SUMMARY
Plasma concentrations of theophylline were determined in healthy volunteers following a single oral dose of six slow release preparations, immediately following a standard breakfast. There were no significant differences between the different preparations. The time taken to reach maximum plasma concentration, tmax, was found to be longer than in previous studies in which the drug was administered on an empty stomach.
1 Concomitant saliva and plasma theophylline concentrations were measured in six healthy male volunteers following single dose administration of two sustained release preparations (Nuelin SA and Phyllocontin Continus). 2 Using mean values, a good correlation was obtained between saliva and plasma drug concentrations. Prediction of plasma values using individual saliva was poor and varied widely. The ratio of saliva to plasma concentrations in the same individual, assessed under standardised conditions, was not always reproducible.
Theo-Dur, 300 mg twice daily, and Uniphylline, 600 mg once daily taken with food were compared in an open cross-over study in healthy volunteers. Uniphylline had significantly (P less than 0.001) higher peaks, lower troughs and wider variation in theophylline concentrations than Theo-Dur. Peak plasma concentrations were reached earlier for Theo-Dur but the difference failed to reach statistical significance (0.05 less than P less than 0.1). There was no significant difference between the two drugs in area under the plasma concentration time curve. Therapeutic occupancy lasted significantly longer (P less than 0.05) with Theo-Dur; eight volunteers attained 24 h therapeutic occupancy after administration of Theo-Dur compared to 4 h with Uniphylline.
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