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Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice.
Brand Name
Hyftor
Generic Name
Sirolimus
Active Ingredient
SirolimusCategory
mTOR Inhibitor Immunosuppressant [EPC]
Variants
1
Different strengths and dosage forms
| Strength | Form | Route | NDC |
|---|---|---|---|
| 2 mg/g | GEL | TOPICAL | 73683-101 |
Detailed information about Hyftor
This page is for informational purposes only and does not replace medical advice. Before using any prescription or over-the-counter medication for Hyftor, you must consult a qualified healthcare professional.
Sirolimus is a potent mTOR inhibitor immunosuppressant used primarily to prevent organ rejection in kidney transplants and to treat lymphangioleiomyomatosis (LAM). It belongs to the kinase inhibitor class and works by blocking T-cell activation.
Dosage for sirolimus is highly individualized and depends on the patient's immunologic risk, body weight, and the specific condition being treated.
For patients at low to moderate immunologic risk, the standard regimen often begins with a loading dose (a higher initial dose to reach therapeutic levels quickly).
For patients at high immunologic risk (e.g., those receiving a second transplant or with high antibody levels), the dosing may be more aggressive, often starting with a loading dose of up to 15 mg and maintenance doses adjusted to achieve specific blood trough levels (usually 10-20 ng/mL for the first year).
Sirolimus is approved for use in pediatric patients (children and adolescents) aged 13 years and older who are considered at low to moderate immunologic risk following a kidney transplant.
Interestingly, because sirolimus is primarily cleared by the liver, no dosage adjustment is typically required for patients with impaired kidney function. However, the drug is often used in combination with other medications that do affect the kidneys, so close monitoring is essential.
For patients with impaired liver function, the maintenance dose should be reduced. For those with mild to moderate hepatic impairment (Child-Pugh Class A or B), it is recommended to reduce the maintenance dose by approximately 33%. For severe hepatic impairment (Child-Pugh Class C), the maintenance dose should be reduced by about 50%. Loading doses generally do not need adjustment.
Clinical studies did not include enough subjects aged 65 and over to determine if they respond differently than younger subjects. However, since elderly patients often have reduced liver or kidney function and take multiple medications, dosing should be approached with caution, usually starting at the lower end of the dosing range.
If you miss a dose of sirolimus, take it as soon as you remember. However, if it is almost time for your next scheduled dose, skip the missed dose and return to your regular schedule. Never take two doses at once to make up for a missed one. If you miss multiple doses, contact your healthcare provider immediately.
Experience with sirolimus overdose is limited. Reported cases have generally shown similar side effects to standard doses but with increased severity. Signs may include extreme swelling, high blood pressure, or signs of infection. In the event of an overdose, seek emergency medical attention or contact a Poison Control Center immediately.
> Important: Follow your healthcare provider's dosing instructions exactly. Do not adjust your dose or stop taking this medication without medical guidance, as this could lead to organ rejection.
Sirolimus affects various systems in the body. Because it suppresses the immune system, many side effects are related to the body's reduced ability to fight infection or repair tissue.
> Warning: Stop taking Sirolimus and call your doctor immediately if you experience any of these serious symptoms.
Prolonged use of sirolimus carries specific long-term risks:
The FDA has issued several 'Black Box' warnings for sirolimus, which are the most serious warnings a medication can have:
Report any unusual symptoms to your healthcare provider immediately. Regular blood monitoring is the only way to ensure the drug stays within a safe and effective range.
Sirolimus is a high-alert medication that requires vigilant monitoring by a transplant specialist or a physician experienced in managing LAM. Patients must be committed to regular blood tests to measure the concentration of the drug in their system. Because sirolimus has a narrow therapeutic index, small changes in the dose or interactions with other substances can lead to either toxicity or drug failure (organ rejection).
1. Immunosuppression Risks: Increased susceptibility to infection and the possible development of lymphoma and other malignancies, particularly of the skin, may result from immunosuppression. Only physicians experienced in immunosuppressive therapy and management of organ transplant patients should use sirolimus.
2. Liver Transplant Risk: Sirolimus is NOT recommended for use in liver transplant patients. Clinical studies showed an increased risk of hepatic artery thrombosis (blood clots), which can lead to the loss of the transplanted liver or death. Most of these cases occurred within 30 days of the transplant.
3. Lung Transplant Risk: Sirolimus is NOT recommended for use in lung transplant patients. Reports have linked its use to 'bronchial anastomotic dehiscence,' a severe complication where the surgical wounds in the airway fail to heal and split open.
Because sirolimus stays in the body for a long time and is affected by many factors, you will need regular 'trough' level blood tests. These tests are usually taken just before your next scheduled dose.
Sirolimus generally does not interfere with the ability to drive or operate machinery. However, if you experience side effects like dizziness or blurred vision, avoid these activities until you know how the medication affects you.
While there is no direct 'black box' interaction between alcohol and sirolimus, alcohol can stress the liver, which is the primary organ responsible for breaking down sirolimus. Excessive alcohol consumption should be avoided. Additionally, the oral solution contains a small amount of ethanol (alcohol).
Never stop taking sirolimus abruptly. For transplant patients, stopping this medication can lead to immediate and irreversible organ rejection. If the drug must be stopped (for example, due to severe side effects or before a major surgery), it must be done under the strict supervision of your transplant team, who will likely start a different immunosuppressant to protect your organ.
> Important: Discuss all your medical conditions, especially any history of high cholesterol, liver disease, or skin cancer, with your healthcare provider before starting Sirolimus.
Certain drugs interact so severely with sirolimus that they should never be used concurrently:
Sirolimus does not typically interfere with the chemical process of most laboratory tests, but it significantly alters the results of many clinical tests, including:
For each major interaction, the mechanism usually involves the CYP3A4 enzyme system or the P-glycoprotein (P-gp) transporter. Inhibitors slow down the breakdown (leading to toxicity), while inducers speed it up (leading to rejection). Management always involves frequent blood level monitoring and precise dose adjustments by a specialist.
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking, including over-the-counter cold medicines and vitamins.
There are several situations where sirolimus should strictly never be used:
These are conditions where the risks of sirolimus may outweigh the benefits, requiring a careful risk-benefit analysis by a physician:
> Important: Your healthcare provider will evaluate your complete medical history, including any previous transplant complications or allergic reactions, before prescribing Sirolimus.
Sirolimus is classified as a medication that carries significant risks during pregnancy. Based on animal studies and its mechanism of action (inhibiting cell growth), sirolimus can cause fetal harm.
It is not known whether sirolimus is excreted in human breast milk. However, because many drugs are excreted in milk and because sirolimus has the potential for serious adverse reactions in nursing infants (such as immune suppression and growth issues), a decision should be made whether to discontinue nursing or discontinue the drug. In most cases, breastfeeding is not recommended for women taking sirolimus.
Clinical trials of sirolimus did not include sufficient numbers of patients aged 65 and older to determine if they respond differently than younger patients.
Sirolimus is unique among transplant drugs because it is not significantly cleared by the kidneys. Therefore, no initial dose adjustment is needed for patients with renal impairment. However, sirolimus is often used in combination with cyclosporine, which is toxic to the kidneys. If a patient's kidney function declines (as measured by GFR), the healthcare provider may choose to reduce the dose of the other medications rather than the sirolimus.
Because the liver is the primary site of sirolimus metabolism, impairment here is critical.
> Important: Special populations require individualized medical assessment and more frequent blood monitoring to ensure safety.
Sirolimus is a potent inhibitor of the mammalian target of rapamycin (mTOR) signaling pathway. At the cellular level, sirolimus enters the cell and binds to a specific immunophilin called FK-binding protein-12 (FKBP-12). This sirolimus-FKBP-12 complex then targets and inhibits the mTOR Complex 1 (mTORC1).
mTOR is a serine/threonine kinase that plays a central role in sensing nutrient availability and regulating cell growth. In T-lymphocytes, the inhibition of mTORC1 blocks the signaling pathways activated by various cytokines (like Interleukin-2, IL-15, and IL-7). This inhibition prevents the T-cells from progressing from the G1 (gap) phase to the S (synthesis) phase of the cell cycle. Unlike calcineurin inhibitors, sirolimus does not inhibit cytokine production; instead, it inhibits the cell's response to those cytokines.
| Parameter | Value |
|---|---|
| Bioavailability | ~14% (Oral) |
| Protein Binding | ~92% (Primarily Albumin) |
| Half-life | ~62 hours (Range 46-78h) |
| Tmax | 1-2 hours |
| Metabolism | Hepatic (CYP3A4) and P-gp |
| Excretion | Fecal 91%, Renal 2.2% |
Sirolimus is the prototype of the mTOR Inhibitor class. Other drugs in this class include everolimus (used in transplants and oncology) and temsirolimus (used in oncology). It is distinct from calcineurin inhibitors (like tacrolimus and cyclosporine) and antimetabolites (like mycophenolate mofetil).
Common questions about Hyftor
Sirolimus is primarily used to prevent the body from rejecting a kidney transplant by suppressing the immune system's response to the new organ. It is also FDA-approved to treat a rare lung disease called lymphangioleiomyomatosis (LAM), where it helps slow the growth of abnormal cells in the lungs. In some clinical settings, it may be used off-label for other types of organ transplants or specific vascular conditions. Because it is a potent medication, it is only prescribed by specialists in transplant medicine or pulmonology. It works differently than other common immunosuppressants, making it a valuable option for certain patients.
The most common side effects of sirolimus include swelling in the legs and hands (edema), high blood pressure, and increased levels of cholesterol and triglycerides in the blood. Patients also frequently report mouth sores, abdominal pain, and changes in blood counts, such as anemia or low platelets. Because it suppresses the immune system, an increased risk of infections is also a primary concern. Most of these side effects are managed through dose adjustments or additional medications. Your doctor will perform regular blood tests to monitor for these issues.
There is no direct, dangerous interaction between alcohol and sirolimus, but moderation is essential. Alcohol can place additional stress on the liver, which is the organ responsible for breaking down sirolimus. Furthermore, the oral liquid version of sirolimus contains a small amount of ethanol. It is always best to discuss your alcohol consumption with your transplant team, as they can provide guidance based on your overall liver health and other medications you may be taking. Avoiding excessive drinking is generally recommended for all transplant recipients.
Sirolimus is generally not recommended during pregnancy because animal studies have shown it can be toxic to a developing fetus. It works by inhibiting cell growth, which is a process vital for fetal development. Women of childbearing age should use highly effective birth control while taking sirolimus and for at least 12 weeks after stopping the medication. If you are planning a pregnancy or become pregnant, you must notify your healthcare provider immediately. They will help you weigh the risks of the medication against the risk of organ rejection during pregnancy.
Sirolimus has a very long half-life, meaning it stays in your system for a long time and takes a while to build up to a steady level. It typically takes about 5 to 7 days of consistent dosing to reach a 'steady state' in your blood. While it begins working on your immune cells shortly after the first few doses, its full protective effect for a transplant or its full therapeutic effect for LAM may take weeks to be fully realized. This is why doctors often use a 'loading dose' (a larger initial dose) to speed up this process. Regular blood monitoring is used to confirm the drug has reached the target level.
No, you should never stop taking sirolimus suddenly, especially if you have had an organ transplant. Stopping the medication can cause your immune system to immediately attack and reject the transplanted organ, which can be life-threatening and irreversible. If the medication needs to be stopped due to a severe side effect or an upcoming surgery, your doctor will manage the transition carefully. They will usually start a different immunosuppressant to ensure your body remains protected. Always consult your transplant team before making any changes to your medication regimen.
If you miss a dose of sirolimus, take it as soon as you remember. However, if it is almost time for your next scheduled dose, you should skip the missed dose and simply take the next one at the regular time. Do not take two doses at once to 'catch up,' as this can lead to toxic levels of the drug in your blood. Consistency is vital for keeping the drug levels steady, so try to take it at the same time every day. If you miss more than one dose, contact your healthcare provider for specific instructions.
Sirolimus is not typically associated with significant gain in body fat, but it very commonly causes fluid retention, which can lead to an increase in weight. This fluid retention often appears as swelling (edema) in the ankles, legs, or hands. If you notice a sudden, rapid increase in weight or severe swelling, you should notify your doctor. Additionally, sirolimus is often taken with corticosteroids (like prednisone), which are well-known for causing increased appetite and weight gain. Your healthcare team can help you determine the cause of any weight changes.
Sirolimus has many significant drug interactions because it is processed by the CYP3A4 enzyme in the liver. Many common medications, including certain antibiotics, antifungals, and blood pressure drugs, can cause sirolimus levels to become dangerously high or too low. Even herbal supplements like St. John's Wort can interfere with it. It is critical to provide your doctor and pharmacist with a complete list of all medications and supplements you take. They will monitor your blood levels closely whenever a new medication is started or stopped to ensure your sirolimus dose remains safe.
Yes, sirolimus is available as a generic medication in both tablet and oral solution forms. Generic versions are required by the FDA to be bioequivalent to the brand-name version (Rapamune), meaning they work the same way in the body. Using the generic version can be a more cost-effective option for many patients. However, because sirolimus is a 'narrow therapeutic index' drug, some transplant doctors prefer that patients stay on the same manufacturer's version (whether brand or generic) to avoid slight variations in blood levels. Always check with your doctor before switching between different versions of the drug.
Other drugs with the same active ingredient (Sirolimus)