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Circadian variation in plasma theophylline concentrations during maintenance therapy with a sustained‐release preparation in patients with obstructive airways disease.
Author(s) -
Taylor DR,
Duffin D.,
Kinney CD,
McDevitt DG
Publication year - 1984
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.1365-2125.1984.tb05017.x
Subject(s) - theophylline , circadian rhythm , morning , dosing , bronchodilator , diurnal temperature variation , pharmacokinetics , medicine , maintenance dose , plasma concentration , anesthesia , endocrinology , chemistry , zoology , asthma , biology , atmospheric sciences , geology
Circadian variation in plasma theophylline concentrations was studied in eight patients with obstructive airways disease during regular 12‐ hourly dosing at 09.00 and 21.00 h with a sustained‐release theophylline formulation. After regular dosing for a minimum period of 3 days, plasma concentration measurements were made at 09.00, 13.00, 21.00 and 01.00 h on 3 consecutive days and at more regular intervals during a complete 24 h period on day 4. On each day, theophylline concentrations for the first 4 h of the dosing interval were consistently higher during the day than at night. However, the differences were significant only at 13.00/01.00 h on day 2, and for each of the first 4 h on day 4. On day 4, following the dose at 21.00 h the mean peak plasma theophylline concentration occurred 6.9 +/‐ 0.8 h after dosing; in contrast, after the morning dose the mean peak concentration occurred at 4.5 +/‐ 0.8 h. However, the mean 'steady‐ state' concentrations during the two dose intervals were not significantly different. Thus circadian variations in plasma drug concentrations do occur in patients taking maintenance theophylline therapy: differing rates of absorption may account for the observed pattern.