Kishida M, Hukushima K, Iikura Y
Department of Pediatrics, Tottori University, School of Medicine.
Arerugi. 1990 Oct;39(10):1422-6.
We have reported that the morning mean rate of absorption (ka) in immediate release aminophylline tablet is significantly faster than the evening one without any obvious change in AUC, the distribution (Vd), the rate of elimination (kel) or the elimination half-time (t1/2) and this altered absorption is a cause of circadian variation of theophylline concentrations with sustained-release preparations. Now, we examined the effect of posture on theophylline absorption. Seven asthmatic children were given immediate release aminophylline tablets at the same time in the morning on two separate occasions. On one day they remained standing and on the other lying. Serum theophylline concentration was measured at 0, 0.5, 1, 2, 3, 4, 5 hours after dosing. Mean theophylline levels were higher in the standing position at all time and only the mean rate of absorption (ka) was significantly faster without any obvious change in parameters of pharmacokinetics. This result was almost consistent with differences of day and night theophylline kinetics. We conclude that slowness of absorption in the evening is mainly induced by difference in posture.
我们曾报道，速释氨茶碱片的早晨平均吸收速率（ka）显著快于晚上，而曲线下面积（AUC）、分布容积（Vd）、消除速率（kel）或消除半衰期（t1/2）均无明显变化，这种吸收变化是缓释制剂中茶碱浓度昼夜变化的一个原因。现在，我们研究了体位对茶碱吸收的影响。七名哮喘儿童在两个不同的早晨同时服用速释氨茶碱片。一天他们保持站立，另一天则躺着。给药后0、0.5、1、2、3、4、5小时测量血清茶碱浓度。在所有时间点，站立位的平均茶碱水平均较高，仅平均吸收速率（ka）显著加快，而药代动力学参数无明显变化。这一结果与昼夜茶碱动力学的差异几乎一致。我们得出结论，晚上吸收缓慢主要是由体位差异引起的。
