General
The use of HYFTORTM Gel, 0.2% may cause local symptoms such as irritation (dry skin, dermatitis, erythema, pruritus, acne). Localized symptoms are most common [see Adverse Reactions (6)].
Bacterial and Viral Skin Infections
Before commencing treatment with HYFTORTM Gel, 0.2%, cutaneous bacterial or viral infections at treatment sites should be resolved. Studies have not evaluated the safety and efficacy of HYFTORTM Gel, 0.2% in the treatment of clinically infected angiofibroma.
Sun Exposure
During the course of treatment, patients should minimize or avoid natural or artificial sunlight exposure, even while HYFTORTM Gel, 0.2% is not on the skin. It is not known whether HYFTORTM Gel, 0.2% interferes with skin response to ultraviolet damage.
Immunocompromised Patients
The safety and efficacy of HYFTORTM Gel, 0.2% in immunocompromised patients have not been studied.
Risk Summary
HYFTORTM Gel, 0.2% is not absorbed systemically following topical administration, and maternal use is not expected to result in fetal exposure of the drug.
Based on animal studies and the mechanism of action, sirolimus may cause fetal harm when administered orally to a pregnant woman [see Clinical Pharmacology (12)]. There are no adequate and well-controlled studies of topically administered sirolimus in pregnant women. The experience with HYFTORTM Gel, 0.2% when used by pregnant women is too limited to permit assessment of the safety of its use during pregnancy. However, in animal studies with oral sirolimus, it was embryo/fetotoxic in rats at sub-therapeutic doses [see Nonclinical Toxicology (13)]. Advise pregnancy women of the potential risk to the fetus.
The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss or other adverse outcomes. In the US general population, the estimate background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively.
Data
Animal Data
No studies have been conducted with the topical route of administration.
In oral rat embryo-fetal development studies, pregnant rats were administered sirolimus orally during the period of organogenesis (Gestational Day 6-15). Sirolimus produced embryo-fetal lethality at 0.5 mg/kg (2.5-fold the clinical oral dose of 2 mg; based on body surface area) and reduced fetal weight at 1 mg/kg (5-fold the clinical oral dose of 2 mg, based on body surface area). The no observed adverse effect level (NOAEL) for fetal toxicity in rats was 0.1 mg/kg (0.5-fold the clinical oral dose of 2 mg, based on body surface area). Maternal toxicity (weight loss) was observed at 2 mg/kg (10-fold the clinical oral dose of 2 mg, based on body surface area). The NOAEL for maternal toxicity was 1 mg/kg. In combination with cyclosporine, rats had increased embryo-fetal mortality compared with sirolimus alone.
In oral rabbit embryo-fetal development studies, pregnant rabbits were administered sirolimus orally during the period of organogenesis (Gestational Day 6-18). There were no effects on embryo-fetal development at doses up to 0.05 mg/kg (0.5-fold the clinical oral dose of 2 mg, based on body surface area); however, at doses of 0.05 mg/kg and above, the ability to sustain a successful pregnancy was impaired (i.e., embryo-fetal abortion or early resorption). Maternal toxicity (decreased body weight) was observed at 0.05 mg/kg. The NOAEL for maternal toxicity was 0.025 mg/kg (0.25-fold the clinical oral dose of 2 mg, based on body surface area).
In an oral pre- and post-natal development study in rats, pregnant females were dosed during gestation and lactation (Gestational Day 6 through Lactation Day 20). An increased incidence of dead pups, resulting in reduced live litter size, occurred at 0.5 mg/kg (2.5-fold the clinical oral dose of 2 mg based on body surface area). At 0.1 mg/kg (0.5-fold the clinical oral dose of 2 mg, based on body surface area), there were no adverse effects on offspring. Sirolimus did not cause maternal toxicity or affect developmental parameters in the surviving offspring (morphological development, motor activity, learning, or fertility assessment) at 0.5 mg/kg, the highest dose tested.
Risk Summary
HYFTORTM Gel, 0.2% is not absorbed systemically by the mother following topical administration, and breastfeeding is not expected to result in exposure of the child to HYFTORTM Gel, 0.2%. However, it is not known whether sirolimus is excreted in human milk. Because of the potential for serious adverse reactions in nursing infants from sirolimus, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
After oral administration, sirolimus is present in the milk of lactating rats. There is potential for serious adverse effects from sirolimus in breastfed infants based on mechanism of action [see Clinical Pharmacology (12)].
The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for HYFTORTM Gel, 0.2% and any potential adverse effects on the breastfed child from HYFTORTM Gel, 0.2% or from the underlying maternal condition.
Contraception
Females
Advise females of the potential for reprotoxicity as animal studies have shown that oral sirolimus can be harmful to the developing fetus. Females of reproductive potential are recommended to use highly effective contraceptive method during administration of HYFTORTM Gel, 0.2%.
Males
Advise patients that the reproductive risk of HYFTORTM Gel, 0.2% is unknown.
Infertility
In fertility studies with oral sirolimus, changes in male rats included atrophic testes, epididymides, prostate, seminiferous tubules and/or reduction in sperm counts, which resulted in reduced fertility. In females, reduced size of ovaries and uteri was observed. These changes observed in male and female rats occurred following oral administration of sirolimus at doses approximately 10 times or 2 times the clinical dose, respectively.
Absorption
Sirolimus blood concentrations ranged from undetectable to 0.50 ng/mL after multiple doses of 0.2% HYFTORTM Gel, 0.2% in the Phase 3 study, with 90% of the patients having blood concentrations less than 0.22 ng/mL. In the long-term study, periodic blood sampling demonstrated a similar distribution of sirolimus blood levels in pediatric and adult patients.
Mean peak sirolimus blood concentrations in healthy normal volunteers following oral administration (2 mg) was 5.5 ng/mL and could not be detected following topical administration of a dosage corresponding to 1.6 mg. The lowest sirolimus blood level at which systemic effects (e.g., immunosuppression) can be observed is not known.
Systemic levels of sirolimus have also been measured in pediatric patients
Special Populations: Pediatrics
The absorption of sirolimus was not increased in pediatric patients with TS treated with HYFTORTM Gel, 0.2%.
Distribution
There was no evidence based on blood concentrations that sirolimus accumulates systemically upon topical application in patients with TS for periods of up to 1 year.
Metabolism
Studies evaluating the metabolism of HYFTORTM Gel, 0.2% have not been conducted.
Sirolimus is a substrate for both CYP3A4 and P-gp. Sirolimus is extensively metabolized after oral administration in the intestinal wall and liver and undergoes counter-transport from enterocytes of the small intestine into the gut lumen. Inhibitors of CYP3A4 and P-gp increase sirolimus concentrations. Inducers of CYP3A4 and P-gp decrease sirolimus concentrations. Sirolimus is extensively metabolized by O-demethylation and/or hydroxylation. Seven (7) major metabolites, including hydroxy, demethyl, and hydroxydemethyl, are identifiable in whole blood. Some of these metabolites are also detectable in plasma, fecal, and urine samples. Sirolimus is the major component in human whole blood and contributes to more than 90% of the immunosuppressive activity.
Excretion
Studies evaluating the excretion of HYFTORTM Gel, 0.2% have not been conducted.
After a single dose of [14C] sirolimus oral solution in healthy volunteers, the majority (91%) of radioactivity was recovered from the feces, and only a minor amount (2.2%) was excreted in urine. The mean ± SD terminal elimination half-life (t½) of sirolimus after multiple dosing in stable renal transplant patients was estimated to be about 62 ± 16 hours.
Drug Interaction Studies
Formal topical drug interaction studies with HYFTORTM Gel, 0.2% have not been conducted. Based on its extent of absorption, interactions of HYFTORTM Gel, 0.2% with systemically administered drugs are unlikely to occur but cannot be ruled out [see Clinical Pharmacology (12)]. The concomitant administration of strong CYP3A4/P-gp inducers or strong CYP3A4/P-gp inhibitors that decrease or increase sirolimus concentrations should be avoided.
Information for Patients
Patients using HYFTORTM Gel, 0.2% should receive and understand the information in the Medication Guide. Please refer to the Medication Guide for providing instruction and information to the patient.
What is the most important information patients should know about HYFTORTMGel, 0.2%?
The safety of using HYFTORTM Gel, 0.2% for a long period of time is not known. A very small number of people who have used oral sirolimus have had cancer (for example, skin or lymphoma). However, a link with HYFTORTM Gel,0.2% has not been shown. Because of this concern, instruct patients:
- Use HYFTORTM Gel, 0.2% only on areas of skin that have angiofibroma. Do not use HYFTORTM Gel, 0.2% on children under 3 years old.
HYFTORTM Gel, 0.2% comes in one strength: 0.2% (w/w%)
- HYFTORTM Gel, 0. 2% is for use on children aged 3 years and older and adults.
Advise patients to talk to their prescriber for more information.
How should HYFTORTMGel, 0.2% be used?
Advise patients to: