[Are theophylline determinations useful to the clinician during treatment with a sustained-release form of theophylline?]

The aims of the study were the correlation between dosage and plasmatic levels of slow release theophylline and the reason for dosage adjustment. 64 pharmacokinetic studies were performed in 58 asthmatic children between 17 months and 16 years. Plasmatic levels of theophylline were performed by fluoroimmunology technique at H0 (before the dose) 2 (H2), 4 (H4), 6 (H6) and 8 (H8) hours after the dose of slow release theophylline. The best correlation between dose and plasmatic levels were observed at H4 and H6 for Armophylline and Euphylline respectively. Dosage adjustment were based both upon clinical state and plasmatic levels in 55 cases. In 9 cases the modification of dose were decided only because of plasmatic levels out the therapeutic range. The authors proposed a schema of dosage modifications based upon clinical state; plasmatic levels must be used as a guide for dose adjustment in patients clinically uncontrolled.