Factors That Affect the Stability of the Clinical Trial Design

Clinical trials often focus on drug therapies and the potential effectiveness of new compounds. As they go through the process, physicians and scientists must do everything possible to keep all the factors similar. Isolating the change so that it is only the drug gives more accurate and repeatable results. If there are multiple "x" factors, no definitive outcome is possible. In such cases, the scientist cannot confidently state that the drug was the catalyst for the change.

Temperature

• Keeping the medication at the appropriate temperature ensures the safety of the chemical compound. Doctors are concerned not only with the storage temperature of the drug, but also with its temperature at administration. During clinical trials, a standard is set for the temperature of the drug and accompanying fluids when the drug is given to the test subject. This provides a uniform scale when measuring the results. Additional trials or sub-trials can test how temperature affects the drug, but only after a baseline is established. The overall design calls for consistency.

Light

• Just as light can fade the paint on a car, it can change the chemical effectiveness of drug compounds. Trials involve new compounds, so the goal is typically to limit light exposure at first. After the drug has been tested, exposure to light is tested as well. Some drugs still require complete darkness. Medications like "nitro," used for heart attack victims, are kept in smoky, black glass vials because the drug has been proved to be more effective when its exposure to light is limited.

Age, Sex, Race

• In order to keep a trial stable, it is often preferable to report results on particular portions of the population. An initial trial will include a cross-section of the population. As the trial continues, subjects will be narrowed to verify the validity of the results in different groups. This allows clinicians to verify that the drug works the same with the body chemistry of many types of people. For instance, African-Americans sometimes respond differently to drugs if they carry the sickle cell gene. According to the Human Genome Project, one in 12 African-Americans carry the sickle cell trait. Psychotropic and antipsychotic drugs are often not recommended for children because of the inability to test those under 18. Their changing brain chemistry can introduce unforeseen reactions and problems with mind-altering medications. Women are given separate heart disease trials because they respond differently to medications and even present different symptoms from men. All of these factors can affect the stability of a trial.

Patient Compliance

• The biggest "x" factor in the stability of a drug trial comes from patient compliance. As with any treatment, if a patient does not follow instructions, it can affect the outcome of the trial. Because you cannot lock up a patient and force him to comply, you must hope that the patient follows orders. The use of other medications, alcohol and activity level can all affect how the drug works with the body. While these factors can be tested in later trials, it is important to remove their impact from the initial testing. Such variables can make the drug harmful, more effective or less effective. With no way of knowing what caused the change, the trial would be deemed unstable.