What's Actually in Compounded GLP-1? Ingredients Explained
A transparent look at every ingredient in compounded semaglutide and tirzepatide and what each one does.
Knowing exactly what is in your medication is your right as a patient. Compounded GLP-1 medications contain a specific set of ingredients, each serving a distinct purpose. This guide breaks down every component so you can make informed decisions about your treatment.
The Active Ingredient: Semaglutide or Tirzepatide
The primary ingredient in compounded GLP-1 is the same peptide used in brand-name medications:
Semaglutide
- Type: GLP-1 receptor agonist peptide
- Molecular weight: ~4,113.58 Da (base form)
- Mechanism: Mimics natural GLP-1 hormone
- Brand equivalents: Wegovy, Ozempic
- Forms available: Base or sodium salt
Tirzepatide
- Type: Dual GIP/GLP-1 receptor agonist peptide
- Molecular weight: ~4,813.45 Da
- Mechanism: Activates both GIP and GLP-1 receptors
- Brand equivalents: Mounjaro, Zepbound
- Advantage: Dual-action mechanism
Inactive Ingredients (Excipients)
Excipients are non-active ingredients that serve essential roles in medication stability, safety, and comfort. Here is what you will typically find in a compounded GLP-1 vial:
Common Excipients in Compounded GLP-1
| Ingredient | Purpose | Typical Amount |
|---|---|---|
| Bacteriostatic water (BAC water) | Solvent and preservative carrier | Base of solution |
| Benzyl alcohol | Antimicrobial preservative | 0.9% in BAC water |
| Sodium phosphate dibasic | pH buffer | Varies by formulation |
| Sodium phosphate monobasic | pH buffer | Varies by formulation |
| Sodium chloride | Tonicity adjustment (reduces injection pain) | ~0.9% (isotonic) |
| Sodium hydroxide / HCl | pH adjustment | As needed for target pH |
| L-histidine (some formulations) | Stabilizer for peptide structure | Varies by formulation |
What Each Ingredient Does
Bacteriostatic Water
Bacteriostatic water is sterile water that contains 0.9% benzyl alcohol. The benzyl alcohol inhibits microbial growth, making it safe to draw multiple doses from the same vial over time. This is the most common diluent used in multi-dose compounded injectables.
Benzyl Alcohol
Present in bacteriostatic water at 0.9% concentration, benzyl alcohol serves as the antimicrobial preservative. At this low concentration, it is generally well tolerated. However, patients with known benzyl alcohol sensitivity can request formulations using preservative-free sterile water (single-use vials only).
Phosphate Buffers
Sodium phosphate (dibasic and monobasic) creates a buffer system that maintains the solution at a stable pH, typically between 7.0 and 7.4. Maintaining proper pH is critical for peptide stability and patient comfort during injection. Solutions that drift too far from physiological pH can cause stinging at the injection site.
Sodium Chloride
Added to make the solution isotonic (matching the salt concentration of body fluids). Isotonic solutions minimize pain and tissue irritation at the injection site.
How This Compares to Brand-Name Formulations
| Component | Wegovy (Brand) | Compounded Semaglutide |
|---|---|---|
| Active ingredient | Semaglutide | Semaglutide (same) |
| Preservative | Phenol | Benzyl alcohol (in BAC water) |
| Buffer | Disodium phosphate dihydrate | Sodium phosphate system |
| Tonicity agent | Propylene glycol | Sodium chloride |
| Delivery | Pre-filled pen | Vial with syringes |
Sublingual Formulations
Some compounding pharmacies offer sublingual (under-the-tongue) GLP-1 formulations. These contain additional ingredients:
- Absorption enhancers: Compounds that help the peptide cross the oral mucosa
- Flavoring agents: To improve taste (common options include peppermint)
- Sweeteners: Typically non-caloric options like stevia or sucralose
- Thickening agents: To keep the formulation under the tongue long enough for absorption
Note that sublingual bioavailability is generally lower than injectable, which is why sublingual doses are often higher to achieve equivalent effects.
Allergen and Sensitivity Concerns
Potential Sensitivities
- • Benzyl alcohol: Rare sensitivity; request preservative-free if concerned
- • Semaglutide/tirzepatide: Allergic reactions to the peptide are uncommon but possible
- • Latex: Some vial stoppers may contain latex; check with pharmacy
- • Sulfites: Not typically present in GLP-1 formulations
Always disclose all known allergies and sensitivities to your prescribing provider and compounding pharmacy before starting treatment.
What Should NOT Be in Your Medication
Be wary of compounded GLP-1 products that contain:
- Vitamin B12 (cyanocobalamin): Sometimes added as a marketing claim but provides no proven benefit in this context and complicates potency testing
- BPC-157 or other research peptides: These are not approved for human use and indicate the pharmacy may not follow proper regulations
- Undisclosed additives: Every ingredient should be listed; refuse products with vague labeling
- NAD+ or other "boosters": These combination products may lack stability data and could affect the GLP-1 peptide
How to Read Your Vial Label
What Should Be on Your Vial Label
- Drug name and concentration (e.g., "Semaglutide 5mg/mL")
- Total volume and total drug content
- Route of administration (subcutaneous injection)
- Beyond-use date (expiration)
- Storage requirements
- Pharmacy name, address, and phone number
- Lot or batch number
- Prescribing physician name
Conclusion
Compounded GLP-1 medications contain carefully selected pharmaceutical-grade ingredients, each serving a specific function. The active ingredient is the same semaglutide or tirzepatide found in brand-name products. The differences lie in the excipients used for stability, preservation, and comfort. Understanding these ingredients helps you ask the right questions and ensures you receive a quality product.
Medical Disclaimer: This article is for informational purposes only and does not constitute medical advice. Compounded medications are not FDA-approved finished products. Always consult with a qualified healthcare provider before starting any medication.
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