He Navarre Pharmacovigilance Center detected 11 cases, including one in the Autonomous Community, of hypertrichosis, known as “werewolf syndrome”, in infants whose caregivers used a medicine for the treatment of alopecia. Hypertrichosis is the appearance of unwanted hair in areas other than the scalp, including facial hair growth in women.
This is indicated in its newsletter published this month of October in which it indicates having become aware, in April 2023, of a case occurring in Navarre of a breastfed baby who had gradually developed increased hair on his back, legs and thighs over two months. Pathologies or other medications administered to the baby that could justify the increase in body hair were excluded.
During the interview with the family, it was noted that father used minoxidil 5% topically for the treatment of androgenic alopecia and for one month He was on leave from work to care for his son.. After withdrawal of contact with the drug, the symptoms completely resolved.
Following knowledge of this circumstance, a review of similar reported cases in the Spanish Pharmacovigilance System (FEDRA) database, detecting six additional cases with the same characteristics, all in breast-fed infants whose caregivers were treated with topical minoxidil for the treatment of androgenic alopecia.
The research was extended to similar cases reported in Eudravigilance (European Pharmacovigilance Database) and three additional cases were discovered. A review of the literature provided an additional case.
He Pharmacovigilance Center de Navarra hypothesizes that there is a transfer of minoxidil from adults who use this medication topically to young babies in their care and that, during transfer, the medication is absorbed topically or orally (by “pacifying” example) producing a systemic effect in children.
“The skin of young children is more permeable due to the lower thickness of their stratum corneum and they have a higher surface area to body weight ratio. For this reason, they have an easier time absorbing locally administered drugs systemically,” he explains.
EXPOSURE IN INFANTS “IS SEVERE”
In this report, the Navarre Pharmacovigilance Center warns that the the appearance of generalized hypertrichosis in infants due to accidental exposure to minoxidil “is serious” because “a person, who is not the patient, from a vulnerable age group and for whom the said medicine is not indicated, is exposed to a medicine”.
Furthermore, the appearance of hypertrichosis in children “can be alarming and require numerous laboratory and imaging tests to be performed to rule out endocrine problems, since the initial investigation of the origin of hypertrichosis may focus on the causes in the patient himself. This may generate great stress in patients’ families.”
With all the information collected and following the signal generation procedure of the Spanish Pharmacovigilance System (SEFV-H), the Pharmacovigilance Center of Navarra proposed in May 2023 this signal of hypertrichosis in infants due to accidental exposure to minoxidil for validation within the SEFV-H Technical Committee. The signal was unanimously validated and confirmed in the European Union in June 2023.
For his part, the European Pharmacovigilance Risk Assessment Committee (PRAC)at its June 2024 meeting, made the recommendation to include a warning on these cases of hypertrichosis in infants after skin contact with areas of minoxidil application in caregivers who used topical minoxidil.
