Tirzepatide (10 mg)

At a Glance

Tirzepatide is a first-in-class dual GIP/GLP-1 receptor agonist that simultaneously activates both incretin pathways to suppress appetite, slow gastric emptying, and improve insulin sensitivity. In the SURMOUNT-1 trial, participants receiving tirzepatide achieved up to 22.5% mean body-weight reduction over 72 weeks.[1] It is administered as a once-weekly subcutaneous injection following a gradual dose escalation.

• Reconstitute: Add 2.0 mL bacteriostatic water → 5.0 mg/mL concentration.
• Starting dose: 2.5 mg once weekly (50 units / 0.50 mL) for the first 4 weeks.
• Easy measuring: At 5.0 mg/mL on a U-100 syringe, 1 unit = 0.01 mL = 50 mcg.
• Storage: Lyophilised: freeze at −20 °C; reconstituted: refrigerate at 2–8 °C; use within 4 weeks.

Overview

• Goal: Progressive weight loss and metabolic improvement via dual GIP/GLP-1 receptor agonism — appetite suppression, enhanced insulin sensitivity, and reduced caloric intake.[1]
• Schedule: Once-weekly subcutaneous injection; dose escalated every 4 weeks.
• Dose range: 2.5 mg (initiation) → 10 mg (maintenance target).
• Reconstitution: 2.0 mL BAC water per 10 mg vial → 5.0 mg/mL.
• Storage: Lyophilised at −20 °C; reconstituted at 2–8 °C; use within 4 weeks.

What You’ll Need

Plan based on a 12-week titration (Weeks 1–4: 2.5 mg; 5–8: 5 mg; 9–12: 7.5 mg). Total dose = 60 mg.

• Tirzepatide Vials (10 mg each): 60 mg cumulative → 6 vials.
• Insulin Syringes (U-100, 1 mL): 12 weekly injections (some split into 2) → 16–20 syringes.
• Bacteriostatic Water (10 mL bottles): 2.0 mL per vial → 2 × 10 mL bottles.
• Alcohol Swabs: 2 per injection → 40 swabs per 12-week course.

How to Reconstitute

1. Allow frozen lyophilised vial to reach room temperature (10–15 minutes).
2. Draw 2.0 mL bacteriostatic water with a sterile syringe.
3. Inject slowly down the inner vial wall; do not inject directly onto the powder cake.
4. Gently swirl or roll until fully dissolved — do not shake. Solution should be clear and colourless.
5. Label with reconstitution date; refrigerate at 2–8 °C, protected from light. Use within 4 weeks.

Dosing Schedule

Frequency: Inject once weekly on the same day each week. The 10 mg vial provides 1 dose at the 10 mg maintenance level or 4 doses at the 2.5 mg initiation level. For doses above 5 mg, split into two separate injections at different sites. Slow titration minimises nausea, vomiting, and diarrhoea — the most common adverse effects.[1]

Protocol Details

• Weeks 1–4: 2.5 mg (50 units / 0.50 mL) once weekly — initiation and tolerability assessment.
• Weeks 5–8: 5 mg (100 units / 1.00 mL) once weekly.
• Weeks 9–12: 7.5 mg (split: 75 units × 2 injections at different sites) once weekly.
• Weeks 13+: 10 mg (split: 100 units × 2 injections) once weekly — maintenance.[2]

Storage

• Lyophilised: Store at −20 °C (−4 °F) or below; protect from moisture and light.
• Reconstituted: Refrigerate at 2–8 °C. Do not freeze. Use within 4 weeks.
• Appearance: Clear and colourless. Discard if cloudy, coloured, or particulate.

How Tirzepatide Works

Tirzepatide is a 39-amino acid synthetic peptide featuring a C20 fatty diacid moiety that promotes albumin binding, extending its half-life to approximately 5 days and enabling once-weekly dosing. Unlike pure GLP-1 agonists such as semaglutide, tirzepatide simultaneously activates both the GIP and GLP-1 receptors, producing synergistic metabolic effects.[1]

GIP receptor activation enhances pancreatic beta-cell insulin secretion in a glucose-dependent manner and promotes lipid metabolism in adipose tissue. GLP-1 receptor activation suppresses appetite centrally, slows gastric emptying, and inhibits glucagon secretion. The dual-agonist mechanism delivers greater insulin sensitivity improvement and more pronounced weight loss compared to selective GLP-1 receptor agonists alone, as demonstrated in head-to-head trials.[2]

Good to Know

• Inject on the same day each week to maintain stable plasma levels (half-life ≈ 5 days).
• If a dose is missed by ≤4 days, administer as soon as possible; otherwise skip and resume the next scheduled day.
• Do not advance to the next dose tier if GI side effects are poorly tolerated — hold at the current dose for an additional 4 weeks.
• For doses above 5 mg from a 5.0 mg/mL solution, split into two separate subcutaneous injections at different sites (each ≤1 mL).
• Monitor blood glucose when used alongside other glucose-lowering agents.
• Weight reduction: SURMOUNT-1 (n=2539): up to 22.5% mean weight loss at 72 weeks with 15 mg/week tirzepatide vs. 3.1% placebo.[1]
• Glycaemic control: SURPASS trials demonstrated superior HbA1c reductions compared to insulin glargine, semaglutide 1 mg, and other comparators.[2]
• Insulin sensitivity: Dual GIP/GLP-1 agonism improves whole-body insulin sensitivity to a greater degree than GLP-1 agonism alone.
• GI side effects: Nausea (up to 29%), diarrhoea (~17%), vomiting (~9%) — dose-dependent and typically transient; slow titration mitigates severity.
• Contraindications: Personal or family history of medullary thyroid carcinoma or MEN2 (boxed warning); history of pancreatitis warrants caution.
• For background on Tirzepatide's mechanism, evidence, and safety profile, see What Is Tirzepatide?.

Tips for Best Results

• Pair with a reduced-calorie diet and regular physical activity (both resistance and aerobic) to maximise fat loss while preserving lean mass.
• Eat smaller, more frequent meals to minimise nausea — particularly during early titration phases.
• Prioritise protein intake (1.2–1.6 g/kg/day) to counteract lean-mass loss during caloric deficit.
• Stay well hydrated; GI side effects can increase dehydration risk.
• Track weekly body weight, waist circumference, and fasting glucose to assess response.

Injection Tips

• Clean the vial stopper and injection site with separate alcohol swabs; allow both to air-dry fully before proceeding.
• Using a 29–31 gauge insulin syringe (5/16″ to 1/2″ needle), draw the calculated dose precisely.
• Pinch a fold of skin and insert the needle at 45° into subcutaneous fat (90° is acceptable with a short needle into a well-pinched fold).
• Inject slowly over 2–3 seconds; do not aspirate. Withdraw the needle, apply gentle pressure, and do not rub the site.
• Rotate injection sites (abdomen, thighs, upper arms) and dispose of each syringe in a sharps container immediately after use.