1. Introduction
Obesity is considered one of the most common metabolic disease, often associated with an elevated risk of developing type 2 diabetes mellitus (T2DM), non-alcoholic fatty liver disease, cardiovascular disorders, like hypertension and heart failure with preserved ejection fraction etc., thus reducing the life expectancy of patients [
1,
2,
3,
4].
Recent studies show that obesity increases the number of hospitalizations, the need for mechanical ventilation and the incidence of death in patients with SARS-CoV-2 [
5].
According to the World Health Organization (WHO), in 2022, 2.5 billion adults were overweight, and of them, 890 million were obese (~12.5%). The same report pointed out that the number of overweight children under the age of 5 was 37 million. In the 5 to 19 years group, above 390 million children and teenagers were overweight, of which 160 million were obese [
6].
Known as one of the biggest challenges of modern society at a global level, the fight against obesity has been declared a real public health emergency [
1,
5]. On the other hand, diabetes is considered one of the most widespread worldwide medical conditions and T2DM is the most common form [
7] with both acute and chronic consequences which decrease the quality of life, reduce life expectancy and increase the mortality rate [
8].
One of the global goals of WHO is to stop the increase in diabetes and obesity by 2025 [
6]. Unfortunately, until now, lifestyle changes in terms of daily diet and physical exercise have often proved insufficient to achieve significant weight loss [
7,
9]. The connection between obesity and diabetes is very close, so a large part of obese people are affected by diabetes or have a very high risk of developing T2DM in a very short period, and many patients with diabetes, especially those with T2DM, start to gain weight, soon becoming overweight or obese [
10].
Significant evidence attests that an effective improvement of insulin sensitivity and at the same time reducing the risk of diabetes associated with obesity can be achieved through weight loss [
10]. Over time, several molecules have been administered for the treatment of obesity, but their limited efficacy and/or adverse reactions led to the limitation of their use or even their withdrawal from the market (e.g. sibutramine, amfepramone, rimonabant, benfluorex, dexfenfluramine etc.) [
5,
11,
12,
13]. In this context, the approval of new drugs with adequate efficiency and safety in obesity treatment has been sought. Thus, the approval of the first glucagon-like peptide-1 (GLP-1) receptors agonist (GLP-1 RAs), with similar structures with endogenous hormone, in the treatment of T2DM opened a new era in promoting weight loss and improving health outcomes in obese people, including those with comorbidities [
14].
GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) are two of the main incretin peptide hormones excreted in the intestinal tract [
15], responsible for increasing the secretion of insulin after eating food and also inhibiting the secretion of glucagon [
16,
17,
18,
19]. GLP-1 reduces gastrointestinal motility, which in turn extends the period when nutrients might be absorbed. It also determines the feeling of satiety, enhances resting metabolic rate, and decreases free fatty acid concentrations in plasma [
20]. Extra-pancreatic effects of GLP-1 include delayed gastric emptying [
21] thus reducing the amount of food ingested and suppressing the appetite [
19] by increasing satiety, reducing glycosylated haemoglobin A1c (HbA1c) in patients with T2DM. These effects determined that the use of GLP-1 RAs has a high potential to reduce body weight and to be considered for the treatment of obesity [
15] (
Figure 1). In addition, their clinical use for the treatment of T2DM and obesity has increased interest in the way in which physiological and pharmacological levels of GLP-1 behave on essential tissues important to the pathophysiology of diabetes and its complications. [
17,
22]. Preclinical studies have shown that GIP can decrease body weight by diminishing food intake and enhancing energy expenditure and, in combination with GLP-1 RAs, can have a greater lowering effect on blood glucose and body weight in patients [
19,
20].
GLP-1 RAs have been approved in the treatment of T2DM for improving HbA1c and for reducing the risk of major adverse cardiac events (MACE) in diabetes patients with cardiovascular risk. More recently, some of them (liraglutide β LIR, semaglutide - SEM, and tirzepatide - TIR) have been approved in chronic weight management [
22,
24].
On the other hand, GIP also triggers glucose-dependent insulin excretion and is responsible for a larger fraction of the incretin effect than GLP-1. Depending on glycemic status, the glucagon secretion could be increased in normoglycemic or hypoglycemic patients (glucagonotropic effect) or inhibited in hyperglycemic patients (glucagonostatic effect) [
21,
25,
26].
Currently, there are several GLP-1 RAs approved worldwide, mainly for the treatment of diabetes and obesity, of which TIR is a novel dual GLP-1 RA and GIP receptor agonist (GIP/RAs). Exenatide (EXE) was the first GLP-1 RA in the world approved by the Food and Drug Administration (FDA), in 2005, in the treatment of T2DM, with two administrations per day, before meals [
27]. Later, the European Medicines Agency (EMA) (2009) and FDA (2010) approved the second agonist, LIR, as an adjuvant to diet associated with physical exercises in patients with T2DM. Compared to its predecessor, the latter presents a longer half-life with a greater effect on the reduction of HbA1C; at the same time, it showed cardiovascular benefits in addition to its effects of lowering blood sugar. In addition, it can be administered once a day regardless of meals. Moreover, FDA (December 2014) and EMA (March 2015) approved LIR for the treatment of chronic weight management [
27,
28].
The short-acting time of EXE was improved by the manufacturer and a new formulation was approved in 2012 by the FDA. Compared to the old formulation, the prolonged-release suspension of EXE is administered once a week [
29]. In 2014, the second GLP-1 RA with weekly administration, albiglutide (ALB), was approved by the FDA, and indicated in the treatment of T2DM in patients who cannot reach glycemic goals. In 2018, the manufacturer withdrew ALB for commercial reasons [
30,
31].
Also in 2014, dulaglutide (DUL) was approved by the FDA. It had the big advantage of reaching the therapeutic concentration faster compared to other GLP-1 RAs with weekly administration. SEM was launched in 2017 in injectable form, and it had an extended half-life of 7 days, and in 2019 the oral form of SEM received approval from the FDA, thus being the first oral GLP-1 RA treatment for adults with T2DM [
30,
32]. TIR is the latest one launched on the market, approved in 2022.
LIR was the first GLP-1 RA approved for weight loss in patients without a history of T2DM. In 2014, it was approved by the FDA in adult patients with a body mass index (BMI) larger than 30 kg/m
2 on its own or with a BMI greater than 27 kg/m
2 associated with at least one comorbidity related to weight, such as hypertension, diabetes, or dyslipidemia [
23,
33]. SEM only received approval from the FDA for weight control in 2021 [
33]. In the clinical studies carried out in this respect, SEM was superior in comparison to other long-acting GLP-1 RAs from the same class, namely EXE [
34] and DUL [
35]. Moreover, in addition to its beneficial effects in T2DM and in controlling body weight, it also showed a significant decrease in the rates of deaths due to cardiovascular issues, non-fatal myocardial infarction and non-fatal stroke in T2DM patients at risk of cardiovascular diseases [
33].
The off-label use of SEM for weight loss was promoted by social media and heavily influenced by famous public figures [
7]. This intense media coverage led to numerous shortages of this drug with major consequences for patients with T2DM. Beyond these shortages, the incorrect and inadequate use of GLP-1 RAs can have major consequences on the health status of the population. Until now, various studies have shown the negative impact of these drugs [
36,
37,
38,
39]. This study aimed to identify public interest in searching for information about SEM online and also to analyse the secondary real-world data regarding the use of inadequate doses (overdose, underdose or incorrect dose) or even the off-label use of SEM. In this respect, after the analysis of data presented on the Google Trends Tool, a detailed analysis of the Individual Case Safety Reports (ICSRs) uploaded in EudraVigilance (the European adverse reaction reporting database), was carried out. The evaluation of SEM popularity and safety profile was performed by comparison with other GLP-1 RAs (including ALB, which was withdrawn from the market).
4. Discussion
Reduced appetite and food intake were observed after GLP-1 RAs administration. Thus, their benefits in weight loss are exploited by using them in obese patients with or without diabetes [
48]. Improving the patientsβ adherence to GLP-1 RAs treatment by possible oral administration [
49] was an important objective of the researchers following their approval on the market. Only a few years after the EXE approval in therapy, new molecules have been authorised. SEM presents some differences in pharmacokinetics due to the modifications in GLP-1 structure: (i) improved stability against dipeptide-peptidase-4 enzyme (DPP-4) by substitution of alanine with aminoisobutyric acid; (ii) increased binding to albumin by introducing of a linker and a C18 di-acid chain; (iii) preventing the binding of fatty acid at the wrong site by substitution of Lys with Arg [
50]. On the other hand, to improve the patients' adherence to SEM, its absorption across gastric mucosa was improved by obtaining a co-formulation with sodium N-(8-[2-hydroxybenzoyl]amino)caprylate. Based on this formulation, SEM was the first GLP-1 RAs suitable for oral administration [
51]. Thus, SEM was expected to be very popular in the media and widely used in therapy, often as off-label or as auto medication. Because of this issue, the dosing errors were expected to be quite frequent.
The first item analyzed was the popularity of SEM in Google searches. The term βweight loss semaglutideβ was the most frequently used. Also, the queries related to weight loss have a higher frequency for the other GLP-1 RAs. Additionally, the search interest on Google for each molecule was related in a smaller frequency with the side effects. Based on this information, it could be considered that the people interested in these molecules had a similar search behaviour regarding the safety of the products. Our results are comparable to the ones in the study performed by Han et al., which showed that the greatest relative search was obtained for one of the SEM brand names [
7]. Also, a study published in 2024 showed that SEM was one of the most popular pharmacological and surgical obesity methods searched on Google [
52]. The popularity of SEM on TikTok (an online social media platform), is also very high. 57 of the first 100 video searches under the hashtag β#Ozempicβ were related to βweight lossβ (44 million views), and 29 of 100 were related to βcommon side effects, toxicityβ (24 million views). The βoff-labelβ use was a search term only in 3 of 100 videos (2.8 million views) [
53].
Although SEM was approved on the market more recently than LIR, DUL, EXE, and ALB, the descriptive analysis showed the highest number of ICSRs reported in EV (29% of the total). Its popularity and indication in obesity could contribute to an increase in the prescription numbers and implicitly in its consumption. In 2022, the global market of SEM and LIR increased by 43% from 9.9 to 14.2 billion USD [
54]. Moreover, according to a study published in 2023, prescriptions for SEM increased by 150% / year [
55]. This increase could be justified by a higher efficiency of SEM in weight loss and by a lower cost of treatment [
56,
57]. Other studies showed superior efficiency of SEM compared to LIX [
58], EXE [
58,
59], DUL [
59] and, LIR [
60]. For example, SEM led to an average reduction of body weight of 12.4% in 68 weeks compared to LIR (-5.4% in 56 weeks) [
60]. Therefore, SEM had an improved value for money in weight reduction compared with LIR (estimated cost of 1845 USD per 1% reduction in body weight for SEM, compared to 3256 USD for LIR) [
60].
Regarding the demographic characteristics of patients, in the present study, most of the reports were in the 18-64 years group. Also, the most frequent reports were for females (57.7%), similar to the results of another study performed on the data from the Food and Drug Administration Adverse Event Reporting System (FAERS) between 2018β2022 (54.4%) [
61].
According to the present study, SEM had the lowest number of severe ADRs compared to the analysed molecules. These results are similar to other studies that reported a safety profile consistent with other GLP-1RAs, with a low incidence of severe ADRs for SEM [
59,
62,
63]. Generally, SEM is well tolerated, and most ADRs induced are mild-to-moderate and transient. Although a fatal outcome was reported only for overdosing on SEM and LIR. Anyway, until now, no unexpected safety issues have been reported for SEM [
62,
63]. However, another interesting result of the present study suggests that SEM had a higher number of ADRs reported by each case than DUL and LIR, and similar with TIR. Considering that TIR was recently authorized, it is expected that this situation will be different over time.
This study revealed a higher tendency to report ADRs related to overdosing of SEM (except DUL and EXE), and incorrect dosing compared to LIR and TIR. According to the American Association of Poison Control Centers, a total of 2941 cases related to SEM overdosing were reported between January β November 2023, more than double compared to 2022 [
64]. The overdosing cases reported in the scientific literature were associated with notable gastrointestinal symptoms, even with medical evaluation and treatment with antiemetics and intravenous fluids [
65,
66].
On the other hand, the off-label use of SEM was more frequently reported in EV than other GLP-1 RAs (except TIR). Probably, its advantages (high efficiency and safety, improved value for money in weight reduction, and increased benefits-risk ratio) represent factors for increasing the off-label use of SEM. According to the study performed by Chiappini et al., off-label use of SEM was the fifth most frequent cause of reporting in FAERS (6%) [
61].
Finally, media attention fuels the demand for this type of medication and, at the same time, generates an increase in illegal sales. Thus, the authorities in countries such as Austria, Denmark, Great Britain, Ireland, Switzerland, etc. seek to repress illegal activity with these drugs, approaching different methods of social media monitoring, even reporting the confiscation of falsified pens with SEM in some EEA states [
67]. Moreover, both manufacturers and regulatory agencies in the field of medicine issued warnings about the penetration of counterfeit products into the drug supply chain, finding them in retail pharmacies [
68,
69,
70]. In this context, greater attention must be paid, both to the way of prescribing and also to the counselling of patients regarding the identification of fakes and the judicious use of medicines.
Limitations of the Study
Certain limitations should be considered for this study. Our searches included only active pharmaceutical ingredients. The online environment is extensive; besides Google, other search engines and social media platforms are widely used. We acknowledge that these results may not offer the full depiction of the off-label use for weight loss phenomenon. Some ADRs from the EudraVigilance spontaneous reporting system are related to the low reporting rate or to the inaccuracy of the information contained in the reports. The number of ADRs reported could be influenced by the extent of drug use, the awareness of the reporter, the severity and outcome of the reaction, etc. Moreover, information such as concomitant medication or other suspected drugs, comorbidities, medical status, etc. could be missing, thus affecting this analysis. Other limitations are the lack of a denominator or the lack of certainty of a causal relationship between the reported ADRs and the suspected drug. Not at least, off-label use could be a factor in the underreporting of adverse drug reactions. Further studies are needed for an extensive evaluation of the safety profile of SEM and other GLP-1 RAs.
Author Contributions
Conceptualization A.B., C.D., A.A., C.M., A.F. and L.V.; methodology, A.B., C.D., A.A., C.M., L.R., S.G, A.J., F.G. and L.V.; software, A.B., C.D., A.A., A.M., A.L., C.M., and A.F. validation, A.B., C.D., A.A., S.G., C.M., and L.V.; formal analysis, A.B., A.A., C.D., C.M., L.R., S.G, A.M., F.G. and L.V.; investigation, A.B., A.M., A.C., A.J., A.L., C.M., and L.V.; data curation, A.B., C.D., A.A., S.G., C.M., L.R. and L.V.; resources, A.B., C.D., A.F. and L.V.; writingβoriginal draft preparation, A.B., C.D., A.A., A.F., A.C., C.M. and L.V.; writingβreview and editing, A.B., C.D., A.A., A.F., A.C., L.R., A.M., A.L., C.M. and L.V.; visualization, A.B., C.D., A.A., A.F., A.C., L.R., A.J., A.M., S.G., A.L., F.G., C.M. and L.V.; supervision, A.A., S.G., F.G., C.M. and L.V. All authors have read and agreed to the published version of the manuscript.