Intranasal Cocaine and Temperature Regulation During Exercise

University of Texas Southwestern Medical Center27 enrolled

Overview

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

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

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

SINGLE

Enrollment

Conditions

Hyperthermia Cocaine Use Exercise

Interventions

CocaineDRUG

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.

LidocaineDRUG

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.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 50 YearsHealthy volunteers:

Medical Language ↔ Plain English

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

Locations (1)

University of Texas Southwestern Medical Center

Dallas, Texas, United States

Outcomes

Primary Outcomes

Change in Core Temperature

Core temperature will be measured either from a temperature sensor pill or from a rectal temperature probe.

Time frame: Core temperature is measured at baseline and at 60 minutes of heat exposure.

Secondary Outcomes

End Skin Temperature

Skin temperature will be measured from small temperature sensitive electrodes attached to the participant's skin

Time frame: 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

Time frame: 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

Time frame: 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.

Time frame: 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

Time frame: These values will be obtained at end of the 60 minute heat exposure (90 minutes post cocaine/ lidocaine administration)

Data from ClinicalTrials.gov

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