As we all know, growth hormone (GH) is essential to maintaining human health. Its primary role is to promote bone growth in children, muscle repair in adults, fat metabolism, and tissue regeneration. On April 3, 2025, a research team from Zhejiang University in China invented a smart growth hormone-controlled release transdermal patch that mimics biological rhythms. Hydroxypropyl Methyl Cellulose（HPMC） plays an essential role in it.
At the same time, the research team published a paper entitled 《Biorhythm-mimicking growth hormone patch》 in the journal Nature Materials. Growth hormone is released in the human body in a pulse mode, which usually has a peak release at night, and the pulse occurs every 3-4 hours at night, each lasting 1-2 hours. The controlled release of growth hormone transdermal patch realizes the three-stage pulse drug delivery mode of “rapid release + delayed release” through microneedle multi-module integration technology. Significant growth-promoting effects were shown in both healthy rats and growth-knockout mouse models.
Traditional clinical treatment of recombinant human growth hormone relies on daily subcutaneous injection, which has two major pain points:
Although the existing slow-release technology reduces the administration frequency, achieving multi-stage pulse release within a few hours is challenging. It cannot accurately match the secretion peak at night. Therefore, developing a new drug delivery system with synchronous rhythm and convenient use has a broad clinical demand.
To simulate the first secretion peak of hormones at night, inspired by the design principle of effervescent tablets, the research team introduced effervescent components (citric acid and sodium bicarbonate) into the polymer cross-linked microneedles structure to construct an “instant release” module through which carbon dioxide was rapidly generated by the reaction with tissue fluid to form a porous structure to accelerate the release of hormones from microneedles.
To simulate the second and third peaks of hormone secretion at night, inspired by the design principle of oral delay tablets, the research team used a core-shell microneedle structure to construct a “delayed release” module. Specifically, hydroxypropyl methylcellulose (HPMC), a pharmaceutical excipient that can swell and delay, was introduced into the polymer cross-linked microneedles as the core structure of core-shell microneedles. The water-insoluble microneedle shell structure was prepared by drying the medicinal excipient ethyl cellulose, and polyethene glycol was introduced as a pore-causing agent to allow the microneedle shell to dissolve slowly through the pore-causing agent in the interstitial fluid to form a pore channel to enable the interstitial fluid to immerse in the microneedle core. By changing the HPMC concentration of the microneedle core, the swelling rate can be accurately regulated, and the shell rupture delay and hormone release can be achieved at the expected time point. Three microneedle modules are integrated into a coin-sized patch using UV curing technology to ensure microneedle structural stability and multi-stage pulse release.
Figure 1. Schematic diagram of a smart growth hormone transdermal patch designed to simulate biological rhythm. a. Human growth hormone secretion at night mainly presents three continuous pulse release behaviors. b. The transdermal patch realizes the three-stage pulse drug delivery mode of “rapid release + delayed release” through microneedle multi-module integration technology.
BRIGHT Patch demonstrated excellent growth promotion in a healthy rat model, with an average body length increase of 10.1 mm and a significant increase in tibia and femur length during the 60-day detection period compared with the daily subcutaneous injection group, but no abnormal weight gain. It shows the positive effect of biorhythm-simulated release mode on stimulating growth (Figure 2a,b). Further, compared with the commercial long-acting growth hormone preparation, the BRIGHT patch group of rats also showed excellent growth promotion effects. When the circadian rhythm of the BRIGHT patch group was disturbed, its growth promotion effect was significantly inhibited, which verified the critical role of circadian rhythm in the biological rhythm simulation release behaviour. BRIGHT Patch also showed an excellent growth promotion effect in the growth gene knockout mouse model, and its growth level was close to that of normal mice of the same age; the bone growth quality was significantly improved, and the bone trabecular thickness and quantity were close to that of normal mice (Figure 2c-e).
Figure 2. Study on the growth promotion effect of a transdermal bright growth hormone patch simulating biological rhythm. A, b. Study on the growth promotion effect of a transdermal patch in a standard rat model. S.C. is a subcutaneous injection, and EF-MN is an “instant release” microneedle patch. c,d, Study on growth promotion effect of transdermal patch in gene knockout mouse model. e, Goldner staining image of tibial trabecula of gene knockout mice after transdermal patch treatment. Normal means normal mice of the same age.
The biosafety assessment results showed that there were very few residual components on the skin after the use of the BRIGHT Patch. All the auxiliary materials used were pharmaceutical grade, with good biocompatibility and potential for long-term safe use. HPMC is becoming increasingly indispensable in drug excipients. Its role and advantages are also obvious, and the era of sleep can quietly grow tall has arrived!
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