ABSTRACT
A gas chromatographic/mass spectrometric method is developed and validated for simultaneous determination of nitecapone and its 13C6-labelled analogue in human plasma using (2H6,13C6)nitecapone as internal standard. The method involves extraction of the analytes from plasma to ethyl acetate-hexane mixture (20:80) and conversion to bis(trimethylsilyl) ethers prior to determination by gas chromatography/mass spectrometry using selected ion monitoring. The quantification range is 0.5-2000 ng ml-1. Precision ranges from 11.3% (coefficient of variation) at low levels to 2.4% at high levels. Recovery is about 50% in the whole range. The method is applied to a pharmacokinetic study where nitecapone diluted with 14C-labelled nitecapone is given intravenously concomitantly with an oral dose of (13C6)nitecapone.
Subject(s)
Catechol O-Methyltransferase Inhibitors , Catechols/blood , Pentanones/blood , Carbon Isotopes , Catechols/pharmacokinetics , Gas Chromatography-Mass Spectrometry/methods , Humans , Male , Pentanones/pharmacokineticsABSTRACT
An experimental study was designed for assessement of whether two recently marketed flavored chlorhexidine mouthrinses, Hibitane Dental (ICI) and Plak-Out (Hawe), have a good plaque-inhibiting effect as the 0.2% aqueous solution of chlorhexidine gluconate. Thirteen dental students used in different sequences each one of the three rinses fro 1 week by rinsing twice daily for 1 min. During the rinsing periods no other oral hygiene measures were allowed. Between two rinsing periods the subjects cleaned their teeth mechanically for 1 week. At the start of each test and control period, the teeth were professionally cleaned with rubber cups and an abrasive paste. At the end of the five 1-week periods the mesial, lingual and facial aspects of the teeth in the right halves of the jaws of each participant were scored for the Plaque Index by the same investigator. After the mechanical cleaning, higher PII scores were recorded than after the chlorhexidine rinses. No difference could be observed among the PII scores after rinsing with the aqueous or the two flavored chlorhexidine solutions.
