SERUM THEOPHYLLINE PROFILE WITH ONCE-DAILY THEOPHYLLINE (UNIPHYL) FOLLOWING CONVERSION FROM INTRAVENOUS THEOPHYLLINE IN ADULT ASTHMATIC-PATIENTS

Although guidelines are available for conversion from intravenous (IV) theophylline to twice-daily, oral, controlled-release theophylline, t he optimal method for conversion to Uniphyl(R), a chronotherapeuticall y formulated, once-daily theophylline preparation, has not been previo usly evaluated. The present study was designed to prospectively evalua te a method for converting patients from IV theophylline to Uniphyl, t o formulate simple, practical dosage recommendations for use in clinic al practice. Ten patients with acute exacerbation of asthma receiving IV theophylline for greater-than-or-equal-to 48 hours and with steady state serum theophylline concentrations (STCs) between 4.5 and 15.5 mg /L (25 and 86 mumol/L) were enrolled into the study. Patients with STC s greater-than-or-equal-to 4.5 and < 12 mg/L (greater-than-or-equal-to 25 and <66 mumol/L) and those with STCs greater-than-or-equal-to 12 a nd less-than-or-equal-to 15.5 mg/L (greater-than-or-equal-to 66 and le ss-than-or-equal-to 86 mumol/L) received their first Uniphyl dose imme diately following termination of IV theophylline (No Time Lapse [NTL' group) and after a 4-hour delay (Time Lapse [TL] group), respectively. The differences in the area under the curve values between Uniphyl do sing and IV theophylline were 11% in the NTL group (1214.6 +/- 247.9 m umol/h . L-1 vs 1370.4 +/- 148.1 mumol/h . L-1, 95% confidence interva l, 74% to 103%; P = 0.068) and 10% in the TL group (1959.4 +/- 165.1 m umol/h . L-1 vs 1784.6 +/- 119.4 mumol/h . L-1, 95% confidence interva l, 103% to 117%; P = 0.013). The results suggest that patients with ST Cs less-than-or-equal-to 15.5 mg/L (less-than-or-equal-to 86 mumol/L) may be safely converted from IV to oral theophylline by giving the fir st Uniphyl dose immediately on discontinuation of the infusion, or aft er a 4-hour delay, based on the prevailing theophylline concentration.