Injectable Local Anesthetic Agents

Amide local anesthetics available for dental usage include lidocaine, mepivacaine, articaine, prilocaine and bupivacaine. They differ from each other in their duration of action (Table 1) and the maximum dosage that may be safely administered to patients (Table 2).

Table 1 demonstrates the variation in duration of action of injectable local anesthetics in minutes. There is variation in duration between anesthetics, pulp and soft tissue, and maxillary infiltration and mandibular blocks.

Table 1. Duration of Injectable Local Anesthetics (in minutes).3
Anesthetic Pulp Soft Tissue
Lidocaine 2%
1:100,000 epi
60 minutes 180-240 minutes
Mepivacaine 3%
Plain I (infiltration)
5-10 minutes 90-120 minutes
Articaine 4%
1:200,000 epi
1:100,000 epi
45-60 minutes
60-75 minutes
180-240 minutes
180-300 minutes
Prilocaine 4% plain
Infiltration
Block
10-15 minutes
60-120 minutes
40-60 minutes
120-240 minutes
Prilocaine 4% + epi
1:200,000 epi
60-90 minutes 180-480 minutes

The duration of pulpal anesthesia for bupivacaine (90+ minutes) is greater than lidocaine (60 minutes) and articaine (60-75 minutes) and is also greater for soft tissue (240-720 minutes) compared to lidocaine and articaine (180-300 minutes). There are no procedures in pediatric dentistry that warrant 1.5 hours of pulpal anesthesia and over 4 hours of soft tissue anesthesia. The prolonged time of duration of action increases the likelihood of self-inflicted, post-operative soft tissue injury and therefore the use of bupivacaine is not recommended in pediatric patients and those patients with special needs.4

Another difference among injectable anesthetic agents is the maximum recommended doses. This is extremely relevant in pediatric dentistry where there is a wide variation in weight between patients and thus not all patients should receive equal amounts of local anesthetic for the same procedure. Table 2 summarizes the maximum recommended doses of local anesthetic agents as per the American Academy of Pediatric Dentistry (AAPD) Guidelines.

Table 2. Maximum Recommended Dosage of Local Anesthetic Agents (AAPD).1
Anesthetic Maximum Dosage Maximum Total Dosage mg/1.7ml carpule
mg/kg mg/lb
Lidocaine 2% 1:000,000 epi 4.4 2.0 300mg 34mg
Mepivacaine 3% plain 4.4 2.0 300mg 51mg
Articaine 4% 1:100,000 epi 7.0 3.2 500mg 68mg
Prilocaine 4% plain 8.0 3.6 600mg 68mg
Bupivacaine 0.5% 1:200,000 epi 1.3 0.6 90mg 8.5mg

Note the AAPD maximum recommended dosages differ from the manufacturer’s maximum recommended dosages as illustrated in Table 3.

Table 3. Maximum Recommended Dosage of Local Anesthetic Agents (MRD).3
Anesthetic Maximum Dosage Maximum Total Dosage mg/1.7ml cartridge
mg/kg mg/lb
Lidocaine 2% 1:000,000 epi 7.0 3.2 500mg 34mg
Mepivacaine 3% plain 6.6 3.0 400mg 51mg
Articaine 4% 1:100,000 epi 7.0 3.2 None Listed 68mg
Prilocaine 4% plain 6.0 2.7 400mg 68mg
Bupivacaine 0.5% 1:200,000 epi 2.0 0.9 90mg 8.5mg

Using the AAPD maximum recommended dosages (Table 2), one can calculate the maximum recommended dosage and amount of local anesthetic agent for patients of specific weight and type of anesthetic. For example:

To calculate the maximum amount of lidocaine 2% with 1:100,000 epinephrine and the number of cartridges that can be safely administered to a 30 pound patient, the clinician would perform the following calculations.

Maximum Dosage (mg/lbs) X weight (lbs) = Maximum Total Dosage (mg)
2.0 X 30 = 60 mgs
Maximum Total Dosage (mg) ÷ mg/cartidge = Maximum # cartridges
60 ÷ 36 = 1.67 cartridges

Thus for a 30 pound child one can safely administer 1.67 cartridges of lidocaine 2% with 1:100,000 epinephrine.

To calculate the maximum amount of mepivacaine 3% plain and the number of cartridges that can be administered to a 30 pound patient the clinician would perform the following calculations.

Maximum Dosage (mg/lbs) X weight (lbs) = Maximum Total Dosage (mg)
2.0 X 30 = 60 mgs
Maximum Total Dosage (mg) ÷ mg/cartidge = Maximum # cartridges
60 ÷ 54 = 1.1 cartridge

Note the difference between the number of cartridges of lidocaine 2% and mepivacaine 3% that can be administered to a 30 pound child is due to the difference in the number of mg of anesthetic solution in a 1.8cc cartridge of anesthesia; lidocaine contains 36 mg and mepivacaine contains 54 mg.

Table 4 provides an quick dosage approximation and amount of local anesthetic for patients of specific weight and type of anesthetic.

Table 4. Quick Dosage Chart for AAPD Maximum Recommended Dosages.4
Maximum Number of 1.8ml Cartridges
Age Kg Lbs 2% Lidocaine 3% Mepivicaine 4% Articaine
1+ yrs 7.5 16.5 0.9 0.6 0.7
2-3 yrs 10.0 22.0 1.2 0.8 1.0
12.5 27.5 1.5 1.0 1.2
4-5 yrs 15.0 33.0 1.8 1.2 1.5
17.5 38.5 2.1 1.4 1.7
6-8 yrs 20.0 44.0 2.4 1.6 2.0
22.5 49.5 2.8 1.8 2.2
9-10 yrs 25.0 55.0 3.1 2.0 2.4
30.0 66.0 3.7 2.4 2.9
11+ yrs 32.5 71.5 4.0 2.6 3.2
35.0 77.0 4.3 2.9 3.4
37.5 82.5 4.6 3.1 3.7
40.0 88.0 4.9 3.3 3.9

The maximum amount of local anesthetic agent needs to be reduced if the patient is receiving a supplementary dose of enteral or parenteral sedative agent for behavior management. The action of the sedative has an additive depressive effect on the central nervous and cardiovascular systems can initiate overdose consequences (see Complications of Local Anesthesia).