Scientific deep-dive

Compounded Tirzepatide vs Compounded Semaglutide: Differences, Efficacy, Storage & Stability

Side-by-side comparison of compounded tirzepatide vs compounded semaglutide: molecule differences (GLP-1 only vs dual GIP+GLP-1), efficacy (STEP-1 −14.9% vs SURMOUNT-1 −20.9%), fridge life (28–90 day pharmacy-assigned BUD), regulatory status post-Feb 2025, and common additives (B12, NAD+). Sourced from Wegovy and Zepbound FDA labels and PubMed primary studies.

By Eli Marsden · Founding Editor
Editorially reviewed (not clinically reviewed) · How we verify contentLast reviewed
12 min read·8 citations
  • Compounded tirzepatide
  • Compounded semaglutide
  • Compounded GLP-1 comparison
  • How long does compounded tirzepatide last in the fridge
  • Beyond-use date GLP-1
  • USP 797 sterile compounding
  • 503A vs 503B
  • FDA enforcement discretion 2025
  • SURMOUNT-5 head-to-head
  • Compounded vs brand GLP-1
  • B12 semaglutide additive
  • Compounded tirzepatide storage

This comparison is part of Weight Loss Rankings' compounded GLP-1 editorial series — FDA labels, PubMed primary sources, and verified pricing only. No sponsored content. No AI-generated claims.

You are on compounded semaglutide or compounded tirzepatide — or you are trying to decide between them. The short version: same molecules as Wegovy and Zepbound, but with a different regulatory status, pharmacy-assigned stability windows, and a dose-titration schedule that mirrors the brand. The long version — molecules, efficacy, fridge life, regulatory status, and additives — is below.

How we sourced this guide

Every mechanism-of-action claim comes verbatim from the Wegovy and Zepbound FDA labels on DailyMed (NIH) — verified by DailyMed SetID. Clinical trial numbers come from the PubMed-indexed primary publications (STEP-1 PMID 33567185, SURMOUNT-1 PMID 35658024, SURMOUNT-5 PMID 40353578). Regulatory status reflects FDA Drug Shortages Database entries as of May 2026. Storage guidance reflects USP <797> sterile compounding standards and typical pharmacy beyond-use date assignments — not manufacturer data (which covers brand-name products only).

TL;DR — the practical differences at a glance

FeatureCompounded SemaglutideCompounded Tirzepatide
Same molecule as brandYes — semaglutide (same as Wegovy)Yes — tirzepatide (same as Zepbound)
Receptor targetsGLP-1 receptor onlyDual GIP + GLP-1 receptors
Mean weight loss (brand trial)~14.9% at 68 wk (STEP-1)~20.9% at 72 wk (SURMOUNT-1)
FDA-approved productNo — not FDA-approvedNo — not FDA-approved
Enforcement discretion endedFeb 2025 (shortage resolved for 503B)Mar 2025 (shortage resolved for 503B)
Fridge life (typical)28–90 days (pharmacy-specific BUD)28–90 days (pharmacy-specific BUD)
Common additivesB12 (cyanocobalamin), benzyl alcoholB12 (cyanocobalamin), NAD+ (sometimes)
Typical self-pay cost/mo$99–$350$149–$400

Both are compounded preparations — meaning made by a licensed pharmacy, not by Novo Nordisk or Eli Lilly. Neither is an FDA-approved product. Both have the same molecule as the brand-name counterpart but differ in regulatory status, QC standards, stability data, and additives. The rest of this article goes deeper on each of those differences.

What “compounded” actually means

When a telehealth provider says you are getting “compounded semaglutide” or “compounded tirzepatide,” they mean a preparation made by a licensed compounding pharmacy under two possible legal frameworks in the Federal Food, Drug, and Cosmetic Act:[7]

  • Section 503A — traditional compounding pharmacy. Fills a patient-specific prescription for an individually identified patient. The pharmacy must be licensed in the state where it operates and in the state where the patient resides (in most cases). Quality and sterility standards are governed by USP <797> for sterile products.[7]
  • Section 503B — outsourcing facility. An FDA-registered facility that can produce larger volumes without a patient-specific prescription. Subject to current Good Manufacturing Practice (cGMP) standards. The legal basis for 503B bulk-compounding of semaglutide and tirzepatide narrowed significantly after FDA declared both shortages resolved in early 2025.[6]

Compounded ≠ FDA-approved generic

A compounded preparation is not an FDA-approved generic drug. It has not undergone an Abbreviated New Drug Application (ANDA) process, has not been required to demonstrate bioequivalence to the brand-name drug, and is not subject to the same post-market surveillance the brand must maintain. The FDA acknowledges compounding as a legitimate practice for individual patient needs — but explicitly states that compounded drugs “are not FDA-approved and do not undergo FDA's drug approval process.”[7]

Compounded semaglutide vs Wegovy: what's the same, what's different

What is the same

The active molecule is semaglutide in both. The Wegovy prescribing information describes the mechanism this way (Section 12, DailyMed SetID ee06186f-2aa3-4990-a760-757579d8f77b):[1]

“Semaglutide is a GLP-1 receptor agonist that selectively binds to and activates the GLP-1 receptor, the target for native GLP-1. Semaglutide reduces body weight through a reduction of energy intake. Semaglutide lowers body weight by reducing appetite and caloric intake, primarily via central nervous system actions.” [1]

Compounded semaglutide contains the same molecule and is expected to bind the same GLP-1 receptor by the same mechanism. The standard dose ladder mirrors the brand: typically 0.25 mg/week escalating to 0.5, 1.0, 1.7, and 2.4 mg/week — matching the Wegovy titration schedule.[1]

What is different

  • Regulatory status. Wegovy is FDA-approved (NDA 214730) and has passed manufacturing review, post-market surveillance, and bioequivalence standards. Compounded semaglutide has none of these.
  • Supply-chain QC. Novo Nordisk's manufacturing process is audited by the FDA. A compounding pharmacy is audited by state boards and, for 503B facilities, the FDA — but to a different standard. Third-party potency testing is the primary quality signal available to patients choosing a compounding pharmacy.
  • Stability and beyond-use date. Wegovy has manufacturer-validated stability data. Compounded semaglutide has a pharmacy-assigned beyond-use date (BUD) based on USP <797> standards and the pharmacy's own testing. These are not equivalent.[8]
  • Additives. Wegovy contains sodium phosphate dibasic anhydrous, sodium phosphate monobasic monohydrate, propylene glycol, phenol, and water for injection — no B12. Many compounding pharmacies add cyanocobalamin (B12) or other ingredients not present in the brand. This changes the formulation.[1]
  • Salt form. Some early compounding pharmacies used semaglutide acetate rather than the base or sodium salt used in Wegovy. The FDA flagged acetate-salt formulations as potentially problematic in 2024 guidance. Verify which salt form your pharmacy uses.

Compounded tirzepatide vs Zepbound: what's the same, what's different

What is the same

The active molecule is tirzepatide in both. The Zepbound prescribing information describes the mechanism this way (Section 12, DailyMed SetID 487cd7e7-434c-4925-99fa-aa80b1cc776b):[2]

“Tirzepatide is a dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist. Tirzepatide is a 39-amino acid peptide that acts as an agonist at both the GIP receptor and the GLP-1 receptor, the targets for native GIP and GLP-1, respectively.” [2]

This dual-agonist mechanism — activating both GIP and GLP-1 receptors simultaneously — is what distinguishes tirzepatide from semaglutide, which targets only the GLP-1 receptor.[2]Compounded tirzepatide contains the same tirzepatide molecule and is expected to produce the same dual receptor agonism. The dose ladder typically mirrors Zepbound: 2.5 mg/week escalating to 5, 7.5, 10, 12.5, and 15 mg/week.[2]

What is different

  • Regulatory status. Zepbound is FDA-approved (NDA 217806) and has passed all FDA manufacturing and approval requirements. Compounded tirzepatide has not.
  • Stability data. Eli Lilly holds validated stability data for Zepbound. Compounding pharmacies assign a BUD per USP <797> standards. These are different standards, and the compounded BUD is typically shorter.[8]
  • Additives. Zepbound contains sodium phosphate dibasic heptahydrate, sodium phosphate monobasic monohydrate, mannitol, polysorbate 80, and water for injection — no B12, no NAD+. Compounded tirzepatide preparations frequently include cyanocobalamin and sometimes NAD+ or other ingredients.[2]
  • Vial vs pen. Zepbound is dispensed as a prefilled autoinjector pen. Compounded tirzepatide typically comes in a multi-dose vial requiring syringe draw. See our pen vs vial practical differences guide for technique detail.

Efficacy comparison (with the cross-trial caveat)

No clinical trial has been conducted on compounded semaglutide or compounded tirzepatide. Efficacy is inferred from brand-name trials by molecule equivalence — a reasonable inference, but not clinical-trial-validated for the compounded preparations specifically.

STEP-1 (Wegovy / semaglutide)

Wilding et al., NEJM 2021 (PMID 33567185) randomized 1,961 adults with BMI ≥ 30 (or ≥ 27 with comorbidity) to semaglutide 2.4 mg weekly or placebo for 68 weeks. Mean body-weight change from baseline: −14.9% in the semaglutide group vs −2.4% in placebo. [3]

SURMOUNT-1 (Zepbound / tirzepatide)

Jastreboff et al., NEJM 2022 (PMID 35658024) randomized 2,539 adults with BMI ≥ 30 (or ≥ 27 with comorbidity) to tirzepatide (5, 10, or 15 mg) or placebo for 72 weeks. Mean body-weight change at the 15 mg dose: −20.9% vs −3.1% placebo.[4]

SURMOUNT-5: the only valid head-to-head

STEP-1 and SURMOUNT-1 used different patient populations, different trial durations, and different time periods. Cross-trial comparisons are methodologically weak. The only trial that directly compared tirzepatide vs semaglutide in the same population at the same time is SURMOUNT-5 (Aronne et al., NEJM 2025, PMID 40353578):[5]

SURMOUNT-5 randomized adults with obesity (BMI ≥ 30, or ≥ 27 with comorbidity) without diabetes to tirzepatide or semaglutide for 72 weeks. Tirzepatide produced greater mean weight loss than semaglutide. This is the strongest available comparative evidence.[5]

Cross-trial caveat

All efficacy figures above come from brand-name trials using FDA-approved preparations. No compounded-specific trial data exists. The efficacy of compounded preparations is presumed to be similar to the brand by molecule equivalence — but this presumption has not been clinically validated. Individual response to either drug varies substantially. Discuss expected response with your prescriber, not this article.

Storage and stability: how long does compounded GLP-1 last in the fridge?

This is the most common patient question about compounded GLP-1 — and the answer is more nuanced than most pharmacy FAQs suggest, because the beyond-use date is assigned by your specific compounding pharmacy, not by Eli Lilly or Novo Nordisk. Your vial label is the authoritative source. What follows are the general principles.

Refrigerated storage (the default)

Most compounding pharmacies assign compounded semaglutide and compounded tirzepatide vials a refrigerated storage condition: 36–46°F (2–8°C), in the body of the fridge (not the door, where temperature fluctuates). This matches the brand-name storage condition: the Wegovy prescribing information states, “Store at 36°F to 46°F (2°C to 8°C).” [1]

Beyond-use date: 28 to 90 days refrigerated

Under USP <797> sterile compounding standards, compounding pharmacies assign a beyond-use date (BUD) — the date after which the preparation should not be used. For refrigerated sterile compounded peptide preparations, BUDs typically range 28 to 90 days from the date of compounding, depending on:[8]

  • The pharmacy's stability data for that specific formulation (concentration, diluent, additives)
  • Whether the vial has been opened (punctured vials may carry shorter BUDs than sealed vials)
  • Whether the pharmacy has conducted extended stability studies beyond USP default categories
  • The specific BUD category assigned under the revised USP <797> (2023 revision)

Your vial label is authoritative

This article gives general principles. The date printed on your specific vial label — assigned by your pharmacy based on their stability testing — is what you must follow. Do not rely on another patient's pharmacy BUD, a telehealth company's FAQ, or general internet guidance over your actual label.

Room temperature: 14 to 30 days (varies by pharmacy)

Many pharmacies allow patients to store an in-use vial at room temperature for a limited window — typically 14 to 30 days at up to 77°F (25°C). For comparison, the Wegovy prescribing information states: “After first use, WEGOVY can be stored at room temperature, not above 77°F (25°C)” for up to 28 days.[1]The room-temperature limit on your compounded vial is pharmacy-specific — some will be shorter. Keep the vial capped and protected from light during room-temperature storage.

Do not freeze

Freezing is not recommended for compounded semaglutide or compounded tirzepatide. Both are peptide-based injectables. Freezing can cause protein denaturation, peptide aggregation, or structural changes that reduce potency or safety. The Wegovy prescribing information states explicitly: “Do not freeze Wegovy. If Wegovy has been frozen, throw it away.” [1]Apply the same caution to compounded preparations. If your vial accidentally froze (for example, near a freezer vent), discard it and contact your pharmacy.

Light exposure

Both compounded semaglutide and compounded tirzepatide should be stored in their original packaging or a light-protective container. The Wegovy label specifies protection from light.[1]Peptide-based drugs can degrade with prolonged UV exposure. Do not leave the vial on a windowsill or in a hot car.

Signs a vial should be discarded

Inspect the solution before each injection. Discard the vial if it:

  • Appears cloudy or discolored (should be clear and colorless)
  • Contains visible particles, flakes, or crystals
  • Is past its printed beyond-use date
  • Has been frozen
  • Was stored above the labeled maximum temperature

Regulatory status: the February 2025 inflection point

The legal landscape for compounded GLP-1s changed materially in early 2025. Understanding the current status requires distinguishing between the two frameworks:

Semaglutide: shortage resolved February 2025

On February 21, 2025, FDA issued a declaratory order finding that semaglutide injection was no longer in shortage.[6]Under FDCA sections 503A(b)(1)(D) and 503B(a)(2), the shortage condition that had justified bulk compounding of semaglutide was removed. For 503B outsourcing facilities, the legal basis for large-scale bulk compounding of semaglutide effectively ended, subject to a grace period. 503A pharmacies can still compound semaglutide for individual patients under a valid patient-specific prescription where a documented clinical justification exists (for example, a formulation need that the brand cannot meet).[7]

Tirzepatide: shortage resolved March 2025

FDA resolved the tirzepatide injection shortage in March 2025 with a similar enforcement framework — removing the shortage-based legal basis for 503B bulk compounding, while leaving 503A patient-specific compounding available under appropriate clinical justification.[6]

The current landscape is unsettled

Multiple compounding pharmacies and telehealth companies have challenged FDA enforcement in federal court. Some 503A compounders continue to operate. The regulatory environment as of May 2026 is in transition.

Verify with your pharmacy before starting or refilling

Do not rely on this article or your telehealth provider's marketing to determine whether your specific compound is currently being prepared within a compliant legal framework. Ask your pharmacy directly: under what legal basis are you currently compounding this preparation, and do you have documentation of patient-specific clinical justification? A compliant pharmacy should be able to answer this clearly.

Common additives in compounded GLP-1s

Compounded GLP-1 preparations often contain ingredients not found in the brand-name drugs. The most common:

Cyanocobalamin (vitamin B12)

The most frequently seen additive. “B12 + sema” and “B12 + tirz” compounds are widespread among telehealth providers. B12 is not an ingredient in brand-name Wegovy or Zepbound.[1][2]Rationale cited by pharmacies varies: potential antiemetic properties, patient preference, or formulation stability. There is no FDA-reviewed clinical evidence that B12 improves GLP-1 efficacy or reduces side effects in compounded form. Patients with Leber's hereditary optic neuropathy should not receive cyanocobalamin.

NAD+ (nicotinamide adenine dinucleotide)

Occasionally added to compounded tirzepatide formulations, marketed for purported cellular energy benefits. No clinical evidence in the context of compounded GLP-1 preparations. Verify any additive's rationale and contraindications with your prescriber.

Glutathione, L-carnitine, and other peptides

Some compounders offer multi-ingredient preparations combining GLP-1 molecules with glutathione, L-carnitine, or even other peptides. These formulations have not been studied in combination with semaglutide or tirzepatide in any published trial. More additives = more unknown interactions.

When evaluating a compounded GLP-1 offer, ask the pharmacy for the complete formulation ingredients, concentrations, and the clinical justification for each additive.

Side effects: same as brand?

Yes — in principle. Same molecule means the same pharmacological mechanism means the same expected side-effect profile. The Wegovy prescribing information (Section 6.1) lists the most common adverse reactions as:[1]

“The most common adverse reactions (incidence ≥ 5%) in STEP 1 [are] nausea (44%), diarrhea (30%), vomiting (24%), constipation (24%), abdominal pain (20%), headache (14%), fatigue (11%), dyspepsia (9%), dizziness (8%), abdominal distension (7%), eructation (7%), hypoglycemia (5%), flatulence (5%), gastroenteritis (5%), and gastroesophageal reflux disease (5%).” [1]

The Zepbound prescribing information (Section 6.1) lists its most common adverse reactions as:[2]

“The most common adverse reactions (incidence ≥ 5%) in SURMOUNT-1 [are] nausea (32%), diarrhea (23%), vomiting (19%), constipation (17%), abdominal pain (10%), dyspepsia (9%), injection site reactions (7%), belching (6%), hair loss (6%), fatigue (5%), hypersensitivity reactions (5%), gastroesophageal reflux disease (5%), and flatulence (5%).” [2]

Compounded preparations with additives (B12, NAD+, other peptides) may produce additional side effects beyond the GLP-1 molecule alone. Injectable B12, for example, can cause pain at the injection site, flushing, or mild allergic reactions at high doses. Any additive-related side effects are not captured in the brand clinical trials.

Both Wegovy and Zepbound carry a class-wide Boxed Warning for thyroid C-cell tumors based on rodent data. Both are contraindicated in patients with personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). These contraindications apply to the molecule and therefore extend to compounded preparations of the same molecule.[1][2]

How to choose between compounded semaglutide and compounded tirzepatide

This is a clinical decision — not a product-preference decision. The following framework can inform a conversation with your prescriber, not replace it.

Choose compounded tirzepatide if…

  • Efficacy is the top priority. The best available head-to-head evidence (SURMOUNT-5, PMID 40353578) shows tirzepatide producing greater mean weight loss than semaglutide in the same population.[5]
  • You have insulin resistance or type 2 diabetes. The dual GIP+GLP-1 mechanism may offer additional metabolic benefit in patients with insulin resistance.[2]
  • You have already tried semaglutide with insufficient response.

Choose compounded semaglutide if…

  • GI side effects are a top concern. In head-to-head evidence, semaglutide tends to produce somewhat lower rates of nausea and GI events than tirzepatide at maximum doses. The SURMOUNT-5 results should be reviewed with your prescriber for the full comparison.[5]
  • Cost is the primary constraint. Compounded semaglutide tends to be slightly cheaper at starting doses.
  • Semaglutide has worked for you previously and you want to continue the same molecule.

Dose-titration preference

Both follow multi-step titration ladders designed to minimize GI side effects during the ramp-up period. Tirzepatide's dose ladder has more steps (2.5 → 5 → 7.5 → 10 → 12.5 → 15 mg) than semaglutide's (0.25 → 0.5 → 1.0 → 1.7 → 2.4 mg). Both ladders specify a minimum 4-week interval between dose increases in the brand labels.[1][2]Confirm titration schedule with your prescriber and pharmacy.

Cost comparison

Pricing for compounded GLP-1s is volatile and provider-specific. As a general orientation based on verified provider data (see our GLP-1 pricing index for current numbers):

ProductTypical range (monthly)Notes
Compounded semaglutide$99–$350Starting dose lowest; maintenance doses higher
Compounded tirzepatide$149–$400Wider range due to more dose steps
Brand Wegovy (NovoCare self-pay)~$299All-dose subscription pricing
Brand Zepbound (LillyDirect vials)~$299–$550Dose-dependent; vial format only

For the full verified pricing breakdown — including the cheapest verified compounded semaglutide providers in our database — see:

Important cautions for patients

This is a YMYL (Your Money or Your Life) topic. Read these cautions.

Compounded ≠ FDA-approved. Neither compounded semaglutide nor compounded tirzepatide is an FDA-approved drug. They have not passed the FDA manufacturing review, bioequivalence testing, or post-market surveillance required of Wegovy and Zepbound. Quality depends on the specific pharmacy.

Verify your pharmacy is licensed. Use the NABP (National Association of Boards of Pharmacy) e-Profile or your state pharmacy board to verify that the pharmacy compounding your medication is licensed. Look for PCAB (Pharmacy Compounding Accreditation Board) accreditation as a quality signal.

Verify current compliance. Given the post-shortage regulatory environment, ask your pharmacy under what legal basis they are currently compounding your specific preparation. A compliant pharmacy can explain this.

No compounded-specific clinical trial data. Efficacy claims are extrapolated from brand-name trials by molecule equivalence. This is not the same as compounded-preparation-specific evidence.

Storage is pharmacy-specific. Your vial's beyond-use date, room-temperature limits, and handling instructions are specific to your pharmacy's formulation and stability testing. This article gives general principles only.

Do not self-prescribe. Compounded GLP-1 injections require a valid prescription from a licensed prescriber. The prescriber-patient relationship and ongoing monitoring are not optional.

Frequently asked questions

Related research

References

  1. 1.Novo Nordisk Inc. WEGOVY (semaglutide) injection, for subcutaneous use — US Prescribing Information. Section 2 (dosage, storage), Section 6 (adverse reactions), Section 12 (mechanism of action: GLP-1 receptor agonist, glucose-dependent insulin secretion, glucagon suppression, gastric emptying delay), Section 14 (STEP-1 clinical trial data: −14.9% mean weight loss at 68 weeks). DailyMed (NIH). 2026. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ee06186f-2aa3-4990-a760-757579d8f77b
  2. 2.Eli Lilly and Company. ZEPBOUND (tirzepatide) injection, for subcutaneous use — US Prescribing Information. Section 2 (dosage, storage), Section 6 (adverse reactions), Section 12 (mechanism of action: dual GIP and GLP-1 receptor agonist), Section 14 (SURMOUNT-1 clinical trial data: −20.9% mean weight loss at 72 weeks). DailyMed (NIH). 2026. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=487cd7e7-434c-4925-99fa-aa80b1cc776b
  3. 3.Wilding JPH, Batterham RL, Calanna S, Davies M, Van Gaal LF, Lingvay I, McGowan BM, Rosenstock J, Tran MTD, Wadden TA, Wharton S, Yokote K, Zeuthen N, Kushner RF; STEP 1 Study Group. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). N Engl J Med. 2021. PMID: 33567185.
  4. 4.Jastreboff AM, Aronne LJ, Ahmad NN, Wharton S, Connery L, Alves B, Kiyosue A, Zhang S, Liu B, Bunck MC, Stefanski A; SURMOUNT-1 Investigators. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). N Engl J Med. 2022. PMID: 35658024.
  5. 5.Aronne LJ, Sattar N, Horn DB, Bays HE, Sherling A, McGowan B, Rubino DM, et al.; SURMOUNT-5 Investigators. Tirzepatide versus Semaglutide Once Weekly in Obesity without Diabetes (SURMOUNT-5). N Engl J Med. 2025. PMID: 40353578.
  6. 6.U.S. Food and Drug Administration. FDA Declaratory Order: Resolution of the Semaglutide Injection Shortage (February 21, 2025). FDA determined that semaglutide injection is no longer in shortage, removing the legal basis under FDCA 503B(a)(2) for outsourcing facilities to bulk-compound semaglutide. FDA Drug Shortages Database. 2025. https://www.accessdata.fda.gov/scripts/drugshortages/dsp_ActiveIngredientDetails.cfm?AI=Semaglutide+Injection&st=r
  7. 7.U.S. Food and Drug Administration. Human Drug Compounding: 503A and 503B — Questions and Answers. Explains the regulatory distinction between 503A traditional compounding pharmacies (patient-specific prescriptions, state-licensed) and 503B outsourcing facilities (larger volumes, cGMP, FDA-registered). FDA.gov. 2024. https://www.fda.gov/drugs/human-drug-compounding/compounding-and-fda-questions-and-answers
  8. 8.United States Pharmacopeia. USP General Chapter <797> Pharmaceutical Compounding — Sterile Preparations. Governs beyond-use dating, sterility testing, environmental monitoring, and stability standards for all sterile compounded preparations including peptide-based injectables. United States Pharmacopeia. 2023. https://www.usp.org/compounding/general-chapter-797