Tirzepatide is a research peptide studied — and, as Mounjaro and Zepbound, clinically approved — as a once-weekly injection for weight and metabolic outcomes. It is a "dual agonist": it acts on two hormone pathways at once, GLP-1 and GIP. In plain English, that means it can reduce appetite and help the body handle blood sugar and stored fuel at the same time.

This guide covers the typical research-protocol structure: the 2.5 mg start, the slow titration up to 15 mg, how to reconstitute the vial, how to plan supplies, and what the SURPASS and SURMOUNT trial data show. It is an educational reference. It is not medical advice and not a personal treatment plan.

The tirzepatide dosing protocol is a slow climb, not a dose to jump into. The label starting dose is 2.5 mg once weekly, which is treated as an initiation dose rather than a therapeutic one. The dose then steps up by 2.5 mg every 4 weeks so the body can adjust before higher doses are reached.

Standard Titration (SURPASS / SURMOUNT)

Phase	Weeks	Weekly Dose	Notes
Initiation	Weeks 1–4	2.5 mg	Starting dose. The goal is tolerance, not results.
First step	Weeks 5–8	5 mg	First therapeutic dose. GI effects (nausea) may begin.
Escalation	Weeks 9–12	7.5 mg	Appetite suppression usually becomes noticeable.
Escalation	Weeks 13–16	10 mg	Common maintenance dose for many participants.
Escalation	Weeks 17–20	12.5 mg	Higher maintenance dose.
Maximum	Weeks 21+	15 mg	Maximum studied dose. ~22.5% mean weight loss at 72 weeks (SURMOUNT-1).

Plan based on the once-weekly schedule above, using LA LAB's 30 mg vial reconstituted with 3.0 mL bacteriostatic water (10 mg/mL). The standard climb is 2.5→5→7.5→10→12.5→15 mg weekly.

Peptide Vials — 30 mg Vial (3 mL BAC)

Cycle Length	Planning Note
8 weeks	2.5 mg + 5 mg phases = 30 mg total — one 30 mg vial.
12 weeks	Through the 7.5 mg phase ≈ 60 mg total — 2 × 30 mg vials.
16 weeks	Through the 10 mg phase ≈ 100 mg total — 4 × 30 mg vials.
24 weeks	Through the 12.5–15 mg phases ≈ 220 mg total — 8 × 30 mg vials give margin.

Insulin Syringes & BAC Water

One U-100 insulin syringe per weekly injection (a 100-count box covers ~2 years of weekly dosing). Reconstitute each 30 mg vial with 3.0 mL BAC water; a 10 mL bottle covers ~3 vials.

Reconstitution answers two questions. First, how much bacteriostatic water to add to the lyophilised vial. Second, how many syringe units match each weekly dose after mixing. Read across the row for your target dose.

Reconstitution Math — 30 mg Vial (3 mL BAC)

Target Dose	Units (U-100)	Doses / Vial
2.5 mg	25.0 units	12
5 mg	50.0 units	6
7.5 mg	75.0 units	4
10 mg	100.0 units	3
12.5 mg	125.0 units	2.4
15 mg	150.0 units	2

Step-by-Step Reconstitution

Tirzepatide acts on two hormone pathways at the same time: GLP-1 and GIP. Most older compounds in this class (like semaglutide) act on GLP-1 only. The dual action is the main reason tirzepatide has shown stronger weight and glucose numbers than single-pathway compounds.

GLP-1 Receptor (the 'Feel Full' Lever)

The same general pathway used by semaglutide. It slows digestion and helps the body feel fuller for longer, reducing appetite.

GIP Receptor (the 'Handle Fuel' Lever)

GIP is glucose-dependent insulinotropic polypeptide. Adding GIP activity is what makes tirzepatide a dual agonist. In plain English, it supports blood-sugar handling and how the body stores and uses energy, and it may also ease the nausea associated with GLP-1 alone.

Structurally, tirzepatide is a 39-amino acid synthetic peptide with a C20 fatty diacid attachment that binds albumin in the blood. That longer circulation time is the technical reason for the ~5-day half-life and once-weekly dosing.

Tirzepatide side effects are dominated by gastrointestinal symptoms during dose escalation. They were usually mild to moderate and eased as the body adjusted to each dose.

Common Gastrointestinal Effects (SURMOUNT-1)

Effect	Typical Rate (all doses)
Nausea	Up to ~31%
Diarrhoea	Up to ~23%
Constipation	Up to ~17%
Vomiting	Up to ~10%

Conditions That Need Clinician Oversight

• Personal or family history of medullary thyroid carcinoma or MEN 2
• History of pancreatitis or gallbladder disease
• Severe kidney or GI conditions (gastroparesis, IBD flare)
• Diabetic retinopathy or active retinal disease
• Use of insulin or sulfonylureas (hypoglycaemia risk)
• Pregnancy, breastfeeding, or trying to conceive — not studied; effective contraception required in trials

Tirzepatide builds up slowly. Steady-state levels land after about 4 weeks at each dose step — which is why each titration phase is 4 weeks long. Half-life is about 5 days, so after stopping it takes roughly 25 days (5 half-lives) to clear.

Weight Loss by Dose in SURMOUNT-1 (72 Weeks)

Dose	Mean Body Weight Loss
5 mg	-15.0%
10 mg	-19.5%
15 mg	-20.9% to -22.5%
Placebo	-3.1%

Reasonable Markers to Track

• Weekly body weight on the same scale at the same time of day.
• Resting heart rate (a basic wearable or fingertip pulse oximeter is enough).
• Routine labs (CMP including ALT/AST, lipid panel, fasting glucose, HbA1c) before starting and on a regular schedule under clinician oversight.
• Notes on GI symptoms by dose phase — the most useful data point for deciding when to hold a dose.

SURMOUNT-1 (Obesity, NEJM 2022)

2,539 adults with obesity or overweight without diabetes, 72 weeks. The 15 mg dose produced up to 22.5% mean body weight loss; 5 mg produced 15.0%. About 91% of participants on 15 mg lost at least 5% of body weight.

SURPASS Program (Type 2 Diabetes)

Across the SURPASS trials, tirzepatide produced HbA1c reductions of roughly 1.9–2.6% and, in SURPASS-2, outperformed semaglutide 1 mg on both A1C and weight loss at 40 weeks.

SURMOUNT-2 (Obesity + Type 2 Diabetes)

Adults with obesity and type 2 diabetes achieved up to ~15.7% mean weight loss at the 15 mg dose over 72 weeks — a group that typically loses less weight than those without diabetes.

State	Storage	Notes
Lyophilised (powder), sealed	-4°F (-20°C) or below	Long-term; up to 12+ months.
Lyophilised (powder), sealed	35.6–46.4°F (2–8°C)	Several months.
Lyophilised, short shipping	Room temperature short-term	Powder tolerates short-term temperature swings for several weeks.
Reconstituted (liquid)	35.6–46.4°F (2–8°C)	Use within 3–4 weeks; protect from light.

Tirzepatide is approved as Mounjaro (type 2 diabetes) and Zepbound (chronic weight management) by the FDA and in many other markets. Research-use tirzepatide sold by peptide suppliers is a separate, laboratory-use product — it is not the same regulated medicine and is not intended for human consumption. In South Africa it is not registered with SAHPRA. COA verification and correct storage are the buyer's responsibility.