Bioequivalence and Bioavailability Forum

bharathnadh.pharma ☆ India, 2014-01-17 10:48 (4541 d 05:47 ago) Posting: # 12183 Views: 26,221	calculation of Washout period [Regulatives / Guidelines] Post reply
	Dear All, Iam fresher to this field so i would you like to learn basics plese help me in that way. my question Calculation Of Washout Period please explane with exaples. and Time points Also Please Help me sir . Thank you

Dr_Dan
★★

Germany,
2014-01-17 12:48
(4541 d 03:47 ago)

@ bharathnadh.pharma
Posting: # 12184
Views: 24,339

calculation of Washout period

Post reply

Dear bharathnadh.pharma
In a cross-over study the treatment periods should be separated by a wash out period sufficient to ensure that drug concentrations are below the lower limit of bioanalytical quantification in all subjects at the beginning of the second (third etc.) period. Normally at least 5 elimination half-lives are necessary to achieve this.
I hope this helps.
Kind regards
Dan

—
Kind regards and have a nice day
Dr_Dan

Mahesh M ★ India, 2014-01-17 13:26 (4541 d 03:10 ago) @ Dr_Dan Posting: # 12186 Views: 24,058	calculation of Washout period Post reply
	Dear, Its also depands upone Regulatory example US FDA recommended 5 times t 1/2 EMA recommended 10 times t 1/2. and in practice we follow 10 half life to calculate washout period. Regards Mahesh M

jag009 ★★★ NJ, 2014-01-17 18:41 (4540 d 21:54 ago) @ Mahesh M Posting: # 12190 Views: 24,034	calculation of Washout period Post reply
	Hi, One additional comment: Don't just based on the mean, look at the variability as well (SD). John

drgunasakaran1
★★

2014-01-17 18:59
(4540 d 21:36 ago)

@ Mahesh M
Posting: # 12191
Views: 24,066

calculation of Washout period

Post reply

Dear Mr Mahesh,

❝ EMA recommended 10 times t 1/2.

As per EMA BE Guidance "Normally at least 5 elimination half-lives should be provided as Wash out period"
Canadian Guidance states that washout period should be not less than 10 times the mean terminal half-life of the drug.

—
Dr Gunasakaran Sambandan MD
Disclaimer: The replies/posts are my personal opinions, and they do not represent my company's views on the same. LinkedIn

Mahesh M ★ India, 2014-01-20 11:46 (4538 d 04:50 ago) @ drgunasakaran1 Posting: # 12199 Views: 23,826	calculation of Washout period Post reply
	Dear Dr.S.Gunasakaran, ❝ As per EMA BE Guidance "Normally at least 5 elimination half-lives should be provided as Wash out period" ❝ Canadian Guidance states that washout period should be not less than 10 times the mean terminal half-life of the drug. iam sory.. that was mistakenly written due to confusion. Thank you so much sir, Regards Mahesh M

rezowan ☆ 2014-01-23 20:13 (4534 d 20:22 ago) @ drgunasakaran1 Posting: # 12248 Views: 23,763	calculation of Washout period Post reply
	Why washout period is 10 of half life???? please answer me.. Edit: Full quote removed. Please delete everything from the text of the original poster which is not necessary in understanding your answer; see also this post and the Forum’s Policy! [Helmut]

Helmut
★★★

Vienna, Austria,
2014-01-23 20:57
(4534 d 19:38 ago)

@ rezowan
Posting: # 12250
Views: 23,784

Theoretical carry-over

Post reply

Hi rezowan,

❝ Why …

Every regulatory agency is free in their decision to state what in their opinion is “sufficient”. HPFB/TGD wants 10×t_½ (<0.1% of theoretical carry-over), ANVISA 7×t_½ (<1% CO), whereas EMA, FDA, and many others are happy with just 5×t_½ (~3% CO).

❝ … washout period is 10 of half life????

Amount remaining = 2^–x and
amount eliminated = 1 – 2^–x,

where x = multiple of half lives passed.

┌────┬──────────────┬─────────────┐

│  x │ remain. (%)  │ elimin. (%) │

├────┼──────────────┼─────────────┤

│  0 │ 100          │  0          │

│  1 │  50          │ 50          │

│  2 │  25          │ 75          │

│  3 │  12.5        │ 87.5        │

│  4 │   6.25       │ 93.75       │

│  5 │   3.125      │ 96.875      │

│  6 │   1.5625     │ 98.4375     │

│  7 │   0.78125    │ 99.21875    │

│  8 │   0.390625   │ 99.609375   │

│  9 │   0.1953125  │ 99.8046875  │

│ 10 │   0.09765625 │ 99.90234375 │

└────┴──────────────┴─────────────┘

—
Dif-tor heh smusma 🖖🏼 Довге життя Україна!
Helmut Schütz

The quality of responses received is directly proportional to the quality of the question asked. 🚮
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bharathnadh.pharma ☆ India, 2014-01-25 18:33 (4532 d 22:02 ago) @ Helmut Posting: # 12269 Views: 23,641	Theoretical carry-over Post reply
	Thank you very much Mr. Helmut Schütz, I satisfied allot

bharathnadh.pharma
☆

India,
2014-01-18 10:45
(4540 d 05:51 ago)

@ Dr_Dan
Posting: # 12193
Views: 24,001

calculation of Washout period

Post reply

Dear Dr. Dan,

Yes sir it helps to me and here is my own clarification about time points
For example: Drug a having elimination half-life (t1/2) ranged from 8-16 hours and tmax of about 1.5-4 hours. :confused:

Generally we take more than 3 elimination half-life’s so here I took 5.
Half-life=8-16, average 12hrs, 12*5=60hrs based on this I took sample points as shown in below.
0.00, 0.50, 1.00, 1.50, 2.00, 2.50, 3.00, 3.50, 4.00, 4.50, 5.00, 6.00, 8.00, 10.00, 12.00, 16.00, 24.00, 36.00 and 48.00
In these samples up to 4.50 I took half an hour samples because of Tmax.
My calculation is correct are not. Please guide me. :-)

thanks in advance

Edit: Full quote removed. Please delete everything from the text of the original poster which is not necessary in understanding your answer; see also this post! [Helmut]

drgunasakaran1 ★★ 2014-01-18 16:37 (4539 d 23:58 ago) @ bharathnadh.pharma Posting: # 12194 Views: 23,956	calculation of Washout period Post reply
	Dear Mr Bharatnand.pharma, Sampling points seems to be fine. But, it is preferable to go for upper limit of half life (16 hrs) instead of average (12 hrs) while calculating for sampling duration and wash out period. — *Dr Gunasakaran Sambandan MD* Disclaimer: The replies/posts are my personal opinions, and they do not represent my company's views on the same. LinkedIn

bharathnadh.pharma ☆ India, 2014-01-20 06:44 (4538 d 09:51 ago) @ drgunasakaran1 Posting: # 12196 Views: 23,854	calculation of Washout period Post reply
	Dear dr gunasakaran Is there any importance of Tmax while we are taking sample points and please guide me another important key points and precautions about sample time points calculations. Thank you Edit: two posts merged [Ohlbe]

Ohlbe ★★★ France, 2014-01-20 07:37 (4538 d 08:58 ago) @ bharathnadh.pharma Posting: # 12197 Views: 23,891	calculation of Washout period Post reply
	Dear bharathnadh.pharma, Did you look at Helmut's lectures ? — Regards Ohlbe

calculation of Washout period [Regulatives / Guidelines]

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calculation of Washout period

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