In plain English
A peptide medicine starts as an idea. Scientists pick a target, often a receptor (a protein on a cell that a signal molecule binds to). Then they design and test many peptide candidates in the lab [1, 3].
Natural peptides break down quickly in the body, so chemists change them to make them last longer [4, 5]. The best candidate is tested in cells and animals for possible harm (toxicity) before any human study [6].
Next come clinical trials (carefully controlled studies in people), usually in phases [8, 9]. Many candidates fail along the way [9, 15]. If the evidence is strong enough, a company applies to a regulator such as the TGA. The TGA checks the data and decides whether the medicine can be registered [11, 12].
A peptide sold as a “research chemical” has been through none of this. Even if its sequence matches a medicine, it has not been assessed by a regulator [16].
The short version
- Discovery, preclinical tests, trials, review, then monitoring [1, 8].
- The whole process can take 12–15 years [1].
- In Australia, the TGA decides whether a medicine is registered [11].
Key facts
| Stage | What happens | Typical source of guidance |
|---|---|---|
| Discovery | Target selection, screening, hit finding, lead optimisation, candidate selection [1] | Company and academic research |
| Preclinical (nonclinical) | In vitro and animal studies of pharmacology, pharmacokinetics and toxicology [6, 8] | Good laboratory practice; ICH guidelines |
| Clinical trials | Usually described as phases 1–3 before approval and phase 4 after [8, 9] | ICH E8(R1); national trial rules |
| Regulatory review | Evaluation of quality, nonclinical and clinical data [7, 11] | TGA in Australia |
| Post-approval | Pharmacovigilance and manufacturing (GMP) obligations [14] | TGA in Australia |
Stage 1: Discovery
Developing a new drug from an original idea to a finished product is a complex process that can take 12–15 years and cost more than $1 billion [1]. Discovery usually runs through a recognised sequence: target identification and validation, assay development, screening, hit identification, lead optimisation, and finally selection of a candidate for clinical development [1].
Peptide discovery has its own sources of starting points [2]:
- Human hormones. Early efforts focused on natural human hormones.
- Natural sources. Peptide drugs derived from nature, including venoms.
- Design and libraries. Rational medicinal chemistry and peptide-display libraries.
Many peptide drugs act at G protein-coupled receptors (GPCRs). Most of these are agonists made by modifying the sequence of the natural peptide that binds the receptor [3]. For the receptor biology, see How Peptide Signalling Works.
Stage 2: Making a peptide drug-like
Natural peptides typically have poor ADME properties (absorption, distribution, metabolism and excretion): rapid clearance, short half-life, low permeability and sometimes low solubility [4]. Unmodified peptides usually undergo extensive proteolytic cleavage [5].
Developers address these limits with amino acid substitutions, terminal modifications, disulfide bonds, and conjugation to polymers, antibody fragments or albumin [5]. In vitro, in vivo and in silico tools are used to measure ADME properties during optimisation [4]. See Why Peptides Break Down.
Manufacturing is planned in parallel. A medicine’s quality data, including composition, batch consistency, stability and impurity content, are later evaluated by the regulator [7]. For production methods, see How Peptides Are Made.
Stage 3: Preclinical (nonclinical) studies
Before a drug is tested in people, researchers must find out whether it has the potential to cause serious harm, also called toxicity. Preclinical research uses in vitro and in vivo studies, and the US FDA requires good laboratory practice (GLP) for these studies [6].
Internationally harmonised guidance (ICH E8(R1)) describes the nonclinical assessment as usually including toxicology, carcinogenicity, immunogenicity, pharmacology and pharmacokinetics. The scope and timing depend on the drug’s properties, mechanism and ADME profile [8]. In Australia, the TGA evaluates nonclinical pharmacology and toxicology data as part of a registration application [7].
Stage 4: Clinical trials
Clinical development is often described in four phases [8, 9]:
| Phase | Main purpose | Typical size (FDA description) [9] |
|---|---|---|
| Phase 1 | First studies in humans; human pharmacology, tolerability and how the body handles the drug | 20–100 healthy volunteers or people with the condition |
| Phase 2 | Exploratory studies of efficacy and further safety | Up to several hundred people with the condition |
| Phase 3 | Confirmatory studies, often the basis for marketing approval | 300–3,000 people with the condition |
| Phase 4 | Studies after approval | Several thousand people |
ICH E8(R1) stresses that the phase concept is a description, not a requirement, and that phases may overlap or be combined [8]. Attrition is high. The FDA estimates that about 70% of drugs move from phase 1 to phase 2, about 33% from phase 2 to phase 3, and about 25–30% from phase 3 onwards [9]. Success rates also vary widely by disease area; one analysis of more than 21,000 compounds estimated a 3.4% success rate for oncology [15].
In Australia, trials using unapproved therapeutic goods run under the Clinical Trial Notification (CTN) or Clinical Trial Approval (CTA) scheme, and every clinical trial needs approval from a human research ethics committee (HREC) before it starts [10]. These schemes allow unapproved goods to be imported or supplied solely for experimental purposes in humans; they are not a route for individual access [10]. For a fuller explanation, see Clinical Trial Phases Explained.
Stage 5: Regulatory review and TGA approval
What the sponsor submits
To register a prescription medicine on the Australian Register of Therapeutic Goods (ARTG), a sponsoring company must apply to the TGA with data supporting the product’s quality, safety and efficacy, completed forms, and fees [13]. Applications use the international Common Technical Document (CTD) format [11].
What the TGA evaluates
The TGA divides the data into three types [7]:
- Quality data: composition of the drug substance and product, batch consistency, stability, sterility (if applicable) and impurities.
- Nonclinical data: pharmacology and toxicology.
- Clinical data: mostly the findings of clinical trials.
Not every medicine accepted for evaluation is approved, and the proposed indications can change after evaluation [7].
How the standard process runs
The TGA’s registration process for new medicines has eight phases, each ending at a milestone [11]:
- Pre-submission (planning)
- Submission
- First round assessment
- Consolidated request for further information
- Second round assessment
- Expert advisory review
- Decision
- Post-decision
At the expert advisory stage, the TGA delegate can seek advice from the independent Advisory Committee on Medicines (ACM). The TGA has a legislated commitment of 255 working days from acceptance for evaluation to the delegate’s decision [11].
Standard, priority and provisional pathways
The TGA can assess a new prescription medicine through three pathways [12]:
| Pathway | Key features [12] |
|---|---|
| Standard | Review can take up to about 11 months, depending on complexity |
| Priority review | For medicines for serious or life-threatening conditions that meet criteria. Same amount and type of evidence; review can finish up to three months earlier |
| Provisional approval | For promising medicines for serious or life-threatening conditions. Available for a limited period while the company completes final clinical trials, potentially up to two years earlier than the standard pathway |
The sponsor must apply, and the medicine must meet eligibility criteria, such as being a major advance over similar approved medicines [12].
Stage 6: After approval
Registration is not the end of the process. Sponsors of registered prescription medicines have ongoing responsibilities, including pharmacovigilance (such as reporting adverse events) and good manufacturing practice (GMP) [14]. Further studies after approval, usually called phase 4, examine safety and efficacy in wider use [8, 9].
Why this matters for “research peptides”
More than 80 peptide drugs have reached the market worldwide [2], and in 2018 more than 150 peptides were in active clinical development [18]. Each approved product went through the stages above for a specific formulation, manufacturing process and indication.
A peptide sold for laboratory research has not. Even when its sequence matches an approved medicine or a trial candidate, it has no regulatory assessment of quality, safety or efficacy behind it [16]. See Research Peptides vs Approved Peptide Medicines.
What this means in Australia
The ARTG is the line. A prescription medicine can be lawfully supplied in Australia once the TGA has evaluated it and registered it on the ARTG [11, 13]. Peptide products that are not on the ARTG are unapproved therapeutic goods [16].
Trials have their own rules. Unapproved medicines can be supplied for clinical trials only under the CTN or CTA schemes, with HREC approval [10].
Scheduling. The Poisons Standard (October 2026) names a number of peptides individually and in classes. For example, BPC-157 and TB-500 are each in Schedule 4 and Appendix D, clause 5 [17]. Schedule 4 means prescription-only. Appendix D, clause 5 means possessing the substance without authority is illegal. Not being named does not mean a substance is unregulated [16, 17].
“Research use only” labels. In April 2026 the TGA named BPC-157, GHK-Cu, TB-500 and CJC-1295 among its examples of unapproved peptide products. It stated that a “research use only” disclaimer does not make supply lawful, and does not change regulatory status, permit importation, or remove advertising or supply obligations [16].
This is general information, not legal advice. Laws change; check the current Poisons Standard and TGA guidance.
Frequently asked questions
How long does peptide drug development take?
Developing a new drug from idea to market can take 12–15 years and cost more than $1 billion [1].
What is the difference between preclinical and clinical research?
Preclinical (nonclinical) research uses in vitro and animal studies to assess toxicity and pharmacology. Clinical research is carried out in people [6, 9].
How does the TGA approve a new medicine?
The sponsor submits quality, nonclinical and clinical data in CTD format. The TGA evaluates it through an eight-phase process, may seek advice from the Advisory Committee on Medicines, and decides whether to register the medicine on the ARTG [7, 11].
What is provisional approval?
A TGA pathway that can make a promising medicine for a serious or life-threatening condition available for a limited period while final clinical trials are completed [12].
Is a research peptide the same as an approved peptide medicine?
No. An approved medicine has been evaluated for quality, safety and efficacy by a regulator. Research material has not, even if the sequence is the same [16].
References
- Hughes JP, Rees S, Kalindjian SB, Philpott KL. Principles of early drug discovery. Br J Pharmacol. 2011;162(6):1239–1249. doi:10.1111/j.1476-5381.2010.01127.x. PMID: 21091654
- Muttenthaler M, King GF, Adams DJ, Alewood PF. Trends in peptide drug discovery. Nat Rev Drug Discov. 2021;20(4):309–325. doi:10.1038/s41573-020-00135-8. PMID: 33536635
- Davenport AP, Scully CCG, de Graaf C, et al. Advances in therapeutic peptides targeting G protein-coupled receptors. Nat Rev Drug Discov. 2020;19(6):389–413. doi:10.1038/s41573-020-0062-z. PMID: 32494050
- Di L. Strategic approaches to optimizing peptide ADME properties. AAPS J. 2015;17(1):134–143. doi:10.1208/s12248-014-9687-3. PMID: 25366889
- Diao L, Meibohm B. Pharmacokinetics and pharmacokinetic-pharmacodynamic correlations of therapeutic peptides. Clin Pharmacokinet. 2013;52(10):855–868. doi:10.1007/s40262-013-0079-0. PMID: 23719681
- US Food and Drug Administration. The drug development process. Step 2: Preclinical research. fda.gov. Accessed 11 October 2026.
- Therapeutic Goods Administration. TGA evaluation (prescription medicines). tga.gov.au. Accessed 11 October 2026.
- International Council for Harmonisation. ICH E8(R1): General considerations for clinical studies. 2021. database.ich.org. Accessed 11 October 2026.
- US Food and Drug Administration. The drug development process. Step 3: Clinical research. fda.gov. Accessed 11 October 2026.
- Therapeutic Goods Administration. Australian clinical trial handbook. tga.gov.au. Accessed 11 October 2026.
- Therapeutic Goods Administration. Prescription medicines registration process. tga.gov.au. Accessed 11 October 2026.
- Therapeutic Goods Administration. Fast track approval pathways. tga.gov.au. Accessed 11 October 2026.
- Therapeutic Goods Administration. Supply a prescription medicine. tga.gov.au. Accessed 11 October 2026.
- Therapeutic Goods Administration. Your ongoing responsibilities (prescription medicines). tga.gov.au. Accessed 11 October 2026.
- Wong CH, Siah KW, Lo AW. Estimation of clinical trial success rates and related parameters. Biostatistics. 2019;20(2):273–286. doi:10.1093/biostatistics/kxx069. PMID: 29394327
- Therapeutic Goods Administration. Understanding your responsibilities when importing, compounding and supplying unapproved peptide products. Safety advisory, 13 April 2026. tga.gov.au. Accessed 11 October 2026.
- Therapeutic Goods (Poisons Standard—October 2026) Instrument 2026 (F2026L01327). Federal Register of Legislation. legislation.gov.au/F2026L01327/latest/text. Accessed 11 October 2026.
- Lau JL, Dunn MK. Therapeutic peptides: Historical perspectives, current development trends, and future directions. Bioorg Med Chem. 2018;26(10):2700–2707. doi:10.1016/j.bmc.2017.06.052. PMID: 28720325
Important information and disclaimer
General information only. This article is published for general educational and informational purposes. It summarises published scientific literature and public regulatory information as at the “last reviewed” date shown above. It is not medical, health, pharmaceutical, veterinary or legal advice, and it must not be relied on as a substitute for advice from a qualified professional about your circumstances.
Not for human or animal use. Nothing in this article recommends, endorses or describes the use of any substance in humans or animals. Findings from cell, animal or early human studies cannot be assumed to apply to people. The compounds discussed have not been evaluated by the Therapeutic Goods Administration (TGA) for safety, quality or efficacy unless the article expressly states otherwise. Any research materials offered by Iconic Peptides are supplied solely for in vitro and laboratory research.
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Regulatory status. Many peptides are scheduled substances under the Poisons Standard. Some are prescription-only (Schedule 4), and some may not be possessed without authority (Appendix D). The TGA has stated that a “research use only” label does not make supply lawful, change a product’s regulatory status, or remove advertising or supply obligations. State and territory laws may also apply. You are responsible for knowing and complying with all laws that apply to you. Regulatory information in this article may change after the review date.
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