Phenobarbital in newborns with neonatal seizures. A study of plasma levels after intravenous administration.

Phenobarbital plasma levels were studied in a group of 25 newborn infants. Phenobarbital was administered i.v. in all cases throughout the study period. The mean loading dose was 19.4 mg/kg, ranging from 16.4 to 20.5, and the mean maintenance dose was 4.0 mg/kg/day, varying from 2.6 to 5.0. We obtained mean plasma levels of 22.9 micrograms/ml, 24 h after administering the loading dose. Mean plasma levels at 4, 7, 14 and 21 days were in the therapeutic range (15-40 micrograms/ml), with only a few cases falling outside of it. There was no difference in plasma phenobarbital levels between term and pre-term infants. Side effects were not seen in infants without a severe neurological impairment prior to drug administration.

[Loading-doses of carbamazepine and diphenylhydantoin: use in high-risk patients]. / Doses-carga de carbamazepina e difenil-hidantoína: utilização em pacientes de alto risco.

Loading-doses of phenytoin (1000 mg) and carbamazepine (600 mg) were given orally respectively to 10 and 6 patients with uncontrolled epileptic seizures secondary to acute neurological disorders or alcohol withdrawal. In the phenytoin group age varied between 12-73 years and serum concentrations at 2, 4, 6, 8, 12 and 18 hours after drug administration were 7.6, 8.8, 8.7, 8.7, 7.2 and 6.5 micrograms/ml (means). A quantitative method did not detect important side-effects. In the carbamazepine group age varied between 25-56 years and serum concentrations at the same times were 3.9, 5.3, 6.5, 7.5, 7.4 and 8.2 micrograms/ml. Side-effects were discrete. Further medication was not necessary in the 24 hours after drug administration. Although both regimens controlled the clinical situation without relevant side-effects serum concentrations were sub-therapeutic in the case of phenytoin. We suggest the ideal phenytoin oral loading-dose is 1500 mg. The carbamazepine load produced therapeutic concentrations. The stability of serum concentrations for the period of the study shows that those regimens are useful in the subacute control of epileptic seizures in the maintenance treatment of status epilepticus and in alcohol withdrawal.

[Determination of plasma levels of valproic acid (dipropylacetic acid) by gas chromatography]. / Determinação dos níveis plasmáticos do ácido valpróico (ácido dipropilacético) por cromatografia em fase gasosa.

A specific and sensitive procedure for determination of valproic acid at therapeutic concentrations in human plasma has been standardized according to Hershey. The method requires solvents transfer but not solvent evaporation. For preparations of standard solution of high accuracy a sodium salt of valproic acid was used, titred potentiometrically with O.1 N percloric acid. Tests for sensibility and reproductibility were performed. The quality control of the assay was established using a control quality sera (Seronorm, Pharmaca).

Determinacao dos niveis plasmaticos do acido valproico (acido dipropilacetico) por cromatografia em fase gasosa. / Determination of plasma levels of valproic acid (dipropylacetic acid) by gas chromatography

Foi padronizado um metodo de determinacao dos niveis plasmaticos do acido valproico por cromatografia a gas. Trata-se de metodo rapido e exato, que evita etapas como evaporacao ou derivacao. O padrao empregado foi o sal sodico do acido valproico em solucao aquosa, cuja concentracao exata e determinada atraves de titulacao potenciometrica com acido perclorico. O metodo foi avaliado, ao se submeter um plasma controle, as condicoes de analise