Dependence of salivary drug concentration on salivary flow rate

Saliva drug concentrations are a function of the saliva flow rate at which they are collected. Increased saliva flow rate tends to restore the salivary concentration towards the free unbound plasma concentration of drug. For those drugs excluded from the saliva relative to their free plasma concentration, stimulation increases the observed drug levels in the saliva. For those drugs concentrated in the saliva relative to their free plasma concentration, stimulation decreases the observed drug levels in the saliva.