Thesis (M.Sc. in Pharm.)--Chulalongkorn University, 1997

Phenobarbital blood level dose ratio was studied in 69 Thai paediatric patients in neurologic clinic, Chulalongkorn Hospital. Level dose ratio of patients increased with the increasing age (1 month to 3 years = 3.79, 3-5 years = 4.56, 5-14 years = 5.60, and more than 14 years = 9.29). Form scatter diagram between level dose ratio and age, the linear regression equation was L/D = 3.59 + 0.25 (Age), r = 0.727, p<0.0001. Serum concentrations of fifty-nine patients (85.5%) were in acceptable therapeutic range (10-40 micrograms/ml). There were forty-nine patients (71.01%) whose seizures were completely controlled. Among these patients, there were forty-five patients (91.8%) whose serum levels were within the therapeutic range. Side effect from phenobarbital was found in this study were hyperactivity (n = 21), sedative (n = 10), aggressive (n = 3), and ataxia (n = 1). No relationship between side effect incidences and serum level was determined. However, some side effects tend to happen more often in one age group than the others, hyperactivity was found mostly in patients age between 5 to 14 years while sedative was found mostly among patients age more than 14 years.