q

Interaction - alpha blockers

A

Hypotensive effect on first dose, may be worth omitting other hypertensive drug for one day

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2
Q

Interaction - acetylcholinesterase inhibitors

A

Peptic ulceration with NSAIDs and corticosteroids.
Neuroleptic malignant syndrome with antipsychotics.
Bradycardia + heart block chance when with rate limiting medications such as beta blockers.

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3
Q

Interaction - activated charcoal

A

Reduces absorption of many drugs taken, this is partially also how it is effective in overdose poisoning

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4
Q

Interaction - aldosterone antagonists (spironalactone, eplerenone)

A

Increased risk of hyperkalemia with potassium elevating drugs such as ACE inhibitors and ARBs. Also not to be conbined with potassium supplements unless specialist advise.

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5
Q

Interaction - alginates and antacids

A

Can affect absorption of some drugs so to be taken 2 hours apart from ACE inhibitors, cephalosporins, tetracyclines, ciprofloxacin, bisphosphonates, digoxin, levothyroxine, PPIs.
It also increases alkalinity in urine, increasing excretion of aspirin and lithium.

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6
Q

Interaction - allopurinol

A

Can increase chance of hypersensitivity reactions with ACE inhibitors, thiazides or amoxicillin.
Should not be started during attack of gout as may worsen.

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7
Q

Interaction - aminoglycosides (gentamicin, neomycin)

A

Ototoxicity (toxicity in the ear) more likely when given with loop diuretic or vancomycin.
Nephrotoxicity more likely when given alongside ciclospirin, platinum chemotherapy, cephalosporins or vancomycin.

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8
Q

Interaction - aminosalicylates

A

Given with any gastric pH altering medication can cause it to be broken down prematurely or malabsorbed.

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9
Q

Interaction - amiodorone

A

Increases plasma concentrations of digoxin, diltiazem and verapamil. These drug doses would have to be halted to increase risk of bradycardia, AV block and HF.
A lot more interactions for this drug.

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10
Q

Interaction - ACE inhibitors

A

Increased risk hyperkalemia with other potassium elevating drugs.
First dose hypotension with diuretic.
Increased nephrotoxicity when given alongside an NSAID.

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11
Q

Interaction - ARBs (angiotensin receptor blockers)

A

Increased risk hyperkalemia with other potassium elevating drugs.
First dose hypotension with diuretic.
Increased nephrotoxicity when given alongside an NSAID.

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12
Q

Interaction - SSRIs

A

Serotonin syndrome may present when given alongside MAOIs or serotonergic drugs (such as tramadol).
Increased risk of gastro bleeding with aspirin or NSAIDs. Same with anticoagulants.
Avoided with other drugs that cause QT interval prolongation.m

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13
Q

What drugs prolong the QT interval?

A 
Domperidone
Antipsychotics
Quinine
SSRIs
Macrolides
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14
Q

Interaction - tricyclic antidepressants

A

Not to be given alongside MAOIs due to increase 5-HT, noradrenaline in the synapse leading to hypertension, serotonin syndrome and hyperthermia.

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15
Q

Interaction - metoclopramide

A

Increased extrapyramidal effects with antipsychotics.

Can antagonise the effects of dopaminergic treatment used in Parkinson’s disease, bringing back symptoms.

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16
Q

Interaction - domperidone

A

Can prolong QT interval so should be avoided with others.

Metabolised by cytochrome P450 so any inhibitors can cause increase in side effects.

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17
Q

Interaction - antifungal drugs

A

QT interval prolongation

Fluconazole inhibits cytochrome p450

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18
Q

Interaction - antiplatelet ADP-receptor antagonists (clopidgorel, ticagrelor)

A

Clopidgorel is pro drug that needs to be metabolised by cytochrome p450 before active, notably omeprazole can cause lower exposure so lansoprazole or pantoprazole should be used instead.
Increased risk of bleeding with other antiplatelet, anticoagulants or NSAIDs.

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19
Q

Interaction - aspirin

A

Increased risk of bleeding with antiplatelets and anticoagulants.
Can cause gastric irritation with NSAIDs or SSRIs

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20
Q

Interaction - azathioprine

A

Increased risk of infection when given with other immunosuppressive drugs such as corticosteroids.
Allopurinol is xanthine oxidase inhibitor so reduce azathioprine breakdown leading to toxicity.
Reduces effect of warfarin so adjustment may be needed.
Myelosupression may occur leading to leukopenia with other drugs that cause this such as trimethroprim

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21
Q

Interaction - beta blockers

A

Heart failure, bradycardia and asystole can occur when combined with non-dihydropyridine calcium channel blockers such as verapamil and diltiazem.
Reduce effect of Beta2 agonists, may make asthma worse

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22
Q

Interaction - Beta2 agonists

A

Hypokalemia risk when given with theophylline and corticosteroids.
Beta blockers reduce effectiveness.

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23
Q

Interaction - benzodiazapines

A

Sedating effect combination (alcohol, opiods)

Most eliminated by cytochrome p450

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24
Q

Interaction - bisphosphonates

A

Bind strongly to calcium so should be taken atleast 30 mins before milk or calcium supplements.
Reduced absorption with iron supplements and antacids also.

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25
Q

Interaction - calcium supplements

A

Reduced absorption when given with iron supplements, bisphosphonates, tetracyclines and levothyroxine.
IV administration not to be mixed with sodium bicarbonate as can cause precipitation.

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26
Q

Interaction - calcium channel blockers

A

Diltiazem and verapamil can cause heart failure, bradycardia and asystole when given with beta blockers

27
Q

Interaction - carbamazepine

A

Inducer of cytochrome p450 so reduces plasma concentrations of drugs metabolised by cytochrome p450.
Is also metabolised by cytochrome p450.
Interacts with other antiepileptic medication.
Drugs that reduce seizure threshold.

28
Q

Interaction - corticosteroids (systemic use)

A

Increase GI side effects with NSAIDs.
Hypokalemia risk with B2 agonists, theophylline, loop/thiazide diuretics.
Is metabolised by cytochrome p450 so inducers reduce efficacy.

29
Q

Interaction - digoxin

A

Plasma conc increased by amiodorone, calcium channel blockers, spironalactone and quinine leading to toxicity.
Loop/thiazide diuretics cause hypokalemia leading to toxicity of digoxin

30
Q

Interaction - dipetifylpeptidase-4 inhibitors

A

Increased risk of hypoglycemia when given with insulin, alcohol or sulphonylurea.
Efficacy reduced by drugs elevating blood glucose levels (prednisolone, loop/thiazide diuretics)

31
Q

Interaction - DOACs (direct oral anticoagulants)

A

Increased risk of bleeding with other antithrombotic agents.
Effect increased by cytochrome inhibitors and lowered by inducers

32
Q

Interaction - loop diuretics

A

Affects drug levels that are excreted by the kidney - notably lithium levels will rise.
Rise in digoxin toxicity by hypokalemia effect.
Increase effects of aminoglycosides

33
Q

Interaction - thiazide diuretics

A

Reduced effect by NSAIDs.

Avoid use with other potassium lowering drugs.

34
Q

Interaction - dopaminergic treatment in Parkinson’s (levodopa, ropinirole)

A

Antipsychotics and metoclopramide oppose the effects of dopamine so can reverse treatment, presenting Parkinson’s symptoms.

35
Q

Interaction - insulin

A

Hypoglycemia combined effects.

Use with corticosteroids may require higher amounts of insulin.

36
Q

Interaction - iron supplements

A

Effect absorption rates of levothyroxine and bisphosphonates so should be these two should be taken 2 hours before.

37
Q

Interaction - lamotrigine

A

This is metabolised by glucuronidation. So conc would be lowered by inducers, carbamazepine, phenytoin, oestrogens, rifampicin and protease inhibitors. Then heightened by inhibitors, valproate, causing toxicity. These may highlight pre-emptive dose changes before starting medication.

38
Q

Interaction - levetiractam

A

This has few interactions but is worth highlighting as many other antiepileptic drugs do. This makes it an ideal drug to be considered for multi drug therapy in epilepsy or where other drugs may be considered necessary.

39
Q

Interaction - macrolides

A

Inhibit cytochrome p450 (not azithromycin) - increasing drug concs of warfarin and statin.
Also prolonged QT interval so avoided in others that also do this - amiodorone, antipsychotics, quinine, quinolones, SSRIs.

40
Q

Interaction - Metformin

A

Needs to be witheld 48 hours before injecting IV contrast media which is used for CT scans and coronary angiography.

41
Q

Interaction - methotrexate

A

Increased risk of neutropenia when given with clozapine.
Toxicity more likely when given alongside renal function impairing drugs such as NSAIDs and penicillins.
Trimethroprim and phenytoin can increase risk of haematological abnormalities.

42
Q

Interaction - metronidazole

A

> Alcohol <
Increased risk of lithium toxicity.
Increased bleeding risk with warfarin.

43
Q

Interaction - nitrates (isosorbide, glyceryl trinitrate)

A

Not to be used with phosphodiesterase inhibitors (sildenafil) due to enhancing and prolonging the hypotensive effect.
Caution in use with hypertension treatment as hypotension may become prominent.

44
Q

Interaction - NSAIDs

A

Increased risk of GI bleeding with SSRIs, aspirin, steroids and anticoagulants.
Renal impairment risk with ACE inhibitors and diuretics.
NSAIDs also reduce antihypertensive drug effect.

45
Q

Interaction - eye drops

A

Must be taken atleast 5 minutes apart

Lubricants taken used last.

46
Q

Interaction - oestrogens+progesterones

A

Lamotragine absorption reduced, lowering seizure control.

Metabolised by cytochrome p450, so inducers reduce efficacy - rifampicin, carbamazepine.

47
Q

Interaction - tramadol

A

Lower seizure threshold, avoid use with other drugs that do the same (antipsychotics).
Increase risk of serotonin syndrome - SSRIs, MAOIs, tricyclic antidepressants.

48
Q

Interaction - penicillins

A

Reduced renal excretion of methotrexate leading to toxicity.

Some kill off flora bacteria that produce vitamin K so may result in warfarin effect increase.

49
Q

Interaction - phosphodiesterase inhibitors (sildenafil)

A

Not to be used with drugs that increase nitric oxide concentrations, nitrates, nicorandil, as can cause arterial vasodilation and cardiovascular collapse.
Alpha blockers should be taken atleast 4 hours apart due increased chance of hypotension.
Metabolised by cytochrome p450 so inhibitors increase adverse side effects - amiodorone, diltiazem, fluconazole.

50
Q

Interaction - omeprazole

A

Decreases activation of clopidgorel, reducing the antiplatelet effect. Advise to switch to lansoprazole or pantoprazole as evidence suggests safer

51
Q

Interaction - quinine

A

Prolonged QT interval - amiodorone, antipsychotics, quinolones, macrolides, SSRIs

52
Q

Interaction - quinolones

A

Quinolones shouldn’t be taken at same time as antacids or calcium to reduced absorption.
Prolonged QT interval - amiodorone, antipsychotics, quinine, macrolides, SSRIs.
NSAIDs increase seizure risk.
Prednisolone increase tendon rupture risk.

53
Q

Interaction - serotonin 5-HT1-receptor agonists (triptans)

A

Increase risk of serotonin syndrome with other serotonergic drugs - tramadol, SSRIs, tricyclic antidepressants

54
Q

Interaction - tamoxifen

A

Inhibits cytochrome p450 enzyme which metabolises warfarin, leading to increased risk of bleeding.
Fluoxetine and paroxetine inhibit hepatic activation of tamoxifen.

55
Q

Interaction - statins

A

Metabolised by cytochrome p450, inhibitors - amiodorone, diltiazem, itraconazole, macrolides and protease inhibitors can lead to myopathy. Reduce dose required or stop if short course such as clarithromycin.
Amlodipine can also have this effect.

56
Q

Interaction - tetracyclines

A

Not be taken within 2 hours of iron, calcium or antacids due to reduced absorption.
Kill off gut flora that produce vitamin K so enhance warfarin anticoagulant effect.

57
Q

Interaction - levothyroxine

A

Not be taken within 4 hours if calcium, iron or antacids as reduces the absorption.
Levothyroxine induced changes in metabolism can result in required changes to insulin regimens or doses of warfarin.

58
Q

Interaction - trimethroprim

A

Use with aldosterone antagonists, ACE inhibitors and ARBs increase risk of hyperkalemia.
Other drugs that interact with folate metabolism/antagonists such as methotrexate and phenytoin can lead to adverse haematological effects.
Can effect the normal vitamin K producing gut flora, increasing effect of warfarin

59
Q

Interaction - valproate

A

Lamotragine - increased plasma concentration due to valproate inhibiting hepatic enzymes.
Valproate is metabolised by cytochrome p450, conc increased by inhibitors - macrolides, protease inhibitors - and conc decreased, increasing risk of seizures by inducers - carbamazepine.
Carbapenems also decrease valproate conc by an unknown mechanism.

60
Q

Interaction - vitamins

A

Usually oppose mechanisms of drugs when they involve the vitamins such as warfarin and vitamin K

61
Q

Interaction - warfarin

A

Antibiotics decreasing natural flora that produce vitamin K, resulting in higher anticoagulant effect.
Cytochrome p450 inducers decrease warfarin conc - phenytoin, carbamazepine, rifampicin.
Cytochrome p450 inhibitors increase warfarin conc - fluconazole, macrolides
These all significantly effect the anticoagulant effect and can throw INR levels completely off

62
Q

Interaction - z drugs

A

Enhance some hypotensive effects.

Is metabolised by cytochrome p450

63
Q

Interaction - fluids

A

Be aware of which fluid being selected based on medications they are on
Glucose solution in a diabetic may require significant changes to insulin delivery requirements. However this may also be used therapeutically.
Potassium chloride solution fluids may be dangerous in potassium sparing drugs such as aldosterone antagonists, potassium sparing diuretics, ACE inhibitors, and ARBs

Other pharmacy (2 decks)

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