Back to the Top
Dear All
I have not come across discussion previosly on exposure of normal
subjects to Xray especially in a bioequivalence studies.
Some subjects participate frequently albeit after a gap of three
months at minimum, some CROs carry out X ray examination once in six
months or year.
My questions are
1. Is there a validity period for X ray like above?
2. Is X ray very essential and FDA inspectors ask for the same? Can
the physician examining the subjects tell about normality based on
results of lab test, chest examination, sounds and murmurs etc.
without conducting chest X ray
3. How effective chest X ray is in achieving its objective of
detecting any abnormality or infection in a case when all other tests
and examinations do not reveal any abnormality
4. How important is it to do X ray from Insurance point of View
5. Is it ethical to expose normal subject to X ray
6. how frequently should X ray be done if really needed.
I hope there is a radiology specialist involved in PK studies in this
group who can give valuable inputs
with regards
Dr.Prashant
Back to the Top
The following message was posted to: PharmPK
Dear All,
As an Investigator, I would like to join in this discussion, which is
going on for a long time among the investigators and I would like to
share my views.
Like Dr. Prashant has asked, we cannot select a volunteer without doing
a Chest X ray (minimum requirement of any Regulatory) based on only the
clinical examination findings, since there are certain diseases which
cannot be detected by clinical examination alone, such as Pneumonia of
initial stages or a latent TB.
But its validity is the questionable part. How long we can use it? Once
in 6 months or 1 year will be fine, with justification in your
SOP/protocol as it will be repeated if the physician feels it necessary
based on the clinical examination just before the start of the study.
This will address the ethical point also, since exposing a human subject
twice a year will be within the minimum exposure level (A radiologist
can share the acceptable minimum radiation level).
And finally, since FDA has not specified about the X ray requirement, we
can avoid the same, provided if we have a sound scientific
justification, which I believe will not be possible considering the
prevalence of so many latent or sub acute infections in our country.
Hope this discussion will yield some useful information and outcome.
Regards
Dr. M. Joseph
Back to the Top
The following message was posted to: PharmPK
Dear Prasant,
have a look at this thread:
http://forum.bebac.at/forum_entry.php?id=198
where also links to previous discussions are given.
best regards,
Helmut
--
Helmut Schuetz
BEBAC
Consultancy Services for Bioequivalence and Bioavailability Studies
Neubaugasse 36/11
1070 Vienna/Austria
tel/fax +43 1 2311746
Web http://BEBAC.at
BE/BA Forum http://forum.bebac.at
Back to the Top
The following message was posted to: PharmPK
Dear Colleagues:
The discussion on the use of X-Ray studies - and for that matter, any
ionizing radiation - is above all one of radiation safety . In the
US - and I presume in most other countries - any use of ionizing
radiation requires IRB and Radiation Safety Committee approvals if
those studies are not done for well established clinical reasons that
are of direct benefit to the patient. The amount of radiation
exposure allowed per calendar quarter and per year is clearly
specified in Radiation Safety regulations.
Having said this, noninvasive imaging studies using ionizing
radiation - nuclear imaging, be it PET, SPECT or planar, X-ray and
CT, can be of tremendous value in drug development and in patient
monitoring, and hence investigators and clinicians should be able to
document in their approval requests to their IRBs and their Radiation
Safety Committees the potential benefits that the information to be
gained from such studies will provide.
As in all procedures, there is a cost/benefit ratio. What are the
positives/negatives of doing a study, as opposed to the positives/
negatives of not doing such a study?
Professor Walter Wolf, Ph.D.
Distinguished Professor of Pharmaceutical Sciences
Director, Pharmacokinetic Imaging Program
Department of Pharmaceutical Sciences, School of Pharmacy
Chair, Biomedical Imaging Science Initiative
University of Southern California
1985 Zonal Ave., Los Angeles, 90089-9121
Tel: 323-442-1405
Fax: 323-442-9804
E-mail: wwolfw.-a-.usc.edu
PLEASE NOTE NEW WEBSITE
http://www.usc.edu/research/initiatives/bisi/
http://www.usc.edu/schools/pharmacy/faculty_directory/detail.php?id=59
Back to the Top
Dear Prashant,
I am not a radiologist. But i have the following comments which may
help:
1. Many CRO's especially international CRO's do not get chest X-ray
done for normal volunteer recruitment for BA/BE studies or clinical
trials. But a lot of CRO's i believe play it safe. In the Indian
context it has to be borne in mind that subjects are usually from the
lower strata of society and they may be exposed to infectious agents
like mycobacteria etc.
2. Imagine a case where a subject is recruited without X-ray. The
subject may be having a clinically silent focus of pulmonary
tuberculosis, which could (probably) have been detected by chest X-
ray. If this subject develops overt TB a few months after the study,
he may sue the CRO. The insurance company on its part may ask for
baseline X-ray to rule out pre-existing disease in such cases. Hence
from the insurance point of view it may be very important to get the
X-ray done, as it adds to our confidence levels.
Off course this is only a hypothetical situation. But the point is
that there are quite a few diseases which can be diagnosed primarily
from an X-ray (in the absence of more advanced tests) and not from
physical examination or blood tests.
3. There should be no ethical issue i believe if it is done
judiciously and not more often than once in 6 months. For subjects
who come for the studies very often, the duration may be extended
beyond 6 months, taking into consideration the subjects' living
conditions and general hygeine.
4. There is no FDA guidance that i have come across, which mandates
chest X-ray to confirm that a volunteer is normal. But there is
radiation exposure limit set by the RDRC. This says that the limit
for general public is 1mSv (annually) which is equivalent to 50 chest
X-rays (each chest X-ray causes radiation exposure of 0.02 mSv). So
there should be no regulatory issues i suppose.
Hope this helps.
Regards
Dr Srinivas Sidgiddi
Clinical Development
Discovery Research
Dr Reddy's Laboratories Ltd.,
Bollaram Road, Miyapur
Hyderabad - 500049
Ph: 040 2304 5439 Ext. 145
|
Want to post a follow-up message on this topic?
If this link does not work with your browser send a follow-up message to PharmPK@boomer.org with "X ray" as the subject | Support PharmPK by using the |
Copyright 1995-2011 David W. A. Bourne (david@boomer.org)