cinnarizine and Seizures

Cinnarizine, a piperazine derivative, is a widely prescribed medication for the treatment of vestibular disorders and motion sickness. Cinnarizine has antihistaminic, antiserotoninergic, antidopaminergic, and calcium channel-blocking properties. We present the first report in the English literature of cinnarizine poisoning and toxicokinetics. A 30-month-old toddler ingested 225 mg of cinnarizine, 18 times the recommended dose for older children. Four hours later, she became jittery with a wide-based gait and vomited 3 times. She was examined by her family physician, who reported stupor and twitching in both hands. On admission to the hospital, 6 hours after the ingestion, she was stuporous and had 3 short, generalized tonic-clonic convulsions that were controlled with a single dose of midazolam. Full clinical recovery was seen 10 hours after ingestion. Serum cinnarizine levels were 7407, 2629, and 711 ng/mL on admission and at 4 and 12 hours thereafter, respectively, 26.9 times higher than the therapeutic levels in adults. Elimination rate constant, calculated by linear regression of the ln concentrations of the 3 data points, was 0.19. Half-life, calculated from the equation t(1/2) = 0.693/kel, where kel is the elimination rate constant, was 3.65 hours. The manufacturing company revealed that their database contains 23 reports of cinnarizine overdose (adult and children), received between 1972 and 2004. Clinically, these cases reflect mainly symptoms of alterations in consciousness ranging from somnolence to stupor and coma, vomiting, extrapyramidal symptoms, and hypotonia. In a small number of young children, convulsions developed; recovery was uneventful in 4 cases and not reported in 1. The neurologic complication may be explained by the antihistaminic effect of cinnarizine because central nervous system depression and convulsions are known complications of antihistaminic overdose. It is hypothesized that cinnarizine-induced convulsions also are related to the antidopaminergic effect of the drug. Apart from the convulsions, no other adverse effects related to calcium channel-blocking properties, such as bradycardia or hemodynamic instability, were observed. Pediatric patients with cinnarizine overdose need to be observed in a health care facility for potential neurologic complications and be treated symptomatically. The delay to onset of clinical effect should be considered in the observation period.

Topics: Accidents, Home; Child, Preschool; Cinnarizine; Coma; Female; Humans; Seizures

In the brain tissue there exists a highly active "pool" of nonesterified fatty acids (NEFA). The greatest part of NEFA comes from the fraction of nerve endings. It was evidenced that the model convulsive activity provoked by Bemegrid increased NEFA in the brain cortex, hypothalamus and brain stem. Cinnarizine (StugeronR) markedly decreases the convulsive increase of NEFA. The greatest inhibitory effect was observed in the brain cortex. Cinnarizine has an objective stabilizing and anticonvulsive effect on the brain tissue.

Topics: Animals; Bemegride; Brain; Cinnarizine; Fatty Acids, Nonesterified; Male; Rats; Rats, Inbred Strains; Seizures

The anticonvulsant activity of 1-bis(4-fluorophenyl)methyl-4-(3-phenyl-2-propenyl)-piperazine, flunarizine, was studied after intraperitoneal administration in DBA/2 mice (seizures induced by sound), intravenous administration in Papio papio (myoclonus induced by photic stimulation) and oral administration in Wistar rats (seizures induced by cefazolin). Protection against sound-induced seizures was observed after intraperitoneal administration of flunarizine (5-40 mg/kg). The ED50 for suppression of tonic, clonic and wild running phases of sound-induced seizures was 3.3, 9.8 and 17.5 mg/kg, respectively. This protective action was significantly reduced by pretreatment with aminophylline (50 mg/kg, i.p.). In photosensitive baboons flunarizine (0.5-1.0 mg/kg, i.v.) provided partial protection against myoclonic responses to stroboscopic stimulation. After flunarizine (2 mg/kg, i.v.) this protection lasted for more than 5 hr (and was complete at 2-3 hr). Cefazolin-induced seizures in rats were prevented by administration of flunarizine (20-40 mg/kg, orally). The ED50 for the suppression of tonic and clonic seizures evoked by subsequent intravenous administration of cefazolin was 25 mg/kg. The protective effects of flunarizine (40 mg/kg, orally) were maximal after 3-6 hr and were maintained for 16-24 hr. Behavioural effects of flunarizine included signs of sedation in both mice and rats. Tolerance to the antiepileptic effects of flunarizine was not seen after chronic treatment in rats. The role of purinergic receptors and of calcium entry blockade in the anticonvulsant action of flunarizine requires further study.

Topics: Acoustic Stimulation; Animals; Anticonvulsants; Cinnarizine; Epilepsies, Myoclonic; Epilepsy; Female; Flunarizine; Male; Mice; Mice, Inbred DBA; Papio; Photic Stimulation; Rats; Rats, Inbred Strains; Seizures

The time relations of epileptic events have been studied in 3 sets of data: (I) counts of individual epileptiform discharges in twelve 48 h EEG recordings, (IIa) seizure calendars of 30 therapy-resistant outpatients participating in a drug trial, (IIb) seizure calendars of 10 mentally subnormal epileptic patients resident in a long-stay unit. The EEG data I were characterized most often by a Poisson distribution of intervals between discharges and the occurrence of marked periodicities, particularly at night. The periods of rhythmic nocturnal events ranged from 13 to 142 min and did not appear to correspond to the REM/non-REM cycle. In the seizure data IIa and b a Poisson distribution of intervals between events was found in half the patients. Periodicities occurred only in group IIa and did not correspond to weekly or monthly cycles. A stochastic process is considered to be the model which best fits these data.

Topics: Adolescent; Adult; Aged; Anticonvulsants; Brain; Cinnarizine; Electroencephalography; Epilepsy; Female; Flunarizine; Humans; Male; Middle Aged; Placebos; Seizures; Telemetry; Time Factors

The anticonvulsive properties of orally administered cinnarizine [(E)-1-(diphenylmethyl)-4-(3-phenyl-2-propenyl)-piperazine], its difluoro derivative flunarizine [(E)-1-(bis-(4-fluorophenyl)methyl)-4-(3-phenyl-2-propenyl)-piperazine], diphenylhydantoin and phenobarbital, were studied against maximal metrazol seizures (MMS) in rats and maximal electroshock seizures (MES) in mice. In rats (MMS), the lowest ED50 for protection against tonic extension of hindpaws was 4.10 mg/kg (1 h 35 min after treatment) with sodium phenobarbital, 6.04 mg/kg (5 h 45 min) with flunarizine dihydrochloride, 9.84 mg/kg (2 h 34 min) with cinnarizine and 19.30 mg/kg (3 h 38 min) with diphenylhydantoin. In mice (MES), protection against tonic extension of hindpaws was (2 h after treatment) 7.0 mg/kg with diphenylhydantoin, 13.2 mg/kg with sodium phenobarbital, 20.9 mg/kg with flunarizine kihydrochloride and 49.0 mg/kg with cinnarizine. Except at subtoxic doses no side effects were observed in rats and mice given cinnarizine, flunarizine kihydrochloride or kiphenylhydantoin. Phenobarbital induced ataxia in rats and mice at 22 mg/kg and 42.7 mg/kg, respectively, and loss of righting reflex at 112.8 mg/kg and 160 mg/kg, respectively. Flunarizine is the longest-acting drug and has the slowest onset. At a dose of twice the minimal ED50 flunarizine affords protection against tonic extension of hindpaws in rats (MMS) for 23 h 30 min dephenylhydantoin for 11 h 38 min, phenobarbital for 8 h 22 min and cinnarizine for 8 h 16 min. Peak effect was reached with flunarizine at 5 h 45 min, with diphenylhydantoin at 3 h 38 min, with cinnarizine at 2 h 34 min and with phenobarbital at 1 h 35 min. The anti-MMS profiles of cinnarizine and flunarizine resemble that of dephenylhydantoin as all three compounds are selective blockers of tonic extension of hindpaws. Phenobarbital antagonized the whole MMS-pattern, i.e., tremors, clonic convulsions and tonic extension of fore- and hindpaws. However, the effects of phenobarbital against tremors, clonic convulsions and tonic extension of forepaws may reflect more a general CNS-depressant effect than a specific anticonvulsive activity since neurotoxic effects (ataxia and loss of righting reflex) appear at the same doses.

Topics: Animals; Anticonvulsants; Cinnarizine; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Electroshock; Female; Lethal Dose 50; Male; Mice; Pentylenetetrazole; Phenobarbital; Phenytoin; Piperazines; Rats; Seizures; Time Factors