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Pharmacokinetics of sustained release theophylline in low and high multidose regimens.
Author(s) -
Koeter GH,
Jonkman JH,
Vries K,
Schoenmaker R,
Greving JE,
Zeeuw RA
Publication year - 1981
Publication title -
british journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.216
H-Index - 146
eISSN - 1365-2125
pISSN - 0306-5251
DOI - 10.1111/j.1365-2125.1981.tb01283.x
Subject(s) - theophylline , pharmacokinetics , chemistry , pharmacology , bronchodilator , dosage form , chromatography , medicine , asthma
1 The in vitro characteristics (dissolution rate) of a sustained release theophylline preparation (Theo‐Dur were first measured in acid medium (pH = 1) for 2 h and after that in a phosphate buffer (pH = 6.8) for 6 h. 2 The tablets released more than 95% of the active ingredient within 5 h at a rate of approximately 11% of the dose per hour at pH = 1 and about 18% at pH = 6.8. 3 Dose dependency of the pharmacokinetics of theophylline was tested in seven healthy volunteers by giving them either 300 mg Theo‐Dur or 900 mg Theo‐Dur in two doses a day for 5 days in a cross over design. After the last tablet on day 6 the fall‐off curve was followed in order to calculate the pharmacokinetic parameters. 4 Theophylline (300 mg) resulted on day 6 in a mean serum concentration of 4.4 +/‐ 0.8 microgram ml‐1. The dose of 900 mg resulted in a proportional increase in the serum concentration. The result was 13.3 +/‐ 2.2 micrograms ml‐1. 5 The T1/2 (300 mg) was 9.3 +/‐ 1.4 h and the T1/2 (900 mg) was 8.5 +/‐ 2.0 h. These values do not significantly differ (0.10 less than P less than 0.20). 6 It was concluded that theophylline exhibits the rules of linear pharmacokinetics when serum concentrations are in the therapeutic range.