Drug interactions with LA Flashcards
How can practioners minimise the risk of drug interactions with LA?
- using an aspirating syringe; this reduces the likelihood of LA being administered directly into a blood vessel
- adhering to dosing recommendations in product literature
What are the most commonly used amide LAs for dental procedures?
- lidocaine
- prilocaine
- articaine
- mepivacaine
Where does evidence of potential interactions with LA dental preparations come from?
- they came from anecdotal case reports
When are the drug interactions with LA, reported by the BNF, thought to be relevant?
when LA/ vasoconstrictors are used at high doses for specific indications other than dental anaesthesia
State other clinical uses of lidocaine
- as treatment for arrhythmia - doses up to 1750 mg intravenously for over 24 hours
Outline the dose of adrenaline used for anaphylaxis
500 mg IM
Outline the dose of adrenaline used for cardiac arrest
1000 mg IV
How much lidocaine (in mg) does a 2.2ml cartridge of 2% lidocaine in 1:80 000 solution contain?
44mg
How much adrenaline (in mg) does a 2.2ml cartridge of 2% lidocaine in 1:80 000 solution contain?
27.5 mg
How much lidocaine (in mg) does a 1.8ml cartridge of 2% lidocaine in 1:80 000 solution contain?
36mg
How much adrenaline (in mg) does a 1.8ml cartridge of 2% lidocaine in 1:80 000 solution contain?
22.5mg
What is the theoretical consequence of using/delivering more than one local anaesthetic agent (using a combination of local anaesthetic agents)?
- increased risk of myocardial depression
- increased risk of ventricular arrhythmia
What is the consequence of using anti-arrhythmic doses of lidocaine with other anti-arrhythmic agents?
- may result in myocardial depression
What is the consequence of using prilocaine with anti-arrhythmic agents?
myocardial depression
What advice is given for the use of articaine for patients receiving anti-arrhythmic agents?
manufacture advises a caution when administering articaine in such cases
Outline a relevant interaction between lidocaine and antibacterial drugs. State what antibacterials this interaction applies to
- increased risk of ventricular arrhythmia
- quinupristin
- dalfopristin
State the relevant anti-bacterials with potential interaction with LAs
- quinupristin
- dalfopristin
- sulphonamides
Outline the relevant interaction between prilocaine and antibacterials. State the antibacterial drug that this applies to
- increased risk of methaemoglobinaemia
- sulphonamindes e.g. co-trimoxazole
Outline the relevant interaction between lidocaine and antipsychotic agents
- lidocaine at high doses can increase the risk of ventricular arrhythmia
- prolonged QT interval
State the relevant anti-viral agents with potential interactions with LA agents
- fosamprenavir
- darunavir
- atazanavir
- lopinavir
Outline the potential drug interaction between lidocaine and antiviral drugs
antiviral agents appear to increase plasma concentration of lidocaine and potentially increase cardiotoxicity
Outline the drug interaction between lidocaine and betablockers
- high dose lidocaine with beta blockers can cause myocardial depression
- lidocaine clearance is reduced by propanolol; increases toxicity risk when lidocaine is given at high doses
What is the effect of diuretics on lidocaine?
- action of lidocaine is antagonised by hypokalaemia caused by acetazolamide, loop diuretics or thiazides and related diuretics
What is the interaction of lidocaine and 5HT3 antagonists such as dolasetron?
- increased risk of ventricular arrhythmia
Outline the drug interaction between lidocaine and ulcer healing drugs such as cimetidine
- increased plasma concentrations of lidocaine; increased risk of toxicity when high doses of lidocaine are used
- this effect is not seen with other ulcer healing drugs
Outline the drug interaction between lidocaine and sedatives such as midazolam
- midazolam has been reported to cause a modest reduction in serum lidocaine levels but not mepivacaine levels
Outline the nature of the drug interaction between local anaesthetic agents and TCAs
- increaed risk of hypertension and arrhtymias is high doses of adrenaline are given
What is the clinically relevant dose of local anaesthetics if they are given to a patient on TCAs?
None if </= 2 cartridges of 1: 80 000 adrenaline containing solution are used
What is the clinically relevant dose of local anaesthetics if they are given to a patient on non-cardio-selective beta-blockers?
State the non-cardio-selective beta blockers this applies to
None if </= 2 cartridges of a 1: 80 000 adrenaline containing solution is used
if more than 2 cartridges are required then an adrenaline free solution should be used
- propanolol
- nadolol
- timolol
- sotalol
Outline the nature of the reaction between beta-blockers and LA agents
- increased risk of severe hypertension
- bradycardia when adrenaline is given with non-cardioselective beta-blocker
What is the guidance for LA use with patients who abuse cocaine ?
avoid using LA containing adrenaline unless it is certain they have not used cocaine for 24 hours
What is the nature of the interaction between LA agents and cocaine?
cocaine and adrenaline have sympathomimetic effects
increase the risk of arrhythmias
Outline the potential interaction between LA and clonidine
possible risk of hypertension when adrenaline is given with clonidine
What is the clinically relevant dose of LA agents if administered to a patient on diuretics?
none if </= 2 cartridges of 1: 80 000 adrenaline containing solution are used
What is the guidance for the use of dopaminergics such as entacapone and LA ?
- no adverse reactions with entacapone have been reported in the dental setting
- however it is a new drug an caution is vasoconstrictor dosing is required
Outline the potential nature of the reaction between LA and entacapone
serum levels and therefore effects of adrenaline are possibly enhanced by entacapone
The interaction between sympathomimetics and rasagiline (dopaminergic) are not clinically relevant in dentistry. True or false
What is the guidance for use of sympathomimmetics and rasagiline
True
avoid concomitant use of sympathomimetis with rasagiline
sympathmimetics referred to here are those that are present in decongestant medication containing ephedrine or pseudoephedrine
What is the nature of the reaction between LA agents and MAOI antidepressants?
co-administration of higher doses of adrenaline and MAOI antidepressants may produce hypotension or hypertension
What is the nature of the interaction between higher doses of adrenaline and SNRIs/phenothiazines?
Give examples of SNRI implicated in this
prolonged hypotension or hypertension
- duloxetine
- venlafaxine
What is the clinically relevant dose of LA agents when considering its use with SNRIs or phenothiazines
none if doses of adrenaline do not exceed 50 mg / </= 2 cartridges of a 1:80 000 adrenaline containing solution
Warnings about the potential interaction between SNRIs/phenothiazines and LA only appear in product literature for …
Lignospan Special
Of the available vasoconstrictors (felypressin and adrenaline) only ________ is listed as interacting with other drugs
adrenline
Although intraligamentary injection can result in rapid absorption into systemic circulation, why are LA levels unlikely to result in clinically significant drug interactions?
volumes used for intra-ligamentary injections are very small (0.2-0.5 ml; 2.5-6.25 mg of adrenaline respectively)
Intra-osseous injection can lead to rapid absorption into systemic circulation. True or false
True
Infiltration and regional block anaesthesia are not associated with significant systemic absorption. True or false
True
