Sex-related pharmacokinetic differences and mechanisms of metapristone (RU486 metabolite)

Pharmacokinetics, efficacy, and safety of cannabidiol in dogs: an update of current knowledge

In the last 5 years, interest has grown in using phytocannabinoids, particularly cannabidiol (CBD), in veterinary medicine to treat several pathologies, including pain, epilepsy, anxiety, nausea, anorexia, skin lesions, and even some types of cancer, among others. Indeed, due to a positive perception of CBD use, many pet owners are increasingly requesting this option to relieve their pets, and many veterinarians are exploring this possibility for their patients. Besides the widespread empiric use of CBD in pets, the research is trying to obtain proof of its efficacy and lack of adverse effects and to know its pharmacokinetics to define an appropriate posology. This review summarizes all data published so far about the canine pharmacokinetics, efficacy, and tolerability of CBD and cannabidiolic acid (CBDA). Despite a certain number of available pharmacokinetic studies, the kinetic profile of CBD has yet to be fully known, probably because of the very different experimental conditions. In terms of efficacy, most studies have tested CBD' ability to relieve osteoarthritic pain. In contrast, few studies have evaluated its role in epilepsy, behavioral disorders, and skin lesions. From obtained results, some evidence exists supporting the beneficial role of CBD. Nevertheless, the limited number of published studies and the occurrence of bias in almost all require caution in interpreting findings. From tolerability studies, CBD' side effects can be classified as mild or unremarkable. However, studies were prevalently focused on short- to medium-term treatment, while CBD is usually employed for long-term treatment. Further studies are warranted to define better whether CBD could be a valid adjunct in canine treatment.

Pharmacokinetics, toxicological and clinical aspects of ulipristal acetate: insights into the mechanisms implicated in the hepatic toxicity

Ulipristal acetate is a drug used as emergency contraceptive (30 mg) and for the treatment of moderate to severe symptoms of uterine myomas (5 mg). After commercialization, and although the exact number is unknown, serious cases implying ulipristal acetate 5 mg as a contributing factor of liver injury, some leading to transplantation, were reported. These cases prompted to a restrict use of the drug in January 2021 by the European Medicines Agency. This work aimed to fully review pharmacokinetic aspects, namely focusing in the ulipristal acetate metabolism and other hypothetical toxicological underlying mechanisms that may predispose to drug-induced liver injury (DILI). The high lipophilicity, the extensive hepatic metabolism, the long half-life of the drug and of its major active metabolite, the long-term course of treatment, and possibility due to the formation of epoxide reactive may be contributing factors. Scientific results also points evidence to consider monitorization of liver function during ulipristal acetate treatment.

Metapristone (RU486-derivative) inhibits endometrial cancer cell progress through regulating miR-492/Klf5/Nrf1 axis

Background

Endometrial cancer is an invasive gynecological cancer prevalent in the world. The pathogenesis of endometrial cancer is related to multiple levels of regulation, referring to oestrogen, tumor-suppressor gene (e.g. PTEN) or microRNAs (e.g. miR-23a and miR-29b). Metapristone is a hormone-related drug, which is widely used in clinical treatment of endometrial cancer. However, the underlying regulatory mechanism of metapristone on endometrial cancer is still unclear, especially the regulatory effect on microRNAs. The aim of this study is to investigate the specific molecular mechanism of metapristone regulating microRNAs in the treatment of endometrial cancer.

Methods

RL95-2 cells and Ishikawa cells were used as the endometrial cancer models. MiR-492 or si-miR-492 was transfected into RL95-2 cells and Ishikawa cells to explore the role of miR-492 in endometrial cancer. The cell cancer model and mice cancer model were used to confirm the function and mechanism of metapristone affected on endometrial cancer in vitro and in vivo. Mechanically, cell proliferation was monitored using MTT assay, cell colony formation assay and EdU assay. Luciferase reporter assay was used to identify the downstream target gene of miR-492. The protein expression and RNA expression were respectively measured by western blot and qRT-PCR for cell signaling pathway research, subsequently, were verified in the mice tumor model via immunohistochemistry.

Results

Metapristone as a kind of hormone-related drug significantly inhibited the endometrial cancer cell growth through regulating cell apoptosis-related gene expression. Mechanically, miR-492 and its target genes Klf5 and Nrf1 were highly expressed in the endometrial cancer cell lines, which promoted cell proliferation and inhibited cell apoptosis. Metapristone decreased the expression of miR-492 and its target genes Klf5 and Nrf1, leading to endometrial cancer cell growth inhibition in vitro and in vivo.

Conclusion

Metapristone inhibited the endometrial cancer cell growth through regulating the cell apoptosis-related signaling pathway and decreasing the expression of miR-492 and its downstream target genes (Klf5 and Nrf1), which provided the theoretical basis in clinical treatment of endometrial cancer.

Pharmacokinetics of thalidomide in dogs: can feeding affect it? A preliminary study

BACKGROUND

Tumor-associated neoangiogenesis is a crucial target for antitumor therapies. Thalidomide (TAL) is a promising anti-neoangiogenetic drug that has recently been used in the treatment of several malignancies in dogs.

OBJECTIVES

The aim of the study was to assess the pharmacokinetics of TAL after single oral administration in dogs. Additionally, the influence of feeding on the pharmacokinetic profile of TAL in dogs has been preliminarily investigated.

METHODS

Six healthy adult female Labradors were enrolled according to a randomized single-dose, 2-treatment, 2-phase, paired 2 × 2 cross-over study design. The dogs were administered a single 400 mg capsule of TAL in fasted and fed conditions. Blood was collected from 15 min to 48 h after dosing, and TAL quantified in plasma by a validated high-performance liquid chromatography method. The pharmacokinetics of TAL were analyzed using a non-compartmental approach.

RESULTS

TAL concentration was quantifiable up to 10 h and 24 h after fasted and fed conditions, respectively. C_max (fasted, 1.34 ± 0.12 μg/mL; fed, 2.47 ± 0.19 μg/mL) and T_max (fasted, 3 h; fed, 10 h) differed substantially between the 2 groups. AUC and t_1/2λz were significantly higher in fed (42.46 ± 6.64 mg × h/L; 17.14 ± 4.68 h) compared to fasted (12.38 ± 1.13 mg × h/L; 6.55 ± 1.25 h) dogs. The relative oral bioavailability of TAL for the fasted group was low (36.92% ± 3.28%).

CONCLUSIONS

Feeding affects the pharmacokinetics of oral TAL in dogs, showing a delayed, but higher absorption with different rate of elimination. These findings are of importance in clinical veterinary settings, and represent a starting point for further related studies.

Acute liver failure requiring transplantation caused by ulipristal acetate

Ulipristal has recently been suspected to be hepatotoxic by the European Medicines Agency but the evidence base for hepatotoxicity is sparse. This is a brief formal report of a patient administered ulipristal for 6-8 weeks and who developed acute liver failure leading to liver transplantation. The explanted liver showed extensive hepatocyte necrosis and inflammation compatible with drug-induced liver injury and cirrhosis. The usual causes of acute hepatitis and cirrhosis were eliminated. There were no other potential causative drugs. This case suggests that ulipristal may cause acute hepatitis, with pre-existing cirrhosis probably contributing to the severity of liver injury observed in this case. Ulipristal prescribers must remain vigilant and monitor liver function in their patients.

Unexpected differences in the pharmacokinetics of N-acetyl-DL-leucine enantiomers after oral dosing and their clinical relevance

The enantiomers of many chiral drugs not only exhibit different pharmacological effects in regard to targets that dictate therapeutic and toxic effects, but are also handled differently in the body due to pharmacokinetic effects. We investigated the pharmacokinetics of the enantiomers of N-acetyl-leucine after administration of the racemate (N-acetyl-DL-leucine) or purified, pharmacologically active L-enantiomer (N-acetyl-L-leucine). The results suggest that during chronic administration of the racemate, the D-enantiomer would accumulate, which could have negative effects. Compounds were administered orally to mice. Plasma and tissue samples were collected at predetermined time points (0.25 to 8 h), quantified with liquid chromatography/mass spectrometry, and pharmacokinetic constants were calculated using a noncompartmental model. When administered as the racemate, both the maximum plasma concentration (Cmax) and the area under the plasma drug concentration over time curve (AUC) were much greater for the D-enantiomer relative to the L-enantiomer. When administered as the L-enantiomer, the dose proportionality was greater than unity compared to the racemate, suggesting saturable processes affecting uptake and/or metabolism. Elimination (ke and T1/2) was similar for both enantiomers. These results are most readily explained by inhibition of uptake at an intestinal carrier of the L-enantiomer by the D-enantiomer, and by first-pass metabolism of the L-, but not D-enantiomer, likely by deacetylation. In brain and muscle, N-acetyl-L-leucine levels were lower than N-acetyl-D-leucine, consistent with rapid conversion into L-leucine and utilization by normal leucine metabolism. In summary, the enantiomers of N-acetyl-leucine exhibit large, unexpected differences in pharmacokinetics due to both unique handling and/or inhibition of uptake and metabolism of the L-enantiomer by the D-enantiomer. Taken together, these results have clinical implications supporting the use of N-acetyl-L-leucine instead of the racemate or N-acetyl-D-leucine, and support the research and development of only N-acetyl-L-leucine.

Modulation of glucocorticoid receptor in human epileptic endothelial cells impacts drug biotransformation in an in vitro blood-brain barrier model

Objective

Nuclear receptors and cytochrome P450 (CYP) regulate hepatic metabolism of several drugs. Nuclear receptors are expressed at the neurovascular unit of patients with drug‐resistant epilepsy. We studied whether glucocorticoid receptor (GR) silencing or inhibition in human epileptic brain endothelial cells (EPI‐ECs) functionally impacts drug bioavailability across an in vitro model of the blood–brain barrier (BBB) by CYP‐multidrug transporter (multidrug resistance protein 1, MDR1) mechanisms.

Methods

Surgically resected brain specimens from patients with drug‐resistant epilepsy, primary EPI‐ECs, and control human brain microvascular endothelial cells (HBMECs) were used. Expression of GR, pregnane X receptor, CYP3A4, and MDR1 was analyzed pre‐ and post‐GR silencing in EPI‐ECs. Endothelial cells were co‐cultured with astrocytes and seeded in an in vitro flow‐based BBB model (DIV‐BBB). Alternatively, the GR inhibitor mifepristone was added to the EPI‐EC DIV‐BBB. Integrity of the BBB was monitored by measuring transendothelial electrical resistance. Cell viability was assessed by glucose‐lactate levels. Permeability of [³H]sucrose and [¹⁴C]phenytoin was quantified. CYP function was determined by measuring resorufin formation and oxcarbazepine (OXC) metabolism.

Results

Silencing and inhibition of GR in EPI‐ECs resulted in decreased pregnane X receptor, CYP3A4, and MDR1 expression. GR silencing or inhibition did not affect BBB properties in vitro, as transendothelial electrical resistance and P_sucrose were unaltered, and glucose metabolism was maintained. GR EPI‐EC silencing or inhibition led to (1) increased P_phenytoinBBB permeability as compared to control; (2) decreased CYP function, indirectly evaluated by resorufin formation; (3) improved OXC bioavailability with increased abluminal (brain‐side) OXC levels as compared to control.

Significance

Our results suggest that modulating GR expression in EPI‐ECs at the BBB modifies drug metabolism and penetration by a mechanism encompassing P450 and efflux transporters. The latter could be exploited for future drug design and to overcome pharmacoresistance.