Quite often additional information about drugs side effects is found during new preclinical and clinical trials after their approval and registration[
It is worth noting that the drug label information indicates about no effect on the adrenal hormones secretion such as cortisol or aldosterone and the lack of need for glucocorticoid or mineralocorticoid replacement therapy with exemestane treatment[
To gain further insight into association between ascites and exemestane treatment, we have studied the concentration of hormones with mineralocorticoid activity and estimated liver function - the main reasons of ascites formation.
As stated above, these results based on fragment of our main research related to the studying of third-generation aromatase inhibitors’ effect on metabolic syndrome pathogenesis[
Experimental metabolic syndrome in hamsters was induced by feeding them high-calorie diet containing large amount of fat (37%) and fructose (29%) for 9 weeks[
In this experiment we used steroidal third-generation aromatase inhibitor exemestane (Exemestanum-Vista®, Mistral Capital Management Ltd, England) registered in some European countries (including in Ukraine). Importantly, that it was a generic drug. Animal equivalent dose (AED) of exemestane was calculated taking into account the average daily therapeutic dose for humans and interspecies difference in mass and body surface area[
After 9 weeks of the experiment animals were euthanized in inhalation anesthesia, blood and liver tissues were collected, the serum was prepared from blood. Serum samples were then stored at -20 °C and tissue samples were fixated in 10% formaldehyde solution until further experimentation.
The level of serum albumin was photometrically measured by standard commercial kit «Albumin HP002.01» based on reaction with bromocresol green (Felicit-Diagnostics Ltd, Ukraine).
Liver tissue sections (6-7 µm) were stained by hematoxylin and eosin to study their morphological characteristics[
The cortisol content was measured by electrochemiluminescent analyzer Cobas E 411 (Roche Hitachi, Germany) using the basic Elecsys Cortisol II reagent module (Roche Diagnostics GmbH, Germany). The aldosterone level was measured by microplate reader ER-500 (SINNOWA, China) using the standard Aldosterone ELISA (LDN, Germany) reagent kit.
Comparisons of experimental data were carried out using the nonparametric methods of analysis (Mann-Whitney U-Test). All data were analyzed using computer programs STATISTISA 7.0 and MS Excel 2007 software. The results are presented as mean ± SEM. A
During the laparotomy we have noted that 19 of 20 female animals administrated exemestane had signs of ascites. The accumulation of pellucid fluid in the abdominal cavity of the female hamster was about 1.5-3.5 mL, depending on body mass. In the abdominal cavities of animals in other groups the presence of fluid excess was not marked.
The most common reason of drug-induced ascites is liver damaging during medicine’s metabolism, that decreases hepatic protein-synthesis function. Reduced amount of proteins with buffering properties causes to liquid relocation from bloodstream into the abdominal cavity[
The effect of exemestane on serum albumin concentration in experimental metabolic syndrome
Experimental groups | Serum albumin concentration (g/L) | |
---|---|---|
Age of 1 month (at the beginning of experiment) | Age of 2.5 months (at the beginning of experiment) | |
Control group | 38.3 ± 3.2 | 36.5 ± 2.5 |
DIMetS | 34.6 ± 2.5 | 35.9 ± 3.0 |
EX | 35.7 ± 2.4 | 37.4 ± 2.8 |
Values are means ± SEM.
Also no one animal had any signs of liver damage (fibrosis, necrosis), that would lead to an extremely loss of its function
Liver tissue sections: A: control group hamster, absolutely normal structure without any pathological signs, H&E stain, ×250; B: EX group hamster, normal structure, no signs of fatty dystrophy, uneven enlarged sinusoidal blood capillaries, H&E stain, ×200; C: DIMetS group hamster, vacuolar dystrophy of hepatocytes with temperate violation of tissue structure, enlarged sinusoidal blood capillaries, H&E stain, ×200. EX: exemestane
On the other hand, taking into account the fact that exemestane affects the activity of the aromatase enzyme as pseudosubtrate, it is possible that this drug or its metabolites may also affect other enzymes of steroidogenesis, which probably brings hormonal balance in the direction of mineralocorticoids and glucocorticoids hyperproduction. The increase in content of hormones with mineralocorticoid activity causes to intensive fluid and Na+ flow into the extracellular and cavity space[
It was determined that under the influence of a high-calorie diet young and mature female hamsters in the DIMetS group had moderate elevation of cortisol and aldosterone levels in serum
The effect of exemestane on adrenal hormones content in experimental metabolic syndrome
Experimental groups | Cortisol (nmol/L) | Aldosterone (pg/mL) |
---|---|---|
Age of 1 month (at the beginning of experiment) | ||
Control group | 15.98 ± 1.16 | 25.65 ± 3.02 |
DIMetS | 22.38 ± 1.27* | 37.26 ± 6.21 |
EX | 35.02 ± 3.00*/** | 102.44 ± 16.46*/** |
Age of 2.5 months (at the beginning of experiment) | ||
Control group | 20.95 ± 1.11 | 29.49 ± 4.71 |
DIMetS | 25.34 ± 1.70* | 47.25 ± 9.12* |
EX | 41.05 ± 3.05*/** | 84.67 ± 13.48*/** |
Values are means ± SEM.
In young female hamsters Exemestane administration causes to significantly increase in cortisol content by 2.2 times compared to the control and by 1.6 times compared to DIMetS; serum aldosterone content in EX group was increased by 4.0 and 2.7 times respectively. In adult female hamsters under the influence of exemestane, it was a significant increase in cortisol and aldosterone level by 2.0 times and 2.9 times respectively (in comparison with control animals) and by 1.6 times and 1.8 times (in comparison with DIMetS animals).
In our study we have taken into account that on the background of metabolic syndrome, the content of these hormones in the blood usually increases[
It should also be said that in the study we used a generic drug; probably this specificity is not associated with the original medicine. All in all, obtained experimental data create necessity for further pre-clinical and clinical studies of the exemestane safety in metabolic syndrome comorbidity.
In conclusions, the results suggest that under the conditions of experimental metabolic syndrome exemestane could be able to violate the mineral metabolism of animals through increased production of hormones with mineralocorticoid properties, in particular cortisol and aldosterone. Probably, exemestane or its metabolites are capable of inhibiting other steroidogenesis enzymes than aromatase. It should be taken into account and studied in detail in subsequent clinical trials related to the exemestane efficacy and safety in various cohorts of patients, especially females with mineral and metabolic abnormalities.
Experiment design, experimental modeling, assays, statistical processing, interpretation of the received data: Lytkin D
Eexperiment design, statistical processing, interpretation of the received data: Zagayko A
Experimental modeling, assays, interpretation of the received data: Briukhanova T
All authors have made an equal contribution.
Not applicable.
None.
All authors declared that there are no conflicts of interest.
Bioethic approval was obtained prior to the commencement of the study.
Not applicable.
© The Author(s) 2019.