What the public rules say
TB-500 has no FDA approval; 503A is a one-patient pharmacy rule.
This page covers FDA's record, the July 2026 meeting, and the pharmacy rule for one patient's made-to-order medicine.
FDA held a public review, but no result is posted
TB-500 lacks FDA drug approval. FDA also marks an older request for TB-500 as withdrawn. Before that, the drug sat in Category 2, a group FDA uses for raw drugs that may bring grave safety trouble. The agency gives no answer about what pharmacies may do after the withdrawal.
A public meeting plan named two chemical forms of TB-500 but did not compare their safety. FDA's pharmacy advisers met July 23–24, 2026. They asked if rule 503A should let a pharmacy use TB-500 as raw material for a certain patient [17]. Other drugs, including BPC-157, were separate items and don't change the TB-500 question [17].
The public review gave no final answer. Advisers considered whether the raw drug belonged on the allowed list. Their meeting left TB-500's status unchanged [17]. FDA staff favored keeping it off the list. By September 2026, FDA had posted no vote count. You still cannot find FDA's next step for TB-500.
FDA's 503A one-patient pharmacy page lists a withdrawn request
FDA once placed the TB-500 piece of thymosin beta-4 in Category 2 under rule 503A. That group holds raw drugs FDA thinks may carry grave safety trouble. That status began on September 29, 2023. On its page current as of April 22, 2026, FDA places the request among those withdrawn [18]. The old notes remain. They warn that some ways of taking the drug could wake an immune response and that much needed safety evidence is absent. Both notes came with the September 29, 2023 update [18].
The withdrawal leaves you with two points. First, TB-500 no longer appeared in Category 2. FDA gives no answer on whether a 503A pharmacy making a drug just for its patient may use it now [18][19]. Second, no finished TB-500 medicine has FDA approval [19]. The pharmacy rule and drug approval settle different matters.
FDA's entry links the fragment to thymosin beta-4 [18]. TB-500 is that small fragment, while thymosin beta-4 is its much larger parent protein.
503A covers one patient; 503B covers clinic batches
Two parts of federal law guide pharmacies that make drugs to order. Section 503A lets a licensed pharmacy prepare medicine for the patient whose doctor wrote the prescription. Section 503B applies to FDA-registered pharmacies that prepare bigger batches for clinics. FDA inspects those pharmacies and holds them to stricter rules [19].
A pharmacy cannot begin with any raw drug it chooses. An official drug-quality standard may cover the material. FDA may have approved it as part of a medicine. Or FDA may have placed it on the 503A approved raw-material list [19]. FDA reviews materials that aren't listed. Pharmacy advisers may offer advice, but the agency makes the final choice [19].
On January 7, 2025, FDA changed how it sorts new requests. Category 1 allows some raw drugs for now while review goes on. Category 2 marks drugs with grave safety concerns, so that short-term break ends when a request is updated [19]. FDA's page dated April 22, 2026 shows the TB-500 Category 2 request as withdrawn.
A made-to-order medicine starts with a doctor
A doctor generally starts by meeting one patient. After judging that person's needs, the doctor may write a valid prescription for a made-to-order medicine [19]. This is legal background only; it cannot guide medical or legal choices in your case. This page offers no drug.
A state-licensed pharmacy under 503A may prepare that patient's medicine. An FDA-registered 503B pharmacy can prepare bigger batches for clinics [19]. You may meet the doctor by video or phone. Even then, the doctor must judge your case and write a real prescription [19]. A remote visit cannot turn a barred raw drug into a lawful one.
The raw-drug question for TB-500 remains open. FDA marks the request as withdrawn but does not explain later use by a 503A pharmacy [19]. TB-500 once sat in Category 2, the group for raw drugs with grave safety concerns. The FDA advisers' July 2026 talk did not change that answer for TB-500 [17].
The sports ban applies in and out of competition
The FDA question doesn't change sports rules. World Anti-Doping Agency rules bar TB-500 and thymosin beta-4 at events and in the time between them [5]. The ban covers small protein drugs, growth aids, and tissue-repair drugs. That rule matters to you if you compete. Sports labs can detect TB-500 as well as the full protein. A 2024 test improved the measurement of TB-500 and the material remaining when it falls apart [15]. Racehorse drug cases helped bring about tests in horses and people [5].
TB-500 has no drug approval, and pharmacy use is unclear
TB-500 is the small thymosin beta-4 piece, and FDA drug approval does not cover it [19]. In September 2023, FDA placed it in Category 2 under pharmacy rule 503A. That group marks raw drugs with grave safety concerns. FDA now calls the request withdrawn without telling pharmacies what follows [18]. Sports rules also bar the fragment [5]. This is broad background, not legal advice for you.
TB-500 is not FDA approved for people
No. FDA has not approved TB-500 for people [19]. The agency once placed the thymosin beta-4 piece in Category 2 under pharmacy rule 503A. That group flags raw drugs with grave safety concerns. FDA later called the 2023 request withdrawn and kept its safety notes online [18]. Firms offer TB-500 for work in labs and animals. A research sale does not amount to drug approval.
FDA's 503A one-patient pharmacy page leaves TB-500 use unclear
FDA calls TB-500 a small piece of thymosin beta-4. Its September 29, 2023 update placed the drug in Category 2 under pharmacy rule 503A. FDA said the drug might wake an immune response and that needed safety facts were absent. The agency's page current as of April 22, 2026 now puts the request among withdrawn ones [18]. FDA advisers talked about it at the July 23–24, 2026 meeting. The talk made no final choice, and FDA staff favored leaving it off the list [17].
A compounding pharmacy may not be able to use TB-500
FDA's current page calls the TB-500 request withdrawn. The safety notes remain, but normal pharmacy use under rule 503A is not explained [18][19]. In a usual case, a doctor meets the patient and may write that person's prescription. A 503A pharmacy can prepare medicine for that patient. A 503B site can prepare bigger clinic batches. Both must start with raw drugs the law allows [19].
TB-500 is banned in tested sport
Yes. Sports rules bar TB-500 and thymosin beta-4 at events and in the time between them [5]. The ban covers small protein drugs, growth aids, and tissue-repair drugs. A lab can detect either substance. A 2024 test measures TB-500 along with material remaining when it falls apart [15].