We read with great interest the article entitled “Management of ketamine cystitis: national guidelines from the French Association of Urology (CUROPF/CTMH)” by A. Bourillon et al., published in the issue of The French Journal of Urology [1].

This is a particularly important and useful article in the context of the growing use of ketamine and its derivatives in France, either as a drug or as a medication. In 2024, ketamine has had its French marketing authorization extended to chronic pain and more specifically to refractory neuropathic pain.

In France, drug dependence assessment and information centers monitor and assess the clinical complications of psychoactive substances at risk of abuse in the framework of Addictovigilance, leading the French Drug Agency (ANSM) to take preventive and information measures [2]. Ketamine has been specifically monitored as a product with an abuse/dependence potential [3]. French Addictovigilance data have clearly shown that the repeated, regular and prolonged use of ketamine, whatever its purpose (recreational, therapeutic, addictive, chemsex, etc.) constitutes the breeding ground for the emergence of these urinary complications [3]. Their update in 2024 shows the extent of this regular use, often by nasal route, as shown by the increase of both serious addictovigilance reports and ketamine users among patients of addictology centers. Since 2020, esketamine (the S-enantiomer of ketamine) has been available in France as a nasal spray to treat severe forms of depression, associated to oral antidepressants. Under medical supervision, esketamine is self-administered twice a week during weeks 1–4 in the induction phase, followed by maintenance treatment once weekly during weeks 5–8, and then every 2weeks or once weekly from week 9 forward. As mentioned in the Summary of product characteristics, in clinical studies with esketamine, despite no reported case of interstitial cystitis a higher rate of lower urinary tract symptoms was observed (pollakiuria, dysuria, micturition urgency, nocturia, and cystitis) in esketamine-treated patients compared with placebo-treated patients. The expert panel the French Association for Biological Psychiatry and Neuropsychopharmacology recommends the use of esketamine as a first-line add-on agent, in accordance with the current regulatory framework in France, and the use of intravenous ketamine as a second-line add-on agent, off-label in treatment resistant depression in France.

Besides, regarding the synthetic analogues of ketamine, which are substances that mimic its effects with much greater pharmacological potency, lead to more intense or longer-lasting effects. Among these synthetic products, methoxetamine administered to animals also induces urinary abnormalities objectified in experimental situations (versus placebo, versus ketamine).

In conclusion, all these data support a class effect with ketamine and its analogues at the origin of the urinary complications comprehensively described by Bourillon et al. They underline the essentiality of the close collaboration between urologists and pharmacologists from Addictovigilance centres in order to be more reactive to the emergence of these products, their methods of use and their complications. Furthermore, these data emphasize the importance of extending the patient interview to all psychoactive substances beyond alcohol and tobacco.

Disclosure of interest

The authors declare that they have no competing interest.