CompletedNCT00426010Updated Dec 13, 2011

Measuring Placebo Effect by Elimination and Investigating Mechanism of Action

An interventional study of caffeine/placebo in Placebo Effect and Placebo Mechanisms of Action, sponsored by King Faisal Specialist Hospital & Research Center. Completed at 1 site in Saudi Arabia. Open to participants aged 18 Years to 40 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2011-12-13.

Sponsored by King Faisal Specialist Hospital & Research Center · Not applicable, Interventional, and Treatment

Phase: Not applicable
Study type: Interventional
Enrollment: 180
Allocation: Randomized
Ages: 18 Years to 40 Years
Sex: All

Study 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.

Read the 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.

Conditions studied

Placebo Effect
Placebo Mechanisms of Action

Keywords

Placebo effect
Caffeine
Systolic BP
VAS

In context

Lead sponsor

King Faisal Specialist Hospital & Research Center is the lead sponsor of 98 studies on the registry; 18 are open to participants now.

Counted across the registry records on this site, refreshed daily.

Who can participate

Ages eligible: 18 Years to 40 Years
Sexes eligible: All
Accepts healthy volunteers: Yes

Inclusion criteria

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

Exclusion criteria

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

Study design

Phase: Not applicable
Primary purpose: Treatment
Allocation: Randomized
Intervention model: Crossover assignment
Masking: Triple (Participant, Care provider, Outcomes assessor)
Enrollment: 180 participants (estimated)

Study arms

Active comparator
1
overt then covert caffeine
Drug: caffeine/placebo
Active comparator
2
covert then overt caffeine
Drug: caffeine/placebo
Active comparator
3
overt then covert placebo
Drug: caffeine/placebo
Active comparator
4
covert then overt placebo
Drug: caffeine/placebo

Interventions

Drugcaffeine/placebo
caffeine or placebo, either overt or covert

What researchers measure

Primary outcomes

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

Secondary outcomes

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

Study locations

1 site

Center for Clinical Studies & Empirical Ethics, KFSH & RC
Riyadh, 11211, Saudi Arabia

References and documents

Publications

Hammami MM, Al-Gaai EA, Alvi S, Hammami MB. Interaction between drug and placebo effects: a cross-over balanced placebo design trial. Trials. 2010 Nov 19;11:110. doi: 10.1186/1745-6215-11-110. PubMed 21092089 ↗

Updates

Tracking since Sep 25, 2026

No changes since tracking began. The registry record was last updated on Dec 13, 2011, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗

Registry details

Key details

Study ID: NCT00426010
Lead sponsor: King Faisal Specialist Hospital & Research Center
Collaborators: King AbdulAziz City for Science and Technology
First posted: Jan 24, 2007
Start date: Jan 2007
Primary completion: Feb 2009
Completion: Feb 2009
Last update: Dec 13, 2011

Study contacts

Muhammad M Hammami, MD, PhD

principal investigator · KFSH & RC, Riyadh

View the source record on ClinicalTrials.gov ↗

Not currently enrolling

This study is completed, as verified in Dec 2011. You cannot join it, but the record below documents what was studied.

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