Compounds › Verified against primary sources

Dose adjustment for renal function

Where the data exist, the package insert says not to adjust anything — and the real risk sits three sections up, in an item almost nobody reads

Partially approvedVerified against primary sources

Experimental material. Read before using anything from here.

Nothing on this page is a medical recommendation, prescription or treatment plan. It is an organized translation of protocols circulating in research communities and, where it exists, of what published trials tested. The two are marked differently — and they are not equivalent.

Most of the compounds here have no FDA approval for human use. Several are sold labeled "research use only", which means they have not gone through purity, sterility or dosage controls for human consumption. A community-reported dose is not a validated dose: it is what someone reported having done.

Talk to a licensed health professional before considering any of these compounds. If you already use one and feel anything unexpected, seek care — do not wait for the next routine test.

Specific attention for this compound: "No dose adjustment" answers only one question — whether the drug accumulates in a diseased kidney — and not the other, whether the drug can make the kidney worse. The page also brings the trap that catches those who train: creatine, muscle mass and a high-protein diet raise blood creatinine without kidney injury, and the eGFR calculated from it comes out worse than reality. In those cases the right test is cystatin C.

Summary

A page born from a declared gap: the kidney disease page says it provides no dose adjustment, and this one explains why. I extracted section 8.6 directly from the openFDA label endpoint, compound by compound. Semaglutide and tirzepatide: no adjustment, not even in end-stage renal disease, because the pharmacokinetics do not change. Bremelanotide: caution below 30 mL/min/1.73 m². Tesamorelin: the package insert states that pharmacokinetics in renal impairment have not been established — in an FDA-approved peptide. For the other eleven compounds queried, from BPC-157 to Cerebrolysin, the FDA database returned zero labels: there is nothing to adjust because there is nothing to consult. And the finding that reorganizes the reading: the two GLP-1s carry, in the warnings, an item called Acute Kidney Injury from Volume Depletion — the renal risk does not come from the molecule, it comes from vomiting and diarrhea dehydrating whoever keeps taking it.

What this page is — and what it refuses to be

The kidney disease page on this site ends by saying that it does not provide dose adjustment for renal impairment, and that the absence is deliberate. This page is the explanation of that sentence, and it has two uncomfortable halves.

The first: for most of the compounds catalogued here, renal adjustment does not exist because the data do not exist — there is no pharmacokinetic study in diseased kidneys, no agency label, nothing to transcribe. An adjustment table invented by analogy would have the same appearance of authority as the tables on the rest of the site and would be fiction.

The second is more counterintuitive: where the data exist, they almost always say not to adjust anything. Not because the kidney does not matter, but because the thing that hurts the kidney, in those cases, is not the molecule — it is the vomiting. That is written in the same package insert, a few sections above, and almost nobody reads that part.

What the package insert says, literally

I extracted the text directly from the openFDA label endpoint on September 4, 2026. It is not a paraphrase of an article or a summary of a package insert: it is section 8.6 of each label, translated without cuts.

Compound	Product	What the package insert determines	A detail the package insert adds
Semaglutide	Ozempic / Rybelsus	The recommended dose in patients with renal impairment is the same as for those with normal renal function.	Safety was evaluated in a 26-week study with 324 patients with moderate renal impairment (eGFR 30 to 59 mL/min/1.73 m²). In patients with renal impairment including end-stage renal disease, no clinically relevant change in pharmacokinetics was observed
Tirzepatide	Mounjaro	No dose adjustment is recommended for patients with renal impairment.	In people with renal impairment including end-stage renal disease, no change in pharmacokinetics was observed. But the package insert orders monitoring of renal function when initiating or escalating the dose in those with renal impairment who report severe adverse gastrointestinal reactions
Bremelanotide	Vyleesi	No adjustment in mild to moderate renal impairment (eGFR 30–89 mL/min/1.73 m²).	Use with caution in severe renal impairment (eGFR < 30), because these patients may have an increase in the incidence and severity of adverse reactions — nausea and vomiting
Tesamorelin	Egrifta SV	Not established.	The package insert says, in so many words, that the pharmacokinetics of tesamorelin in patients with renal or hepatic impairment have not been established. It is an FDA-approved peptide, with a label in force, and the renal data simply do not exist
Oxytocin	Pitocin	There is no renal impairment section on the label.	The label's specific-populations and clinical-pharmacology fields contain no passage on renal function

"No adjustment" is not the same as "safe to use"

This is where careless reading gets expensive. When the package insert says there is no dose adjustment, it is answering one question: does a diseased kidney make the drug accumulate in the blood? For semaglutide and tirzepatide, the measured answer was no — not even on dialysis.

It is not answering the other question, which is the one that matters: can this drug make my kidney worse? That answer is elsewhere in the same document.

The real risk is three sections above, in the same package insert

The two GLP-1s on this site carry, in the warnings and precautions section, an item with its own name: Acute Kidney Injury from Volume Depletion. The text is practically identical on both labels:

"Acute Kidney Injury from Volume Depletion: monitor renal function in patients reporting adverse reactions that could lead to volume depletion."

Translating the mechanism: the renal risk of these drugs does not come from their being eliminated by the kidney. It comes from nausea, vomiting and diarrhea — which the same package insert lists as common reactions — dehydrating the person to the point where the kidney, which depends on volume to filter, goes into acute failure. Anyone who vomits for three days and keeps the dose because "no adjustment needed in renal impairment" read the wrong section.

That reorganizes the entire practical question. It is not how much to reduce the dose. It is at what point to stop and drink water.

Where there is no package insert, there is nothing

I queried the same openFDA endpoint, on September 4, 2026, looking for any label — from any manufacturer, from any period — for the remaining compounds in this reference. The result is the table below, and it is this page's entire argument.

Compound	Labels in the FDA database	What this means for renal adjustment
Tirzepatide	8	There is a section 8.6 — the data exist and are transcribed above
Semaglutide	5	There is a section 8.6 — the data exist and are transcribed above
Thymosin alpha-1 (thymalfasin)	0	Nothing to consult
Cerebrolysin	0	Nothing to consult
Semax	0	Nothing to consult
Selank	0	Nothing to consult
Sermorelin	0	Nothing to consult
BPC-157	0	Nothing to consult
Epitalon	0	Nothing to consult
Ipamorelin	0	Nothing to consult
GHK-Cu	0	Nothing to consult
Melanotan	0	Nothing to consult

The conclusion that table imposes, and what it does not authorize

There is no published renal adjustment for most of the compounds on this site. It is not that I failed to find it: there is no label, and without a pharmacokinetic study in diseased kidneys there is nothing to derive a number from.
That does not mean they are dangerous to the kidney. Absence of data is not data of harm. Saying "not studied, therefore toxic" is the same reasoning error as "natural, therefore safe", only with the sign flipped.
And it does not mean they are safe. Tesamorelin shows that not even agency approval guarantees the data: it has a label in force in the United States and the label itself declares that the pharmacokinetics in renal impairment have not been established.
What the table authorizes is one sentence only: anyone with reduced renal function who intends to use anything on this list is outside any published reference, and the decision is clinical, individual, with lab results in hand.

Before adjusting anything: is the number you have reliable?

Every renal adjustment table in the world depends on an estimate of the kidney's filtration. That estimate is not measured — it is calculated from blood creatinine, and the calculation has traps that hit this site's audience head-on.

The equation in force is CKD-EPI 2021, published by Inker and colleagues in the New England Journal of Medicine. What is new about it is what was removed: the race correction factor.

The joint task force of the National Kidney Foundation and the American Society of Nephrology published its recommendations in the American Journal of Kidney Diseases in 2021, and there are three. The first is immediate implementation of the creatinine equation refit without the race variable in all laboratories in the United States — because it does not include race in the calculation or in the report, included diversity in its development, is available to any laboratory and has acceptable performance, with consequences that do not disproportionately affect any group. The second is a national effort toward routine use of cystatin C, especially to confirm eGFR in those who have or are at risk of chronic kidney disease, because combining the two markers is more accurate than either one alone. The third is research into new filtration markers.

The trap that catches people who train

Blood creatinine does not come only from the kidney: it comes from muscle. The more muscle mass, the more creatinine circulates — with a perfectly healthy kidney. The same goes for a high-protein diet and for creatine supplementation.

According to PubMed, a systematic review with meta-analysis published in BMC Nephrology gathered 21 studies, of which 12 entered the meta-analysis (177 people in the creatine group and 263 in the controls). The finding: creatine increased serum creatinine in a small, statistically significant way (mean difference 0.07; 95% CI 0.01 to 0.12; p = 0.03) — and produced no statistically significant difference in glomerular filtration rate. The authors' conclusion is that the increase reflects metabolic turnover, not kidney injury.

A caveat about that number, which I record instead of correcting: the published abstract reports the mean difference in µmol/L, a unit in which 0.07 would be a variation with no clinical meaning whatsoever. I do not know whether it is a unit error in the abstract or a genuinely minuscule effect. I reproduce it as published and flag the doubt — I do not fix someone else's number by deduction.

The practical consequence does not depend on that doubt: anyone who lifts weights, eats a lot of protein or takes creatine may receive a report with an eGFR worse than reality. And if someone adjusts a dose based on that report, they adjusted for the wrong reason.

The way out: cystatin C

Cystatin C is a small protein, filtered by the kidney, whose concentration does not depend on muscle mass. A review in the Cleveland Clinic Journal of Medicine from September 2025 is explicit: in athletes or in people using creatine supplements, cystatin C remains unchanged, which ensures a more accurate assessment. It is indicated when altered muscle mass, dietary variation or other conditions compromise the creatinine-based estimate — and the recommendation, in those cases, is the combined CKD-EPI equation with both markers.

And there is a practical criterion published by the National Kidney Foundation itself, which serves as the trigger for ordering the test: cystatin C as a confirmatory test when creatinine-based eGFR falls between 45 and 59 mL/min/1.73 m² with albuminuria below 30 mg/g — the exactly ambiguous range, in which the report does not say whether there is disease.

The reverse also holds: anyone who has lost muscle mass — prolonged hospitalization, cachexia, amputation, spinal cord injury — has low creatinine for lack of muscle, and the calculation returns a renal function better than the real one. In that case the error is more dangerous, because it reassures.

What to do, in order

Know the number before, not after. Creatinine and eGFR by CKD-EPI 2021 are routine, inexpensive tests. Anyone using anything from this site without ever having seen their own eGFR is deciding in the dark by choice, not for lack of access.
If you train hard, eat a lot of protein or take creatine, order cystatin C along with it. Not to get a better number: to get the right number. It may come back worse, too.
Do not stop the workup at a single measurement. Chronic kidney disease is defined by an abnormality that persists for more than three months. A single bad eGFR may be that day's dehydration.
Order albuminuria as well. The amount of albumin in the urine is the other axis of the classification, and it can be abnormal while eGFR is still normal — it is frequently the first sign, and it does not show up in the creatinine test.
With the GLP-1s, the trigger for action is not the eGFR: it is vomiting. Vomiting, diarrhea or low fluid intake for more than one day are the moment to seek whoever prescribed — it is written in the package insert warning, not my interpretation.
Dose adjustment is a clinical act. This page has no table of percentage reduction by eGFR band, and that is not an omission: for most of the compounds here, that table does not exist anywhere, and for those where it does, the published answer is "do not adjust".

What this page is not

This is not guidance to adjust dose on your own, nor to skip adjusting. It is the transcription of what appears on labels and the count of what appears nowhere.
Does not cover hepatic impairment, which is the other elimination route and has its own section (8.7) in the same package inserts — that one is in liver: dose adjustment, and what actually does the damage.
Does not cover interaction with nephrotoxic drugs. Non-steroidal anti-inflammatories, iodinated contrast, some antibiotics and their combination with dehydration are frequent causes of acute kidney injury, and none of that was surveyed here.
Does not replace the Brazilian package insert. What is above is the American label. For what applies in Brazil, the source is the package-insert database — and the GLP-1 page checked against the package insert, on this same site, shows that the two texts diverge on points that matter.

References

This page did not come from the secondary source. The text of each package insert was extracted by me from the openFDA label endpoint (api.fda.gov/drug/label.json), field use_in_specific_populations and warnings_and_cautions, on September 4, 2026, and is transcribed above in literal translation. The count of nonexistent labels came from the same endpoint. The articles cited came from PubMed, with DOI.

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