Summary: Treating debilitated elderly patients through nasogastric tube (NGT) can change the pharmacokinetic characteristics of drugs, mainly those that are slow released (SR). The purpose of this study was to compare pharmacokinetic parameters between patients who receive SR theophylline orally and those who receive it through NGT.
Patients and methods: The authors studied elderly patients in the geriatric ward receiving SR theophylline for chronic obstructive lung disease. In 17 patients fed by NGT (group I), theophylline was removed from the capsule and mixed with 10 mL of water. Group II included 15 patients who swallowed the drug orally. Theophylline blood levels were measured, as were peak concentration (C(max) ), time to peak (T(max) ), and area under the serum concentration-time curves (AUC).
Results: The mean daily dose was not statistically different between the two groups: 320 +/- 130 (200-500) mg/d in group I and 360 +/- 85 (200-500) mg/d in group II, given twice daily. All pharmacokinetic measurements were lower in group I as compared with group II: trough theophylline blood levels were 3.78 +/- 3.2 (0.5-10.77) microg/mL versus 8.63 +/- 4.6 (0-15.61) microg/mL ( P= 0.002); C(max) was 6.53 +/- 4.1 (1.3-13.33) microg/mL versus 10.51 +/- 3.30 (4.3-16.28) microg/mL (P = 0.0058), and AUC was 50.04 +/- 38.59 (11-112) microg/h/mL versus 80.37 +/- 28.8 (23-148) microg/h/ml (P = 0.024). CONCLUSIONS Patients receiving the drug through NGT had variability and unexpectedly low blood levels. Therefore, the pharmacokinetic parameters of SR preparations should be evaluated before their administration through NGT.