I’ve used water-based suspensions for some obscure tryptamine and arycyclohexylamine salts in the past, and the bioavailability didn’t seem to be impacted. Ofc rapa is a larger molecule that doesn’t have overt psychoactive effects, so it’s harder to say whether it was actually absorbed.
Title:
Subcutaneous Rapamycin Injection Protocol — 10 mg Weekly Dose, 0.5 ml Volume, DMSO/PEG-400/PBS Vehicle (No Oil)
Hello everyone,
I wanted to share a detailed and practical protocol for subcutaneous rapamycin injections that I have developed, based on discussions here and available literature. The goal was to create a sterile, convenient, and bioavailable preparation without the use of oil vehicles.
Protocol summary:
- Dose: 10 mg rapamycin per injection
- Frequency: once weekly
- Injection volume: 0.5 ml per dose (small volume for comfort)
- Vehicle composition: 20% DMSO, 40% PEG-400, 40% sterile PBS (pH 7.4)
- Total preparation: 100 mg rapamycin dissolved in 5 ml vehicle, divided into 10 × 0.5 ml sterile syringes
- Storage: syringes frozen at -20°C, thawed immediately before use, no refreezing
- Administration: subcutaneous injection (abdomen or thigh), injection done slowly to minimize discomfort
Preparation steps:
- In a sterile environment, dissolve 100 mg rapamycin in 1 ml DMSO until fully dissolved.
- Add 2 ml PEG-400 and mix thoroughly until clear.
- Add 2 ml sterile PBS (pH 7.4) and mix gently.
- Using a 0.22 µm sterile syringe filter, filter the solution directly into 10 sterile insulin syringes (0.5 ml per syringe).
- Cap syringes with sterile caps or needle covers and freeze immediately at -20°C.
Notes:
- This vehicle composition balances solubility and tissue tolerance, avoiding the complexity and sterility challenges of oil-based depots.
- The protocol aims for practical weekly dosing with acceptable bioavailability and minimal irritation.
- The volume of 0.5 ml per injection improves patient comfort for subcutaneous delivery.
- Freezing aliquots individually maintains sterility and stability over 10 weeks.
- Slow injection technique recommended.
If anyone has experience with alternative vehicles, depot methods, or different dosing strategies, I’d love to hear your feedback.
Thanks for reading!
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Hong Kong, 27 July 2026
New Drug Application for Sirolimus for Injection (Albumin-bound) Accepted by the NMPA
The Board of Directors (the ‘‘Board’’) of CSPC Pharmaceutical Group Limited (the ‘‘Company’’, together with its subsidiaries, the ‘‘Group’’) is pleased to announce that the new drug application for Sirolimus for Injection (Albumin-Bound) (the ‘‘Product’’) independently developed by the Group has been accepted by the National Medical Products Administration (the ‘‘NMPA’’) of the People’s Republic of China. Following review by the Center for Drug Evaluation of the NMPA, the Product has also been included in the Breakthrough Therapy Drug Program and granted Priority Review status.
The Product is a macrolide antibiotic immunosuppressant and a highly selective inhibitor of the mammalian target of rapamycin (‘‘mTOR’’). Sirolimus binds to the immunophilin FKBP12 to form an immunosuppressive complex, blocking the activation of the mTOR pathway. On the one hand, it inhibits cytokine-mediated T-lymphocyte activation and proliferation, and arrests cell cycle progression from the G1 phase to the S phase; on the other hand, it downregulates antibody production, thereby exerting potent immunosuppressive effects. The new drug application for the Product was submitted as a Class 2.2 modified new drug under chemical drug classification, with a proposed indication for unresectable locally advanced or metastatic malignant perivascular epithelioid cell tumour (‘‘PEComa’’).
The new drug application is primarily based on a pivotal Phase Ib/III clinical study that enrolled patients with histologically confirmed, unresectable locally advanced or metastatic malignant PEComa who had not previously received mTOR inhibitor therapy. The pivotal Phase III clinical trial met its predefined primary endpoint. Compared with the investigator’s choice of conventional therapies in the control group, the Product demonstrated significant efficacy advantages, with statistically significant and clinically meaningful results, enabling rapid and deep tumour responses. Given the current lack of a unified standard treatment regimen for malignant PEComa, the Product has the potential to establish a new treatment standard in this therapeutic area and support the development of a standardised treatment framework for the benefit of patients with PEComa. The Product has demonstrated a favourable overall safety profile, with generally manageable adverse reactions and a wide safety margin. Its favourable benefit-risk profile makes it a core therapeutic drug for this rare and difficult-to-treat tumour type.
Sirolimus for Injection (Albumin-Bound) is the first intravenous sirolimus formulation approved for clinical research in China. At present, the Group is advancing a pivotal Phase III clinical trial of the Product in combination with fulvestrant for the treatment of HR+/HER2- breast cancer and continues to explore the efficacy and safety of the Product as a monotherapy and in combination regimens across various solid tumours, with the aim of benefiting more cancer patients in the future.
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