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Phenytoin and phenobarbital concentrations in saliva and plasma measured by radioimmunoassay
Author(s) -
Cook C. E.,
Amerson Ellen,
Poole W. Kenneth,
Lesser Philip,
O'Tuama Lorcan
Publication year - 1975
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1002/cpt1975186742
Subject(s) - saliva , phenytoin , chemistry , radioimmunoassay , phenobarbital , anticonvulsant , chromatography , endocrinology , blood plasma , medicine , epilepsy , biochemistry , psychiatry
Saliva and plasma levels of phenytoin (DPH) and phenobarbital (PB) in a series of epileptic patients were compared by means of a radioimmunoassay (RIA) that required only 10 µ11 of saliva or plasma. There was an excellent linear relation (r = 0.98) between the logarithms of the concentrations of DPH in the two fluids. The ratio saliva/plasma was remarkably constant at 0.10 and was unaffected by varying levels of PB. The ratio was close to the fraction of DPH reported unbound in plasma at 37°. PB plasma and saliva levels were also closely related (r = 0.98 for logarithm of plasma and saliva levels). This relation was nonlinear [plasma concentration = 4.43 × (salivary concentration) 0.86 ], but could be approximated by the ratio plasma/saliva = 3.4. The simplicity of sample collection and the sensitivity of the RIA procedure suggest that clinical monitoring of these anticonvulsant levels may be carried out by RIA on saliva samples.