Saliva therapeutic drug monitoring

Zuidema J, Hold KM, de Boer D, Maes RA (1996) Saliva as a specimen for therapeutic drug monitoring in pharmacies. Pharm World Sci 18(6) 193-194... 

Berkovitch M, Goldman M, Silverman R, Chen-Levi Z, Greenberg R, Marcus O, Lahat E. Therapeutic drug monitoring of once daily gentamicin in serum and saliva of children. Eur J Pediatr 2000 159(9) 697-8. 

The measurement of drugs in saliva is of interest both for purposes of therapeutic drug monitoring and for the detec-... 

Kintz, R, and Samyn, N. (2002) Use of alternative specimens Drugs of abuse in saliva and doping agents in hair. Therapeutic Drug Monitoring, 24,239-246. 

Saliva is not an important route of excretion since most of the chemicals present in saliva will eventually reach the gastrointestinal tract to be reabsorbed or eliminated in the feces. The unbound fraction of several therapeutic drugs may diffuse passively from plasma into saliva. This provides a noninvasive means of indirectly monitoring plasma concentrations of drugs like lithium, phenytoin, and theophylline. Metals like lead, cadmium, and mercury are also present in saliva. 

Saliva is a possible alternative sampling fluid to plasma for therapeutic monitoring. A sample can be collected with minimal patient discomfort. Perhaps more importantly, saliva is protein-free, and saliva provides a measurement of the concentration of free (unbound) drug in the plasma (assuming distributional equilibrium). Saliva sampling has been proposed for therapeutic monitoring of anticonvulsant medications such as phenytoin and carbamazepine. It may also be beneficial in special patient populations such as children. 

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