Look in such cases we should focusing on the properties of its similar medication for exsmple 

Are you sure that amohetamin excretion is through salivation mainly?

First we should be carfull about the route of its excretion.

If we ensure about its saliva excretion of smphetamin 

At that time we can collect the saliva of the vilunter

But be carfull sbout the effect of medication and plasma concentration of medication 

As a general rule if medication go out from our body it does not has pharmavological effect

So saliva is not correct and exact route of dtug excretion 

Becouse mainly the content of saliva returning to plasma cerculation

So at the end we should focus on plasma data mostly.

Hi David,

It is very practical to collect plasma or oral samples to monitor amphetamine levels after a single dose. If you need a quantitative measure, the beneath data and recommendations have to be kept in mind. The several studies involving methamphetamine collected oral saliva (OS) the use of citric acid stimulated the production of OS almost halved the concentration of methamphetamine. The concentrations of methamphetamine in OS are on average several-fold higher than plasma in two studies and correlated strongly with the corresponding plasma concentration. The half-life in OS is about 11 h on average. Amphetamine is not always detected in OS following administration of methamphetamine. When present, concentrations are about one-tenth that of methamphetamine. Amphetamines are weak bases and are subject to ion trapping in OS, providing the advantage of higher concentrations in OS than plasma. For samples collected by expectoration, mean peak OS concentrations after single 10- or 20-mg doses are 106.1 (24.7) μg/L (range 25–312 μg/L) during the period of 4–8 h after dosing and 192.2 (120.8) μg/L (range 75–322) 2–12 h after dosing. The linear correlation between OS and plasma concentrations, although significant, is only 0.222. The median OF/plasma methamphetamine ratio is about 2.0 and is highly variable within and between participants. Methamphetamine was detected in the OS of all study participants for 24 h; amphetamine was detected in only 62.5% (low) and 100% (high) of samples after administration at 8.6 (6.5) μg/L (range 4–21 μg/L) and 14.3 (6.1) μg/L (range 3–20 μg/L). Interestingly, OS is not contaminated by oral administration of this preparation, as noted by a lag time before first drug detection. If methamphetamine was smoked, extensive contamination of the oral cavity would be expected. The OS detection rate at 50 μg/L was only 4% after 10 mg and 28.6% after 20 mg methamphetamine, which are therapeutic doses and quite low compared to abuse doses. Detection times for OS are much shorter than those for urine.

Best wishes,

Ilya

The four know mechanisms whereby a drug could be transferred from the blood into saliva via salivary gland, there is no evidence that pinocytosis plays any role. However, the other three mechanisms are known to be involved.

 DIFFUSION

 The most common route for substances to migrate from blood to saliva is via unaided or passive diffusion. The capillaries surrounding the salivary glands are quite porous for many small molecules. A serum molecule reaching saliva by diffusion must cross 5 barriers: the capillary wall; the interstitial space; the basal cell membrane of the acinus or duct cell; and luminal cell membrane.. The ability of molecule to diffuse passively throught cell membranes depends partly on its size, and partly on the electrical charge that it carries. If a molecule is polar in nature, or if it separates into changed ions while in solution, it will have a hard time passing throught the ductal cell membranes, which are composed a phospholipids. The salivary concentrations of the lipid soluble unconjugated steroids such as cortisol and testosterone approximate the unbound plasma concentration. The concentration of the lipid-insoluble, conjugated steroid dehydroepiandrosterone sulphate is approximately 1% of the unbound plasma concentration.

 ACTIVE TRANSPORT

 An active transport mechanism clearly operates for many electrolytes and for some proteins such as IgA. This mechanism has also been proved for some drugs. Lithium ions would be expected to appear in saliva by ultrafiltration. However, the findings of a S/P ratio of more than two indicates an active secretory mechanism. The polymeric IgA, which is secreted by B-lymphocyte cells in close proximity to salivary cells, is then bound by IgA receptors presented on acinus cells and then gets released into saliva. It has been shown that secretion of IgA is increased by nervous stimulation of the salivary glands, but the exact manner in which the transport is accelerated is not yet understood. 

 ULTRAFILTRATION

 The ultrafiltration is a third means of transportation of molecules from blood stream into saliva, small polar molecules such as glycerol enter into saliva. The transportation of molecules from blood stream into saliva, is filtration through the spaces between acinus and ductal cells. The S/P rations of several small polar, lipid-insolubile compounds are plotted as a function of their molecular weight .

Only molecules that are < 1900Da (such as water, ions, catecholamines and steroids) are transferred throught the ultrafiltration mechanism, and their concentration in saliva are 300 to 3000 times lower than in plasma.