Relationship between serum concentration and daily dose of dantrolene in cerebral palsy patients.

Serum concentration of dantrolene and its active metabolite, 5-hydroxydantrolene were determined in 27 cerebral palsy patients. Correlation coefficients between the oral dose of dantrolene and serum levels of dantrolene and its major metabolite, 5-hydroxydantrolene were rather small in cerebral palsy patients. The mean half-times of dantrolene and 5-hydroxydantrolene were 3.41 (n = 6) and 4.00 (n = 5) hours, respectively. These values were about a half of those reported earlier [Lietman et al., 1974; Meyler et al., 1979; Flewellen et al., 1983]. The poor correlation between serum level and dose may be due to the variation in an extent of oral dantrolene availability.