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Registeridentical pH [Dissolution / BCS / IVIVC]
posted by Helmut 
– Vienna, Austria, 2019-09-10 12:58 (2482 d 20:23 ago) – Posting: # 20571
Views: 13,689
Hi amer,
![[image]](img/uploaded/image485.png)
Dissolution at \(\small{pH\;2}\) is rather unusual. Recall the definition: \(\small{pH=-\log_{10}[\text{H}^{+}]}\), where \(\small{[\text{H}^{+}]}\) is the activity of the \(\small{[\text{H}^{+}]}\) ion. Hence, at \(\small{pH\;2}\) you have \(\small{10^{0.8}\approx6.31\times}\) lower activity of \(\small{[\text{H}^{+}]}\) than at \(\small{pH\;1.2}\). Whether this is relevant, depends on the \(\small{pk_\text{a}}\) of the drug. However, it might lead to wrong conclusions.
Valid predictions based on IVIVC require dissolution at identical pH values. Repeat the exercise at \(\small{pH\;1.2}\).
❝ I have constructed IVIVC using in vivo data and dissolution data done at pH 1.2. if i have a new dissolution data (say done at pH 2), how can i predict the in vivo concentrations based on the new dissolution…
Dissolution at \(\small{pH\;2}\) is rather unusual. Recall the definition: \(\small{pH=-\log_{10}[\text{H}^{+}]}\), where \(\small{[\text{H}^{+}]}\) is the activity of the \(\small{[\text{H}^{+}]}\) ion. Hence, at \(\small{pH\;2}\) you have \(\small{10^{0.8}\approx6.31\times}\) lower activity of \(\small{[\text{H}^{+}]}\) than at \(\small{pH\;1.2}\). Whether this is relevant, depends on the \(\small{pk_\text{a}}\) of the drug. However, it might lead to wrong conclusions.Valid predictions based on IVIVC require dissolution at identical pH values. Repeat the exercise at \(\small{pH\;1.2}\).
—
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Helmut Schütz
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Dif-tor heh smusma 🖖🏼 Довге життя Україна!
Helmut Schütz
The quality of responses received is directly proportional to the quality of the question asked. 🚮
Science Quotes
Complete thread:
- predicting in vivo PK profiles from in vitro data after establishing IVIVC amer 2019-09-09 05:04
![[Mix]](https://static.bebac.at/img/mix.png "open in Mix view")
- external predictability for ivivc yjlee168 2019-09-09 10:46
- external predictability for ivivc amer 2019-09-10 02:31
- identical pHHelmut 2019-09-10 10:58
- identical pH yjlee168 2019-09-10 15:30
- R scripts/codes for in-vivo conc. yjlee168 2019-09-10 15:13
- Software validation, another round Helmut 2019-09-10 15:37
- Deconvolution mittyri 2019-09-10 15:54
- Software validation, another round yjlee168 2019-09-11 10:29
- Software validation, another round Helmut 2019-09-11 13:39
- Software validation, another round amer 2019-09-12 05:26
- Should we also consider to validate the validation? yjlee168 2019-09-12 09:46
- Who inspects the inspectors? Helmut 2019-09-13 12:07
- Who inspects the inspectors? nobody 2019-09-13 12:55
- Sapienti sat Helmut 2019-09-13 12:59
- Who inspects the inspectors? nobody 2019-09-13 12:55
- Who inspects the inspectors? Helmut 2019-09-13 12:07
- Should we also consider to validate the validation? yjlee168 2019-09-12 09:46
- Software validation, another round amer 2019-09-12 05:26
- Software validation, another round Helmut 2019-09-11 13:39
- R scripts/codes for in-vivo conc. amer 2019-09-11 05:35
- Bioavailabity term in predicted in-vivo conc. yjlee168 2019-09-11 10:16
- Software validation, another round Helmut 2019-09-10 15:37
- identical pHHelmut 2019-09-10 10:58
- external predictability for ivivc amer 2019-09-10 02:31
- external predictability for ivivc yjlee168 2019-09-09 10:46
Ing. Helmut Schütz