kasi
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2007-02-07 11:52
(6259 d 22:42 ago)

Posting: # 506
Views: 7,625
 

 water while drug admin [Study Per­for­mance]

hello
good afternoon

why we are giving 240 ml of water while administrating the drug.
why we are following physical activity restrictions (2 hours post dose). is this mandatory. is the deviation effect the bioavailability of the drug.
why we are following water restriction (1 hr pre dose and 1 hr post dose).
during water restriction can we allow the subject for urination. if not what is the reason.

thank you

Regards,
Raaz
Helmut
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2007-02-07 12:54
(6259 d 21:40 ago)

@ kasi
Posting: # 507
Views: 6,371
 

 water while drug admin

Dear kasi!

❝ why we are giving 240 ml of water while administrating the drug.


See this post.
The often claimed ‘rationale’ is the size of the American standard cup (8 fluid ounces = ½ pint = 236.5882365 ml), which is assumed to be taken together with the drug. Another mythical connection exists between this volume and the volume used in the BCS (250 ml). People advocating 240 ml are talking about the solubility of the drug, but often forget that:
  • water has a half life of about 10 minutes in the stomach,
  • such a volume may be unrealisticly high in clinical practice (especially for females, elderly,…),
  • AFAIK there is not a single study published (e.g., BE of the same formulation given with 240 ml v.s. 100 ml) supporting such a claim (actually I have seen one – unpublished – study of an ASA-for­mu­lation, where BA was 200% if given with only 50 ml compared to 240 ml).
Many regulations suggest 100 ml - 150 ml instead of 240 ml (see this post)!

❝ why we are following physical activity restrictions (2 hours post dose). is this mandatory. is the deviation effect the bioavailability of the drug.


Physical activity influences
  • gastric motility (→ absorption) and/or
  • hepatic blood flow (→ metabolization).
If you don’t standardize physical activity, you may increase intra-subject variability.

❝ why we are following water restriction (1 hr pre dose and 1 hr post dose).


History? ;-)

❝ during water restriction can we allow the subject for urination. if not what is the reason.


What else. Do you want them to pee their pants?
Once the drug is eliminated into the bladder, it will never be reabsorbed. So why not empty it?

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kasi
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2007-02-14 13:33
(6252 d 21:01 ago)

(edited by HS on 2007-02-14 14:40)
@ Helmut
Posting: # 519
Views: 6,183
 

 water while drug admin

❝ ❝ why we are following water restriction (1 hr pre dose and 1 hr post dose).


❝ History? ;-)


Dear HS
thanks for ur clear clarification.a small request let me know about the history of water restriction, at least brief.

Edit: Full quote removed. [HS]

Regards,
Raaz
Helmut
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2007-02-14 16:11
(6252 d 18:24 ago)

@ kasi
Posting: # 523
Views: 6,303
 

 water while drug admin

Dear kasi!

❝ ❝ ❝ why we are following water restriction (1 hr pre dose and 1 hr post dose).

❝ ❝

❝ ❝ History? ;-)


❝ […] a small request let me know about the history of water restriction, at least brief.


OK, it’s something the FDA likes (which does not conform with many other countries…)
See this post (and followings) for details.

Concerning FDA’s history:
  • Nothing was stated in the July 1992 BE Guideline.
  • The Draft Guideline on Food-Effect Studies (October 1997) stated for the fasted treatments: ‘Following an overnight fast of at least 10 hours, subjects should take the drug product with 180 ml (6 fl oz) of water. […] Water can be allowed ad libitum after 2 hours.’
  • The 1 h before/after restriction appeared first in the October 2000 BE Guideline and was carried over to the 2003 Revision.
It’s reasonable to restrict fluid intake before administration to some extent, because otherwise subjects will more likely develop difficulties getting FDA’s 240ml down their throats…

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