Theophylline disposition following parenteral feeding of malnourished patients

OBJECTIVE: To investigate the effect of parenteral nutrition on theophylline disposition in malnourished patients. DESIGN: Before-after trial. SETTING: Tertiary care center. PATIENTS: Ten patients with historic, anthropometric, and laboratory evidence of malnutrition. INTERVENTIONS: Patients received two 5-mg/kg intravenous infusions of theophylline separated by at least 48 hours of glucose-based parenteral nutrition providing the entire estimated nutritional requirements. MAIN OUTCOME MEASURES: Following each theophylline administration, serum theophylline samples were collected over a 24-hour period for delineation of maximum plasma concentrations, volume of distribution, elimination rate constant, clearance, and area under the curve. RESULTS: Peak plasma theophylline concentrations were significantly lower prior to feeding (5.3 mumol/L, 95 percent confidence interval [CI] 0.78-10.0 mumol/L, p = 0.028). Volume of distribution decreased after parenteral feeding (0.08 L/kg, 95 percent CI 0.006-0.15 L/kg, p = 0.037). The elimination rate of theophylline increased after parenteral feeding reflected by an increase in the elimination rate constant (0.06 h-1, 95 percent CI 0.01-0.10 h-1, p = 0.023). CONCLUSIONS: This study suggests that parenteral nutrition using a glucose-based solution acutely influences theophylline disposition in malnourished patients.