Favipiravir does not appear to be a major teratogen: Case series from Türkiye

INTRODUCTION

Favipiravir has gained attention during the Coronavirus Disease-2019 pandemic due to its potential antiviral effect against Severe Acute Respiratory Syndrome Coronavirus-2. Favipiravir has been identified as a teratogen in animal studies, but there is limited human data. We aimed to evaluate the pregnancy outcomes of women exposed to favipiravir during the pandemic.

MATERIAL AND METHODS

Pregnant women who were exposed to favipiravir and applied to Marmara University School of Medicine Medical Pharmacology Outpatient Clinic Teratology Information Service between December 2020-September 2021 are included in the study. The demographic information, medical and obstetric histories of patients were acquired during admission, the outcomes of the pregnancies and the characteristics of the infants were gathered by regular phone calls. The infants whose parents consented were evaluated by a pediatrician for general well-being and congenital anomalies.

RESULTS

22 pregnant women were included in this study. 81.8 % received the recommended favipiravir dose (8000 mg in 5 days), in the first trimester. Two patients were lost to follow-up, there was one elective termination and 19 live births. Congenital anomalies were found in 2 infants, one of whom had 9q34 duplication syndrome. Except for these, all newborns examined by the pediatrician were healthy.

DISCUSSION

Within a limited case series, a subset of the infants exposed to favipiravir prenatally were followed up to 1 year of age. Two infants exhibited congenital malformations that cannot be directly linked to favipiravir due to confounding variables. Considering the limited data published, favipiravir does not appear to be a major teratogen.

Involvement of orexin type-2 receptors in genetic absence epilepsy rats

Introduction

Orexin is a neuropeptide neurotransmitter that regulates the sleep/wake cycle produced by the lateral hypothalamus neurons. Recent studies have shown the involvement of orexin system in epilepsy. Limited data is available about the possible role of orexins in the pathophysiology of absence seizures. This study aims to understand the role of orexinergic signaling through the orexin-type 2 receptor (OX2R) in the pathophysiology of absence epilepsy. The pharmacological effect of a selective OX2R agonist, YNT-185 on spike-and-wave-discharges (SWDs) and the OX2R receptor protein levels in the cortex and thalamus in adult GAERS were investigated.

Methods

The effect of intracerebroventricular (ICV) (100, 300, and 600 nmol/10 μL), intrathalamic (30 and 40 nmol/500 nL), and intracortical (40 nmol/500 nL) microinjections of YNT-185 on the duration and number of spontaneous SWDs were evaluated in adult GAERS. The percentage of slow-wave sleep (SWS) and spectral characteristics of background EEG were analyzed after the ICV application of 600 nmol YNT-185. The level of OX2R expression in the somatosensory cortex and projecting thalamic nuclei of adult GAERS were examined by Western blot and compared with the non-epileptic Wistar rats.

Results

We showed that ICV administration of YNT-185 suppressed the cumulative duration of SWDs in GAERS compared to the saline-administered control group (p < 0.05). However, intrathalamic and intracortical microinjections of YNT-185 did not show a significant effect on SWDs. ICV microinjections of YNT-185 affect sleep states by increasing the percentage of SWS and showed a significant treatment effect on the 1-4 Hz delta frequency band power during the 1-2 h post-injection period where YNT-185 significantly decreased the SWDs. OXR2 protein levels were significantly reduced in the cortex and thalamus of GAERS when compared to Wistar rats.

Conclusion

This study investigated the efficacy of YNT-185 for the first time on absence epilepsy in GAERS and revealed a suppressive effect of OX2R agonist on SWDs as evidenced by the significantly reduced expression of OX2R in the cortex and thalamus. YNT-185 effect on SWDs could be attributed to its regulation of wake/sleep states. The results constitute a step toward understanding the effectiveness of orexin neuropeptides on absence seizures in GAERS and might be targeted by therapeutic intervention for absence epilepsy.

Pharmacokinetic characterization of favipiravir in patients with COVID-19

This prospective observational study describes the pharmacokinetic characteristics of favipiravir in adult patients hospitalized for mild to moderate COVID-19 with a positive RT-PCR test. Favipiravir was administered for 5 days, with a loading dose of 3200 mg and a maintenance dose of 1200 mg/day. Serial blood samples were collected on Day-2 and Day-4 of the therapy. Laboratory findings of the patients (n=21) and in-hospital mortality were recorded. Favipiravir concentrations exhibited substantial variability and a significant decrease during the treatment of COVID-19. The median favipiravir trough concentration (C_0-trough ) on Day-2 was 21.26 (IQR, 8.37-30.78) μg/mL whereas it decreased significantly to 1.61 (IQR, 0.00-6.41) μg/mL on Day-4, the area under the concentration versus time curve decreased by 68.5%. Day-2-C_0-trough of female patients was higher than male patients. Our findings indicate that favipiravir concentrations show significant variability during the treatment of COVID-19 and therapeutic drug monitoring may be necessary to maintain targeted concentrations.