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Pharmacology · Pharmacokinetics · continued

Coming back to: Time to steady state after a dose increase posts 61–90

This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.

TD
titration_diaryTL325 May 2026#61
AJ
a.jansenTL2 Moderator26 May 2026#62

post #61 answers the question as asked. The question underneath it is different.

Hepatic metabolism: the degree to which each compound is hepatically metabolised versus renally cleared is known but varies. Severe liver disease changes clearance.

0 likes 2mo
GT
g.tanakaTL3Regular28 May 2026#63
r.venkatesan, post #10: Volume of distribution: the theoretical volume the drug distributes into. For albumin-binding compounds, volume is reduced compared to drugs that do not bind protein. That is relevant to understanding how much free drug is available. Go to post

Coming back to post #61, because the follow-up matters more than the original answer.

Renal clearance: these compounds are cleared partly via the kidney. In severe renal impairment, clearance is slowed and accumulation risk is higher. Dose adjustments might be needed.

22 likes in reply to #10 2mo
IG
i.guerreroTL2 Moderator29 May 2026#64

Individual variation: people vary in how quickly they absorb, distribute, metabolise, and excrete these compounds. That variation is partly genetic and partly due to individual biology (gut motility, kidney and liver function). It explains why two people on the same dose have different response magnitudes.

10 likes 2mo
DB
dr_bhattacharyaTL3Physician30 May 2026 · edited#65

Worth separating two things that post #61 runs together.

Half-life: semaglutide ≈ 165–184 hours (about a week). Tirzepatide ≈ 5 days. Liraglutide ≈ 13 hours. The half-life determines how much accumulation happens at steady state and how long it takes to clear after stopping.

3 likes 2mo
DV
d.vukovicTL2 Moderator1 Jun 2026#66

post #65 is right about the mechanism and I think understates the practical bit.

For anyone arriving from a search: the marked solution above is the direct answer, and the replies underneath it add the caveats that make it safe to use.

0 likes 2mo
MD
m.dalgaardTL3Regular2 Jun 2026#67
m.lindqvist, post #17: This follows post #14 rather than contradicting it. I disagree with the reply above, and I think the disagreement is substantive rather than terminological. The distinction being drawn does not survive when you look at the published data for this specific question. I would be glad to be shown wrong on this, because the version I am… Go to post

Half-life: semaglutide ≈ 165–184 hours (about a week). Tirzepatide ≈ 5 days. Liraglutide ≈ 13 hours. The half-life determines how much accumulation happens at steady state and how long it takes to clear after stopping.

30 likes in reply to #17 2mo
RM
r.mensaTL2 Moderator3 Jun 2026#68
a.ilunga, post #3: I read the opening post twice before replying, because I had assumed the opposite. Practical note that does not fit anywhere else. Whatever you conclude from this topic, write down what you did and when. The single most useful thing in your own records is not any individual result; it is that they are dated and consecutive. Go to post

Individual variation: people vary in how quickly they absorb, distribute, metabolise, and excrete these compounds. That variation is partly genetic and partly due to individual biology (gut motility, kidney and liver function). It explains why two people on the same dose have different response magnitudes.

15 likes in reply to #3 2mo
H
HHidalgoTL2Member5 Jun 2026#69

On post #65 — agreed on the reasoning, with one qualification.

Renal clearance: these compounds are cleared partly via the kidney. In severe renal impairment, clearance is slowed and accumulation risk is higher. Dose adjustments might be needed.

5 likes 2mo
EF
e.ferreiraTL3Regular6 Jun 2026#70

Fasting requirement for oral semaglutide: food and large fluid volumes reduce absorption. The fasting window (30 minutes before and 30 minutes after) is designed to maximise absorption. Violating it measurably reduces exposure.

1 like 2mo
MA
m.achebeTL2 Moderator7 Jun 2026#71

Picking up post #68: that is the part I would want checked first.

Thank you for the correction. I have edited my earlier post with a note rather than silently, so the thread still makes sense to read. The error was mine and it was the kind that comes from remembering a figure instead of looking it up.

18 likes 2mo
NP
n.petrovTL2 Moderator9 Jun 2026#72
f.rasmussen, post #53: This follows post #50 rather than contradicting it. Volume of distribution: the theoretical volume the drug distributes into. For albumin-binding compounds, volume is reduced compared to drugs that do not bind protein. That is relevant to understanding how much free drug is available. Go to post

Volume of distribution: the theoretical volume the drug distributes into. For albumin-binding compounds, volume is reduced compared to drugs that do not bind protein. That is relevant to understanding how much free drug is available.

0 likes in reply to #53 2mo
AS
a.silvaTL2 Moderator10 Jun 2026#73

Accumulation at steady state: with a week-long half-life, steady-state concentration is reached around 4 to 5 half-lives (about 4 to 5 weeks). Before that, concentration is rising with each dose. The clinical implication: escalating before 4 weeks means escalating before steady state.

0 likes 2mo
VK
v.krastevTL2 Moderator11 Jun 2026#74

Albumin binding: semaglutide binds albumin through a fatty side chain, which sequesters the free form and extends the half-life. Tirzepatide also has albumin binding (different mechanism) which extends its half-life compared to an unmodified peptide.

4 likes 2mo
SC
so.cardosoTL2 Moderator12 Jun 2026#75

This follows post #72 rather than contradicting it.

Bioavailability: oral semaglutide has low bioavailability (roughly 1%) due to peptide instability. That is why the oral dose (14 mg) is so much larger than the injectable dose. Comparing them by mass is meaningless.

24 likes 2mo
VS
v.sjobergTL2 Moderator14 Jun 2026#76
e.iyer, post #48: Hepatic metabolism: the degree to which each compound is hepatically metabolised versus renally cleared is known but varies. Severe liver disease changes clearance. Go to post

I read post #74 twice before replying, because I had assumed the opposite.

SNAC (the oral bioavailability enhancer): sodium N-(8-[2-hydroxybenzoyl]amino) caprylate transiently raises gastric pH and promotes absorption. Without it, oral bioavailability is too low for clinical use. With it, bioavailability is still variable between people.

0 likes in reply to #48 1mo
BN
b.nilsenTL2 Moderator15 Jun 2026#77

Hepatic metabolism: the degree to which each compound is hepatically metabolised versus renally cleared is known but varies. Severe liver disease changes clearance.

1 like 1mo
SD
s.dziedzicTL2 Moderator16 Jun 2026#78

SNAC (the oral bioavailability enhancer): sodium N-(8-[2-hydroxybenzoyl]amino) caprylate transiently raises gastric pH and promotes absorption. Without it, oral bioavailability is too low for clinical use. With it, bioavailability is still variable between people.

7 likes 1mo
CR
compounding_ruthTL4Pharmacist17 Jun 2026#79
no.silva, post #57: Accumulation at steady state: with a week-long half-life, steady-state concentration is reached around 4 to 5 half-lives (about 4 to 5 weeks). Before that, concentration is rising with each dose. The clinical implication: escalating before 4 weeks means escalating before steady state. Go to post

Fasting requirement for oral semaglutide: food and large fluid volumes reduce absorption. The fasting window (30 minutes before and 30 minutes after) is designed to maximise absorption. Violating it measurably reduces exposure.

32 likes in reply to #57 1mo
HD
h.delgadoTL2 Moderator19 Jun 2026#80
so.cardoso, post #75: This follows post #72 rather than contradicting it. Bioavailability: oral semaglutide has low bioavailability (roughly 1%) due to peptide instability. That is why the oral dose (14 mg) is so much larger than the injectable dose. Comparing them by mass is meaningless. Go to post

Coming back to post #78, because the follow-up matters more than the original answer.

Renal clearance: these compounds are cleared partly via the kidney. In severe renal impairment, clearance is slowed and accumulation risk is higher. Dose adjustments might be needed.

0 likes in reply to #75 1mo
EP
e.piresTL2 Moderator20 Jun 2026#81

Two things before anyone answers the substance.

First, the context in the first post is clear and specific. Second, the question is framed so that an answer can actually address it. Both are the norm here and both matter more than they sound.

5 likes 1mo
AK
a.kowalskiTL2 Moderator21 Jun 2026#82

Accumulation at steady state: with a week-long half-life, steady-state concentration is reached around 4 to 5 half-lives (about 4 to 5 weeks). Before that, concentration is rising with each dose. The clinical implication: escalating before 4 weeks means escalating before steady state.

0 likes 1mo
TW
t.wojcikTL2 Moderator22 Jun 2026#83

Worth separating two things that post #79 runs together.

Hepatic metabolism: the degree to which each compound is hepatically metabolised versus renally cleared is known but varies. Severe liver disease changes clearance.

28 likes 1mo
JD
j.dahlbergTL2 Moderator24 Jun 2026#84
e.pires, post #81: Two things before anyone answers the substance. First, the context in the first post is clear and specific. Second, the question is framed so that an answer can actually address it. Both are the norm here and both matter more than they sound. Go to post

post #83 is right about the mechanism and I think understates the practical bit.

Bioavailability: oral semaglutide has low bioavailability (roughly 1%) due to peptide instability. That is why the oral dose (14 mg) is so much larger than the injectable dose. Comparing them by mass is meaningless.

13 likes in reply to #81 1mo
MS
m.strand_rphTL3Pharmacist25 Jun 2026#85

Volume of distribution: the theoretical volume the drug distributes into. For albumin-binding compounds, volume is reduced compared to drugs that do not bind protein. That is relevant to understanding how much free drug is available.

8 likes 1mo
CO
c.ostergaardTL2 Moderator26 Jun 2026#86

For anyone arriving from a search: the marked solution above is the direct answer, and the replies underneath it add the caveats that make it safe to use.

2 likes 1mo
HS
hana.satoTL4 Moderator27 Jun 2026#87
Staff post. Actions described here are recorded in the public moderation log and may be challenged in Meta.

On post #83 — agreed on the reasoning, with one qualification.

Individual variation: people vary in how quickly they absorb, distribute, metabolise, and excrete these compounds. That variation is partly genetic and partly due to individual biology (gut motility, kidney and liver function). It explains why two people on the same dose have different response magnitudes.

0 likes 30d
FA
f.amankwahTL2 Moderator29 Jun 2026#88
f.danquah, post #7: Coming back to post #5, because the follow-up matters more than the original answer. SNAC (the oral bioavailability enhancer): sodium N-(8-[2-hydroxybenzoyl]amino) caprylate transiently raises gastric pH and promotes absorption. Without it, oral bioavailability is too low for clinical use. With it, bioavailability is still variable… Go to post

Half-life: semaglutide ≈ 165–184 hours (about a week). Tirzepatide ≈ 5 days. Liraglutide ≈ 13 hours. The half-life determines how much accumulation happens at steady state and how long it takes to clear after stopping.

19 likes in reply to #7 29d
KH
ka.haddadTL2 Moderator30 Jun 2026#89

Albumin binding: semaglutide binds albumin through a fatty side chain, which sequesters the free form and extends the half-life. Tirzepatide also has albumin binding (different mechanism) which extends its half-life compared to an unmodified peptide.

0 likes 28d
FA
f.abrahamsenTL2Member1 Jul 2026#90

This follows post #87 rather than contradicting it.

Individual variation: people vary in how quickly they absorb, distribute, metabolise, and excrete these compounds. That variation is partly genetic and partly due to individual biology (gut motility, kidney and liver function). It explains why two people on the same dose have different response magnitudes.

0 likes 27d