Tirzepatide in Costa Rica: what it is, what the studies measured, and what to check in the vial
· Novatheris
Anyone searching for tirzepatide in Costa Rica tends to find two things: big promises and few sources. This article goes the other way. What the molecule is, what the published trials measured, which questions are still open, and what to check in a vial before using it in a research project.
Everything below comes from published, linked studies. If a figure is not in a study, you will not find it here.
What tirzepatide is
Tirzepatide is a single peptide that activates two receptors at once: the GIP receptor and the GLP-1 receptor. Both are hormones the gut releases after a meal.
Its backbone comes from the GIP sequence. It carries one key change: a 20-carbon fatty-acid chain that binds albumin, the most abundant protein in blood. That binding slows elimination, so the molecule lasts about a week in the body.
That is why it is called a dual agonist. Agonist means it switches the receptor on, the same way the natural hormone would.
The chemistry in short
These are the identity data worth keeping in a lab notebook:
- Formula: C225 H348 N48 O68.
- Molecular weight: 4813.53 Da.
- Sequence: based on GIP, with Aib at positions 2 and 13, a C-terminal amide, and lysine 20 attached to eicosanedioic acid through a spacer.
- Elimination half-life in humans: about 5 days, according to the drug's label.
- Half-life in animals: no published figure found.
- CAS: 2023788-19-2.
The molecular weight matters more than it seems. It is one of the things a lab report confirms when it says the vial contains the right peptide.
What the published studies measured
Tirzepatide is one of the molecules with the most large trials behind it. These are the four we use as the basis of the product's fact sheet.
SURMOUNT-1. A phase 3 trial with 2539 adults with obesity or overweight and without diabetes, over 72 weeks. It reported mean weight change of -15.0 %, -19.5 % and -20.9 % depending on dose, versus -3.1 % with placebo. You can read it in Jastreboff et al., N Engl J Med 2022.
SURPASS-2. An open-label phase 3 trial with 1879 adults with type 2 diabetes, over 40 weeks, comparing tirzepatide with semaglutide. It is in Frías et al., N Engl J Med 2021.
SURMOUNT-5. The only published head-to-head obesity trial against semaglutide: 751 adults without diabetes, 72 weeks. It measured mean weight change of -20.2 % with tirzepatide and -13.7 % with semaglutide. It is in Aronne et al., N Engl J Med 2025.
SURMOUNT-4. A withdrawal trial. After 36 weeks of open-label treatment, 670 participants were randomized to continue or switch to placebo for another 52 weeks. It is in Aronne et al., JAMA 2024.
Be careful with how these figures are read. They are averages from large groups, in people followed by physicians inside a protocol. They do not describe what will happen in any single case, and they are not a usage guide.
What the studies still do not answer
This part almost never shows up on pages that sell peptides. For us it is the most useful one.
What happens on discontinuation. In SURMOUNT-4, those switched to placebo regained 14.0 % of body weight over the next 52 weeks. Those who stayed on tirzepatide lost another 5.5 %. Only 16.6 % of those who stopped kept at least 80 % of what they had lost, versus 89.5 % of those who continued.
Lean mass. The SURMOUNT-1 body composition substudy measured DXA in only 160 of the 2539 participants. There, lean mass fell 10.9 % and fat mass 33.9 %. About a quarter of the weight lost was lean mass, the same proportion as in the placebo group. It is a post hoc analysis in a small part of the trial. It was published by Look et al. in Diabetes Obes Metab 2025.
Physical function. A 2026 systematic review pooled 35 studies on body composition with this class of molecules. None measured strength, gait, or the ability to stand up from a chair. It is known how much tissue is lost, not what happens to function. It is the review by Batsis et al. in Ann Intern Med 2026.
The comparison with semaglutide. SURMOUNT-5 was open-label: participants and investigators knew who received what. And it lasts 72 weeks. There is no blinded or longer comparison between the two.
Tirzepatide in Costa Rica: what to check in the vial
A vial of white powder looks the same whatever is inside. That is why the label alone is not enough. What gives real information is the lab report for that batch.
When you look at a tirzepatide vial, check three things:
- That the report comes from an independent lab, not from the seller.
- That it states the measured purity and confirms the identity of the peptide.
- That it matches the batch and the strength of the vial in your hand, not another product.
At Novatheris every batch is sent for analysis to Janoshik or Freedom Diagnostics, and we publish the full report. The purity we require is +99.5 %. You can see the tirzepatide one on its lab report page.
Delivery inside Costa Rica takes 2 hours in the GAM (the Greater Metropolitan Area around San José) and 24 hours in the rest of the country.
How it is stored
Tirzepatide as a powder, or lyophilized (freeze-dried), is stored at -20 °C, where it is stable. Once reconstituted, it goes at 2 to 8 °C and only for the short term.
Before opening a vial that comes out of the freezer, let it reach room temperature with the cap closed. That keeps warm air from condensing water inside.
For research, not personal use
The tirzepatide we sell is a research reagent. It is not a medicine, it comes with no directions for use, and we do not give doses. The trials cited above worked under medical supervision and closed protocols, and outside that context there is no established dose.
If your project needs tirzepatide, its product page has the full fact sheet with every citation, and the lab report is one tap away. If you work with the three-peptide combination, there is also the tirzepatide kit.