Pharmacokinetic comparison of a once-daily and twice-daily theophylline delivery system.
The steady-state pharmacokinetics of a formulation of a 24-hour extended-release theophylline preparation (Uni-Dur) were compared with a twice-daily formulation (Theo-Dur) in healthy volunteers. Eighteen healthy, adult, male volunteers received both treatments (600-mg dose of Uni-Dur every morning for 5 doses or 300 mg every 12 hours for 10 doses of Theo-Dur) in a randomized, two-way crossover design with no washout period between treatments. Blood samples were collected just before doses 3, 4, and 5 of Uni-Dur and before doses 5, 7, and 9 of Theo-Dur, as well as at 2-hour intervals for 24 hours following doses 5 of Uni-Dur and doses 9 and 10 of Theo-Dur. The mean serum theophylline concentration-time curves were similar for both formulations from 2 to 18 hours postdose, and the maximum serum theophylline concentrations were comparable (7.66 micrograms/mL for Uni-Dur compared with 7.78 micrograms/mL for Theo-Dur). Fluctuations in serum theophylline concentrations were greater with Uni-Dur (139 +/- 85% compared with 72 +/- 25% normalized to trough serum concentrations; 77 +/- 22% compared with 53 +/- 13% normalized to average steady-state serum concentrations). Based on the area under the curves, the extent of absorption of Uni-Dur was 91.42 +/- 14.24% of Theo-Dur. These findings suggest that the clinical response in patients treated with once-daily Uni-Dur may be equivalent to Theo-Dur given every 12 hours. Furthermore, because of the similar serum concentration over time profiles of the two formulations, it is unlikely that additional monitoring of serum levels during a conversion will be necessary.[1]References
- Pharmacokinetic comparison of a once-daily and twice-daily theophylline delivery system. González, M.A., Kisicki, J., Straughn, A.B. Clinical therapeutics. (1994) [Pubmed]
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