Intralipid® 20% for Reversal of Local Anesthetics

Phase 4

Active, not recruiting

• Conditions: Anesthesia, Local
• Interventions: Drug: Lidocaine 2%; Drug: Lidocaine 1%; Drug: Bupivacaine 0.25%; Drug: Bupivacaine 0.5%; Drug: Intralipid, 20% Intravenous; Other: Saline intravenously; Other: Saline

• Registration Number: NCT03968822
• Lead Sponsor: Hospital for Special Surgery, New York

Brief Summary

In order to determine if Intralipid 20% can be used to reverse the effects of local anesthetics, the investigators will recruit 18 volunteers who will be asked to come to HSS for two study visits. Small amounts of local anesthetics will be injected into the volunteers' thighs during both visits. During one visit volunteers will receive Intralipid 20% and during the other visit they will receive a saline solution. The study team will measure how quickly normal sensation returns to the thighs when the volunteers get Intralipid 20% compared to saline.

Detailed Description

The purpose of this study is to determine if a fat solution (Intralipid 20%) given intravenously can reverse the effects of local anesthetics. Local anesthetics are drugs that cause numbness when they are injected into different parts of the body. Local anesthetics are important drugs because they allow doctors to perform surgeries and other procedures on patients; however, there are certain instances where it would be helpful to reverse the effects of local anesthetics and reduce the amount of time that they produce numbness. In order to determine if Intralipid 20% can be used to reverse the effects of local anesthetics, the investigators will recruit 18 volunteers who will be asked to come to HSS for two study visits. Small amounts of local anesthetics will be injected into the volunteers' thighs during both visits. During one visit volunteers will receive Intralipid 20% and during the other visit they will receive a saline solution. The study team will measure how quickly normal sensation returns to the thighs when the volunteers get Intralipid 20% compared to saline.

Study Timeline

• Study First Submitted: 2019-05-21
• Study First Submitted QC: 2019-05-28
• Study First Posted: 2019-05-30
• Study Start: 2019-07-26
• Status Verified: 2025-03
• Last Update Submitted: 2025-04-01
• Last Update Posted: 2025-04-03
• Primary Completion: 2025-10
• Study Completion: 2026-10

Recruitment & Eligibility

• Status: ACTIVE_NOT_RECRUITING
• Sex: All
• Target Recruitment: 18

Inclusion Criteria

• English speaking
• BMI 18-25, with body weight between 50-100kg

Exclusion Criteria

• ASA III or higher
• Pregnant Women
• Allergy to study medications (lidocaine, bupivacaine, soybeans, eggs)
• Use of drugs affecting the sensorium (including opioids, benzodiazepines, antipsychotics, gabapentinoids)

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Intralipid 20% IV Bolus	Lidocaine 1%	This is 1 out of the 2 study visits. The patient will receive 6 injections (3 in each thigh). The 6 injections are: 1. lidocaine 1% 2. lidocaine 2% 3. bupivacaine 0.5% 4. bupivacaine 0.25% 5. saline 6. no injection Each test solution will be injected over 5 seconds through a 27G needle and tuberculin syringe at a 30 degree angle. The patient will also receive an intravenous bolus in the arm of Intralipid 20%. Participant will be blindfolded for these activities so they will not know what they received during the visit.
Intralipid 20% IV Bolus	Intralipid, 20% Intravenous	This is 1 out of the 2 study visits. The patient will receive 6 injections (3 in each thigh). The 6 injections are: 1. lidocaine 1% 2. lidocaine 2% 3. bupivacaine 0.5% 4. bupivacaine 0.25% 5. saline 6. no injection Each test solution will be injected over 5 seconds through a 27G needle and tuberculin syringe at a 30 degree angle. The patient will also receive an intravenous bolus in the arm of Intralipid 20%. Participant will be blindfolded for these activities so they will not know what they received during the visit.
Intralipid 20% IV Bolus	Saline	This is 1 out of the 2 study visits. The patient will receive 6 injections (3 in each thigh). The 6 injections are: 1. lidocaine 1% 2. lidocaine 2% 3. bupivacaine 0.5% 4. bupivacaine 0.25% 5. saline 6. no injection Each test solution will be injected over 5 seconds through a 27G needle and tuberculin syringe at a 30 degree angle. The patient will also receive an intravenous bolus in the arm of Intralipid 20%. Participant will be blindfolded for these activities so they will not know what they received during the visit.
Saline	Bupivacaine 0.25%	This is 2 out of the 2 study visits. The patient will receive 6 injections (3 in each thigh). The 6 injections are: 1. lidocaine 1% 2. lidocaine 2% 3. bupivacaine 0.5% 4. bupivacaine 0.25% 5. saline 6. no injection Each test solution will be injected over 5 seconds through a 27G needle and tuberculin syringe at a 30 degree angle. The patient will also receive an intravenous bolus in the arm of Saline. Participant will be blindfolded for these activities so they will not know what they received during the visit.
Saline	Saline intravenously	This is 2 out of the 2 study visits. The patient will receive 6 injections (3 in each thigh). The 6 injections are: 1. lidocaine 1% 2. lidocaine 2% 3. bupivacaine 0.5% 4. bupivacaine 0.25% 5. saline 6. no injection Each test solution will be injected over 5 seconds through a 27G needle and tuberculin syringe at a 30 degree angle. The patient will also receive an intravenous bolus in the arm of Saline. Participant will be blindfolded for these activities so they will not know what they received during the visit.
Saline	Saline	This is 2 out of the 2 study visits. The patient will receive 6 injections (3 in each thigh). The 6 injections are: 1. lidocaine 1% 2. lidocaine 2% 3. bupivacaine 0.5% 4. bupivacaine 0.25% 5. saline 6. no injection Each test solution will be injected over 5 seconds through a 27G needle and tuberculin syringe at a 30 degree angle. The patient will also receive an intravenous bolus in the arm of Saline. Participant will be blindfolded for these activities so they will not know what they received during the visit.
Saline	Lidocaine 1%	This is 2 out of the 2 study visits. The patient will receive 6 injections (3 in each thigh). The 6 injections are: 1. lidocaine 1% 2. lidocaine 2% 3. bupivacaine 0.5% 4. bupivacaine 0.25% 5. saline 6. no injection Each test solution will be injected over 5 seconds through a 27G needle and tuberculin syringe at a 30 degree angle. The patient will also receive an intravenous bolus in the arm of Saline. Participant will be blindfolded for these activities so they will not know what they received during the visit.
Intralipid 20% IV Bolus	Lidocaine 2%	This is 1 out of the 2 study visits. The patient will receive 6 injections (3 in each thigh). The 6 injections are: 1. lidocaine 1% 2. lidocaine 2% 3. bupivacaine 0.5% 4. bupivacaine 0.25% 5. saline 6. no injection Each test solution will be injected over 5 seconds through a 27G needle and tuberculin syringe at a 30 degree angle. The patient will also receive an intravenous bolus in the arm of Intralipid 20%. Participant will be blindfolded for these activities so they will not know what they received during the visit.
Saline	Lidocaine 2%	This is 2 out of the 2 study visits. The patient will receive 6 injections (3 in each thigh). The 6 injections are: 1. lidocaine 1% 2. lidocaine 2% 3. bupivacaine 0.5% 4. bupivacaine 0.25% 5. saline 6. no injection Each test solution will be injected over 5 seconds through a 27G needle and tuberculin syringe at a 30 degree angle. The patient will also receive an intravenous bolus in the arm of Saline. Participant will be blindfolded for these activities so they will not know what they received during the visit.
Intralipid 20% IV Bolus	Bupivacaine 0.25%	This is 1 out of the 2 study visits. The patient will receive 6 injections (3 in each thigh). The 6 injections are: 1. lidocaine 1% 2. lidocaine 2% 3. bupivacaine 0.5% 4. bupivacaine 0.25% 5. saline 6. no injection Each test solution will be injected over 5 seconds through a 27G needle and tuberculin syringe at a 30 degree angle. The patient will also receive an intravenous bolus in the arm of Intralipid 20%. Participant will be blindfolded for these activities so they will not know what they received during the visit.
Intralipid 20% IV Bolus	Bupivacaine 0.5%	This is 1 out of the 2 study visits. The patient will receive 6 injections (3 in each thigh). The 6 injections are: 1. lidocaine 1% 2. lidocaine 2% 3. bupivacaine 0.5% 4. bupivacaine 0.25% 5. saline 6. no injection Each test solution will be injected over 5 seconds through a 27G needle and tuberculin syringe at a 30 degree angle. The patient will also receive an intravenous bolus in the arm of Intralipid 20%. Participant will be blindfolded for these activities so they will not know what they received during the visit.
Saline	Bupivacaine 0.5%	This is 2 out of the 2 study visits. The patient will receive 6 injections (3 in each thigh). The 6 injections are: 1. lidocaine 1% 2. lidocaine 2% 3. bupivacaine 0.5% 4. bupivacaine 0.25% 5. saline 6. no injection Each test solution will be injected over 5 seconds through a 27G needle and tuberculin syringe at a 30 degree angle. The patient will also receive an intravenous bolus in the arm of Saline. Participant will be blindfolded for these activities so they will not know what they received during the visit.

Primary Outcome Measures

Name	Time	Method
Time to complete normal sensation after lidocaine 1%	up to 24 hours	The time (measured in minutes) when the participant reports normal sensation of both cold swab and pinprick at the injection site of lidocaine 1%.; Although measured for each individual participant, the average time across all participants is reported.
Time to complete normal sensation after lidocaine 2%	up to 24 hours	The time (measured in minutes) when the participant reports normal sensation of both cold swab and pinprick at the injection site of lidocaine 2%.; Although measured for each individual participant, the average time across all participants is reported.
Time to complete normal sensation after Bupivacaine 0.5%	up to 24 hours	The time (measured in minutes) when the participant reports normal sensation of both cold swab and pinprick at the injection site of Bupivacaine 0.5%.; Although measured for each individual participant, the average time across all participants is reported.
Time to complete normal sensation after Bupivacaine 0.25%	up to 24 hours	The time (measured in minutes) when the participant reports normal sensation of both cold swab and pinprick at the injection site of Bupivacaine 0.25%.; Although measured for each individual participant, the average time across all participants is reported.

Secondary Outcome Measures

Name	Time	Method
Time to normal pin prick sensation after lidocaine 2%	up to 24 hours	The time (measured in minutes) when the participant reports normal sensation of pinprick at the injection site of lidocaine 2%.; Although measured for each individual participant, the average time across all participants is reported.
Time to normal pinprick sensation after Bupivacaine 0.5%	up to 24 hours	The time (measured in minutes) when the participant reports normal sensation of pinprick at the injection site of Bupivacaine 0.5%.; Although measured for each individual participant, the average time across all participants is reported.
Time to normal cold swab sensation after Bupivacaine 0.5%	up to 24 hours	The time (measured in minutes) when the participant reports normal sensation of cold swab at the injection site of Bupivacaine 0.5%.; Although measured for each individual participant, the average time across all participants is reported.
Time to normal cold swab sensation after Bupivacaine 0.25%	up to 24 hours	The time (measured in minutes) when the participant reports normal sensation of cold swab at the injection site of Bupivacaine 0.25%.; Although measured for each individual participant, the average time across all participants is reported.
Time to normal pinprick sensation after Bupivacaine 0.25%	up to 24 hours	The time (measured in minutes) when the participant reports normal sensation of pinprick at the injection site of Bupivacaine 0.25%.; Although measured for each individual participant, the average time across all participants is reported.
Time to normal cold swab sensation after lidocaine 2%	up to 24 hours	The time (measured in minutes) when the participant reports normal sensation of cold swab at the injection site of lidocaine 2%.; Although measured for each individual participant, the average time across all participants is reported.
Time to normal cold swab sensation after lidocaine 1%	up to 24 hours	The time (measured in minutes) when the participant reports normal sensation of cold swab at the injection site of lidocaine 1%.; Although measured for each individual participant, the average time across all participants is reported.
Time to normal pinprick sensation after lidocaine 1%	up to 24 hours	The time (measured in minutes) when the participant reports normal sensation of pinprick at the injection site of lidocaine 1%.; Although measured for each individual participant, the average time across all participants is reported.

Trial Locations

Locations (1)

Hospital of Special Surgery; 🇺🇸 New York, New York, United States