Primus Anabolics

QuickStart Highlights

Retatrutide is a novel triple agonist targeting GLP-1, GIP, and glucagon receptors, studied for substantial weight loss and metabolic improvement in obesity and type 2 diabetes.

With a prolonged half-life of approximately 6 days, this peptide allows for a convenient subcutaneous dosage once per week with a gradual titration protocol to optimize tolerability.

Reconstitution

Add 3.0 ml of bacteriostatic water → 10.0 mg/ml concentration for convenient weekly dosing.
Typical weekly range: 2–12 mg once a week (gradual escalation over 12+ weeks).
Simple measurement: At 10.0 mg/ml, 1 unit = 0.01 ml ≈ 100 mcg on a U-100 insulin syringe.
Storage: Lyophilized: freeze at −20 °C (−4°F); after reconstitution, refrigerate at 2–8 °C (35.6–46.4 °F) and use within 2–4 weeks.

Educational guide for reconstitution and weekly dosing

Standard / gradual approach (3 ml = 10.0 mg/ml)

Week(s)	Weekly dose (mcg) (mg)	Units (per injection) (mL)
Weeks 1–4	2,000 mcg (2 mg)	20 units (0.20 mL)
Weeks 5–8	4,000 mcg (4 mg)	40 units (0.40 mL)
Weeks 9–12	8,000 mcg (8 mg)	80 units (0.80 mL)
Weeks 13+	12,000 mcg (12 mg)	120 units (1.20 mL) — divide into 2 injections or use 2 vials

Frequency:

Inject once per week subcutaneously. This schedule follows clinical trial protocols that demonstrated significant weight loss (up to 24% at 48 weeks with 12 mg weekly) while minimizing gastrointestinal adverse events through gradual escalation.

Starting at 2 mg weekly (vs. 4 mg) significantly reduces initial GI side effects. The 30 mg vial size with 3.0 ml reconstitution provides an excellent concentration (10.0 mg/ml) for convenient measurement. For the maintenance dose (12 mg = 1.20 ml), it is divided into two 0.60 ml injections at different sites or an additional vial is reconstituted.

Reconstitution Steps

Draw 3.0 ml of bacteriostatic water with a sterile syringe.
Inject slowly down the side of the vial; avoid foaming.
Gently swirl/roll until dissolved (do not shake vigorously).
Label with reconstitution date and refrigerate at 2–8 °C (35.6–46.4 °F), protected from light.

Note: The 30 mg vial size is highly efficient for weekly protocols. With a concentration of 10.0 mg/ml, lower doses (2–8 mg) fit comfortably in a single syringe, while the maintenance dose (12 mg) requires dividing into two injection sites or using a second vial for the remaining 0.20 ml (2 mg).

Required Supplies

Plan based on a weekly 12 to 48-week protocol with gradual titration to the maintenance dose.

Peptide vials (Retatrutide, 30 mg each): Highly efficient vial size:
- 12 weeks (2→4→8 mg titration): 2 vials
- 24 weeks (up to 12 mg): 7 vials
- 48 weeks (maintenance at 12 mg): 17 vials
Bacteriostatic water (10 ml bottles): Use 3.0 ml per vial for reconstitution.
- 12 weeks (2 vials): 6 ml → 1 × 10 ml bottle
- 24 weeks (7 vials): 21 ml → 3 × 10 ml bottles
- 48 weeks (17 vials): 51 ml → 6 × 10 ml bottles

Protocol Overview

Concise summary of the once-a-week regimen based on clinical trial protocols.

Objective: Achieve substantial weight loss (up to 24% of body weight) and improve metabolic parameters through triple receptor agonism.
Schedule: weekly subcutaneous injections for 12+ weeks with gradual dose escalation.
Dose range: 2–12 mg once a week; clinical trials tested up to 12 mg as the maximum maintenance dose.
Reconstitution: 3.0 ml per 30 mg vial (10.0 mg/ml) provides optimal concentration with minimal waste, the most efficient vial size available.
Storage: Lyophilized frozen at −20 °C (−4°F); reconstituted solution refrigerated at 2-8°C (35.6–46.4°F); use within 2–4 weeks.

Dosing Protocol

Weekly titration approach based on clinical trial evidence.

Start: 2 mg once a week for the first 4 weeks to establish tolerability
Escalation: Increase to 4 mg weekly (Weeks 5–8), then 8 mg weekly (Weeks 9–12)
Maintenance: 12 mg weekly (Week 13 onwards) for maximum efficacy; 8 mg weekly is an alternative maintenance dose
Frequency: Once per week (subcutaneous); consistent day/time recommended.
Cycle duration: minimum 12 weeks for titration; clinical trials extended to 48 weeks showing sustained weight loss
Timing: Any consistent weekly schedule; rotate injection sites each week.

Storage Instructions

Proper storage maintains peptide stability and potency.

Lyophilized: Store at −20 °C (−4 °F) or colder for long-term preservation; protect from moisture and light.
Reconstituted: Refrigerate at 2–8 °C (35.6–46.4 °F) immediately after mixing; use within 2–4 weeks for maximum potency
Handling: Allow frozen vials to reach room temperature before opening to minimize condensation; never expose reformulated solution to heat or direct sunlight.
Aliquots: For prolonged storage beyond 4 weeks, consider freezing unused aliquots; avoid repeated freeze-thaw cycles.

Important Notes

Practical considerations for safe and effective weekly administration.

Weekly consistency: Choose a specific day/time for your weekly injection and maintain this schedule throughout the protocol.
Gradual dosing is essential: starting at 2 mg weekly (vs. higher doses) significantly reduces initial gastrointestinal side effects
Efficient vial size: The 30 mg vial provides excellent value with minimal waste, only 2 vials needed for the first 12 weeks of titration.
Use new sterile insulin syringes for each injection; dispose of them immediately in a puncture-proof sharps container
Rotate injection sites weekly (abdomen, thighs, upper arms) at least 1 inch apart to prevent local irritation or lipohypertrophy
For the 12 mg maintenance dose (1.20 ml), divide into two 0.60 ml injections at different sites or use a second vial for the volume remaining.
Monitor gastrointestinal side effects (nausea, diarrhea); if severe, consider extending time at the current dose before escalating.

How it works

Retatrutide is a first-in-class triple agonist that simultaneously activates three key metabolic hormone receptors: GLP-1 (glucagon-like peptide-1), GIP (glucose-dependent insulinotropic polypeptide), and glucagon. This triple mechanism produces synergistic effects on appetite suppression, energy expenditure, and glucose metabolism that exceed single or dual agonists.

The GLP-1 component reduces appetite and slows gastric emptying; GIP improves insulin secretion and may support fat metabolism; glucagon receptor activation increases energy expenditure and promotes fat oxidation. With a prolonged half-life of approximately 6 days, retatrutide allows for convenient once-a-week dosing while maintaining therapeutic levels.

In clinical trials, participants receiving 12 mg of retatrutide weekly lost an average of 24% of their body weight over 48 weeks. In adults with type 2 diabetes, retatrutide (up to 12 mg per week) achieved approximately 17% weight loss at 36 weeks, along with HbA1c reductions of approximately 2.0% compared to placebo.

A 2025 meta-analysis of three trials (8,780 participants) confirmed that retatrutide achieved a significantly greater weight reduction than placebo (mean difference approximately 14% of body weight) without a significant increase in overall adverse events.

Potential Benefits and Side Effects

Observations from phase 2 and phase 3 human clinical trials.

Potential benefits:
- Substantial weight loss: Up to 24% reduction in body weight at 48 weeks with 12 mg weekly dosing
- Glycemic improvement: Significant HbA1c reductions (approximately 2.0%) in adults with type 2 diabetes
- Metabolic benefits: Improvements in lipid profiles, blood pressure, and cardiovascular risk markers
- Convenient dosing: Once-weekly subcutaneous administration improves adherence compared to daily regimens
Common side effects:
- Gastrointestinal effects: Nausea, diarrhea, vomiting, and constipation are the most common adverse events; usually mild to moderate and decrease over time
- Starting at 2 mg weekly (vs. 4 mg) significantly reduces initial GI adverse events
- Injection site reactions: mild redness, swelling, or discomfort at injection sites may occur; rotate sites to minimize.
- General safety profile: meta-analysis found no significant increase in overall adverse events compared to placebo

Injection Technique

Subcutaneous injection guides based on clinical best practices and CDC recommendations

Pre-injection preparation:
- Wash hands thoroughly with soap and water
- Clean vial stopper with an alcohol swab and allow to air dry.
- Select injection site (abdomen, thigh, or upper arm) and clean with a fresh alcohol swab; let it dry completely.
- Draw the prescribed dose carefully; check for air bubbles and expel if present.
Injection procedure:
- Pinch a skin fold of approximately 1 inch between the thumb and index finger
- Insert the needle at a 90-degree angle (45 degrees if subcutaneous fat layer is thin) into the pinched skin
- Do not aspirate for subcutaneous injections (aspiration is not required and can increase discomfort)
- Inject slowly and steadily; press the plunger completely.
- Withdraw the needle directly and apply gentle pressure with a clean gauze if necessary.