Eflornithine

Eflornithine is a synthetic analogue of the amino acid ornithine and an irreversible (suicide) inhibitor of ornithine decarboxylase (ODC), the enzyme that catalyzes the first and rate-limiting step in the synthesis of polyamines, molecules that cells need for growth and division ^[3]. It was originally developed in the 1970s as a candidate anticancer drug.

Its most established use is against second-stage human African trypanosomiasis caused by Trypanosoma brucei gambiense, a parasitic disease of sub-Saharan Africa that is fatal if untreated. Eflornithine largely displaced the older and highly toxic arsenic-based drug melarsoprol for this indication. Because eflornithine given on its own requires prolonged intravenous infusions, it is now usually combined with oral nifurtimox in a simpler, safer regimen called nifurtimox-eflornithine combination therapy (NECT); a phase III trial found NECT to be as effective as eflornithine alone while being easier to give, and it has become a first-line treatment ^[1].

A topical cream form of eflornithine is approved to slow the growth of unwanted facial hair (hirsutism) in women. More recently, oral eflornithine has re-entered cancer care; building on the role of polyamines in tumor growth, it received regulatory approval to reduce the risk of relapse in children and adults with high-risk neuroblastoma who have responded to earlier treatment ^[2].

Eflornithine has additionally been used in rare inherited disorders of polyamine metabolism, such as Bachmann-Bupp syndrome, in which an overactive ODC causes developmental problems and hair loss; treated children have shown improvements in hair growth and development ^[3]. The drug appears on the World Health Organization list of essential medicines and is available in intravenous, oral, and topical forms.

Eflornithine cream is prescription only and its side effects stay mostly where you apply it. Some people get temporary stinging, burning, tingling, redness, dryness, acne, or small inflamed hair follicles. It only slows hair growth rather than removing hair, so you still need your usual hair-removal method, and the benefit fades within about two months of stopping. Very little is absorbed through the skin, so body-wide effects are uncommon. Keep it out of the eyes and off broken skin, and give it at least four to eight weeks before judging whether it helps.

Eflornithine, also called alpha-difluoromethylornithine or DFMO, was synthesized in the 1970s by researchers at the Merrell Research Institute, where Albert Sjoerdsma and colleagues designed it as an irreversible inhibitor of the enzyme ornithine decarboxylase in the hope of creating an anticancer drug. Although it disappointed as a broad cancer therapy, it found a dramatic second life in the 1980s and 1990s as a treatment for West African sleeping sickness, so effective at reversing the advanced, often fatal stage of the disease that it became known as the resurrection drug.

In 2000 a topical formulation was approved under the brand name Vaniqa to slow the growth of unwanted facial hair in women. Decades of laboratory interest in its ability to deplete the polyamines that fuel cell proliferation eventually returned it to oncology: in December 2023 the United States Food and Drug Administration approved oral eflornithine, marketed as Iwilfin, to reduce the risk of relapse in high-risk neuroblastoma following prior therapy. It remains on the World Health Organization's List of Essential Medicines for human African trypanosomiasis.

Eflornithine is celebrated as one of pharmacology's great repurposing stories, a compound that failed at its original goal yet went on to save lives against a devastating parasitic disease and later returned, decades after its discovery, as an approved cancer maintenance therapy. Its 2023 approval for high-risk neuroblastoma is particularly meaningful in pediatric oncology, where preventing relapse after intensive treatment is a longstanding challenge and the propensity-matched survival data were encouraging.

In dermatology its topical form offers a genuinely different mechanism for managing unwanted facial hair, slowing rather than merely removing it. The honest limitations are that its anti-parasitic use historically required demanding intravenous regimens, and that its effects, whether on hair or on tumor cells, depend on continued treatment because they work by suppressing an ongoing metabolic pathway. Even so, its breadth of proven uses across parasitology, dermatology, and oncology is genuinely rare.