Fig. 6. Time required for a 50% decrease in concentration after continuous infusion of variable length (context-sensitive half-time). Simulations were performed for a child (20 kg body weight, 5 yr of age), a lean adult (50 kg, 30 yr), an adult of average weight (70 kg, 30 yr), an obese adult (110 kg, 30 yr), and an elderly individual (65 kg, 80 yr), based on the final model parameters (table 4).