biphenylylacetic-acid and Seizures

Concomitant administration of certain fluoroquinolone antimicrobials and nonsteroidal antiinflammatory agents (NSAIDs) induces serious convulsion in humans. There are differences in convulsive activity among fluoroquinolones and in the potentiation of fluoroquinolone-induced convulsion among NSAIDs, but a comprehensive, quantitative comparison has not been carried out. This study evaluates the inhibitory effects of twelve fluoroquinolones (ciprofloxacin, enoxacin, fleroxacin, gatifloxacin, levofloxacin, lomefloxacin, norfloxacin, ofloxacin, pazufloxacin, prulifloxacin, sparfloxacin, and tosufloxacin) alone or in the presence of an NSAID (4-biphenylacetic acid, diclofenac sodium, loxoprofen, lornoxicam or zaltoprofen) on the GABA(A) receptor binding of [(3)H]muscimol in an in vitro study using mice synaptic plasma membrane. The rank order of inhibitory effects of the fluoroquinolones was prulifloxacin asymptotically equal to norfloxacin > ciprofloxacin > or = enoxacin > gatifloxacin > or = ofloxacin asymptotically equal to tosufloxacin asymptotically equal to lomefloxacin > levofloxacin > or = sparfloxacin > or = pazufloxacin asymptotically equal to fleroxacin. 4-Biphenylacetic acid most potently enhanced the inhibitory effects of the fluoroquinolones, while zaltoprofen, loxoprofen, lornoxicam and diclofenac had essentially no effect. The clinical risk of convulsion for each combination was estimated using a pharmacodynamic model based on receptor occupancy using the in vitro data set obtained and pharmacokinetic parameters in humans collected from the literature. The combinations of 4-biphenylacetic acid with prulifloxacin and enoxacin were concluded to be the most hazardous.

Topics: Animals; Anti-Bacterial Agents; Anti-Infective Agents; Anti-Inflammatory Agents, Non-Steroidal; Ciprofloxacin; Diclofenac; Dioxolanes; Drug Combinations; Drug Interactions; Enoxacin; Fleroxacin; Fluoroquinolones; Gatifloxacin; Levofloxacin; Male; Mice; Microbial Sensitivity Tests; Naphthyridines; Norfloxacin; Ofloxacin; Oxazines; Phenylacetates; Piperazines; Receptors, GABA-A; Seizures

We sought to determine the changes in brain interleukin-1beta (IL-1beta) following the coadministration of norfloxacin (25 mg/kg, i.p.) with biphenylacetic acid (100 mg/kg, p.o.) in rats. Norfloxacin provoked clonic convulsions in rats treated concomitantly with biphenylacetic acid, a major metabolite of the nonsteroidal anti-inflammatory drug fenbufen. Seizure activity was analyzed by EEG monitoring. Behavioral changes were also monitored. IL-1beta expressions in the prefrontal cortex and hippocampus at different time intervals were studied by reverse transcriptase-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). The epileptiform discharges appeared in all the rats, accompanied with limb twitching and clonic-tonic seizures after administration of norfloxacin coadministered with biphenylacetic acid. Norfloxacin plus biphenylacetic acid-induced convulsions rapidly and transiently enhanced IL-1beta mRNA in the prefrontal cortex and hippocampus. IL-1beta mRNA expression in the prefrontal cortex and hippocampus was detected as soon as 30 min after norfloxacin injection, and decayed to control levels by 6 h. ELISA analysis revealed significant increase of the IL-1beta protein in the prefrontal cortex and hippocampus at 2 h and 6 h. Administration of either norfloxacin or biphenylacetic acid alone did not elicit convulsions and increase in IL-1beta mRNA and protein expressions. The results suggest that the increased IL-1beta expressions in the prefrontal cortex and hippocampus induced by norfloxacin with biphenylacetic acid relate to seizure activities, and that these brain regions play pivotal roles in norfloxacin-induced convulsions.

Topics: Animals; Anti-Infective Agents; Anti-Inflammatory Agents, Non-Steroidal; Brain; Drug Interactions; Electroencephalography; Hippocampus; Interleukin-1beta; Male; Norfloxacin; Phenylacetates; Prefrontal Cortex; Rats; Rats, Sprague-Dawley; RNA, Messenger; Seizures; Time Factors

The proconvulsant effect of biphenyl acetic acid (BPAA) on several fluoroquinolones (FQs) was investigated in vivo, by measuring drug concentrations in the biophase at the onset of convulsions. Male Sprague-Dawley rats (n = 134) were given BPAA orally, at various doses 1 h before starting FQ infusion, which was maintained until the onset of maximal seizures, when cerebrospinal fluid (CSF) and plasma samples were collected for drug concentration determination. The FQ-BPAA interactions in the biophase (CSF) were adequately described on most occasions by an inhibitory Emax effect model with a baseline effect parameter. The efficacy of the proconvulsant effect was characterized by the ratio of the CSF concentrations of FQs at the onset of convulsant activity when BPAA was absent (CCSF0, FQs) and as BPAA CSF concentrations tended toward infinity (CCSFbase, FQs). This ratio varied from 15 for enoxacin to 1.9 for sparfloxacin. The potency of the proconvulsant effect was characterized by the CSF concentration of BPAA corresponding to a proconvulsant effect half of its maximum. This parameter varied between 0.18 +/- 0.06 micromol/L with enoxacin and 15.0 +/- 12.1 micromol/L with sparfloxacin. The CSF diffusion of all FQs was apparently non-linear, as well as the plasma protein binding of BPAA, complicating interpretation of plasma data. The important variability in the proconvulsant effect of BPAA demonstrated in this study between various FQs suggests that in vitro gamma-aminobutyric acid (GABA) binding experiments conducted in the presence of BPAA are unlikely to be good predictors of FQ convulsant risk in clinical practice.

Topics: Animals; Anti-Infective Agents; Anti-Inflammatory Agents, Non-Steroidal; Convulsants; Dose-Response Relationship, Drug; Drug Interactions; Fluoroquinolones; Male; Phenylacetates; Rats; Rats, Sprague-Dawley; Receptors, GABA; Seizures

Fluoroquinolones (FQs) are associated with a low incidence of central nervous system (CNS) side effects, possibly leading to convulsions, especially when co-administered with nonsteroidal anti-inflammatory drugs (NSAIDS). Although the in vivo pro-convulsant activity of NSAIDS is essentially unknown, the convulsant potential of FQs is traditionally evaluated by in vitro gamma-aminobutyric acid (GABA) binding experiments in the presence of 4-biphenyl acetic acid (BPAA), the active metabolite of fenbufen. The aim of this study was therefore to investigate the BPAA-norfloxacin convulsant interaction in vivo. Male Sprague-Dawley rats (n = 27) were given BPAA orally, at various doses 1 h before norfloxacin infusion, which was maintained until the onset of maximal seizures, when cerebrospinal fluid (CSF) and plasma samples were collected for analysis. An inhibitory E(max) effect model with a baseline effect parameter was fitted to the norfloxacin versus BPAA concentrations in the CSF, previously shown to be part of the biophase. This model includes three parameters: the concentrations of norfloxacin in the absence of BPAA (C(CSF0, Nor)), and when BPAA concentration tends toward infinity (C(CSFbase, Nor)), and the BPAA concentration for which half of the maximal effect is observed (C(CSF50, BPAA)). The maximal proconvulsant effect of BPAA is given by the C(CSF0, Nor) / C(CSFbase, Nor) ratio, estimated to approximately 6 in this study. Derived models were developed in plasma to account for the non-linear CSF diffusion of norfloxacin and protein binding of BPAA. In conclusion this study has shown that the convulsant interaction between norfloxacin and BPAA in rats, can be adequately characterized by modelling of the CSF concentrations of the two drugs at the onset of activity, following their administration in various proportions.

Topics: Animals; Convulsants; Drug Interactions; Male; Norfloxacin; Phenylacetates; Rats; Rats, Sprague-Dawley; Seizures

The quinolone antibacterials enoxacin and norfloxacin (2.5 mg/kg, i.v.) provoked clonic convulsions in mice treated concomitantly with biphenylacetic acid (BPAA, 100 mg/kg, i.p.), a major metabolite of the nonsteroidal anti-inflammatory drug fenbufen. Gel-shift assays showed that enoxacin-induced convulsions resulted in increases in nuclear activator protein 1 (AP-1) DNA- and cyclic AMP responsive element (CRE)-binding activities in the cerebral cortex and hippocampus, but not in other regions, such as the cerebellum and thalamus. In contrast, ofloxacin and levofloxacin, at the same doses, in the presence of BPAA did not evoke convulsions or increase these DNA-binding activities. Administration of these quinolones and BPAA alone elicited neither convulsions nor increases in these DNA-binding activities. These results suggest that the increased nuclear AP-1 DNA- and CRE-binding activities in the cerebral cortex and hippocampus induced by quinolones with BPAA correlated with seizure activities and that these brain regions play pivotal roles in quinolone-induced convulsions.

Topics: Animals; Anti-Infective Agents; Anti-Inflammatory Agents, Non-Steroidal; Brain; Cyclic AMP Receptor Protein; Electroencephalography; Enoxacin; Male; Mice; Norfloxacin; Phenylacetates; Seizures; Transcription Factor AP-1

Convulsions induced by the interaction of new quinolone antimicrobial agents (NQs) and nonsteroidal anti-inflammatory drugs (NSAIDs) were previously reported, and blockade of GABA(A) receptor by NQs and its potentiation with NSAIDs were considered as one of its possible mechanisms. However, useful methodology for prediction of convulsive potencies of NQs with or without NSAIDs in vivo based on in vitro screening was not established. Therefore, we applied the Xenopus oocytes translation system of exogenous messenger RNA (mRNA) to examine the mechanism of convulsion induced by interaction of NQs and NSAIDs, and the relationship between convulsive potencies in vivo and inhibitory effect on GABA-induced current response in vitro was investigated. This system also has alternative possibility for the in vivo toxicological studies sacrificing innumerous animals. Glutamic acid, kainic acid, quisqualic acid, NMDA, and serotonin-induced currents were not modified by ENX of NQs and/or FLB of NSAIDs, while glycine- and ACh-induced currents were slightly inhibited. GABA (10 microM)-induced current was inhibited by norfloxacin (NFLX), ciprofloxacin, ENX, and ofloxacin (OFLX) with IC50 of 17, 33, 58, and 280 microM, respectively. IC50 of NQs decreased to 1/3 (OFLX)-1/165 (NFLX) in the presence of 10 microM FLB, while FLB did not modulate the GABA response in the absence of NQs. CSF concentration of ENX at the time of convulsion in clinical situation approximated the IC50 of ENX for the GABA response. The increase of incidence for NQs-induced convulsion by concomitant NSAIDs in vivo could also be explained by the potentiation of inhibitory effects of NQs with FLB in the normal range of CSF concentration of these drugs. We also examined convulsive potency (threshold dose for convulsion) in CNS by intracerebral infusion of NQs to mice with or without FLB pretreatment, and significant correlations between the convulsive potencies and IC50 of NQs for the GABA response were observed. These findings suggested that the blockade of GABA-ersic neurotransmission in CNS is a dominant mechanism of convulsion induced by NQs and that the convulsant-adverse reaction of NQs in vivo may be predicted from the inhibitory effect on the GABA(A) receptor in vitro using the Xenopus oocytes translation system of exogenous mRNA.

Topics: Animals; Anti-Infective Agents; Anti-Inflammatory Agents, Non-Steroidal; Bicuculline; Brain Chemistry; Cells, Cultured; Ciprofloxacin; Dose-Response Relationship, Drug; Drug Synergism; Enoxacin; Female; GABA-A Receptor Antagonists; Injections, Intraventricular; Male; Membrane Potentials; Mice; Microinjections; Norfloxacin; Oocytes; Phenylacetates; Receptors, GABA-A; RNA, Messenger; Seizures; Xenopus laevis

1. Contribution of nitric oxide to the convulsive seizures induced by fluoroquinolones (FQs) coadministered with 4-biphenyl acetic acid (BPAA), the active metabolite of fenbufen, was assessed in mice. 2. Enoxacin + 4-biphenyl acetic acid caused clonic seizures in all treated mice, followed by tonic seizures and death. These events were associated with a significant increase in intracerebellar cyclic GMP. 3. Pretreatment with the nitric oxide synthase (NOS) inhibitor, NG-nitro-L-arginine methylester (L-NAME), but not with D-NAME, significantly reduced the incidence of convulsions and lethality, as well as the increase in cyclic GMP. 4. Pretreatment with N-methyl-D-aspartic acid (NMDA)-receptor antagonist, MK-801, inhibited only the transition of clonic seizure to tonic seizure without affecting the incidence of clonic seizure and lethality. 5. These findings suggest that FQs + BPAA exert convulsions by activating NOS partly through the mediation of the NMDA receptor in the brain cells.

Topics: Animals; Anti-Infective Agents; Anti-Inflammatory Agents, Non-Steroidal; Ciprofloxacin; Convulsants; Cyclic AMP; Dizocilpine Maleate; Enoxacin; Enzyme Inhibitors; Male; Mice; Mice, Inbred Strains; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase; Ofloxacin; Phenylacetates; Seizures

To mimic the excretion route of the quinolone antibacterial agent levofloxacin (LVFX) in humans, we produced an excretion-limited (EL) model in male Sprague-Dawley rats by bile duct ligation and unilateral nephrectomy. We then examined the relationship between brain levels of LVFX and its convulsant effects in control and EL animals. Serum concentrations of LVFX in EL animals (EL + LVFX) were 2.38- and 1.59-fold and brain concentrations were 1.33- and 1.19-fold those of the controls (control + LVFX) at 30 min after a single intravenous injection of 10 and 100 mg/kg LVFX, respectively. Furthermore EL animals became more susceptible to the convulsant effect of LVFX with a 1.28-fold decrease in convulsion-inducing dose. In combination with oral pretreatment with 400 mg/kg 4-biphenylacetic acid (BPAA), convulsion-inducing doses in the control (control + LVFX + BPAA) and EL (EL + LVFX + BPAA) groups were markedly decreased by 2.25 and 9 times that of the control + LVFX group. EL operation and BPAA pretreatment slowed the elimination of LVFX in the serum and brain 4 hr later in the following order: EL + LVFX + BPAA, control + LVFX + BPAA, EL + LVFX, and control + LVFX groups. This order reflects that for the convulsion-inducing doses. These results suggest that EL rats may be a useful model for humans and that the convulsant effect of LVFX with or without BPAA arises not only from the attainment of maximum brain concentration but also from delayed disappearance from the brain.

Topics: Administration, Oral; Animals; Anti-Infective Agents; Anti-Inflammatory Agents, Non-Steroidal; Bile Ducts; Brain; Dose-Response Relationship, Drug; Drug Synergism; Infusions, Intravenous; Injections, Intravenous; Levofloxacin; Ligation; Male; Nephrectomy; Ofloxacin; Phenylacetates; Rats; Rats, Sprague-Dawley; Seizures

We quantified the amount of inhibition of gamma-aminobutyric acid (GABA)A receptor binding required for the onset of convulsions induced by ciprofloxacin in combination with biphenylacetic acid (BPAA) in mice. In fasting mice iv ciprofloxacin given 30 min after oral BPAA (50 mg/kg) induced convulsions at doses of 40 mg/kg or above. In contrast, ofloxacin caused no convulsions even at 100 mg/kg, the highest dose tested. When mice received 40 mg/kg of ciprofloxacin or ofloxacin, maximal brain concentrations of each quinolone at 30 min were 0.37 or 1.97 micrograms/g, respectively. These brain concentrations of ciprofloxacin and ofloxacin were not affected by combination with BPAA. In the presence of ciprofloxacin and BPAA (at brain tissue concentrations which induced convulsions), the binding of 3H-muscimol to GABAA receptor sites was inhibited by approximately 30%. Using results from a similar binding study, an impracticable iv dose of ofloxacin (500 mg/kg) was estimated to be required to inhibit GABAA receptor binding by 30%, and therefore to induce similar convulsions to those seen with ciprofloxacin at a dose of 40 mg/kg. These results may indicate that epileptic convulsions occur when ciprofloxacin and BPAA interact with each other to antagonize at least 30% of GABAA receptor binding in mice, and provide evidence for a significant role of GABAA receptor inhibition in the occurrence of quinolone-induced convulsions.

Topics: Animals; Anti-Infective Agents; Brain; Female; Fluoroquinolones; GABA-A Receptor Antagonists; Male; Mice; Muscimol; Phenylacetates; Rats; Rats, Sprague-Dawley; Seizures; Synaptic Membranes

The combination of some new quinolone antibacterial agents with 4-biphenylacetic acid (BPAA), a metabolite of fenbufen, is known to specifically induce functional blockade of the gamma-aminobutyric acid (GABA) receptors. The mechanisms of these drug interactions were further examined. Scatchard analysis of [3H]muscimol binding to rat brain plasma membranes in the presence of enoxacin and BPAA revealed that a significant decrease in the number of muscimol binding sites was produced without affecting the affinity of binding to the receptors. In the presence of norfloxacin, BPAA inhibited muscimol binding the most potently of the six BPAA-related compounds tested. Fenbufen and 9,10-dihydro-gamma-oxo-2-phenanthrenebutyric acid also inhibited the binding, and 4-biphenylcarboxylic acid and methyl 4-biphenylacetate inhibited it slightly, but 3-benzoylpropionic acid exhibited no competitive inhibition. Accordingly, hybrid molecules of norfloxacin and BPAA were synthesized for stereochemical analysis of these drug interactions. A hybrid with a -CONH(CH2)3- chain between norfloxacin and BPAA (flexible structure) inhibited muscimol binding, and intracisternal injection of this hybrid caused clonic convulsions in mice more potently than the combination of norfloxacin and BPAA did. In contrast, a hybrid linked by -CONH- (stretched structure) showed almost no such inhibitory effect. 1H NMR analysis indicated the presence of intramolecular attraction at the quinoline ring of the hybrid exhibiting the antagonistic activity. These results suggest the possibility that quinolones and BPAA interact with the GABA receptor at nearby sites and that the binding affinity of quinolones to the GABA receptors is largely enhanced by the intermolecular interaction with BPAA.

Topics: Animals; Binding Sites; Drug Interactions; GABA Antagonists; Magnetic Resonance Spectroscopy; Muscimol; Norfloxacin; Phenylacetates; Rats; Rats, Sprague-Dawley; Receptors, GABA; Seizures

The combination of some new quinolone antibacterials with 4-biphenylacetic acid (BPAA) functionally inhibits the gamma-amino-butyric acid (GABA) receptors and thereby induces clonic convulsions. We examined the effects of ofloxacin and its optical isomers on this quinolone-induced neurotoxicity. Norfloxacin at 10(-5) M alone or at 10(-7) M in combination with BPAA (10(-4) M) inhibited [3H]muscimol binding to rat brain synaptic membranes. Ofloxacin and its optical isomers did not affect muscimol binding by themselves. While they slightly reduced muscimol binding at 10(-4) M in combination with BPAA, the inhibitory activity of the l-isomer levofloxacin (DR-3355) on muscimol binding was slightly, but significantly, weaker than that of the d-isomer DR-3354 and ofloxacin. Intracisternal injection of norfloxacin (5 micrograms), ofloxacin, levofloxacin or DR-3354 (50 micrograms each) induced clonic convulsions in mice. The incidence of these convulsions was enhanced by the combination with BPAA (50 micrograms). The epileptogenic activity of levofloxacin was also weaker than that of DR-3354 or ofloxacin when quinolones were given alone or in combination with BPAA. These results suggest that epileptogenic activity of quinolones is closely related to the inhibitory potency in GABA receptor binding and that levofloxacin may have lower neurotoxicity than ofloxacin and DR-3354.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Cisterna Magna; GABA Antagonists; In Vitro Techniques; Injections; Isomerism; Levofloxacin; Mice; Mice, Inbred Strains; Norfloxacin; Ofloxacin; Phenylacetates; Protein Binding; Receptors, GABA; Seizures

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Ciprofloxacin; Drug Interactions; Female; Mice; Phenylacetates; Seizures; Theophylline