Lidocaine

Question 1

What is lidocaine?

Answer 1

Amide local anaesthetic

Question 2

What is the pKa of lidocaine?

Answer 2

7.9

Question 3

What is the partition coefficient of lidocaine?

Answer 3

3

Question 4

How protein bound is lidocaine?

Answer 4

65%

Question 5

What are the pharmacokinetics of lidocaine?

Answer 5

Fast onset, medium duration (1-2hrs)

Question 6

Where is lidocaine metabolised?

Answer 6

Hepatic metabolism, excreted in urine (<10% unchanged)

Question 7

What are the SEs of lidocaine?

Answer 7

• lip tingling
• seizures
• coma

Question 8

What are the CIs to lidocaine?

Answer 8

• allergy/hypersensitivity
• can’t use with adrenaline in digits

Question 9

What is the absorption/distribution of lidocaine?

Answer 9

• 33% ionised in blood
• 64% protein bound
• volume of distribution 0.7 - 1.5 L/kg
• half life 90 mins

Question 10

What are the signs of local anaesthetic toxicity?

Answer 10

4 mcg/ml:

• perioral tingling
• dizziness
• tinnitus
• parasthesia

> 5mcg/ml

• altered consciousness
• coma
• seizures

> 10mcg/ml

• AV block
• refractory hypotension
• cardiac arrest

Question 11

What is the dose of lidocaine?

Answer 11

3mg/kg or 7mg/kg if given with adrenaline

Question 12

What % of lidocaine and bupivacaine are unionized at plasma pH? What does this affect?

Answer 12

Lidocaine 25% unionized

Bupivacaine 15% unionized

Affects speed of onset - lidocaine faster onset