Pharmacology of LA (extras)

Question 1

What happens as soon as LA hits the blood stream?

Answer 1

It starts to BREAK DOWN

Question 2

Describe what LA does to sodium channels

Answer 2

REVERSIBLY BLOCKS THE SODIUM CHANNELS meaning we cannot proceed with the cycle, stopping the action potential process

Question 3

What does it mean if we have a more uncharged la agent

Answer 3

THE EASIER IT GOES THROUGH THE MEMBRANE

Question 4

What does it mean if we have a more charged la agent

Answer 4

EASIER IT IS TO BIND TO THE SODIUM CHANNELS

Question 5

What does it mean if the la is more soluble

Answer 5

the more lipid soluble the drug, the more it will work better !
- when injected it combines to plasma proteins

Question 6

what is the half-life (measure of how long it lasts in the body) of lidocaine

Answer 6

1.6 hours

Question 7

What happens if LA is metabolised

Answer 7

• it will no longer work! - the liver is the main site of the drug breakdown. if a pt has liver disease we may reduce the dose that we give as it may not be broken down as effectively.

Question 8

What will the effects of REDUCING BLOOD SUPPLY mean for the lasting effects of LA(4)

Answer 8

• LONGER LASTING
• it counteracts the vasodilation caused by the anaesthetic
• if we reduce blood flow, we will get less LA in the blood stream, reducing the systemic side effects, it will also reduce haemorrhage
• IF WE DIDNT HAVE A VASOCONSTRICTOR, WE WOULD GET INCREASED BLOOD FLOW

Question 9

What is the MAX DOSAGE SYSTEM in LA for patients

Answer 9

normally, we would use a cartridge for every 10kg of bodyweight eg 70kg patient - we would use a max of 7 cartridges - DO NOT EXCEED 7 CARTS eg if someone is 80kg still max is 7 carts

Question 10

when would we avoid using lidocaine with adrenaline

Answer 10

IF THE PT HAS UNSTABLE ANGINA - in general, avoid if the pt has any unstable heart conditions

Question 11

what is the USP of articaine

Answer 11

ability to diffuse through bone
can achieve anaesthesia of lower posterior teeth by infiltration

Question 12

why do we have vasoconstrictors in LA(6)

Answer 12

• increases the speed on onset
• counteracts with the vasodilatory effects of the LA agent
• extends the duration of LA
• improves depth of anaesthesia
• lower blood levels of LA
• reduce haemhorrage

Question 13

What are some contraindications of using LA on a patient (5)

Answer 13

Allergy or Hypersensitivity: Patients who have a known allergy or hypersensitivity to local anesthetic agents or any of their components should not receive LA containing those ingredients.

Severe Cardiovascular Disease: Patients with severe cardiovascular disease, such as unstable angina, recent myocardial infarction (heart attack), or uncontrolled hypertension, may be at increased risk of adverse cardiovascular effects from LA containing vasoconstrictors like epinephrine.

Uncontrolled Hypertension: Patients with uncontrolled hypertension (high blood pressure) may be at increased risk of cardiovascular complications from LA containing vasoconstrictors.

Certain Medications: Some medications, such as monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants, can interact with LA containing vasoconstrictors and potentiate their cardiovascular effects. Patients taking these medications should be carefully evaluated before receiving LA with vasoconstrictors.

Certain Medical Conditions: Patients with certain medical conditions, such as hyperthyroidism etc

Question 14

What are some contra-indications of using lidocaine?

Answer 14

Certain medical conditions/drugs that may indicate the dose to be reduced eg liver disease, renal disease, drugs like beta-blockers and calcium channel blockers

Question 15

What are some contra-indications for using lidocaine W EPINEPHERENE

Answer 15

medical conditions
liver disease - high risk of toxicity due to IMPAIRED metabolism
cardiac disease - impact upon use of epinepherene