Every clinic has a washout period during which you are
not allowed to do a study at the same clinic or any other clinic.
The minimum period is 30 days since last dose, however
some washouts go based on last study procedure (such as out patient
visits or how much blood you gave during the study).
The washout period may vary from study to study depending
half-life of the drug.
Certain studies like radio-labeled drugs will have a 1
year washout before you can do another radio-labeled drug.
In addition to the clinic's washout policy, the sponsor
may impose a longer washout period.
Some studies will have a longer washout before you can
In general, you can sign up and screen for another study
during the washout period as long as the check in date is at least 30
days after your last dose in the previous study. However,
depending on how fast your body recovers from a study, you may want to
wait the full period to avoid problems with screening.
screen too soon after a study typically have lower
red blood cell, hemoglobin,
and iron. If these levels are too low, you
could get banned from participating in studies
because having low levels is unhealthy and unsafe
for participating in a study.
Be forewarned that many
clinic participate in the VCT (Verified Clinical
Trials) program which tracks when you do a study to
ensure the next study meets washout periods. I
do not mention these clinics because it shouldn't
matter. You know the rules and if you break
them, the consequences can be dire like being banned
from a clinic. Sometimes the only way to drive
this message home is to allow people to find out the
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