Hyftor: Uses, Dosage & Side Effects

What Is Hyftor and What Is It Used For?

Hyftor contains the active substance sirolimus, also widely known as rapamycin, a naturally derived macrolide compound originally isolated from the bacterium Streptomyces hygroscopicus found in a soil sample from Rapa Nui (Easter Island) in the 1970s. While sirolimus was initially developed and used as an immunosuppressive agent in organ transplantation and later as an antiproliferative agent in drug-eluting coronary stents, its ability to inhibit the mechanistic target of rapamycin (mTOR) has made it a uniquely targeted therapy for conditions driven by mTOR pathway overactivation, most notably tuberous sclerosis complex.

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disorder caused by loss-of-function mutations in either the TSC1 gene (encoding hamartin) or the TSC2 gene (encoding tuberin). These two proteins form a complex that acts as a critical negative regulator of the mTOR complex 1 (mTORC1) signaling pathway. When either TSC1 or TSC2 is defective, the brake on mTOR signaling is released, leading to constitutive activation of mTORC1. This results in uncontrolled cell growth, proliferation, and angiogenesis in multiple organ systems, giving rise to the characteristic benign tumors (hamartomas) of TSC that can affect the brain, kidneys, heart, lungs, eyes, and skin.

Facial angiofibromas are one of the most common and visible skin manifestations of TSC, developing in approximately 75 to 80% of affected individuals. They typically appear during early childhood, usually between the ages of 3 and 5 years, and progressively increase in number and size during puberty and into adulthood. Angiofibromas present as small, firm, reddish-pink papules and nodules that cluster symmetrically over the central face, particularly the nasolabial folds, cheeks, chin, and nose. Histologically, they are composed of a mixture of blood vessels, fibrous tissue, and stellate cells with activated mTOR signaling. Although benign, facial angiofibromas can be cosmetically disfiguring, psychologically distressing, prone to bleeding, and in severe cases may interfere with vision or breathing.

Hyftor works by delivering sirolimus directly to the angiofibromas through topical application. When sirolimus penetrates the skin, it binds to the intracellular protein FKBP-12 (FK506-binding protein 12), forming a complex that then binds to and inhibits mTORC1. This inhibition blocks the downstream signaling events that drive angiofibroma growth, including protein synthesis via p70S6 kinase and 4E-BP1, cell cycle progression, and vascular endothelial growth factor (VEGF)-mediated angiogenesis. The net result is a reduction in the size, vascularity, and redness of the treated angiofibromas. Because the gel delivers sirolimus locally to the affected tissue, systemic exposure is substantially lower than with oral sirolimus formulations, thereby minimizing the risk of systemic immunosuppressive side effects.

The clinical development of topical sirolimus for facial angiofibromas has been supported by multiple studies. The pivotal TREATMENT trial, a randomized, double-blind, vehicle-controlled phase III study, demonstrated that Hyftor applied once daily for 12 weeks produced statistically significant improvements in the composite Facial Angiofibroma Severity Index (FASI) compared with vehicle gel. The FASI score encompasses assessments of erythema (redness), size, and elevation of angiofibromas. In the extension phase of this study, continued improvement was observed with ongoing treatment over 12 months, supporting the sustained efficacy of the product. Additional evidence from investigator-initiated studies and case series published over the past decade consistently shows that topical sirolimus formulations at 0.1 to 0.4% concentrations effectively reduce angiofibroma severity in the majority of treated patients.

Hyftor was granted marketing authorization by the European Medicines Agency (EMA) following evaluation through the centralized procedure, recognizing the significant unmet medical need for an approved topical treatment for facial angiofibromas. Prior to Hyftor, patients relied on off-label compounded sirolimus preparations with variable concentrations and formulations, or on procedural interventions such as laser therapy, surgical excision, or electrodesiccation, all of which carry their own limitations and risks of recurrence.

What Should You Know Before Taking Hyftor?

Contraindications

The primary contraindication to using Hyftor is known hypersensitivity (allergy) to sirolimus, to any other mTOR inhibitor (such as everolimus or temsirolimus), or to any of the excipients in the gel formulation. If you have experienced an allergic reaction to any of these substances in the past, you must not use Hyftor. Signs of an allergic reaction may include severe skin rash, hives, swelling of the face or throat, or difficulty breathing.

Hyftor must not be applied to open wounds, cuts, or abrasions on the skin, as broken skin integrity may substantially increase systemic absorption of sirolimus beyond the levels expected from application to intact skin. The gel should also not be applied to skin areas with active infections, including bacterial, viral (such as herpes simplex), or fungal infections, as sirolimus may locally impair immune function and worsen the infection.

Warnings and Precautions

Before starting Hyftor, discuss the following with your healthcare provider:

• Sun sensitivity and skin cancer risk: Sirolimus, even when applied topically, may increase the skin's susceptibility to ultraviolet radiation damage. Patients should practice strict sun protection on treated areas, including daily application of broad-spectrum sunscreen with SPF 30 or higher, wearing protective clothing, and avoiding prolonged sun exposure. The long-term skin cancer risk with topical sirolimus at this low concentration has not been fully characterized, but caution is warranted given the known immunosuppressive properties of mTOR inhibitors.
• Local skin infections: Because sirolimus has local immunosuppressive properties, treated skin areas may be more susceptible to infections, including bacterial (e.g., impetigo, folliculitis), viral (e.g., herpes simplex, molluscum contagiosum), or fungal infections. If signs of skin infection develop at the application site (increased redness, warmth, swelling, pain, pus, or crusting), discontinue Hyftor temporarily and consult your doctor before resuming treatment.
• Concomitant use of other topical products: Avoid applying other topical medications, cosmetics, or moisturizers to the same area immediately before or after Hyftor application, as these may alter the absorption or efficacy of sirolimus. If you need to use other topical products on the face, discuss timing and sequencing with your doctor or pharmacist.
• Systemic sirolimus or everolimus therapy: If you are already taking oral sirolimus (Rapamune) or oral everolimus (Votubia, Afinitor) for other manifestations of TSC or for other conditions, discuss with your doctor whether additional topical sirolimus with Hyftor is appropriate. Although systemic absorption from topical application is low, the cumulative exposure to mTOR inhibition should be considered.

Children and Adolescents

Hyftor is approved for use in patients aged 6 years and older. The safety and efficacy of Hyftor in children younger than 6 years have not been established, and it should not be used in this age group. In clinical studies, pediatric patients aged 6 years and older used Hyftor with a safety and efficacy profile consistent with that observed in adult patients. Parents and caregivers should supervise the application of Hyftor in children to ensure proper use and to prevent accidental ingestion or contact with eyes.

It is particularly important to monitor children for local skin reactions and signs of infection at the treatment site, as younger patients may be less able to communicate skin discomfort. Any concerns about skin reactions in pediatric patients should be discussed promptly with the prescribing physician.

Pregnancy and Breastfeeding

Hyftor should not be used during pregnancy unless the potential benefit to the mother clearly outweighs the potential risk to the fetus. Animal reproductive studies with systemic sirolimus have shown adverse effects on embryo-fetal development, including embryo-fetal toxicity at doses that also caused maternal toxicity. While the systemic exposure to sirolimus from topical application of Hyftor is substantially lower than from oral formulations, a risk to the developing fetus cannot be completely excluded. Women of childbearing potential should use effective contraception during treatment with Hyftor and for 12 weeks after the last application.

It is not known whether sirolimus from topical application of Hyftor is excreted in human breast milk. Systemic sirolimus has been detected in breast milk in animal studies. Given the potential for adverse effects on a breastfed infant, a decision should be made whether to discontinue breastfeeding or to discontinue Hyftor treatment, taking into account the importance of the therapy for the mother. Discuss these considerations with your healthcare provider.

Driving and Operating Machinery

Hyftor is not expected to have any effect on the ability to drive or use machines. Topical application to the face does not cause systemic effects at levels that would impair cognitive or motor function. However, take care not to apply the gel immediately before activities where the product might inadvertently enter the eyes, as this could temporarily impair vision and cause eye irritation.

How Does Hyftor Interact with Other Drugs?

Sirolimus is metabolized primarily by the cytochrome P450 3A4 (CYP3A4) enzyme system in the liver and intestinal wall and is a substrate for the P-glycoprotein (P-gp) efflux transporter. When administered orally for immunosuppression after organ transplantation, sirolimus has well-documented drug interactions with agents that inhibit or induce CYP3A4 or P-gp. However, when applied topically as Hyftor gel, the systemic absorption of sirolimus is minimal, and blood concentrations are generally far below the levels associated with clinically significant pharmacokinetic interactions.

Despite the low systemic exposure, the possibility of drug interactions cannot be entirely dismissed, particularly in patients who apply Hyftor to large skin surface areas, have compromised skin barrier function, or are concomitantly taking potent CYP3A4 inhibitors that could amplify even small amounts of absorbed sirolimus. The following table summarizes theoretical and potential interactions to be aware of:

It is important to note that the overwhelming majority of patients using Hyftor will not experience clinically meaningful drug interactions due to the very low systemic absorption of sirolimus from topical application to intact facial skin. In pharmacokinetic studies, steady-state blood trough concentrations of sirolimus in patients using Hyftor were generally below 1 ng/mL or undetectable, which is well below the therapeutic target range of 5 to 15 ng/mL used in organ transplantation.

Despite the low interaction risk, it is always good clinical practice to inform your doctor, pharmacist, or nurse about all medicines you are currently using, including prescription medications, over-the-counter drugs, herbal supplements, and any other topical products applied to the face. This ensures comprehensive monitoring and helps your healthcare team identify any potential issues.

What Is the Correct Dosage of Hyftor?

Hyftor should always be used exactly as your doctor has instructed. The gel is intended for topical (external) use only and should be applied to the facial skin where angiofibromas are present. Do not apply the gel to areas of normal skin where angiofibromas are not present, as there is no benefit to treating unaffected skin and doing so would unnecessarily increase the total amount of sirolimus applied.

Adults

The application procedure is straightforward but should be followed carefully for optimal results:

1. Cleanse: Wash the face with a mild, non-irritating cleanser and pat dry thoroughly. Wait until the skin is completely dry before application.
2. Apply: Squeeze a pea-sized amount of gel onto a clean fingertip. Gently spread a thin, even layer over each area of angiofibromas. Do not rub vigorously.
3. Avoid sensitive areas: Do not apply near the eyes, on the eyelids, on the lips, inside the nose, or on mucous membranes. If accidental contact occurs, rinse thoroughly with water.
4. Wash hands: Wash your hands immediately and thoroughly after application to prevent inadvertent transfer to eyes, mouth, or other body areas.
5. Allow to dry: Allow the gel to dry for approximately 10 minutes before applying sunscreen, moisturizer, or cosmetics.

Treatment with Hyftor is generally intended to be long-term. Clinical studies have demonstrated that angiofibromas tend to gradually regrow after treatment is discontinued, with a return toward pre-treatment severity over weeks to months. For this reason, ongoing maintenance therapy is usually recommended. Your doctor will periodically reassess the need for continued treatment and monitor for any adverse effects.

Children (6 Years and Older)

The amount of gel used should be proportional to the surface area of angiofibromas, which may be smaller in younger children. The total daily application should be adjusted accordingly, using the minimum amount necessary to cover the affected areas with a thin layer. Children should be reminded not to touch or rub their face after application and to avoid transferring the gel to their eyes or mouth.

Elderly Patients

No dose adjustment is required for elderly patients. However, TSC-related facial angiofibromas are most commonly treated in younger age groups. Elderly patients with TSC should be monitored for any signs of skin fragility or delayed wound healing at the application site, as age-related changes in skin integrity may affect local tolerance. The treating physician should exercise clinical judgment regarding the continued benefit-risk ratio of treatment in elderly patients.

Missed Dose

If you forget to apply Hyftor at the usual time, apply it as soon as you remember on the same day. If you do not remember until the next day, simply skip the missed dose and continue with your regular daily application schedule. Do not apply a double amount to make up for a forgotten dose. Missing an occasional dose is unlikely to significantly affect the overall treatment outcome, but consistent daily application is important for optimal results.

Overdose

Accidental application of too much Hyftor gel or application to excessively large areas is unlikely to cause serious systemic effects due to the limited absorption of sirolimus through intact skin. However, excessive application may increase the risk and severity of local skin reactions such as irritation, redness, and peeling. If you accidentally apply significantly more gel than recommended, gently remove the excess by washing the treated area with mild soap and water. If the gel is accidentally ingested (for example, by a child), contact your doctor or a poison control center immediately, as oral ingestion of sirolimus can cause systemic effects including immunosuppression.

What Are the Side Effects of Hyftor?

Like all medicines, Hyftor can cause side effects, although not everybody who uses it will get them. The side effects observed during clinical trials and post-marketing experience are categorized below by their frequency of occurrence. The overall safety profile of Hyftor is favorable, reflecting the limited systemic exposure achieved with topical sirolimus application. The vast majority of reported adverse reactions are localized to the skin at the application site and are generally mild and self-limiting.

In the pivotal phase III TREATMENT trial, the rate of local adverse reactions was higher in the Hyftor group compared with the vehicle (placebo gel) group, but serious adverse events were rare and comparable between groups. Long-term safety data from extension studies support the continued tolerability of Hyftor with daily use over 12 months and beyond.

It is important to distinguish between the expected local skin reactions that often occur during the early weeks of treatment (which typically diminish with continued use) and more serious or unexpected reactions that should prompt medical attention. Most patients find that any initial irritation improves within the first 2 to 4 weeks of treatment as the skin acclimatizes to the medication.

The local skin reactions listed above are the most frequently encountered side effects and are consistent with the known pharmacological properties of topical sirolimus. The irritation, dryness, and redness that many patients experience during the first weeks of treatment typically reflect the local antiproliferative and anti-inflammatory effects of sirolimus on the skin. These reactions are generally self-limiting and tend to diminish in intensity with continued daily use as the skin adapts.

Systemic side effects are not expected with Hyftor when used as directed on intact facial skin, because the blood concentrations of sirolimus achieved are far below the levels associated with systemic immunosuppression. In the clinical trial program, there were no clinically meaningful differences between Hyftor and vehicle groups in laboratory parameters (blood counts, lipids, liver function, or kidney function), confirming the absence of significant systemic mTOR inhibition from topical use.

If you experience any side effects that are not listed above, or if any side effect becomes severe or bothersome, inform your doctor or pharmacist. You can also report side effects directly to your national medicines regulatory authority (such as the EMA, FDA, or MHRA) to help contribute to the ongoing monitoring of the safety of this medicine.

How Should You Store Hyftor?

Proper storage of Hyftor is essential to maintain the stability and efficacy of the sirolimus gel throughout its period of use. Sirolimus is a macrolide compound that can degrade upon exposure to light, elevated temperatures, and oxidation. The following storage guidelines should be carefully observed:

• Refrigerated storage: Store unopened tubes of Hyftor in a refrigerator at 2 to 8 °C (36 to 46 °F). This is the recommended long-term storage condition to ensure the chemical stability of the sirolimus active ingredient. Keep the gel in its original carton to protect from light.
• In-use storage: Once the tube has been opened, Hyftor may be stored at room temperature (below 25 °C / 77 °F) for a maximum period of 4 weeks. This allows for convenient daily use without needing to retrieve the tube from the refrigerator each time. Discard any remaining gel 4 weeks after first opening, regardless of how much product remains in the tube.
• Do not freeze: Freezing may alter the gel formulation and reduce the efficacy and consistency of the product. If Hyftor has been accidentally frozen, do not use it; discard it and obtain a new tube.
• Keep out of sight and reach of children: Store the tube in a safe location where children cannot access it. Accidental ingestion of sirolimus can cause serious systemic effects.
• Do not use after expiry date: Check the expiry date on the tube and carton. Do not use Hyftor after the expiry date (EXP) printed on the packaging. The expiry date refers to the last day of that month.

Do not dispose of Hyftor tubes in household waste or wastewater. Ask your pharmacist how to dispose of medicines you no longer need. These measures help to protect the environment from pharmaceutical contamination.

What Does Hyftor Contain?

Each gram of Hyftor gel contains 2 mg of sirolimus (0.2% w/w) as the active pharmaceutical ingredient. Sirolimus is a macrocyclic lactone compound with the molecular formula C₅₁H₇₉NO₁₃ and a molecular weight of 914.2 g/mol. It is practically insoluble in water but soluble in organic solvents, which necessitates a specialized gel formulation to deliver the drug effectively to the skin.

The excipients (inactive ingredients) in Hyftor include:

• Ethanol (anhydrous): Serves as a solvent for sirolimus and as a penetration enhancer to facilitate drug delivery through the skin. Patients with known sensitivity to alcohol-based topical products should be aware of this ingredient, as it may contribute to the initial stinging or burning sensation experienced upon application.
• Propylene glycol: Acts as a humectant and co-solvent, helping to maintain the gel consistency and enhance skin penetration of sirolimus. Propylene glycol may cause skin irritation in some individuals.
• Carbomer: A polymeric gelling agent that provides the gel structure and viscosity, ensuring even distribution of sirolimus across the application area.
• Trolamine (triethanolamine): A pH adjuster used to neutralize the carbomer and maintain the optimal pH of the gel formulation for stability and skin compatibility.
• Purified water: The aqueous base of the gel formulation.

Hyftor is supplied in aluminum tubes with a polyethylene screw cap. The gel itself is a clear to slightly opalescent, colorless to slightly yellowish preparation. Before each use, inspect the gel visually. Do not use if the gel has changed color significantly, has separated, or appears contaminated. The tube sizes available may vary by market; consult your pharmacist or the product packaging for the specific tube size dispensed in your country.

Hyftor does not contain parabens, fragrance, or dyes. It does not contain latex. The product is suitable for patients with latex allergy.