The pharmacokinetics and bioavailability (F) of thephylline from a new sustained-release granule formulation (Theodur G) and from a standard sustained-release tablet formulation (Theodur) in single oral dose were studied in 6 pediatric patients.
The new formulation showed a mean maximal plasma concentration per dose per weight (C
max) of 1.17kg/1 (range 0.67 to 1.35kg/1) attained at 6.7 (5-8)hours (T
max) postdose, whereas the standard formulation produced a peak plasma concentration of 1.11 (0.77-1.81)kg/1 at 8.8 (6-12) lours. No significant differences in C
max or T
max were observed between these two sustained-release products. The mean bioavailability for theophylline from Theodur G was 98.8% (65.8-131.6) while the mean F value of Theodur was 88.4% (61.2-132). The mean residence times (MRT) of Theodur G and Theodur were 15.1 (12.5-18.1) and 13.9 (10.6-18.9) hours, respectively. No significant differences in F and MRT were observed between these two products. The mean absorbed fraction-time profile exhibited a faster absorption for Theodur in the first 2 hours and a more prolonged absorption in Theodur G.
These results indicate that the products are equivalent with respect to the extent and rate of bioavailability.
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