Choosing the dose of an antiepileptic drug must be individualized to the patient based on age, weight, co-medications, and genetics. Age is the most important variable. There are major differences in dosing among neonates, infants, children, adults, and the elderly. In general, neonates have poor absorption of drugs and slow metabolism. This is even more prominent in premature infants.
Metabolism slows in late adolescence and appears to be stable throughout most of adulthood.
In the elderly, however, there is a decline in hepatic capacity, and drug metabolism slows. Although these general concepts are well known, specific details of change in metabolism during the aging process have not been well studied. Most of our dosing data was obtained from adults in pharmacokinetic studies of limited scope. Data for children, especially for those in the transition years from adolescence to adult, are limited, and information for the elderly is sparse. Nevertheless, some dosing guidelines for various age groups are available, but the physician must monitor blood levels to adjust doses to attain the desired levels.