Test 2 Flashcards
Are local anaesthetics vasodilators or vasoconstrictors ?
Vasodilators
What does the vasodilating property of local anaesthetic cause?
- Increased rate of anaesthetic absorption into the bloodstream by enabling the anaesthetic to be carried away frm the injection site
- Decrease in the duration of the anaesthetic’s action by enabling it to diffuse quickly from the injection site
3, Higher plasma levels of local anaesthetic increasing the risk of toxicity - Increased bleeding in the area due to increase in blood flow
What are solutions added to local anaesthetic solutions to delay the absorption of local anaesthetics?
Vasoconstrictors
What are the two vasoconstrictors currently used in North America?
Epinephrine
Levonordefrin
What are the four reasons vasoconstrictors are added to anaesthetic?
- To decrease the blood flow in the area of anaesthetic administration by constricting the blood vessels.
- To provide hemostasis
- To increase the duration of the anaesthetic effects, thus improving the success rate and intensity of the nerve blood
- To reduce the risk of systemic toxicity by allowing a lower administered dose
How many mL of solution in a LA cartridge?
1.8mL
How many mL in an articaine cartridge?
1.7mL
2% lidocaine contrains what concentration of local anaesthetic agent?
2%
What is the ratio (eg. 1:100 000)?
Concentration of vasoconstrictor
What is the most widley used LA with a vasoconstrictor?
Lidocaine 2%
What LA has less vasodilation than lidocaine and is metabolized in the liver?
Mepivacaine 3% plan or 2% Levonordefrin
What LA has limited vasodilation, is metabolized primarily in the lung and then the liver, lasts for 10-60 minutes for pulpal anaestheia when plain and 60-90 minutes with 1:200 000 epi?
4% Prilocaine
What LA has a shorter half life (45 minutes), lowest toxicity, rapid biotransformation, is mostly metabolized in plasma with 10% in the lungs and lasts 120-300 minutes with 1:200 000 epi or 180=360 minutes with 1:100 000 epi?
4% Articaine
What LA has a longer onset of action but longer duration, lasts 240-540 minutes with 1:200,000 epi, is more lipid soluble so less concentraion of drug needed than other LA agents, has the longest half-life at 3.5 hours, the highest toxicity, and is metabolized in the liver?
Bupivacaine 0.5% (Marcaine)
What LAs are metabolized in the liver?
Lidocaine
Mepivacaine
Bupivacaine
What LA is primarily metabolized in the lungs and then the liver?
Prilocaine
What LA is primarily metabolized in the plasma and 10% in the lungs?
Articaine
What are the LAs in the DC clinic?
4% Septanest 1:100 000 (Articaine)
2% Xylocaine 1:100 000 (Lidocaine)
4% Citanest Plain (Prilocaine)
Where are LAs excreted?
Kidneys
Small percent unchanged in urine
What is the composition of LA solutions?
- LA agent
2.Vasoconstrictor - vasoconstrictor preservatives: sodium bisulfite, metabisulfite, acetone sodium bisulfite - Sodium hydroxide
- Sodium chloride
What is the function of vasoconstricor preservatives?
Provide a prolonged shelf life of approximately 18 months via antioxidant properties
What are the disadvantages to vasocontrictor preservatives?
Increase solution’s acidity - slower onset of action
Potential for allergic reactions
What acts as a buffer in LA solution that alkalinizes or adjusts, the pH of the solution between 6 and 7?
Sodium hydroxide
What acts as a buffer creating an injectable solution that is isotonic and compatible with tissues?
Sodium chloride