Measuring Placebo Effect by Elimination and Investigating Mechanism of Action

Not Applicable

Completed

• Conditions: Placebo Effect; Placebo Mechanisms of Action
• Interventions: Drug: caffeine/placebo

• Registration Number: NCT00426010
• Lead Sponsor: King Faisal Specialist Hospital & Research Center

Brief Summary

We propose to measure the effect of placebo by elimination as well as by a "balanced placebo" design, determine its interaction with active drug, and explore whether placebo exerts part of its effect at the pharmacokinetics level.

Detailed Description

Placebos have been in use for centuries in medical practice. However, there is continued controversy regarding their effectiveness and mechanisms of action.

The results of the study are expected to further our understanding of a widely used medical intervention, i.e., placebo, and of how to maximize its potential beneficial effect. It will also help assess the appropriateness of measuring the placebo effect by elimination, which has important ethical implications in relation to the design of randomized clinical trials.

Comparison: caffeine vs placebo. Dependent variables:4 hours area under the curve (AUC) of pharmacodynamics endpoints as well as pharmacokinetics endpoints in a subgroup.

Study Timeline

• Study Start: 2007-01
• Study First Submitted: 2007-01-23
• Study First Submitted QC: 2007-01-23
• Study First Posted: 2007-01-24
• Primary Completion: 2009-02
• Study Completion: 2009-02
• Status Verified: 2011-12
• Last Update Submitted: 2011-12-11
• Last Update Posted: 2011-12-13

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 180

Inclusion Criteria

• Males and nonpregnant females 18 and 40 years of age with at least high school education.

Exclusion criteria:

• Include evidence of clinically relevant deviation from normal health (such that it may affect the endpoints, make the ingestion of caffeine dangerous, or affect the pharmacokinetics/pharmacodynamics of caffeine),
• Pregnancy,
• Poor venous access,
• Hypertension (more than 140/90),
• Heart disease,
• History of panic attacks,
• Average daily caffeine consumption of more than 300 or less than 100 mg,
• Smoking,
• Alcohol abuse,
• Taking any medication other than birth control bills (including over-the-counter drugs) within one week from starting the study,
• Hypersensitivity to caffeine or related compounds,
• Hemoglobin of less than 13 gm/L, and recent (one week) acute illness

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Exclusion Criteria

Not provided

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Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
1	caffeine/placebo	overt then covert caffeine
2	caffeine/placebo	covert then overt caffeine
3	caffeine/placebo	overt then covert placebo
4	caffeine/placebo	covert then overt placebo

Primary Outcome Measures

Name	Time	Method
4 hours area under the curve (AUC) of peripheral systolic blood pressure	4 hours
4 hours area under the curve (AUC) of energy level measured by Visual Analogue Scales.	4 hours
4 hours area under the curve (AUC) of alertness level measured by Visual Analogue Scales.	4 hours
4 hours area under the curve (AUC) of nausea measured by Visual Analogue Scales.	4 hours

Secondary Outcome Measures

Name	Time	Method
Cmax of serum caffeine (in a subgroup)	4 hours
Tmax of serum caffeine (in a subgroup)	4 hours
t1/2 of serum caffeine (in a subgroup)	14 hours
AUC of serum caffeine (in a subgroup)	14 hours

Trial Locations

Locations (1)

Center for Clinical Studies & Empirical Ethics, KFSH & RC; 🇸🇦 Riyadh, Saudi Arabia