Japan will reduce the price of the diabetes medication 'Mounjaro' by 25% starting in August. While this will lessen the financial burden on diabetes patients, the Nihon Keizai Shimbun reports that prescriptions for Mounjaro for cosmetic and weight loss purposes may increase.
Mounjaro, developed by Eli Lilly, is a treatment for type 2 diabetes that was approved in Japan in 2022. It mimics the action of the gut hormone incretin to suppress appetite and lower blood sugar levels. Its weight loss effects have led to increased use among young women for cosmetic purposes, representing an 'off-label use' of a drug approved for diabetes treatment.
In Japan, such off-label prescriptions are recognized at the discretion of medical professionals. However, public health insurance does not cover these prescriptions, meaning patients must bear the full cost, similar to non-covered treatments in South Korea. The legal basis for direct regulation of off-label prescriptions by administrative authorities is also limited.
Despite the existence of separate obesity treatments with the same active ingredient, Mounjaro is widely prescribed in cosmetic settings. Eli Lilly also sells an obesity treatment called 'Zepbound,' which contains the same active ingredient, but it is subject to specific conditions for prescription by medical institutions under the Ministry of Health, Labour and Welfare's optimal use guidelines. Mounjaro does not have such restrictions, and its wholesale price is lower than that of Zepbound.
So, how much of the Mounjaro sold in Japan is prescribed for cosmetic and weight loss purposes? While exact figures are not publicly available, sales statistics provide a rough outline. According to the U.S. research firm IQVIA, Mounjaro's sales in Japan from October to December last year amounted to approximately 38.8 billion yen (about $345 million), making it the third highest-selling medical drug. This averages to about 13 billion yen per month. In contrast, estimates based on the National Database (NDB) of the Ministry of Health, Labour and Welfare, which only accounts for insurance-covered treatments, suggest a monthly sales figure of about 8.3 billion to 12.5 billion yen. The Nihon Keizai Shimbun estimates that the sales for off-label use could reach up to 5 billion yen per month when considering the differences in these statistics.
The growth of Mounjaro's off-label market can be attributed to Japan's online medical consultation structure, which allows patients to complete consultations, prescriptions, and deliveries via smartphone without visiting medical institutions or undergoing in-person examinations. The process is convenient and cost-effective. The online medical service 'Diet Beauty' advertises Mounjaro prescriptions starting at 18,000 yen per month. For medical institutions, it is easier to enter the market by providing online prescriptions without significant capital investment. The beauty medical market in Japan is also rapidly expanding, with the Yano Research Institute reporting that its size has increased by about 1.6 times since 2020, reaching 631 billion yen in 2024.
In response to the surge in Mounjaro sales, the Japanese government has decided to cut the drug's price by 25% starting in August. This decision follows the application of a 'sustainability special price adjustment' rule, which reduces prices when the sales of insured drugs exceed expectations. While this aims to alleviate the burden on diabetes patients and health insurance finances, it may have the opposite effect in the cosmetic off-label market.
Concerns Over Price Reduction Side EffectsThe issue is that the effects of the price reduction will not be limited to insured treatments. Pharmaceuticals are supplied from manufacturers to wholesalers and then to medical institutions. Wholesalers do not distinguish whether Mounjaro is used for diabetes treatment under insurance or for cosmetic purposes in off-label use. If the price decreases, the purchase price for cosmetic clinics may also drop. Hiroaki Mamiya, an associate professor at Ritsumeikan University, warns that the price reduction intended to lower medical costs could inadvertently encourage the use of Mounjaro for cosmetic purposes in the off-label market. If clinics pass on the price drop to patients, accessibility will increase, and if they maintain existing prices, profitability will improve, incentivizing expanded prescriptions.
In practice, there have already been reports of side effects. A gastroenterologist operating a clinic in Tokyo treated three young female patients who complained of bloating and nausea. Endoscopic examinations revealed that all three had food from the previous evening still in their stomachs. Mounjaro has a known effect of slowing gastrointestinal motility. The doctor believes that all three cases are related to Mounjaro use.
The side effects are not trivial. Nausea and lethargy can occur, as well as severe side effects like acute pancreatitis. The effects of long-term use in healthy individuals, as opposed to diabetes patients, are still unknown. The doctor cautioned, 'Suppressing appetite with medication can lead to eating disorders.' The Ministry of Health, Labour and Welfare issued a notice on June 16 requesting medical institutions to ensure appropriate use.
While the side effects themselves are concerning, another issue is who will bear the treatment costs. Patients prescribed Mounjaro through off-label use must pay the full price, but treatment for side effects may be covered by health insurance. While the price reduction may increase profits for cosmetic clinics, the costs of treating health complications could fall on public insurance, potentially creating a new burden from a measure intended to reduce medical expenses. The doctor pointed out, 'It is insufficient for the Ministry of Health, Labour and Welfare to merely issue a notice for appropriate use. Without specific sanctions against doctors who prescribe inappropriately, the trend of cosmetic prescriptions will not decrease.'
South Korea's situation is different. The Ministry of Health and Welfare plans to include obesity treatments in the list of medications restricted to non-face-to-face prescriptions starting in December 2024, making it unlikely that Japan's online structure, which allows consultations, prescriptions, and deliveries to be completed online, will spread. However, the trend of increasing off-label prescriptions for cosmetic purposes is not unique to Japan. The paradox of policies aimed at lowering drug prices encouraging misuse and shifting the costs of side effect treatments to public insurance is not just a Japanese issue.
* This article has been translated by AI.
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