Intranasal Cocaine and Temperature Regulation During Exercise

Assess the effects of intranasal cocaine on temperature regulation and whole-body sweat rate during exercise in warm environmental conditions.

Study Overview

• Status: Completed
• Conditions: Hyperthermia; Exercise; Cocaine Use
• Intervention / Treatment: Drug: Cocaine; Drug: Lidocaine

Detailed Description

Previously it was shown that intranasal cocaine attenuates skin blood flow and sweating responses during passive heat stress, when compared to placebo. However, nothing is known about the effects of cocaine on whole-body temperature regulation during mild to moderate exercise in warm environmental condition.

This project will test the hypothesis that intranasal cocaine attenuates whole-body sweat rate, resulting in greater elevations in core temperature during mild to moderate exercise in warm environmental conditions.

Primary data include core temperature, skin temperatures, and whole body sweat rate. Secondary variables include cardiovascular responses, perceptions of exercise exertion and thermal comfort, and metabolic heat production. Intranasal lidocaine will be used as the placebo for cocaine. The selection of the drug administered during the first experimental trial will be randomized, with the other drug administered during the second experimental trial.

• Study Type: Interventional
• Enrollment (Actual): 27
• Phase: Phase 2; Phase 1

Contacts and Locations

Study Locations

• United States
  • Texas
    • Dallas, Texas, United States, 75390
      • University of Texas Southwestern Medical Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• 18 to 50 years of age
• Healthy
• Body mass index less than 31 kg/m^2
• Speak English
• Systolic blood pressure <140 mmHg
• Diastolic blood pressure <90 mmHg

Exclusion Criteria:

• Subjects not in the defined age range
• Participants who have cardiac, respiratory, neurological, and/or metabolic illnesses
• Any known history of renal or hepatic insufficiency/disease
• Pregnancy or breast feeding
• Body mass less than 60 kilograms
• Current smokers, as well as individuals who regularly smoked within the past 3 years
• Individuals with a history of drug abuse within the past 5 years
• Individuals who have an unexplained positive urine drug screen (e.g., some agents cause false-positive results and when agent abstained the drug screen is negative, one example could be an over the counter supplement)
• Currently taking pain modifying medications

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Hot-Humid; Participants will complete the trial in environmental conditions 38 degrees Celsius with 40% humidity.	Drug: Cocaine; Cocaine (cocaine hydrochloride 4% nasal solution) will be administered (3 mg/kg) intranasally prior to entering the warm environmental conditions and performing 60 minutes of exercise.; Drug: Lidocaine; Lidocaine (lidocaine hydrochloride 4% nasal solution) will be administered (3 mg/kg) intranasally prior to entering the warm environmental conditions and performing 60 minutes of exercise.
Experimental: Hot-Dry; Participants will complete the trial in environmental conditions 41 degrees Celsius with 15% humidity.	Drug: Cocaine; Cocaine (cocaine hydrochloride 4% nasal solution) will be administered (3 mg/kg) intranasally prior to entering the warm environmental conditions and performing 60 minutes of exercise.; Drug: Lidocaine; Lidocaine (lidocaine hydrochloride 4% nasal solution) will be administered (3 mg/kg) intranasally prior to entering the warm environmental conditions and performing 60 minutes of exercise.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Core Temperature	Core temperature will be measured either from a temperature sensor pill or from a rectal temperature probe.	Core temperature is measured at baseline and at 60 minutes of heat exposure.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
End Skin Temperature	Skin temperature will be measured from small temperature sensitive electrodes attached to the participant's skin	Measured at the end of heat exposure, 90 minutes from cocaine/lidocaine administration
End Heart Rate	Heart rate will be measured from ECG electrodes attached to the participant	Measured at the end of heat exposure, 90 minutes from Cocaine/ lidocaine administration
Whole Body Sweat Rate	Whole body sweat rate is calculated by subtracting the participants post-heat exposure nude body weight from their pre-heat exposure nude body weight	Within 30 minutes before exposure to warm environmental conditions (before cocaine/ lidocaine administration) and immediately after the heat exposure (90 minutes post cocaine/ lidocaine administration)
End Mean Arterial Pressure	Systolic and diastolic blood pressure will be measured from a cuff placed on the upper arm.	Measured at the end of heat exposure, 90 minutes from cocaine/ lidocaine administration
End Thermal Sensation	Subjective assessment of how hot the subject feels. Title of Scale: Thermal Sensation Scale; Minimum value: -50 "unbearably cold"; Maximum value: 50: "unbearably hot" Scale presents numbers in increments of 5	These values will be obtained at end of the 60 minute heat exposure (90 minutes post cocaine/ lidocaine administration)

Collaborators and Investigators

• Sponsor: University of Texas Southwestern Medical Center

Study record dates

Study Major Dates

• Study Start (Actual): September 1, 2023
• Primary Completion (Actual): June 5, 2024
• Study Completion (Actual): August 1, 2024

Study Registration Dates

• First Submitted: March 16, 2023
• First Submitted That Met QC Criteria: March 29, 2023
• First Posted (Actual): April 12, 2023

Study Record Updates

• Last Update Posted (Actual): July 14, 2025
• Last Update Submitted That Met QC Criteria: June 25, 2025
• Last Verified: June 1, 2025

More Information

Terms related to this study

• Keywords: thermoregulation; skin blood flow; sweating
• Additional Relevant MeSH Terms: Wounds and Injuries; Body Temperature Changes; Heat Stress Disorders; Hyperthermia; Physiological Effects of Drugs; Molecular Mechanisms of Pharmacological Action; Peripheral Nervous System Agents; Anesthetics, Local; Anesthetics; Central Nervous System Depressants; Sensory System Agents; Neurotransmitter Agents; Anti-Arrhythmia Agents; Voltage-Gated Sodium Channel Blockers; Sodium Channel Blockers; Membrane Transport Modulators; Dopamine Uptake Inhibitors; Neurotransmitter Uptake Inhibitors; Dopamine Agents; Vasoconstrictor Agents; Lidocaine; Cocaine
• Other Study ID Numbers: STU-2023-0094

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No