Theophylline Concentrations in Serum and Saliva after Oral Microcrystalline and Sustained‐Release Preparations in Asthmatics

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Abstract
Theophylline concentrations in saliva were compared with those in serum in 13 asthmatic patients after single and multiple oral dosage of a microcrystalline theophylline tablet (Nuelin) and a sustained-release preparation (Nuelin Retard). There was wide individual variation in the ratio of serum to saliva concentrations indicating that, even when individual serum to saliva ratios were established, the use of saliva theophylline measurements alone is unreliable for the routine monitoring of theophylline therapy. Both preparations produced mean serum theophylline concentrations within the 10-20 .mu.g/ml range, the sustained-release tablet giving higher morning trough values and smaller trough to peak variation. The preparations were qualily and highly bioavailable. Side effects were reported by 3 patients, which were the patients with the highest AUC [area under the concentration-time curve]. The Nuelin Retard preparation appears to provide smooth, sustained serum theophylline concentrations within the therapeutic range and the simple, twice-daily dosage should result in improved patient compliance.