Comprehensive medication guide to Sirolimus including estimated pricing, availability information, side effects, and how to find it in stock at your local pharmacy.
Estimated Insurance Pricing
$0–$50 copay per month for generic sirolimus on most commercial insurance plans (Tier 2–3); brand Rapamune is typically Tier 4 or specialty tier and almost always requires prior authorization.
Estimated Cash Pricing
$163–$497 retail for generic sirolimus 1 mg tablets (30-day supply); as low as $35–$67 with GoodRx or SingleCare coupons. Brand Rapamune costs $1,000–$3,400+ per month without insurance or assistance.
Medfinder Findability Score
72/100
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Sirolimus — also known as rapamycin and sold under the brand name Rapamune — is a prescription immunosuppressant medication used primarily to prevent organ rejection after kidney transplantation and to treat a rare lung disease called lymphangioleiomyomatosis (LAM). It belongs to a drug class called mTOR inhibitors. Sirolimus was originally isolated in 1972 from a bacterium (Streptomyces hygroscopicus) found in soil samples from Easter Island (Rapa Nui), which is how the name rapamycin originated.
The FDA approved sirolimus in 1999 for kidney transplant rejection prevention, making it one of the major immunosuppressant options in transplant medicine. In May 2015, sirolimus became the first FDA-approved oral treatment for LAM. A specialized formulation — nab-sirolimus (Fyarro) — was later approved for malignant perivascular epithelioid cell tumors (PEComa). Generic sirolimus is manufactured by multiple companies including Zydus, Amneal, Teva, and Glenmark.
Sirolimus is available as oral tablets (0.5 mg, 1 mg, 2 mg) and an oral solution (1 mg/mL). Because it is a specialty medication with a narrow therapeutic index, it requires regular blood level monitoring (therapeutic drug monitoring) throughout treatment. It is not a controlled substance and has no DEA schedule.
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Sirolimus works by inhibiting mTOR (mechanistic target of rapamycin), a protein inside immune cells that acts as a master regulator of cell growth and proliferation. When sirolimus enters immune cells, it binds to a protein called FKBP-12. The resulting sirolimus-FKBP12 complex then binds to and blocks mTOR, preventing immune cells (particularly T-cells and B-cells) from dividing in response to signals from cytokines like interleukin-2 (IL-2).
This mechanism is fundamentally different from calcineurin inhibitors like tacrolimus and cyclosporine, which prevent T-cell activation upstream. Sirolimus acts downstream by arresting the cell cycle in the G1 phase, preventing progression to S phase where cell division would occur. This makes sirolimus particularly valuable for patients who need to reduce or eliminate calcineurin inhibitor exposure — such as those with calcineurin inhibitor-induced nephrotoxicity — because sirolimus is significantly less damaging to kidney function.
In lymphangioleiomyomatosis, mTOR is pathologically overactive due to TSC2 gene mutations, driving uncontrolled proliferation of LAM cells in lung tissue. By inhibiting mTOR, sirolimus directly targets the molecular driver of disease progression, stabilizing lung function and slowing cyst formation. The mTOR pathway is also a key regulator of cellular aging, which is why sirolimus is being actively investigated in longevity research.
0.5 mg — tablet
1 mg — tablet
Most commonly prescribed tablet strength
2 mg — tablet
1 mg/mL — oral solution
Liquid form; requires refrigeration
Sirolimus has a findability score of 72 out of 100, meaning it is generally available but can be intermittently difficult to locate at standard retail pharmacies. As of early 2026, sirolimus is not listed on the FDA's or ASHP's active drug shortage databases — a positive development compared to some years past. Multiple generic manufacturers (Zydus, Amneal, Teva, Glenmark) now produce sirolimus tablets, providing meaningful supply redundancy.
Despite adequate national supply, many patients encounter stocking gaps at their local retail pharmacy because sirolimus is a specialty medication with relatively low prescription volume. Pharmacies typically order it on demand rather than keeping it stocked. The oral solution (1 mg/mL) and 0.5 mg tablet strength are particularly prone to availability gaps. Patients in areas with fewer transplant centers may face more consistent stocking challenges.
To find sirolimus in stock near you without calling every pharmacy yourself, use medfinder. medfinder contacts pharmacies in your area to check availability and texts you the results. Specialty pharmacies and transplant center-affiliated pharmacies are also highly recommended for more consistent sirolimus supply, particularly for the oral solution formulation.
Sirolimus is not a controlled substance and requires no special DEA certification to prescribe. Any licensed physician, nurse practitioner, or physician assistant can write a sirolimus prescription. However, because sirolimus requires therapeutic drug monitoring, complex drug interaction management, and coordination with a transplant or subspecialty program, it is typically initiated and managed by specialists.
Telehealth follow-up appointments are available at many transplant centers for established patients on sirolimus, making prescription renewals and trough level reviews more convenient. New patients initiating sirolimus typically require an in-person assessment first.
No. Sirolimus is not a controlled substance and is not scheduled by the DEA. Any licensed prescriber — physician, nurse practitioner, or physician assistant — can legally prescribe sirolimus without any special DEA registration or triplicate prescription requirements.
Sirolimus prescriptions can be transferred between pharmacies without restriction, and prescriptions can be called in, faxed, or transmitted electronically like other non-controlled medications. Because sirolimus is a specialty medication requiring complex management (therapeutic drug monitoring, interaction screening), it is typically prescribed and managed by specialists rather than general practitioners, but this is based on clinical complexity — not legal restriction.
Common side effects that many patients experience include:
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Everolimus (Zortress)
Closest alternative — same mTOR inhibitor class, shorter half-life, approved for kidney and liver transplant; not interchangeable mg-for-mg with sirolimus
Tacrolimus (Prograf)
Gold standard calcineurin inhibitor; different mechanism, first-line for most transplants; more nephrotoxic than sirolimus
Cyclosporine (Neoral, Gengraf)
Older calcineurin inhibitor; generally less effective than tacrolimus but well-established alternative
Mycophenolate mofetil (CellCept)
Antimetabolite often used in combination regimens alongside calcineurin inhibitors or sirolimus
Belatacept (Nulojix)
IV monthly infusion; T-cell costimulation blocker for kidney transplant; avoids calcineurin inhibitor nephrotoxicity
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Voriconazole (Vfend)
majorContraindicated — potent CYP3A4 inhibitor that dramatically increases sirolimus levels, potentially 10-fold or more
Ketoconazole / Itraconazole
majorStrong CYP3A4 inhibitors; significantly increase sirolimus blood levels; avoid or reduce sirolimus dose with close monitoring
Rifampin (Rifampicin)
majorPotent CYP3A4 inducer; can reduce sirolimus levels by up to 90%, risking sub-therapeutic exposure and rejection
Cyclosporine
majorIncreases sirolimus AUC ~2-fold; take sirolimus 4 hours after cyclosporine; dose adjustment required
Grapefruit juice
majorInhibits intestinal CYP3A4; significantly raises sirolimus blood levels; must be avoided completely
St. John's Wort
majorStrong CYP3A4 inducer; substantially reduces sirolimus levels; contraindicated during sirolimus therapy
Carbamazepine / Phenytoin / Phenobarbital
majorAnti-seizure CYP3A4 inducers; decrease sirolimus concentrations; monitor levels and adjust dose if used together
Cannabidiol (CBD)
moderateMay inhibit CYP3A4; potential to increase sirolimus levels; dose reduction and additional monitoring recommended
Sirolimus (Rapamune) is one of the most pharmacologically interesting drugs in transplant medicine — originally discovered in soil bacteria from Easter Island, it has become a critical tool for kidney transplant recipients and the only oral treatment for LAM. Its mTOR-inhibiting mechanism distinguishes it from calcineurin inhibitors and provides a valuable alternative for patients who need to minimize kidney damage from tacrolimus or cyclosporine.
Access challenges are real but manageable. Generic sirolimus is produced by multiple manufacturers, keeping national supply stable. The primary challenge is stocking at retail pharmacies, which can be solved by using specialty pharmacies, mail-order supplies, and early refill practices. Cost can be dramatically reduced using GoodRx or SingleCare coupons for generic sirolimus (as low as $35/month) or through Pfizer's RxPathways program for brand Rapamune.
If you're having trouble locating sirolimus at your pharmacy, medfinder helps you find which pharmacies near you have it in stock — quickly, without the calls. Always take sirolimus exactly as prescribed, never miss doses without contacting your transplant team, and keep up with your scheduled blood level monitoring.
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