Bioequivalence and Bioavailability Forum • A boring question about bioavailability?

Darborn
☆

Taiwan,
2024-08-01 11:05
(132 d 19:32 ago)

Posting: # 24118
Views: 2,005

A boring question about bioavailability? [Off Topic]

According to the guideline, "absolute bioavailabiliy" is defined as bioavailability of formulation A compared to formulation B (which is a intravenous formulation), while "relative bioavailability" is defined when formulation B is a non-intravenous formulation.

So here is the question, if two formulation are both intravenous formulation, should I call is absolute BA study or relative BA study? :confused:

Edit: Please follow the Forum’s Policy. [Helmut]

Helmut
★★★

Vienna, Austria,
2024-08-01 14:05
(132 d 16:32 ago)

@ Darborn
Posting: # 24119
Views: 1,704

ƒ of IV = 1 by definition, but…

Post reply

Hi Darbon,

❝ According to the guideline, …

Which guideline are you referring to?

❝ […] if two formulation are both intravenous formulation, should I call is absolute BA study or relative BA study? :confused:

The EMA’s guideline (page 23):

Bioequivalence studies are generally not required if the test product is to be administered as an aqueous intravenous solution containing the same active substance as the currently approved product. However, if any excipients interact with the drug substance (e.g. complex formation), or otherwise affect the disposition of the drug substance, a bioequivalence study is required unless both products contain the same excipients in very similar quantity and it can be adequately justified that any difference in quantity does not affect the pharmacokinetics of the active substance.

If the conditions for waiving are not applicable, call it a comparative BA study.

<nitpick>
- »Bioequivalence study« is a misnomer. Bioequivalence is the desired result of a comparative biovailability study.
  Only Health Canada consistently uses ‘comparative BA’. See also the funky footnote in this article.
</nitpick>

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

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Darborn
☆

Taiwan,
2024-08-01 14:36
(132 d 16:01 ago)

@ Helmut
Posting: # 24120
Views: 1,707

ƒ of IV = 1 by definition, but…

Post reply

Actually it's not about a bioequivalence study or comparative BA study. It's about two intravenous formulations that one of them has longer half-life hence larger exposure. So I'm just bothered by which one of bioavailability fits this situation by definition, absolute or relative.

BTW, the guideline I refer to is FDA's "Bioavailability Studies Submitted in NDAs or INDs — General Considerations", page 3. :-)

Edit: Please follow the Forum’s Policy. Guidance linked. [Helmut]

Helmut
★★★

Vienna, Austria,
2024-08-01 15:43
(132 d 14:54 ago)

@ Darborn
Posting: # 24122
Views: 1,674

IV: Different half-lives?

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Hi Daborn,

it would be nice to say “hello” or similar in the future.

❝ It's about two intravenous formulations that one of them has longer half-life hence larger exposure.

Half-life (based on \(\small{k_\text{el}}\) – or \(\small{CL}\), if you belong to the other church) is a property of the drug. Can you give more details please?

❝ the guideline I refer to is FDA's "Bioavailability Studies Submitted in NDAs or INDs — General Considerations", page 3.

Nothing stated about parenterals in the entire guidance. If you are concerned about the terminology only, use the generic term Comparative Bioavailability Study. Fits to any.

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

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Darborn ☆ Taiwan, 2024-08-02 04:39 (132 d 01:58 ago) @ Helmut Posting: # 24123 Views: 1,618	IV: Different half-lives? Post reply
	Hi Helmut, Forgive me for impoliteness, thinking this just a random talk about this question. It do has a longer half-life, and I'm just trying to find the right terminology (so I put this under "off topic" category . Thank you for patient explanation Darborn

Helmut
★★★

Vienna, Austria,
2024-08-02 09:52
(131 d 20:45 ago)

@ Darborn
Posting: # 24125
Views: 1,634

IV: Liposome encapsuled drug, pegylated biologic?

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Hi Darborn,

❝ It do has a longer half-life, …

I cannot imagine any case where this is possible for a small molecule. Is it a liposome encapsulated¹ drug (doxorubicin, cisplatin, amphotericin B, …) or pegylated² biologic (filgrastim, recombinant factor VIII, …)?

Liu P, Chen G, Zhang J. A Review of Liposomes as a Drug Delivery System: Current Status of Approved Products, Regulatory Environments, and Future Perspectives. Molecules. 2022; 27(4): 1372. Open access doi:10.3390/molecules27041372.
Gao Y, Josh, Zhao Z, Mitragotri S. PEGylated therapeutics in the clinic. Bioeng Transl Med. 2024; 9(1): e10600. doi:10.1002/btm2.10600. Free Full text.

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

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Darborn ☆ Taiwan, 2024-08-06 07:15 (127 d 23:22 ago) @ Helmut Posting: # 24141 Views: 1,428	IV: Liposome encapsuled drug, pegylated biologic? Post reply
	Hi Helmut, It is actual a FDC which the elimination of one drug is interupted by another. So the overall exposure is increased to reduce the administration times per day.