Compounded semaglutide and retatrutide: what Barbados' new law allows

Why compounded GLP-1s matter to Barbados

Barbados' neighbours are already dealing with them. In June 2026, Saint Lucia's Ministry of Health, Wellness and Nutrition said it was "increasingly concerned by reports of medications, including GLP-1 products and compounded GLP-1 formulations" offered by establishments and providers that are not licensed pharmacies³. PAHO has warned that demand "may encourage their commercialization through unofficial channels"¹¹, and WHO says demand "has fueled the spread of falsified and substandard products"¹⁰. During the June 2026 debate on Barbados' new medicines law, minister Marsha Caddle warned that some products sold locally "were banned in many other jurisdictions"¹².

The compounding test in section 43(4)

The Barbados Medical Products Act, 2026 (Act 2026-12), which comes into force by Proclamation, starts from a ban: no person may "import, manufacture, advertise, distribute, sell or offer for sale, or otherwise place on the market, a medical product unless the product has been registered and granted marketing authorisation by the Authority" (section 43(1))¹. Section 43(4) carves out pharmacy compounding, but only for "a particular patient", in a quantity no greater than needed for treatment, and only where¹:

• the product contains no component whose sale is prohibited by law or whose marketing authorisation application has been rejected; and
• "the active component of the medical product appears in another medical product in relation to which marketing authorisation has been granted by the Authority".

The Act also defines an "extemporary medicine" as one made in a pharmacy for an individual patient on a doctor's prescription or a healthcare institution's order, or one made to a written description of the process where "no commercially suitable licensed product is available" (section 2), and limits compounding and dispensing of listed drugs to pharmacists, or graduate and intern pharmacists under supervision, on registered premises (section 35)¹. Importing any drug needs a licence from the Authority (section 37)¹. Products already on sale get 12 months after commencement to apply for registration (section 43(3))¹.

What that means for semaglutide, tirzepatide and retatrutide

Read plainly, the test ties compounding to registration. Compounded semaglutide or tirzepatide would only fit the exemption once a semaglutide or tirzepatide product holds marketing authorisation from the Barbados Medical Products Authority¹. Retatrutide is in a weaker position still: it is an investigational molecule⁵ that the FDA treats as an unapproved drug², and as long as no product containing it holds marketing authorisation in Barbados, its active component cannot meet the test. The FDA reached the same result under US law, stating that "Retatrutide and cagrilintide cannot be used in compounding under federal law"².

Labels do not change this. The FDA has warned sellers of unapproved semaglutide, tirzepatide, retatrutide and similar drugs labelled as not for people but sold to consumers with dosing instructions, saying their quality is unknown². In Barbados, section 55(4) separately says a person shall not "sell, dispense, supply, assemble or manufacture a medical product for the purpose of a clinical trial or medical research on the product" without the Authority's authorisation or a written exemption¹.

The evidence on retatrutide, and on unregulated supply

Retatrutide acts on GIP, GLP-1 and glucagon receptors. In a phase 2 trial in 338 adults with obesity, weight fell by 24.2% at 48 weeks in the highest-dose group versus 2.1% on placebo; adverse events were mainly gastrointestinal and dose-related, and heart rate rose in a dose-dependent way, peaking at 24 weeks⁴. In December 2025, Eli Lilly reported phase 3 TRIUMPH-4 topline results in adults with obesity or overweight and knee osteoarthritis: 28.7% average weight loss at 68 weeks with the highest dose, versus 2.1% with placebo⁵.

Outside trials, the picture is different. A JAMA news report in November 2026 said unapproved retatrutide sold online is "no bargain"⁶. In a BMJ Case Reports case, a woman in her mid-20s had refractory nausea and vomiting after four weekly injections of an unverified product "reported to contain retatrutide", given in a wellness setting by a self-described life coach⁷. In Cureus, a man with type 1 diabetes developed ketonaemia of 4.3 mmol/L after an online product marketed as retatrutide, though an infection may also have contributed⁸. For semaglutide, the FDA links some compounded-product adverse events to dosing errors by patients and professionals²; test purchases of online semaglutide found purity of 7.7% to 14.37%⁹, and EudraVigilance data showed more hypoglycaemia with suspected counterfeit semaglutide than with the genuine product¹³.

Practical points for prescribers in Barbados

The BMJ case authors advise clinicians to "ask explicitly about injections, peptides, research chemicals, online products and substances recommended by non-medical wellness practitioners"⁷. Until the Authority publishes its register, physicians can check whether a product is authorised before recommending a compounded version, and report suspected reactions to the National Pharmacovigilance Programme the Act creates¹.