[Saliva and plasma levels of carbamazepine have a poor correlation: a pilot study]. / Relación entre niveles de carbamazepina en saliva y plasma: estudio piloto.

UNLABELLED: Carbamazepine is one of the most commonly used anticonvulsants for the treatment of epilepsy and its plasma concentrations must be monitored periodically to obtain a useful and safe clinical effect. There is not a good relationship between the dose of the carbamazepine and their effects in humans, but the effects of this drug have been well correlated with its plasma levels. AIM: To measure the correlation between plasma and saliva levels of carbamazepine in children with epilepsy. MATERIAL AND METHODS: Saliva and plasma levels of carbamazepine were measured by using instrumental planar chromatography in 11 epileptic children aged 8 to 15 years treated with the drug for at least six months. RESULTS: The mean saliva/plasma ratio was 0.18+/-0.05 and the mean of carbamazepine concentration in saliva, expressed as a percentage of concentrations in plasma, was 17.97+/-5.40. There was a poor linear correlation (r=0.37) between the concentrations of carbamazepine in both fluids. CONCLUSIONS: In this group of epileptic children the correlation between saliva and plasma carbamazepine levels was weak.

Quantitative determination of haloperidol in tablets by high performance thin-layer chromatography.

A densitometric high performance thin-layer chromatography (HPTLC) method was developed and validated for the quantitative analysis of haloperidol in tablets. Chromatographic separation was achieved on precoated silica gel F 254 HPTLC plates using a mixture of acetone/chloroform/n-butanol/acetic acid glacial/water (5:10:10:2.5:2.5 v/v/v/v/v) as the mobile phase. Quantitative analysis was carried out at a wavelength of 254 nm. The method was linear in the 10-100 ng/microL range, with a determination coefficient of 0.999. The coefficients of variation for precision were not higher than 2.35%. The detection limit was 0.89 ng/microL, and the quantification limit was 2.71 ng/microL. The accuracy ranged from 97.76 to 100.33%, with a CV not higher than 4.50%. This method was successfully applied to quantify haloperidol in real pharmaceutical samples, including the comparison with HPLC measurements. The method was fast, specific, with a good precision and accuracy for the quantitative determination of haloperidol in tablets.

Quantitative determination of clozapine in serum by instrumental planar chromatography.

An instrumental planar chromatographic (HPTLC) method for quantitative analysis of clozapine in human serum was developed and validated. Clozapine was extracted with n-hexane-isoamyl alcohol (75:25 v/v). The chromatographic separation was achieved on precoated silica gel F 254 HPTLC plates using a mixture of chloroform and methanol (9:1 v/v) as mobile phase. Quantitative analyses were carried out by densitometry at a wavelength of 290 nm. The method was linear between 10 and 100 ng/spot, corresponding to 0.10 and 1.00 ng/microL of clozapine in human serum after extraction process and applying 10 microL to the chromatographic plates. The method correlation coefficient was 0.999. The intra-assay variation was between 2.10 and 3.33% (n = 5) and the interassay was between 2.67 and 4.44% (n = 9). The detection limit was 0.03 ng/microL, and the quantification limit was 0.05 ng/microL. The method proved to be accurate, with a recovery between 97.00 and 99.00%, with an RSD not higher than 7.22%, and was selective for the active principle tested. This method was successfully applied to quantify clozapine in patient serum samples. In conclusion, the method is useful for the quantitative determination of clozapine in serum.