Developmental Toxicity Studies with Pregabalin in Rats: Significance of Alterations in Skull Bone Morphology

Evaluation of the effects of prenatal exposure to pregabalin and postnatal analysis of dental and mandibular bone tissue development in rat offspring

Pregabalin is a gabapentinoid indicated for the treatment of peripheral neuropathic pain, fibromyalgia, and as an adjuvant therapy for epilepsy. The aim of this study was to evaluate the effects of pregabalin on postnatal development, odontogenesis, and mandibular trabecular tissue using computed microtomography. Pregnant rats (N = 24) were divided into two groups: control group/placebo (C), and treated group (PGB). The PGB group received 200 mg/kg of pregabalin via gavage during the embryonic period and the C group received distilled water under the same design. On the 21st day of pregnancy, delivery occurred naturally. On the first postnatal day, the litters were reduced to four pups (2 males and 2 females) and followed up for 30 days. On postnatal day 30, eight animals from each group were randomly selected for analysis of the lower right first molar and adjacent trabecular bone. In the maternal parameters, the data revealed a significant decrease in body weight gain in addition to a smaller number of live pups. In the postnatal analysis, the exposed pups showed a significant decrease in weight and length and a delay in the eruption of the incisor teeth. Microtomography analysis revealed a significant reduction in enamel volume, a lower volume and percentage of open pores, lower total porosity, and a higher percentage of bone volume. The findings of this study showed that pregabalin altered the eruption chronology of the incisors, decreased enamel volume, affected the microarchitecture of mandibular trabecular bone, and impaired postnatal development. CONCEA-CEUA-UEL n. 11,174.2018.36, State University of Londrina, (UEL), Londrina, Paraná, Brazil; retrospectively registered on August 21, 2018.

Pregabalin alters reproductive performance in male mice and causes congenital anomalies in offspring

CONTEXT

Pregabalin is an anticonvulsant drug with analgesic activity for the treatment of neuropathic pain.

AIMS

To valuate the toxicity of pregabalin in reproductive parameters, spermatogenesis, and teratogenicity in the offspring of mice.

METHODS

Twenty male mice were randomly distributed into two groups: PGB group and group C (n =10 per group). The animals in the PGB group received, via gavage, 200mg/kg of pregabalin diluted in distilled water daily, for a period of 45days. Group C received distilled water under the same experimental design.

KEY RESULTS

In the paternal parameters of the PGB group, there was a significant increase in the size of the testicles, morphological alterations in the spermatozoa, a decrease in the Johnsen score, an increase in the Leydig cells, and a decrease in the serum level of testosterone. In the intrauterine development parameters of females mated with males from the PGB group, a significant decrease in placental weight, weight and length of fetuses, and fetal viability rate was observed. There was a significant increase in the number of resorptions and post-implantation losses. The significant anomalies observed in the offspring were alteration in the size of the kidneys, absent metacarpals and phalanges, alteration in the sternum, and supernumerary thoracic vertebrae.

CONCLUSION

Results suggest that pregabalin had toxic effects on the reproductive function of male mice and teratogenic potential.

IMPLICATIONS

The findings of this study may provide new hypotheses, taking into account the risk-benefit ratio for male reproduction and offspring health.

Antiseizure Medication-Induced Alopecia: A Literature Review

Background: Adverse effects of antiseizure medications (ASMs) remain one of the major causes of non-adherence. Cosmetic side effects (CSEs) are among the most commonly reported side effects of ASMs. In this context, alopecia is one of the CSEs that has a high intolerance rate leading to poor therapeutical compliance. Methods: We performed a literature review concerning alopecia as a secondary effect of ASMs. Results: There are 1656 individuals reported with ASM-induced alopecia. Valproate (983), lamotrigine (355), and carbamazepine (225) have been extensively reported. Other ASMs associated with alopecia were cenobamate (18), levetiracetam (14), topiramate (13), lacosamide (7), vigabatrin (6), phenobarbital (5), gabapentin (5), phenytoin (4), pregabalin (4), eslicarbazepine (3), brivaracetam (2), clobazam (2), perampanel (2), trimethadione (2), rufinamide (2), zonisamide (2), primidone (1), and tiagabine (1). There were no reports of oxcarbazepine and felbamate with drug-induced alopecia. Hair loss seen with ASMs was diffuse and non-scarring. Telogen effluvium was the most common cause of alopecia. A characteristic feature was the reversibility of alopecia after ASM dose adjustment. Conclusions: Alopecia should be considered one important adverse effect of ASMs. Patients reporting hair loss with ASM therapy should be further investigated, and specialist consultation is recommended.

Management of Anti-Seizure Medications during Pregnancy: Advancements in The Past Decade

Management of seizures often involves continuous medication use throughout a patient's life, including when a patient is pregnant. The physiological changes during pregnancy can lead to altered drug exposure to anti-seizure medications, increasing patient response variability. In addition, subtherapeutic anti-seizure medication concentrations in the mother may increase seizure frequency, raising the risk of miscarriage and preterm labor. On the other hand, drug exposure increases can lead to differences in neurodevelopmental outcomes in the developing fetus. Established pregnancy registries provide insight into the teratogenicity potential of anti-seizure medication use. In addition, some anti-seizure medications are associated with an increased risk of major congenital malformations, and their use has declined over the last decade. Although newer anti-seizure medications are thought to have more favorable pharmacokinetics in general, they are not without risk, as they may undergo significant pharmacokinetic changes when an individual becomes pregnant. With known changes in metabolism and kidney function during pregnancy, therapeutic monitoring of drug concentrations helps to determine if and when doses should be changed to maintain similar seizure control as observed pre-pregnancy. This review concentrates on the results from research in the past decade (2010-2022) regarding risks of major congenital malformations, changes in prescribing patterns, and pharmacokinetics of the anti-seizure medications that are prescribed to pregnant patients with epilepsy.

The teratogenic effect of pregabalin on heart, liver and kidney in rats: a light microscopic, electron microscopic and immunohistochemical study

BACKGROUND

Pregabalin (PGB) was approved as new anti-epileptic drugs with little information about its teratogenic effect.

AIM OF THE WORK

to evaluate the developmental toxicity of PGB.

MATERIALS AND METHODS

60 pregnant albino rats were divided into three groups. PGB (500 mg/kg body weight/day) was given to group II, PGB (1250 mg/kg body weight/day) was given to Group III and no medications were given to group I. The pups were normally delivered. Liver, kidney and heart specimens were prepared for histological, immunohistochemical, and morphometric studies.

RESULTS

A dose of 500 mg of PGB had minimal toxic effects in the form of mild collagen deposition and moderate positive caspase-3 immunoexpression. PGB dose of 1250 mg/kg induced gross toxic effects in form of degenerated cardiac myofibres, ruptured blood vessels, vacuolations in the renal cortex, fibrosis and strong positive caspase-3 immunoexpression.

CONCLUSION

PGB at dose of 500 mg/kg revealed minimal toxic changes. PGB cause embryotoxicity in a dose-dependent manner, as the higher dose induced more degenerative changes.

Prenatal Pregabalin Exposure Alters Postnatal Pain Sensitivity and Some Behavioral Responses in Adult Offspring Rats

BACKGROUND

Prenatal antiepileptic drug exposure could demonstrate both congenital malformations and behavioral impairments in offspring.

OBJECTIVE

This study was performed to assess the effects of prenatal exposure to pregabalin (PGB) on pain response, anxiety, motor activity and some behavior of adult offspring rats.

METHODS

Pregnant Wistar rats received PGB (7.5, 15 and 30 mg/kg/ip) during embryonic days 9.5- 15.5. The pain response, anxiety-like behaviors, locomotor activity, motor balance and coordination and anhedonia of adult offspring were examined by tail-flick and hot plate test, open field test, elevated plus maze (EPM), beam balance test and sucrose preference test in their 60th day of life, respectively.

RESULTS

Prenatal exposure to PGB revealed significant dose-dependent reduction in pain sensitivity (increase in pain latency response) in the hot plate test, especially in females, while anxiety-like behavior assessed in EPM and open field significantly reduced in males. In the open field, locomotor activity reduced significantly after exposure to PGB 30 mg/kg and motor coordination decreased dose-dependently, especially in males. Anhedonia, as an indication of sucrose preference or pleasure response, was not changed.

CONCLUSION

These findings suggest that prenatal PGB exposure could be associated with significant changes in pain response, anxiety, locomotor activity and coordination in adult offspring rats.

Pregabalin induced reproductive toxicity and body weight changes by affecting caspase3 and leptin expression: Protective role of wheat germ oil

Pregabalin (PGB) drug abuse is common among the youth. It substituted tramadol before its recent schedule as a controlled drug since April 2019. PGB is an antiepileptic drug acting on the central nervous system. It blocks calcium channels regulating the action of neurotransmitters and causing prolonged depolarization. The present study aimed to investigate the toxic effect of long term pregabalin abuse on the reproductive function and body weight in both male and female albino rats and to evaluate the ameliorative effect of wheat germ oil (WGO). Forty-eight rats were randomly divided into eight groups. The first four groups were males and they were treated as follows: control group (1.5 mL saline), WGO group (1.5 mL L/kg), PGB group (300 mg/kg), and protective group (PGB + WGO). All doses were administrated once per day for 60 days by gastric gavage. The second four groups were females. They were divided and treated the same as the male groups. Pregabalin caused significant weight loss, decreased serum triglyceride level, and increased leptin gene expression in all rats. PGB affected male rats reproduction by decreasing total testosterone serum level and inhibiting spermatogenesis. Reproductive toxicity in females was caused by decreasing pituitary steroids, increasing gonadal hormones, and increasing the number of atretic ovarian follicles. Mechanism of toxicity may be attributed to the PGB oxidative stress effect that induced apoptosis and caused diffuse gonadal atrophy. WGO showed a protective effect on PGB induced toxicity as all measured parameters were relatively improved.

Retinal teratogenicity of pregabalin in chick embryo model

BACKGROUND

Pregabalin is a gamma-aminobutyric acid analog that binds to the α2-δ subunits of the pre-synaptic voltage-dependent calcium channels of nerves with a high affinity and selectivity. In this study, the retinal teratogenic potential of pregabalin was investigated in a chick embryo model.

MATERIALS AND METHODS

Fertilised chicken eggs were divided into groups for administration with different doses of pregabalin. All eggs were opened on the 10th day of incubation. The embryos were dissected and the effects of pregabalin on the retina were investigated histopathologically, morphometrically, and immunohistochemically (Caspase-3).

RESULTS

There was no statistically significant difference between the low dose pregabalin, control, or vehicle control groups in terms of the number of retina layers and retinal thickness. Medium and high dose pregabalin caused a statistically significant decrease in the number of retina layers, as well as sensory retinal and pigment epithelium layer thicknesses. The outer nuclear and outer plexiform layer did not form in the group administered a medium dose. Similarly, the outer nuclear, outer plexiform, inner nuclear, and inner plexiform layer did not form in the high-dose group. No statistically significant difference was observed between the groups in terms of cellular damage and Caspase-3 expression.

CONCLUSION

The use of pregabalin during pregnancy compromises retinal development in a dose-dependent manner. The use of pregabalin in pregnancy causes the aforementioned defects in this system and it may have developmental effects that needs to be further evaluated.

Embryo-Fetal Developmental Toxicity Studies with Pregabalin in Mice and Rabbits

Pregabalin was evaluated for potential developmental toxicity in mice and rabbits. Pregabalin was administered once daily by oral gavage to female albino mice (500, 1250, or 2500 mg/kg) and New Zealand White rabbits (250, 500, or 1250 mg/kg) during organogenesis (gestation day 6 through 15 [mice] or 6 through 20 [rabbits]). Fetuses were evaluated for viability, growth, and morphological development. Pregabalin administration to mice did not induce maternal or developmental toxicity at doses up to 2500 mg/kg, which was associated with a maternal plasma exposure (AUC0-24 ) of 3790 μg•hr/ml, ≥30 times the expected human exposure at the maximum recommended daily dose (MRD; 600 mg/day). In rabbits, treatment-related clinical signs occurred at all doses (AUC0-24 of 1397, 2023, and 4803 μg•hr/ml at 250, 500, and 1250 mg/kg, respectively). Maternal toxicity was evident at all doses and included ataxia, hypoactivity, and cool to touch. In addition, abortion and females euthanized moribund with total resorption occurred at 1250 mg/kg. There were no treatment-related malformations at any dose. At 1250 mg/kg, compared with study and historical controls, the percentage of fetuses with retarded ossification was significantly increased and the mean number of ossification sites was decreased, which correlated with decreased fetal and placental weights, consistent with in utero growth retardation. Therefore, the no-effect dose for developmental toxicity in rabbits was 500 mg/kg, which produced systemic exposure approximately 16-times human exposure at the MRD. These findings indicate that pregabalin, at the highest dose tested, was not teratogenic in mice or rabbits.