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Practice · Dosing & titration · continued

Splitting a weekly dose in two: the pharmacokinetic argument against — the long version posts 31–60

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

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fr.translation_moTL2Translator · FR7 Jul 2024#31

When a dose reduction is the correct response to a side effect: if a side effect is dose-dependent (nausea, constipation, injection discomfort), reducing the dose is a reasonable response. If the side effect is not dose-dependent (e.g., hypoglycemia with insulin), dose reduction does not address the issue.

1 like 2.1y
AT
a.teixeiraTL2 Moderator7 Jul 2024#32

How the published trials escalated: they used specific step sizes and intervals. The STEP programme used a particular cadence; the SURPASS and SURMOUNT programmes used slightly different ones. Reading them side by side shows the variation is real but small.

0 likes 2.1y
AL
aliquot_lineTL3Regular7 Jul 2024#33
il.dumitru, post #17: Splitting a weekly dose in two: the pharmacokinetic argument against is that you want the benefit of long half-life, which gives a slowly changing plasma level from a weekly dosing schedule. Splitting it flattens the curve further but loses the convenience of once-weekly dosing. The trade-off is convenience versus a slightly flatter… Go to post

Coming back to post #31, because the follow-up matters more than the original answer.

The four-week escalation interval is a convention from the pivotal trials, not a pharmacological constant. The pharmacological argument is that with a week-long half-life, four weeks approaches steady state and you can assess the dose fairly. That is an argument for not going faster. It is not an argument against going slower.

17 likes in reply to #17 2.1y
EN
e.nilsenTL2 Moderator7 Jul 2024 · edited#34
cohort_watch, post #10: 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

Picking up post #31: that is the part I would want checked first.

Micro-titration: the concept of increments smaller than the labelled steps. It has no evidence base from trials but is described by some people. The downside is that very small increments are hard to measure accurately with a syringe.

7 likes in reply to #10 2.1y
NM
n.marsdenTL1Member7 Jul 2024#35

Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing.

The correction was fair and I had been repeating something I had not checked carefully enough.

3 likes 2.1y
VS
v.stanescuTL2 Moderator7 Jul 2024#36

post #35 is right about the mechanism and I think understates the practical bit.

Steady state means the plasma concentration is stable from dose to dose. That happens around 4 to 5 half-lives. Before that, the concentration is rising with each dose. Escalating before steady state means escalating on incomplete information about the dose you are on.

0 likes 2.1y
GD
glossary_deskTL3Regular7 Jul 2024#37

I read post #35 twice before replying, because I had assumed the opposite.

The arithmetic of an intermediate dose: if the label says 1.0 mg and 2.0 mg, a dose strictly between them is off-label by definition. Some people compute it anyway. The reasoning is pharmacological — e.g., "I will split the difference between steps" — but it is reasoning from theory, not from evidence.

24 likes 2.1y
AV
a.vestergaardTL2 Moderator7 Jul 2024#38
g.haaland, post #16: Titrating on tolerability rather than on the calendar: some people escalate when they tolerate a dose well, others escalate on the prescribed schedule regardless. The published trials used a calendar-based schedule. Tolerability-based escalation has no formal evidence base but is not uncommon in practice. Go to post

Stepping down deliberately: the withdrawal trials show that stopping is followed by regain. The step-down literature is thinner. The conservative assumption is that stepping down is followed by some regain, with the magnitude unknown.

11 likes in reply to #16 2.1y
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preregisteredTL37 Jul 2024#39
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j.vogelTL2 Moderator7 Jul 2024#40
i.boateng, post #3: Dose equivalence between different incretin analogues is a weak concept. The molecules differ in structure, half-life, receptor selectivity, and in what has been studied clinically. One mg of semaglutide is not equivalent to one mg of something else in any meaningful sense. Go to post

post #39 answers the question as asked. The question underneath it is different.

Dose equivalence between different incretin analogues is a weak concept. The molecules differ in structure, half-life, receptor selectivity, and in what has been studied clinically. One mg of semaglutide is not equivalent to one mg of something else in any meaningful sense.

1 like in reply to #3 2.1y
HF
h.fonsecaTL2 Moderator7 Jul 2024 · edited#41

Splitting a weekly dose in two: the pharmacokinetic argument against is that you want the benefit of long half-life, which gives a slowly changing plasma level from a weekly dosing schedule. Splitting it flattens the curve further but loses the convenience of once-weekly dosing. The trade-off is convenience versus a slightly flatter concentration curve.

22 likes 2.1y
TI
trough_indexTL3Regular7 Jul 2024#42
a.salcedo, post #20: Picking up post #17: that is the part I would want checked first. 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. Go to post

On post #38 — agreed on the reasoning, with one qualification.

Titrating on tolerability rather than on the calendar: some people escalate when they tolerate a dose well, others escalate on the prescribed schedule regardless. The published trials used a calendar-based schedule. Tolerability-based escalation has no formal evidence base but is not uncommon in practice.

0 likes in reply to #20 2.1y
EM
e.mwangiTL2 Moderator7 Jul 2024#43

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.

1 like 2.1y
HK
h.koodziejTL2Member8 Jul 2024#44

Reaching a dose and staying there for a year: the question of whether a stable dose remains effective over years is mostly answered by the withdrawal trials and by real-world reports. The dose does not seem to stop working, but the longest trials are not indefinitely long.

6 likes 2.1y
SL
s.lundgrenTL2 Moderator8 Jul 2024#45
g.haaland, post #16: Titrating on tolerability rather than on the calendar: some people escalate when they tolerate a dose well, others escalate on the prescribed schedule regardless. The published trials used a calendar-based schedule. Tolerability-based escalation has no formal evidence base but is not uncommon in practice. Go to post

post #44 is right about the mechanism and I think understates the practical bit.

Dose equivalence between different incretin analogues is a weak concept. The molecules differ in structure, half-life, receptor selectivity, and in what has been studied clinically. One mg of semaglutide is not equivalent to one mg of something else in any meaningful sense.

30 likes in reply to #16 2.1y
VM
v.milanoviTL38 Jul 2024#46
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ne.laurentTL2 Moderator8 Jul 2024#47

Titrating on tolerability rather than on the calendar: some people escalate when they tolerate a dose well, others escalate on the prescribed schedule regardless. The published trials used a calendar-based schedule. Tolerability-based escalation has no formal evidence base but is not uncommon in practice.

3 likes 2.1y
NB
n.bridgewaterTL2Member8 Jul 2024#48

Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing.

The correction was fair and I had been repeating something I had not checked carefully enough.

10 likes 2.1y
NK
n.kirchnerTL2 Moderator8 Jul 2024#49
s.cabrera, post #22: Reaching a dose and staying there for a year: the question of whether a stable dose remains effective over years is mostly answered by the withdrawal trials and by real-world reports. The dose does not seem to stop working, but the longest trials are not indefinitely long. Go to post

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 in reply to #22 2.1y
IT
integrator_traceTL2Member8 Jul 2024#50

When a dose reduction is the correct response to a side effect: if a side effect is dose-dependent (nausea, constipation, injection discomfort), reducing the dose is a reasonable response. If the side effect is not dose-dependent (e.g., hypoglycemia with insulin), dose reduction does not address the issue.

1 like 2.1y
VS
v.szaboTL3Analytical chemist8 Jul 2024#51

I read post #49 twice before replying, because I had assumed the opposite.

Reaching a dose and staying there for a year: the question of whether a stable dose remains effective over years is mostly answered by the withdrawal trials and by real-world reports. The dose does not seem to stop working, but the longest trials are not indefinitely long.

2 likes 2.1y
HV
h.vargaTL2 Moderator8 Jul 2024#52

How the published trials escalated: they used specific step sizes and intervals. The STEP programme used a particular cadence; the SURPASS and SURMOUNT programmes used slightly different ones. Reading them side by side shows the variation is real but small.

0 likes 2.1y
DO
d.oyelaranTL3Pharmacist8 Jul 2024#53

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.

27 likes 2.1y
KL
k.laurentTL28 Jul 2024#54
K
KLindqvistTL4 Moderator8 Jul 2024#55
Staff post. Actions described here are recorded in the public moderation log and may be challenged in Meta.

The four-week escalation interval is a convention from the pivotal trials, not a pharmacological constant. The pharmacological argument is that with a week-long half-life, four weeks approaches steady state and you can assess the dose fairly. That is an argument for not going faster. It is not an argument against going slower.

4 likes 2.1y
AI
a.ibarraTL2 Moderator8 Jul 2024#56

Steady state means the plasma concentration is stable from dose to dose. That happens around 4 to 5 half-lives. Before that, the concentration is rising with each dose. Escalating before steady state means escalating on incomplete information about the dose you are on.

0 likes 2.1y
NL
n.lehtinenTL2 Moderator8 Jul 2024#57
h.koodziej, post #44: Reaching a dose and staying there for a year: the question of whether a stable dose remains effective over years is mostly answered by the withdrawal trials and by real-world reports. The dose does not seem to stop working, but the longest trials are not indefinitely long. Go to post

On post #53 — agreed on the reasoning, with one qualification.

Holding a dose indefinitely: the trials did not study indefinite holding at a non-maximum dose. The trials escalated to a target and then held that. What happens if you stay at an intermediate dose for years is not formally studied and extrapolation is the best available reasoning.

0 likes in reply to #44 2.1y
LD
l.dziedzicTL2 Moderator8 Jul 2024#58
a.teixeira, post #32: How the published trials escalated: they used specific step sizes and intervals. The STEP programme used a particular cadence; the SURPASS and SURMOUNT programmes used slightly different ones. Reading them side by side shows the variation is real but small. Go to post

post #57 answers the question as asked. The question underneath it is different.

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.

19 likes in reply to #32 2.1y
KR
k.roosTL2 Moderator8 Jul 2024#59

The arithmetic of an intermediate dose: if the label says 1.0 mg and 2.0 mg, a dose strictly between them is off-label by definition. Some people compute it anyway. The reasoning is pharmacological — e.g., "I will split the difference between steps" — but it is reasoning from theory, not from evidence.

8 likes 2.1y
AW
a.weissTL2 Moderator8 Jul 2024#60

This follows post #57 rather than contradicting it.

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 2.1y