Effect of experimentally induced hepatic and renal failure on the pharmacokinetics of topiramate in rats

Exposure to topiramate and acetazolamide causes endocrine disrupting effects in female rats during estrus

BACKGROUND

Idiopathic intracranial hypertension (IIH) is a disease characterized by elevated intracranial pressure (ICP) and is a disease of young females. The first line pharmacological treatments include acetazolamide and topiramate and given the nature of IIH patients and the dosing regimen of these drugs, their effect on the endocrine system is important to evaluate. We aimed to assess the effects of acetazolamide and topiramate on steroid profiles in relevant endocrine tissues.

METHODS

Female Sprague Dawley rats received chronic clinically equivalent doses of acetazolamide or topiramate by oral gavage and were sacrificed in estrus. Tissue specific steroid profiles of lateral ventricle CP, 4th ventricle CP, CSF, serum, uterine horn and fundus, ovaries, adrenal glands and pituitary glands were assessed by quantitative targeted LC-MS/MS. We determined luteinizing hormone (LH) and follicle stimulating hormones (FSH) levels in paired serum by ELISA.

RESULTS

Topiramate increased the concentration of estradiol and decreased the concentration of DHEA in lateral choroid plexus. Moreover, it decreased the concentration of androstenediol in the pituitary gland. Topiramate increased serum LH. Acetazolamide decreased progesterone levels in serum and uterine fundus and increased corticosteroid levels in the adrenal glands.

CONCLUSION

These results demonstrate that both acetazolamide and topiramate have endocrine disrupting effects in rats. Topiramate primarily targeted the choroid plexus and the pituitary gland while acetazolamide had broader systemic effects. Furthermore, topiramate predominantly targeted sex hormones, whereas acetazolamide widely affected all classes of hormones. A similar effect in humans has not yet been documented but these concerning findings warrants further investigations.

Acetazolamide and topiramate lower intracranial pressure through differential mechanisms: The effect of acute and chronic administration

BACKGROUND AND PURPOSE

Diseases of raised intracranial pressure (ICP) cause severe morbidity and mortality. Multiple drugs are utilised to lower ICP including acetazolamide and topiramate. However, the evidence for their use is unclear. We aimed to assess the ICP modulatory effects and molecular effects at the choroid plexus (CP) of acetazolamide and topiramate.

EXPERIMENTAL APPROACH

Female rats were implanted with telemetric ICP probes for physiological, freely moving 24/7 ICP recordings. Randomised cross-over studies were performed, where rats received acute (24 h) high doses of acetazolamide and topiramate, and chronic (10 days) clinically equivalent doses of acetazolamide and topiramate, all via oral gavage. Cerebrospinal fluid (CSF) secretion assays, and RT-qPCR and western blots on in vitro and in vivo CP, were used to investigate drug actions.

KEY RESULTS

We demonstrate that acetazolamide and topiramate achieved maximal ICP reduction within 120 min of administration, and in combination doubled the ICP reduction over a 24-h period. Chronic administration of acetazolamide or topiramate lowered ICP by 25%. Topiramate decreased CSF secretion by 40%. Chronic topiramate increased the gene expression of Slc12a2 and Slc4a10 and protein expression of the sodium-dependent chloride/bicarbonate exchanger (NCBE), whereas chronic acetazolamide did not affect the expression of assessed genes.

CONCLUSIONS AND IMPLICATIONS

Acetazolamide and topiramate are effective at lowering ICP at therapeutic levels. We provide the first evidence that topiramate lowers CSF secretion and that acetazolamide and topiramate may lower ICP via distinct molecular mechanisms. Thus, the combination of acetazolamide and topiramate may have utility for treating raised ICP.

Safety of drug use in patients with a primary mitochondrial disease: An international Delphi-based consensus

Clinical guidance is often sought when prescribing drugs for patients with primary mitochondrial disease. Theoretical considerations concerning drug safety in patients with mitochondrial disease may lead to unnecessary withholding of a drug in a situation of clinical need. The aim of this study was to develop consensus on safe medication use in patients with a primary mitochondrial disease. A panel of 16 experts in mitochondrial medicine, pharmacology, and basic science from six different countries was established. A modified Delphi technique was used to allow the panellists to consider draft recommendations anonymously in two Delphi rounds with predetermined levels of agreement. This process was supported by a review of the available literature and a consensus conference that included the panellists and representatives of patient advocacy groups. A high level of consensus was reached regarding the safety of all 46 reviewed drugs, with the knowledge that the risk of adverse events is influenced both by individual patient risk factors and choice of drug or drug class. This paper details the consensus guidelines of an expert panel and provides an important update of previously established guidelines in safe medication use in patients with primary mitochondrial disease. Specific drugs, drug groups, and clinical or genetic conditions are described separately as they require special attention. It is important to emphasise that consensus-based information is useful to provide guidance, but that decisions related to drug prescribing should always be tailored to the specific needs and risks of each individual patient. We aim to present what is current knowledge and plan to update this regularly both to include new drugs and to review those currently included.

Evaluation of the Effects of Astragalus membranaceus on the Pharmacokinetics of Pemetrexed Disodium and Gemcitabine in Rats by a Simple High-Performance Liquid Chromatography/UV Method

Combination therapy is opted as a potential therapeutic strategy for cancer treatment. Astragalus membranaceus combined with pemetrexed disodium or gemcitabine could reinforce the overall effects and alleviate the adverse effects. To investigate the effects of Astragalus membranaceus on the pharmacokinetics of pemetrexed disodium and gemcitabine, a HPLC method for simultaneous determination of pemetrexed disodium and gemcitabine in rat plasma was developed and validated. Chromatographic separation was achieved on a C18 column using a gradient mode containing water (containing 20 mM NaH₂PO₄ and 0.1% FA) and methanol at a flow rate of 0.8 mL/min. The specificity, linearity, recovery, stability, precision, and accuracy of the HPLC method were all validated. The rats were pretreated with Astragalus extract at the dosage of 3 g/kg for 20 consecutive days until we commence studying the pharmacokinetics of pemetrexed disodium or gemcitabine. There were no significant differences in pharmacokinetic parameters of pemetrexed disodium between the Astragalus extract treatment group and the control group. However, AUC, MRT, and Cl of gemcitabine were changed dramatically after treating with Astragalus extract (p < 0.05). The AUC_(0-t), AUC_(0-∞), and MRT of gemcitabine decreased from 15747.12 ± 497.11 to 12312.41 ± 594.21 mg/L·min, 15976.18 ± 511.33 to 12489.59 ± 682.01 mg/L·min, and 97.83 ± 5.82 to 84.37 ± 2.79 min, respectively. The Cl of gemcitabine increased from 0.019 ± 0.0067 to 0.024 ± 0.0013 L/min/kg. The results showed that the pretreatment of Astragalus extract could exert an influence on the pharmacokinetic characteristics of gemcitabine in rats.

Chronic and intermittent administration of systemic nitroglycerin in the rat induces an increase in the gene expression of CGRP in central areas: potential contribution to pain processing

Background

Calcitonin gene related peptide (CGRP) is a key neuropeptide involved in the activation of the trigeminovascular system and it is likely related to migraine chronification. Here, we investigated the role of CGRP in an animal model that mimics the chronic migraine condition via repeated and intermittent nitroglycerin (NTG) administration. We also evaluated the modulatory effect of topiramate on this experimental paradigm. Male Sprague-Dawley rats were injected with NTG (5 mg/kg, i.p.) or vehicle, every 2 days over a 9-day period (5 total injections). A group of animals was injected with topiramate (30 mg/kg, i.p.) or saline every day for 9 days. Twenty-four hours after the last administration of NTG or vehicle, animals underwent tail flick test and orofacial Von Frey test. Rats were subsequently sacrificed to evaluate c-Fos and CGRP gene expression in medulla-pons region, cervical spinal cord and trigeminal ganglia.

Results

NTG administration induced spinal hyperalgesia and orofacial allodynia, together with a significant increase in the expression of CGRP and c-Fos genes in trigeminal ganglia and central areas. Topiramate treatment prevented NTG-induced changes by reversing NTG-induced hyperalgesia and allodynia, and inhibiting CGRP and c-Fos gene expression in all areas evaluated.

Conclusions

These findings point to the role of CGRP in the processes underlying migraine chronification and suggest a possible interaction with gamma-aminobutyrate (GABA) and glutamate transmission to induce/maintain central sensitization and to contribute to the dysregulation of descending pain system involved in chronic migraine.

Topiramate is more effective than acetazolamide at lowering intracranial pressure

Background

The management of idiopathic intracranial hypertension focuses on reducing intracranial pressure to preserve vision and reduce headaches. There is sparse evidence to support the use of some of the drugs commonly used to manage idiopathic intracranial hypertension, therefore we propose to evaluate the efficacy of these drugs at lowering intracranial pressure in healthy rats.

Methods

We measured intracranial pressure in female rats before and after subcutaneous administration of acetazolamide, topiramate, furosemide, amiloride and octreotide at clinical doses (equivalent to a single human dose) and high doses (equivalent to a human daily dose). In addition, we measured intracranial pressure after oral administration of acetazolamide and topiramate.

Results

At clinical and high doses, subcutaneous administration of topiramate lowered intracranial pressure by 32% (p = 0.0009) and 21% (p = 0.015) respectively. There was no significant reduction in intracranial pressure noted with acetazolamide, furosemide, amiloride or octreotide at any dose. Oral administration of topiramate significantly lowered intracranial pressure by 22% (p = 0.018), compared to 5% reduction with acetazolamide (p = >0.999).

Conclusion

Our in vivo studies demonstrated that both subcutaneous and oral administration of topiramate significantly lowers intracranial pressure. Other drugs tested, including acetazolamide, did not significantly reduce intracranial pressure. Future clinical trials evaluating the efficacy and side effects of topiramate in idiopathic intracranial hypertension patients would be of interest.

Evaluation of Brain Pharmacokinetic and Neuropharmacodynamic Attributes of an Antiepileptic Drug, Lacosamide, in Hepatic and Renal Impairment: Preclinical Evidence

The knowledge of pharmacokinetic and pharmacodynamic properties of antiepileptic drugs is helpful in optimizing drug therapy for epilepsy. This study was designed to evaluate the pharmacokinetic and pharmacodynamic properties of lacosamide in experimentally induced hepatic and renal impairment in seizure animals. Hepatic or renal impairment was induced by injection of carbon tetrachloride or diclofenac sodium, respectively. After induction, the animals were administered a single dose of lacosamide. At different time points, maximal electroshock (MES) seizure recordings were made followed by isolation of plasma and brain samples for drug quantification and pharmacodynamic measurements. Our results showed a significant increase in the area under the curve of lacosamide in hepatic and renal impairment groups. Reduced clearance of lacosamide was observed in animals with renal impairment. Along with pharmacokinetic alterations, the changes in pharmacodynamic effects of lacosamide were also observed in all the groups. Lacosamide showed a significant protection against MES-induced seizures, oxidative stress, and neuroinflammatory cytokines. These findings revealed that experimentally induced hepatic or renal impairment could alter the pharmacokinetic as well as pharmacodynamic properties of lacosamide. Hence, these conditions may affect the safety and efficacy of lacosamide.