# NCA with multiple dose

**URL:** <https://forum.certara.com/t/nca-with-multiple-dose/3406>\
**Category:** Phoenix WNL basics\
**Created:** [May 3, 2019, 9:05pm UTC](https://forum.certara.com/t/nca-with-multiple-dose/3406 "2019-05-03T21:05:29Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![autumnlin](https://avatars.discourse-cdn.com/v4/letter/a/da6949/32.png) [@autumnlin](https://forum.certara.com/u/autumnlin)\
**Post date:** [May 3, 2019, 9:05pm UTC](https://forum.certara.com/t/nca-with-multiple-dose/3406/1 "2019-05-03T21:05:29Z")

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Hi all,

I’m running NCA for a project in which the drug is a b.i.d dose.

The PK parameters for AUClast, AUCinf, etc. are different when I include dose data vs. exclude dose data.

I assume AUCs are not related to dosing so should be the same with or without dose data specified. Is my understanding incorrect?

Thanks.

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<div class="post-metadata">

**Author:** ![ana.henry](https://sea1.discourse-cdn.com/certara/user_avatar/forum.certara.com/ana.henry/32/2578_2.png) [@ana.henry](https://forum.certara.com/u/ana.henry)\
**Post date:** [May 3, 2019, 9:18pm UTC](https://forum.certara.com/t/nca-with-multiple-dose/3406/2 "2019-05-03T21:18:07Z")

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Hello,

NCA is not designed to be used with more than one dosing interval. Although AUC should not be different with or without dose, there are some assumptions that are made about dose that could affect your analysis. For example, if you enter a dose, all the data prior to the time of that dose is ignored.

To help you further you might need to post a phoenix project for at least 1 profile.

Hope this helps,

Ana