Swissmedic Vigilance-News-Edition 35

Fluoroquinolones are effective broad-spectrum antibiotics, but their use is limited by the risk of severe and potentially irreversible adverse drug reactions (ADRs). We describe the case of a young woman treated with a Helicobacter pylori eradication regimen that included levofloxacin, who developed acute neuropsychiatric symptoms – confusion and suicidal intent – followed by a chronic, disabling, multisystem syndrome consistent with a so-called fluoroquinolone-associated disability (FQAD). The clinical manifestations affected her cardiorespiratory, musculoskeletal, neurological, psychiatric, dermatological, vascular, ocular, oral, gastrointestinal and gynaecological systems, leading to profound impairment of quality of life, work incapacity and social withdrawal. The polysymptomatic presentation has not yet resolved and persists more than 9 months after onset. FQAD is a labelled rare but serious condition characterised by persistent multisystemic ADRs, where oxidative stress and mitochondrial toxicity are considered central mechanisms. Antioxidant therapies and, in certain cases, hyperbaric oxygen therapy have been attempted and yielded some benefit, but controlled trials are lacking. This case highlights the need for cautious use of fluoroquinolones, strict adherence to prescribing guidelines and greater awareness of FQAD as a real clinical entity. Pharmacovigilance reporting remains essential to improve recognition and management. 

_{Raffaela Bertoli, Francesca Bedussi, Laura Müller, Alessandro Ceschi}  

Semaglutide and tirzepatide, initially developed for the treatment of type 2 diabetes mellitus, have gained broad use in the management of body weight. Their benefits further include the reduction of cardiovascular risk, nephroprotective effects, improvements in obstructive sleep apnoea and, potentially, in metabolic dysfunction-associated steatotic liver disease. For approved indications in Switzerland, please refer to the specific products’ information at www.swissmedicinfo.ch. The therapeutic benefits of these agents must be weighed against their adverse reactions. The safety profile of both substances is dominated by gastrointestinal harms. Recently, non-arteritic ischemic optic neuropathy was identified as a very rare adverse drug reaction of semaglutide, while an increased risk of suicidal ideation was ultimately not confirmed by the current evidence. However, given that the risk cannot be fully excluded, an assessment is ongoing. Continuous pharmacovigilance is essential for monitoring potential harms, especially given the need for long-term treatment when using semaglutide and tirzepatide for weight management. Finally, healthcare professionals should guide the treatment to optimise outcomes and minimise adverse events.

_{Giulia Paternoster, Stephanie Storre, Thomas Kleppisch, Thomas Stammschulte}

Non-arteritic anterior ischemic optic neuropathy (NAION) is a condition that can result in acute monocular vision loss. Recently, several sources have reported cases of NAION in patients treated with semaglutide. A 68-year-old female patient who has had well controlled type 2 diabetes (T2D) for 12 years and which has been treated with semaglutide for approximately 2 years, presented with sudden loss of vision in her right eye. Ophthalmological investigations ruled out arteritic or inflammatory causes and supported a diagnosis of NAION in the right eye. Recent studies have investigated a possible link between the occurrence of NAION and semaglutide. In June 2025, a review by the European Medicines Agency concluded that NAION is a very rare side effect of semaglutide that could affect up to 1 in 10,000 patients taking semaglutide. Epidemiological studies suggest that semaglutide exposure is thus associated with an approximate doubling of this risk in patients with T2D compared with people not receiving the drug. The mechanism involved is still poorly understood. This is therefore a newly recognised adverse effect with a low estimated absolute risk, but one that prescribers and patients should be aware of because the drug is widely prescribed. This risk still needs to be better characterised.

_{Haithem Chtioui, Faiza Lamine}

Despite extensive preclinical testing and clinical trials conducted prior to marketing authorisation, the safety profile of a medicinal product remains incomplete at the time of commercialisation. In children, developmental physiology – which alters pharmacokinetics (PK) and pharmacodynamics (PD) – frequent off-label use, the lack of age-appropriate pharmaceutical formulations and continuous dose adjustments related to growth all increase the risk of adverse drug reactions (ADRs). These factors highlight the need for robust post-marketing pharmacovigilance to ensure the identification and management of drug-related risks in paediatric populations.  

Pharmacovigilance databases, such as VigiBase^®, contain relatively few paediatric reports, reflecting underreporting driven by lower drug use compared to adults, difficulties in recognising ADRs, potential legal concerns related to reporting ADRs associated with off-label use and insufficient training of healthcare professionals (HCPs) in detecting and reporting ADRs.  

Effective paediatric PV, which enables early detection of ADRs and the safe use of medicines, requires increased awareness and training of healthcare professionals, as well as close collaboration with regulatory authorities to optimise data collection, reporting and data quality. 

_{Frédérique Rodieux, Kuntheavy Ing Lorenzini, Irene Scholz}

Starting in November 2025, Swissmedic is launching a new initiative to improve communication of safety-related updates to the Information for healthcare professionals.  

The key feature of this initiative will be a monthly overview of safety-related updates to the Information for healthcare professionals in the "Safety of Medicines" newsletter, highlighting active substances whose Information for healthcare professionals has been recently updated with new safety information. Furthermore, a cumulative list of safety-related updates will be accessible as an Excel file on the Swissmedic website.

_{Giulia Paternoster, Melanie Patt, Nora Ruef, Lukas Jaggi, Stephanie Storre}

During 2024, Swissmedic received a total of 504 case reports of suspected “adverse events following immunization (AEFIs)” from Switzerland. Although lower in number than in 2023, almost half of these reports were submitted in relation to COVID-19 vaccines. Overall, these figures are a consequence of a continuing, but decreasing, number of COVID-19 vaccinations, and most of these reports describe known reactions. In addition, 260 AEFI reports were submitted for non-COVID vaccines during 2024, which is a similar number compared with 2023 (264 reports) and higher than in 2022 (217 reports). The focus of this report is on non-COVID vaccines. Nevertheless, a brief summary of COVID-19 AEFI reports received during 2024 is presented in the final section.

AEFI reports were recorded, assessed and analysed in the Swiss pharmacovigilance database. Swissmedic is encouraging reporting of AEFIs in high quality, which enables early detection of new safety signals. Important safety issues are evaluated in international collaboration with other regulatory agencies and/or with the participation of the Human Medicines Expert Committee (HMEC) of Swissmedic, if necessary. An increased AEFI reporting rate, followed by an assessment of relevant cases, can lead to risk minimisation measures in order to ensure vaccine safety.

^{Valeriu Toma}

In 2024, a total of 658 reports were submitted, marking a 42.4% increase compared with 2023. The most commonly affected species were dogs (365) and cats (197), followed by cattle (45) and horses (25). The most frequently involved medicinal product types were antiparasitics, vaccines, hormones, nervous system modulators and digestive tract treatments. 

A significant number of the reports (188) involved suspected lack of efficacy, particularly for antiparasitics and hormonal implants used to induce a temporary infertility in male dogs. In these last cases, efficacy was assessed by measuring testosterone levels, which were shown to be too high in 23 cases. 

Reports on vaccines mainly involved local and systemic reactions to frequently used products in dogs and horses. Nervous system modulators were primarily represented by anti-NGF monoclonal antibodies in dogs and cats. Reports saw a sharp rise, likely due to increased awareness. Reports on digestive tract treatments were mainly represented by a new oral antidiabetic for cats (velagliflozin), which led to reports of hyperglycaemia, lethargy and even fatal ketosis in some cases. 

Tox Info Suisse forwarded 206 cases, 73 animal exposures, mostly accidental ingestion of flavoured tablets, and 133 human exposures, often due to confusion with human medicines or accidental contact. One severe case of self-injection with a vaccine containing mineral oil led to necrosis and long-term disability. 

16 safety signals were initiated, resulting in updates to product information to improve safety. 

^{Cedric R. Müntener, Michaela Weber}