In vitro fertilization hormones could one day be administered via painless ‘microneedle’ patches, early research suggests

Patients undergoing in vitro fertilization (IVF) must take daily hormone injections for several weeks until their eggs are collected for surgery. Now, the research team has developed a so-called painless, automated method to deliver these hormones using a light-activated microneedle patch.

Preliminary studies conducted in rats have shown that administration of leuprolide hormone through a patch can be performed painlessly and without releasing foreign substances into the body. Lights can be pre-programmed to turn on at specific times so that the patch releases hormones in the correct rhythm.

These results, published in the journal Small in November 2025, suggest that the patch could one day help solve two of the challenges of in vitro fertilization: the pain of hormone injections and the inconvenience of self-administering the injections at the same time every day for two weeks, said study lead author Marta Cerruti, a materials chemist at McGill University in Montreal. Most patients report feeling a brief, squeezing pain during the injection, but the level of pain varies depending on the patient’s level of needle anxiety.

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Cerruti said Vivian Tam, a doctoral student at the time of the study, suggested the study could help IVF patients. Cerruti said the group had previously considered using the patch to administer cancer drugs to patients.

“From what we’ve read, one of the main reasons for IVF failure is that the drugs are not administered consistently,” she told Live Science. It is hoped that a patch will resolve the issue someday.

Design of hormone delivery systems

In the new study, the team incorporated previous findings from two separate labs at McGill and the INRS research center in Quebec.

The patch consists of tiny needles containing nanoparticles packed with a hormone called leuprolide. Researchers had already developed a potential coating of nanoparticles that would break down when exposed to low-energy light called near-infrared light (NIR). When exposed to NIR, the contents of the nanoparticles spill out.

How this works is that NIR is converted into high-energy ultraviolet (UV) light by the core of the nanoparticle. This UV light breaks the bonds in the particle’s coating, freeing the molecules held inside. “We knew this coating would work,” Cerruti said.

The research team also showed that nanoparticles made from rare earth materials were non-toxic in animal studies. To create the patch, they then incorporated the nanoparticles into microneedles made of an insoluble synthetic polymer that shouldn’t break down, Cerruti said.

The needle makes tiny holes in the outer layer of the skin called the stratum corneum, which is made up of dead skin cells. It’s not painful because the needles don’t go deep enough to reach the sensory nerve endings in the deeper layers of the skin, Tam said.

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In rats, Cerruti said NIR was able to release the drug from the microneedles without releasing the foreign material, or the nanoparticle itself, into the body. If the nanoparticles had entered the body along with hormones, they would have accumulated in the liver or other organs, but the researchers did not observe this in their tests, she said.

One potential challenge with this method is that skin thickness and blood flow vary from patient to patient, said Riffen Kang, an associate professor at the University of Sydney’s School of Pharmacy who was not involved in the study. Ensuring that NIR pulses emit the light needed by different body types may be more difficult than administering the drug in a standard shot, he wrote in an email to Live Science.

NIR penetrates the skin better than visible light, but its efficiency decreases when fatty tissue increases, Kang added. “Because IVF is traditionally a subcutaneous injection, [delivered under the skin]”Researchers need to ensure that the microneedles and light source can communicate effectively at the depths needed to trigger emission,” he explained.

Although the new findings indicate that the hormone reached the rats’ circulatory system as intended, the researchers have not yet tested whether this delivery method has the desired effect of promoting egg maturation, Cerruti said.

According to Kang, the biggest hurdle for nanoparticle-based therapies is biocompatibility, meaning that the materials are compatible with living tissues and do not cause toxic effects or harmful immune responses. Researchers “must demonstrate that these nanoparticles are safely excreted or remain inactive in the skin without long-term toxicity,” he said.

The microneedles are not supposed to degrade in the body, but proving their durability may be difficult, Cerruti said. “The polymer is made of hydrogen, carbon and oxygen, the same elements that we are,” Cerruti said.

Cerruti said the researchers would like to conduct additional studies in rats to determine the effectiveness of this hormone delivery system before moving on to studies in larger animals.

In the first experiment, the research team released only small amounts of the hormone. Cerruti said that to get doses comparable to those used in in vitro fertilization, more patches would need to be used for a given mouse, or more nanoparticles would need to be included in a given patch. It is also possible that the patch size increases and the number of nanoparticles increases.

“One of the biggest barriers to overcome before ultimate clinical application is the limited dose of drug available in the bloodstream,” Cerruti said.