Bioequivalence and Bioavailability Forum • Unequal washout period

ratnakar1811
★

India,
2014-01-15 09:10
(4547 d 23:30 ago)

Posting: # 12172
Views: 3,483

Unequal washout period [Regulatives / Guidelines]

Dear All,

I would like to have your opinion on the unequal washout period in the following situations:

Four period study with no groups
Two or four period study with multiple groups (2 or 3 groups)

Should there be any concern from regulatory point of view (or statistical concern) if we maintain unequal washout period (but within protocol requirements) between different periods of same study or for different groups of the same study?

As far as I am concern it is immaterial, if we are maintaining sufficient washout period to ensure no carryover effect, your views will be highly appreciated. From the forum I realized that Thai FDA may have concern as it has been mentioned in their guideline to maintain equal washout period between groups? Is there any scientific reason apart from consistency/ standardization?

Best Regards,

Ratnakar

Mahesh M ★ India, 2014-01-15 10:05 (4547 d 22:36 ago) @ ratnakar1811 Posting: # 12173 Views: 2,934	Unequal washout period Post reply
	Dear Mr. Ratnakar The main motto of washout between periods is intended to avoid any carry-over of the prior treatment. Usually washout period is intended to minimize the pre-dose concentrations in pharmacokinetic samples and LOQ of your analytical method. I hope there is no question of unequal washout between two periods. Regards Mahesh M

jag009 ★★★ NJ, 2014-01-15 16:46 (4547 d 15:55 ago) @ ratnakar1811 Posting: # 12175 Views: 2,834	Unequal washout period Post reply
	Hi I did a few studies with unequal washout period (3-way/4-way crossover, 2Ts vs R, 3Ts vs R) for FDA submision studies, no issue. I think as long as you can ensure no carryover then you should be okay. John

ratnakar1811 ★ India, 2014-01-21 11:59 (4541 d 20:41 ago) @ jag009 Posting: # 12212 Views: 2,674	Unequal washout period Post reply
	Dear All, Thanks for the reply, I hope there should not be any issue even if we canduct study in multiple groups with unequal washout period. Best Regards, Ratnakar