Influence of chronic aminophylline on antielectroshock activity of diazepam and aminophylline-induced convulsions in mice

Benzodiazepines and Sleep Architecture: A Systematic Review

BACKGROUND

Insomnia, defined as a difficulty in initiating or maintaining sleep, is a relevant medical issue. Benzodiazepines (BZDs) are commonly prescribed to treat insomnia. Two phases characterize human sleep structure: sleep with Non-Rapid Eye Movement (NREM) and sleep with Rapid Eye Movement (REM). Physiological sleep includes NREM and REM phases in a continuous cycle known as "Sleep Architecture."

OBJECTIVE

This systematic review summarizes the studies that have investigated effects of BZDs on Sleep Architecture.

METHODS

The articles selection included human clinical trials (in English, Portuguese, or Spanish) only, specifically focused on BZDs effects on sleep architecture. PubMed, BVS, and Google Scholar databases were searched.

RESULTS

Findings on BZDs effects on sleep architecture confirm an increase in stage 2 of NREM sleep and a decrease in time of stages 3 and 4 of NREM sleep with a reduction in time of REM sleep during the nocturnal sleep.

CONCLUSION

Variations in NREM and REM sleep may lead to deficits in concentration and working memory and weight gain. The increase in stage 2 of NREM sleep may lead to a subjective improvement of sleep quality with no awakenings. BZDz should be prescribed with zeal and professional judgment. These patients should be closely monitored for possible long-term side effects.

Zebrafish Embryo as an In Vivo Model for Behavioral and Pharmacological Characterization of Methylxanthine Drugs

Zebrafish embryo is emerging as an important tool for behavior analysis as well as toxicity testing. In this study, we compared the effect of nine different methylxanthine drugs using zebrafish embryo as a model. We performed behavioral analysis, biochemical assay and Fish Embryo Toxicity (FET) test in zebrafish embryos after treatment with methylxanthines. Each drug appeared to behave in different ways and showed a distinct pattern of results. Embryos treated with seven out of nine methylxanthines exhibited epileptic-like pattern of movements, the severity of which varied with drugs and doses used. Cyclic AMP measurement showed that, despite of a significant increase in cAMP with some compounds, it was unrelated to the observed movement behavior changes. FET test showed a different pattern of toxicity with different methylxanthines. Each drug could be distinguished from the other based on its effect on mortality, morphological defects and teratogenic effects. In addition, there was a strong positive correlation between the toxic doses (TC₅₀) calculated in zebrafish embryos and lethal doses (LD₅₀) in rodents obtained from TOXNET database. Taken together, all these findings elucidate the potentiality of zebrafish embryos as an in vivo model for behavioral and toxicity testing of methylxanthines and other related compounds.

Influence of aminophylline on the anticonvulsive action of gabapentin in the mouse maximal electroshock seizure threshold model

Accumulating evidence indicates that aminophylline [theophylline(2) x ethylenediamine] markedly attenuates the anticonvulsant action of conventional antiepileptic drugs in experimental animal models of epilepsy and evokes severe seizure activity in patients treated with this methylxanthine. The objective of this study was to determine the influence of acute (single) and chronic (twice daily for 14 consecutive days) treatments with aminophylline on the anticonvulsant potential of gabapentin (a second-generation antiepileptic drug) in the mouse maximal electroshock seizure threshold model. Additionally, the effects of acute and chronic administration of aminophylline on the adverse effect potential of gabapentin in terms of motor coordination impairment were assessed in the chimney test. To evaluate pharmacokinetic characteristics of interaction between drugs, total brain concentrations of gabapentin and theophylline were estimated with high-pressure liquid chromatography and fluorescence polarization immunoassay, respectively. Results indicated that gabapentin (at doses of 75 and 100 mg/kg, i.p.) increased the threshold for electroconvulsions in mice. Aminophylline in non-convulsive doses of 50 and 100 mg/kg (i.p.), both in acute and chronic experiments, did not attenuate the anticonvulsant potential of gabapentin in the maximal electroshock seizure threshold test in mice. Similarly, aminophylline at a dose of 100 mg/kg had no impact on the adverse effect potential of gabapentin in the chimney test. Pharmacokinetic evaluation of total brain concentrations of gabapentin and theophylline revealed no significant changes in total brain concentrations of the drugs after both, acute and chronic applications of aminophylline in combination with gabapentin. The data show that aminophylline did not alter the ability of gabapentin to protect mice against seizures induced by electroconvulsive shock. The observed interaction between gabapentin and aminophylline in both acute and chronic experiments was pharmacodynamic in nature.

Pharmacokinetic and pharmacodynamic interactions of aminophylline and topiramate in the mouse maximal electroshock-induced seizure model

The aim of this study was to determine the influence of acute (single) and chronic (twice daily for 14 consecutive days) treatments with aminophylline (theophylline(2).ethylenediamine) on the anticonvulsant potential of topiramate (a broad-spectrum antiepileptic drug) in the mouse maximal electroshock-induced seizure model. Additionally, the effects of acute and chronic administration of aminophylline on the adverse effect potential of topiramate were assessed in the chimney test (motor performance). To evaluate pharmacokinetic characteristics of interaction between topiramate and aminophylline, total brain concentrations of topiramate and theophylline were estimated with fluorescence polarization immunoassay technique. Results indicate that aminophylline in non-convulsive doses of 50 and 100 mg/kg (i.p.), both in acute and chronic experiments, markedly attenuated the anticonvulsant potential of topiramate by raising its ED(50) value against maximal electroconvulsions. Aminophylline at a lower dose of 25 mg/kg did not affect significantly the ED(50) value of topiramate in the acute experiment, but the drug markedly increased the ED(50) value of topiramate during the chronic treatment in mice. Only, aminophylline at 12.5 mg/kg, in both acute and chronic experiments, did not affect the antielectroshock action of topiramate in mice. Moreover, aminophylline at a dose of 100 mg/kg had no impact on the adverse effect potential of topiramate in the chimney test. Pharmacokinetic evaluation of total brain concentrations of topiramate and theophylline revealed that topiramate significantly increased total brain theophylline concentrations following both acute and chronic applications of aminophylline. Conversely, aminophylline did not alter total brain concentrations of topiramate in mice. Based on this preclinical study, one can conclude that aminophylline attenuated the antiseizure action of topiramate in the mouse maximal electroshock-induced seizure model and the observed interaction between drugs was both pharmacokinetic and pharmacodynamic in nature.

Effect of acute versus chronic theophylline administration on acute restraint stress-induced increase of pentylenetetrazol seizure threshold in mice

Various stressful paradigms were found to induce anticonvulsant effects in different seizure models. Methylxanthines, such as theophylline might contribute to the reduction of restraint-induced stress. Therefore, in this study the influence of acute restraint stress on pentylenetetrazol (PTZ) seizure thresholds as well as the effect of acute and chronic theophylline pretreatment on stress-induced modulation of the seizure threshold were assessed in mice. The onset of the three consecutive seizure phases: myoclonic twitch (MTW), generalized clonus (GNCL) and tonic hind limb extension (THE) was delayed after exposure to a 2 h restraint stress by 34%, 23% and 24%, respectively. In nonstressed mice, acute theophylline injection (100 mg/kg, i.p.) decreased the threshold only for THE. However, in stressed animals, the pretreatment with the methylxanthine significantly enhanced the dose of the convulsant producing the same seizure phase. In nonstressed mice, long-term theophylline treatment (50 mg/kg, twice daily for 14 days) increased PTZ threshold for all three seizure phases. In contrast, in chronically treated with theophylline mice exposed to restraint stress, significant decrease in the PTZ threshold for all seizure phases compared to control stressed animals have been observed. These results suggest that, depending on the treatment regimen (acute versus chronic), theophylline specifically and differentially modulates the anticonvulsant effect of restraint stress in mice.

Effects of Saiko-ka-ryukotsu-borei-to, a Japanese Kampo medicine, on tachycardia and central nervous system stimulation induced by theophylline in rats and mice

Effects of Saiko-ka-ryukotsu-borei-to (SRBT) on theophylline-induced tachycardia in anesthetized rats and theophylline-induced locomotion and convulsions in mice were examined. An intraduodenal administration of SRBT (1 g/kg) prevented theophylline (5 mg/kg, i.v.)-induced tachycardia in rats. SRBT also attenuated an increase in arterial blood pressure with a slow reduction in heart rate of rats treated with theophylline, with no influence on the plasma level of theophylline. However, SRBT did not change the beating rate of right atrium isolated from rats in the absence or presence of theophylline or isoproterenol. The locomotor activity of theophylline in mice was reduced by the treatment with SRBT. Furthermore, the latency of convulsions in mice induced by administration of theophylline at a higher dose (240 mg/kg, i.p.) was prolonged by treatment with SRBT (1 g/kg, p.o.) and seven out of fifteen mice were saved from death due to convulsions. These results suggest that theophylline-induced tachycardia and central nervous stimulation are suppressed by SRBT and that SRBT may reduce the undesirable actions of theophylline on the cardiovascular and central nervous systems.

A potential anti-asthmatic drug, CR 2039, enhances the anticonvulsive activity of some antiepileptic drugs against pentetrazol in mice

CR 2039 (4-(1H-tetrazol-5-yl)-N-[4-(1H-tetrazol-5-yl]phenylbenzam ide), in doses of 10, 20, and 100 mg/kg i.p., did not modify the seizure pattern observed after subcutaneous pentetrazol, administered at its CD97 of 90 mg/kg for the clonic phase. However, when combined with antiepileptic drugs, this phenylbenzamide derivative (20 mg/kg) converted the subprotective doses of ethosuximide (100 mg/kg) or valproate (100 mg/kg) against the clonic phase into anticonvulsive ones. The protection observed was comparable to that noted after doubling the doses of these antiepileptics. Also, a combination of valproate (100 mg/kg) with CR 2039 (10 mg/kg) resulted in a clear-cut protection against clonic seizures induced by pentetrazol. The protective efficacy of clonazepam was not affected by the phenylbenzamide derivative up to 40 mg/kg. The potentiation of the anticonvulsive activity of ethosuximide or valproate was not accompanied by increased adverse effects, evaluated in the chimney test (motor coordination) and passive avoidance task (long-term memory). Finally, CR 2039 (20 mg/kg) did not alter the plasma levels of the antiepileptic drugs studied, which speaks against a pharmacokinetic mechanism in the observed results. In conclusion, CR 2039 seems devoid of a hazardous influence of the anti-asthmatic drug, aminophylline, on the anticonvulsive effects of conventional antiepileptics.

Chronic caffeine and the anticonvulsant potency of antiepileptic drugs against maximal electroshock

The anticonvulsant activities of intraperitoneally (IP) given carbamazepine (CBZ) or diphenylhydantoin (DPH), expressed as their respective ED50 values in mg/kg, were assessed after caffeine (CAFF) treatment against maximal electroshock-induced seizures in mice. CAFF was administered IP either in a single dose or every 12 h for 3 (subchronic CAFF) and 14 days (chronic CAFF). Moreover, the protective activity of the antiepileptics was determined in mice which, following chronic CAFF, received a challenge dose of CAFF after either 24 or 72 h since CAFF withdrawal. A significant reduction of the protective efficacy of CBZ was observed after chronic CAFF treatment (in a dose of 11.55 mg/kg), while a single dose and a 3-day treatment did not alter the action of CBZ. In case of CAFF (23.1 mg/kg), a significant elevation of CBZ's ED50 value was noted after 3- and 14-day treatments with CAFF. In contrast, chronic CAFF (23.1-46.2 mg/kg) decreased the anticonvulsive activity of DPH to the same extent as did acute CAFF. Moreover the ED50 values for both, CBZ and DPH, evaluated 24 h after a 14-day treatment with CAFF (in doses of 23.1 and 46.2 mg/kg, respectively), were significantly elevated compared to respective control groups. A strong impairment of the anticon-vulsant action of CBZ and DPH was observed when a challenge dose of CAFF was injected following either 24 or 72 h injection-free time. Pharmacokinetic interactions do not seem to explain the obtained results in terms of total plasma levels of the antiepileptics after chronic treatment with CAFF. Our results may suggest that epileptic patients should avoid CAFF-containing beverages and medicines.

Anticonvulsant activity of phenobarbital and valproate against maximal electroshock in mice during chronic treatment with caffeine and caffeine discontinuation

We evaluated the protective activity (expressed as ED50 values in mg/kg of phenobarbital (PB, 120 min before testing) and valproate (30 min) alone or combined with caffeine in male mice with seizures induced by maximal electroshock (MES). Both antiepileptic drugs (AEDs) were administered by intraperitoneal (i.p.) injection in a single dose to mice receiving intraperitoneal caffeine either in a single dose 30 min before the test or as pretreatment every 12 h for 3 and 14 days. In addition, we determined the ED50 values of the AEDs 24 and 72 h after 14-day treatment with caffeine. Finally, we studied the influence of a challenge dose of caffeine, injected in mice 24 and 72 h after 14 days of treatment with caffeine, on the protective activity of PB or VPA. Caffeine in a single dose of 23.1 mg/kg reduced the anticonvulsant effect of PB. Its protective activity was further impaired after 3 and 14 days of caffeine treatment. The ED50 for VPA was significantly increased both by the single dose of caffeine and by chronic treatment. The anticonvulsant activity of PB and VPA measured 24 and 72 h after 14-day treatment with caffeine did not differ from control values, but a challenge dose of caffeine injected 24 or 72 h after daily injections for 14 days resulted in a significant reduction in the protective activity of both AEDs. Measurement of the total plasma levels of caffeine, VPA, and PB did not suggest pharmacokinetic interactions as an explanation for our results. Our results indicate that chronic caffeine exposure may progressively reduce the antiepileptic potency of VPA and PB.

Influence of a potential anti-asthmatic drug, CR 2039, upon the anticonvulsive activity of conventional antiepileptics against maximal electroshock-induced seizures in mice

CR 2039 [[4-(1H-tetrazol-5-yl)-N-(4-(1H-tetrazol-5-yl]phenylbenza m ide], in doses of 10, 50, and 100 mg/kg i.p., significantly elevated the threshold for electroconvulsions, increasing the CS50 (current strength 50% in mA) values from 6.3 to 7.2, 7.5, and 7.6 mA, respectively. When combined with carbamazepine, diphenylhydantoin, or valproate, CR 2039 (5 and 10 mg/kg) potentiated the anticonvulsive action of these antiepileptics against maximal electroshock-induced convulsions which was reflected by significant decreases in the respective ED50s (in mg/kg). The protective efficacy of phenobarbital was not affected by the phenylbenzamide derivative. The potentiation of the anticonvulsive activity of three antiepileptics was not accompanied by increased adverse effects, evaluated in the chimney test (motor coordination) and passive avoidance task (long-term memory). Finally, CR 2039 (10 mg/kg) did not alter the plasma levels of the antiepileptic drugs studied which speaks against a pharmacokinetic mechanism in the observed results. It is concluded that CR 2039 may prove a safer anti-asthmatic drug for the use in epileptic patients than aminophylline which, either acutely or chronically, considerably impaired the anticonvulsive activity of conventional antiepileptics.