Pharmacokinetic Principles of Drug Distribution in Saliva^a

Exposures associated with clandestine methamphetamine drug laboratories in Australia

“…A number of studies have indicated that oral fluid methamphetamine concentrations are higher than blood plasma (169,171,179,181), however, there was a poor correlation between saliva/oral fluid and plasma methamphetamine concentrations reflecting high intra and inter-individual variability. While some attempts have been made to better define saliva-plasma ratios (S/P) for methamphetamine (171,185) the measure is generally not considered to be a reliable quantitative measure of exposure, and is only considered to be a suitable matrix for screening for drug use (181).…”

A Comparison of Intranasal and Oral Scopolamine for Motion Sickness Prevention in Military Personnel

“…The results of this study would suggest that salivary sampling may 13 not be the most effective assessment of drug concentration for use with intranasal drug delivery due to cross contamination yielding unreliable and invalid drug levels. Haeckel (1993) and Jusko and Milsap (1993) have also determined that the utility of salivary analysis for determining systemic medication levels requires constant pH values of saliva, and is dependent on the pKa of the medication, and the fraction of the drug that is bound in saliva. The variability in pH of the oral fluid influences the saliva to plasma distribution ratio which will greatly impact the ability to accurately detect medication levels (Magerl & Schulz, 2007).…”

“…Salivary flow rate must be taken into consideration, as it is an important factor affecting diffusion of medications, including scopolamine, into oral fluid. According to Jusko & Milsap (1993), changes in salivary flow and time of sampling may complicate the use of saliva for pharmacokinetic purposes. It is possible that even the small dose of scopolamine (0.4mg) used in the present study decreased salivary flow by inhibiting parasympathetic stimulation of secretary glands; this, combined with the inadequacies that may have been inherent within the collection device, may have caused the reporting of abnormal scopolamine levels.…”

“…According to researchers in the field of biochemistry and pharmacology, the primary requisite for use of salivary assays for evaluating the bioavailability of medication is a constant or predictable relationship between the drug concentration in saliva and the drug concentration in plasma (Fatah & Cohen, 2003;Haeckel, 1993;Jusko & Milsap, 1993;Langman, 2007; Margel & Schulz, 2007). Jusko and Milsap (1993) state that the utility of salivary assays for pharmacokinetic and pharmacodynamic studies relies on a drug that exhibits a constant saliva/plasma ratio that is independent of drug concentration, is resistant to changes in salivary 12 flow, and is consistent among individuals. There are currently no published research studies which establish a predictable relationship between salivary assays of scopolamine and plasma levels.…”

Comparative Study on Salivary Distribution of Fluoroquinolones in Rats.

“…Molecular mass, salivary pH, salivary flow rate, degree of ionization, lipid solubility and protein binding are known to be factors that can influence the diffusion of substances into saliva 22) ; therefore, these factors should be considered when salivary distribution of quinolones is discussed. There was no great difference among molecular weights of the quinolones used in this study.…”