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Practice · Dosing & titration · continued

Splitting a weekly dose in two: the pharmacokinetic argument against — the long version posts 91–120

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

NS
n.serranoTL2 Moderator9 Jul 2024 · edited#91

Coming back to post #89, because the follow-up matters more than the original answer.

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.

1 like 2.1y
RM
r.marsdenTL3Regular9 Jul 2024#92

Picking up post #89: that is the part I would want checked first.

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.

0 likes 2.1y
FF
f.fontaineTL2 Moderator9 Jul 2024#93
g.radich, post #85: 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

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.

22 likes in reply to #85 2.1y
GV
g.valckenaereTL3Regular9 Jul 2024#94

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.

10 likes 2.1y
KO
k.okaforTL2 Moderator9 Jul 2024#95

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.

0 likes 2.1y
B
BBramleyTL3Regular9 Jul 2024#96

This follows post #93 rather than contradicting it.

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.

30 likes 2.1y
GE
g.ekstromTL2 Moderator9 Jul 2024#97
a.norgaard, post #78: 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. Go to post

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.

15 likes in reply to #78 2.1y
L
LeitermanTL3Regular9 Jul 2024#98
n.lehtinen, post #57: 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… 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.

6 likes in reply to #57 2.1y
JI
j.ivaturiTL2 Moderator9 Jul 2024#99

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.

5 likes 2.1y
RH
revision_historyTL3Wiki editor9 Jul 2024 · edited#100
n.marsden, post #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. 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.

0 likes in reply to #35 2.1y
ED
e.dalgleishTL3Regular9 Jul 2024#101
steady_state, post #2: 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

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.

8 likes in reply to #2 2.1y
RI
r.ilungaTL2 Moderator9 Jul 2024#102

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.

2 likes 2.1y
D
DOdendaalTL3Regular9 Jul 2024#103

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.

0 likes 2.1y
BT
b.teixeiraTL2 Moderator9 Jul 2024#104

Picking up post #101: that is the part I would want checked first.

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.

27 likes 2.1y
M
MJayawardenaTL3Regular9 Jul 2024 · edited#105
k.okafor, post #95: 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. Go to post

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.

5 likes in reply to #95 2.1y
NZ
n.zielinskiTL2 Moderator9 Jul 2024#106
f.novak, post #72: 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. Go to post

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.

0 likes in reply to #72 2y
O
OTeixeiraTL3Regular9 Jul 2024#107

I read post #105 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.

0 likes 2y
DN
d.nilsenTL2 Moderator9 Jul 2024#108

This follows post #105 rather than contradicting it.

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.

20 likes 2y
BJ
b.jankowiakTL3Regular10 Jul 2024#109

On post #105 — agreed on the reasoning, with one qualification.

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.

19 likes 2y
RM
r.mensahTL2 Moderator10 Jul 2024#110

post #109 answers the question as asked. The question underneath it is different.

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.

8 likes 2y
QZ
q.zhao_qaTL3Quality assurance10 Jul 2024 · edited#111

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.

14 likes 2y
RL
r.lundgrenTL2 Moderator10 Jul 2024#112
h.fonseca, post #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… Go to post

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.

29 likes in reply to #41 2y
FP
forest_plotTL3Evidence synthesis10 Jul 2024#113

post #112 answers the question as asked. The question underneath it is different.

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.

0 likes 2y
SA
s.antonsenTL2 Moderator10 Jul 2024#114

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.

2 likes 2y
BI
blank_injectionTL210 Jul 2024#115
NV
n.villalobosTL2 Moderator10 Jul 2024#116
y.asante, post #30: Coming back to post #28, because the follow-up matters more than the original answer. 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… Go to post

I read post #114 twice before replying, because I had assumed the opposite.

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.

21 likes in reply to #30 2y
MS
m.strand_rphTL3Pharmacist10 Jul 2024#117

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.

0 likes 2y
HB
h.bakkerTL2 Moderator10 Jul 2024#118

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.

1 like 2y
KR
k.redgraveTL2Member10 Jul 2024#119

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.

28 likes 2y
SI
s.ivaturiTL2 Moderator10 Jul 2024#120

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.

0 likes 2y