Anticonvulsant level in saliva, serum, and cerebrospinal fluid.

Levels of four anticonvulsant drugs were measured simultaneously in saliva, spinal fluid, and dialyzed serum, i.e., free drug in serum. The level of diphenylhydantoin and possibly of carbamazepine was the same in the three body fluids. The leves of phenobarbital was the same in spinal fluid and dialyzed serum, but was lower in saliva. The level of primidone was different in each body fluid. The technique is simple (flow of saliva stimulated when the subject chews candle was or Teflon) and will be useful to determine the level of free diphenylhydantoin and carbamazepine, which is more closely related to intoxication or drug failure than is the total level of drug.