Three Routes of Molecular Hydrogen into the Body: Drinking, Inhalation and Bathing Are Not the Same

The H₂ molecule does not change. What does change is where it first encounters the body, the route by which it reaches the circulation, the speed of distribution and the duration of exposure.

Hydrogen water can be consumed.

Molecular hydrogen can be inhaled.

Or the body can be immersed in water containing dissolved H₂.

Chemically, all three approaches involve exactly the same molecule.

H₂.

Biologically, however, they are not equivalent.

Why?

Because the body never responds only to the name of a molecule.

It responds to:

site of entry → concentration gradient → time → distribution → tissue environment → elimination

And this is where the real physiology of molecular hydrogen begins.

The most important principle first

Molecular hydrogen is not a conventional nutrient stored in the body.

Nor is it transported by a specialised carrier in the same way oxygen is transported by haemoglobin.

H₂ is an extremely small, electrically neutral gas that dissolves in biological fluids and can move between compartments according to differences in partial pressure and concentration.

During inhalation, blood flow carries dissolved H₂ through the circulation while the molecule simultaneously diffuses from blood into tissues. Experimental pharmacokinetic studies describe this as a combination of circulatory transport and diffusion.

That means two processes matter at the same time:

diffusion

and

perfusion.

H₂ can cross biological membranes readily.

But where it goes in the body — and how quickly it gets there — is also influenced by tissue blood flow.

Experimental studies indeed show that both the time required to approach equilibrium and the concentration of H₂ differ between organs.

Four stages that determine H₂ exposure

Regardless of the route used, the journey of molecular hydrogen can be divided into four basic stages.

1. Entry

Where does H₂ first meet the biological environment?

• gastrointestinal tract,
• alveoli,
• skin.

2. Absorption

How does it cross from the external environment into the body?

The concentration or partial-pressure gradient and the characteristics of the biological barrier are central.

3. Distribution

How does H₂ move further through the body?

Part of this movement occurs through diffusion, and part through circulation.

4. Elimination

H₂ does not accumulate in the body like a conventional storage molecule.

One important elimination route is the lungs, which is visible in the rapid changes in exhaled H₂ after consumption of hydrogen-rich water.

This framework:

entry → absorption → distribution → elimination

is more informative than simply asking:

“How many ppm does the device produce?”

1. Hydrogen water: through the gastrointestinal tract and portal circulation

When hydrogen-rich water is consumed, the journey of H₂ begins in the gastrointestinal tract.

Molecular hydrogen is physically dissolved in the water.

After drinking, it can diffuse across the gastrointestinal mucosa into the blood.

And this is where an important anatomical difference from inhalation appears.

Blood draining much of the gastrointestinal tract does not immediately enter the systemic arterial circulation.

It first passes through:

portal circulation → liver.

This means the oral route can create a different map of the body’s first exposure to H₂ than inhalation does.

What do human kinetic data show?

One of the classic human studies monitored H₂ in exhaled breath after hydrogen-rich water was consumed.

Exhaled H₂ increased rapidly.

The peak occurred approximately:

10 to 15 minutes after drinking.

Levels then declined quickly.

In another study involving seven adults, exhaled H₂ also peaked after approximately 10 minutes and returned close to baseline within about 60 minutes.

The authors estimated that approximately 59% of the ingested H₂ was subsequently exhaled.

That number should not be treated as a universal constant for every person or every form of hydrogen water.

It came from a small experimental study, and the result depends on factors such as:

• the amount of H₂ ingested,
• water volume,
• the measurement method,
• ventilation,
• individual physiology.

Even so, it demonstrates one principle particularly well:

drinking hydrogen water creates a rapid and transient exposure.

What happens between the intestine and systemic circulation?

Detailed sampling of H₂ from multiple blood vessels is obviously difficult to perform in healthy people.

A substantial part of precise pharmacokinetic knowledge therefore comes from animal models.

One particularly informative study from Keio University examined H₂ after hydrogen-rich fluid was administered directly into the small intestine of pigs.

The investigators measured H₂ simultaneously in:

• the jejunal vein,
• the portal vein,
• the inferior vena cava,
• the carotid artery.

After administration, H₂ rose markedly first in blood draining the intestine and subsequently in portal blood.

In that experiment, H₂ was not detected in the carotid artery.

The authors therefore proposed that substantial loss or processing may have occurred during passage through the liver and subsequently the lungs.

This is important — but it must be interpreted correctly.

It does not mean:

hydrogen water cannot produce systemic biological effects.

It means:

the oral route can create pronounced portal exposure, and its pharmacokinetics are not identical to inhalation.

For that reason, drinking and inhalation cannot be treated as biologically interchangeable simply because both ultimately involve H₂.

Portal exposure may matter in its own right

The gastrointestinal tract and liver are not merely pipes H₂ must pass through before it can “reach the body”.

They are part of the body.

If H₂ is absorbed and passes first through portal circulation and the liver, the result is a regionally different exposure profile.

That is an important concept.

With oral administration, biological relevance may not depend only on:

how much H₂ eventually appears in arterial blood.

It may also depend on:

which tissues were exposed before that point.

The exact significance of this portal exposure in humans, however, has not yet been sufficiently characterised.

2. H₂ inhalation: the alveoli as a direct gateway into circulation

Inhalation follows a completely different route.

H₂ enters the alveolar space of the lungs.

A difference in partial pressure develops between:

alveolar gas

and

blood in the pulmonary capillaries.

Molecular H₂ can then dissolve into the blood and be distributed through the arterial circulation.

This is a substantially more direct systemic route than oral exposure through portal circulation.

FiH₂ → partial pressure → dissolved H₂ in blood

This relationship was described with particular clarity in 2026 by LeBaron, Ohno, Salomez-Ihl, Sano, Kheir and colleagues in Respiratory Research.

The authors proposed that hydrogen inhalation should be described using:

FiH₂

fraction of inspired hydrogen

— the fraction of H₂ in the gas that actually reaches the person’s inspired airflow.

Not merely the gas composition generated by the device.

Not merely ml/min.

According to their physiological model, FiH₂ determines the inspired partial pressure of H₂, which in turn influences the equilibrium concentration of dissolved H₂ in plasma and tissues according to Henry’s law.

This gives a clean physical sequence:

FiH₂
↓
alveolar H₂ partial pressure
↓
dissolved H₂ in blood
↓
distribution to tissues

Henry’s law explains concentration. Fick’s law helps explain rate.

With gases, two separate questions must be distinguished.

How much H₂ can dissolve?

This is related to gas partial pressure and Henry’s law.

How quickly does the system approach equilibrium?

Here, factors such as the following become important:

• pressure gradient,
• ventilation,
• gas exchange,
• cardiac output,
• tissue perfusion,
• diffusion distance.

The 2026 modelling paper notes that available human data show blood H₂ concentrations approaching a plateau during controlled inhalation over approximately 20 minutes.

That means:

concentration influences the level of the exposure environment; time determines how long it persists and whether the system has time to approach equilibrium.

Human measurements confirm rapid entry and rapid decline

In a small study of patients with acute cerebral ischaemia, inhalation of 3–4% H₂ increased hydrogen concentration in both arterial and venous blood, with levels approaching a plateau after approximately 20 minutes.

After inhalation ended, arterial H₂ concentrations fell very quickly — to less than 10% of the preceding level within approximately 6 to 8 minutes.

Venous concentrations declined more slowly and fell below 10% of the plateau after approximately 18 minutes.

The sample size was small.

But the kinetic pattern is clear:

rapid entry → distribution → rapid washout after exposure stops.

H₂ does not behave in blood like oxygen

Oxygen has a highly specialised transport system.

Most O₂ is carried bound to haemoglobin.

Molecular H₂ does not have an equivalent mechanism.

Experimental pharmacokinetic studies show that H₂ is present dissolved in plasma and travels with blood flow while simultaneously diffusing into tissues according to concentration gradients.

That distinction matters.

H₂ is not:

“loaded onto the blood and delivered to a target.”

It is better understood as part of a dynamic equilibrium between gas, blood and tissues.

Not all tissues reach the same concentration at the same speed

Experimental measurements of H₂ directly inside tissues show that distribution is not instantly homogeneous.

In a study using continuous 3% H₂ inhalation in rats, researchers monitored H₂ concentrations directly in:

• brain,
• liver,
• kidneys,
• adipose tissue,
• skeletal muscle.

Different tissues showed different rates of increase and different achieved concentrations.

Skeletal muscle, for example, reached saturation more slowly than several more highly perfused organs.

Other real-time experiments have likewise shown that tissue distribution depends on both the tissue involved and the inhalation conditions.

For humans, this does not justify creating a ranking of organs.

It supports a more important principle:

the same inspired H₂ concentration does not mean that every tissue reaches the same H₂ concentration at the same time.

3. Hydrogen bathing: the route through the skin

From a pharmacokinetic perspective, hydrogen bathing remains the largest unknown.

With this route, H₂ does not enter:

• through the intestine,
• or through the alveoli.

Instead, it creates an interface between:

water containing dissolved H₂ ↔ skin surface

If the concentration of H₂ in the water is higher than in the skin and underlying tissues, a concentration gradient develops.

From a physical perspective, transdermal movement of H₂ is therefore plausible.

The central question, however, is:

During a real bath, can enough H₂ pass through the skin to reach deeper tissues and circulation?

In 2023, an important direct experimental result was published

A study in hairless minipigs — whose skin is used in some contexts as a model with similarities to human skin — monitored H₂ concentration directly in the blood during hydrogen bathing.

During bathing in water containing a high concentration of dissolved H₂, hydrogen levels in the inferior vena cava began rising within 2 minutes.

Levels continued to rise at 10 minutes and reached approximately 45.7 ppb at 20 minutes in that experiment.

During the control bath without H₂, hydrogen remained below the detection limit.

This is an important finding.

It provides direct experimental evidence that H₂ can pass from bath water through the skin and reach the circulation.

But:

the experiment involved only two minipigs.

It cannot therefore be converted automatically into a precise human dosing protocol.

What we still do not know in humans

Human studies of hydrogen bathing do exist.

Some have reported changes in biological markers or physiological outcomes. Others have failed to identify differences in the outcomes studied.

What is still missing are robust human pharmacokinetic studies that repeatedly and simultaneously measure:

• H₂ concentration in bath water,
• H₂ concentration in skin,
• H₂ concentration in venous and arterial blood,
• the time course after the bath ends.

So today we can reasonably say:

Transdermal H₂ entry is supported experimentally.

What we cannot yet say reliably is:

What systemic exposure is created in humans by a specific bath, concentration and duration.

That distinction is essential.

Bath temperature can change more than H₂ exposure

Hydrogen bathing introduces another complication.

Temperature affects:

• skin perfusion,
• thermoregulation,
• vascular responses,
• fluid redistribution,
• and the physical behaviour of dissolved gases in water.

A hydrogen bath therefore cannot be understood simply as:

“skin + H₂”.

The real system is:

H₂ + water + temperature + time + contact area + skin perfusion + H₂ loss from the water

That is why bathing is pharmacokinetically the most complex of the three routes.

Three entry points — three different exposure maps

	Hydrogen water	H₂ inhalation	Hydrogen bath
First biological barrier	gastrointestinal mucosa	alveolar-capillary membrane	skin
First important circulatory compartment	portal circulation	pulmonary → arterial circulation	local cutaneous/subcutaneous circulation, then venous circulation
Exposure profile	brief, pulsed	continuous during inhalation	continuous during contact with water
What determines entry	H₂ concentration in water, volume, speed of consumption	FiH₂, partial pressure, ventilation, time	H₂ concentration in water, gradient, skin, perfusion, time
Strongest pharmacokinetic evidence	human exhaled H₂ + experimental portal circulation	human blood measurements + experimental tissue distribution	direct transdermal evidence currently mainly from experimental models
Main unresolved question	precise systemic distribution in humans	optimal FiH₂ and exposure time	precise systemic dose in humans

This table does not indicate which route is “stronger”. It shows that each route begins in a different biological compartment and creates a different spatial and temporal H₂ exposure profile.

The same total amount of H₂ does not necessarily mean the same biological exposure

Imagine, hypothetically, the same total amount of molecular hydrogen.

One portion is consumed in water.

Another is inhaled.

A third is present in bath water.

Even if the “total amount of H₂” could be precisely quantified for all three routes, the biological situation would still not be the same.

Why?

Because:

drinking may emphasise early exposure of the gastrointestinal tract, portal circulation and liver;

inhalation produces direct pulmonary-to-arterial systemic exposure;

bathing begins locally at the water–skin interface and may subsequently create transdermal transfer.

With H₂, it is therefore incomplete to ask only:

how much?

We must also ask:

where, how and for how long?

Concentration × time creates an exposure profile

In many areas of pharmacology and physiology, exposure is understood through a:

concentration–time profile.

This is a useful way to think about H₂ as well.

A short, higher exposure is not automatically equivalent to:

a longer, lower exposure.

And it is even less accurate to assume that the same technical number on a device means the same concentration in a target tissue.

With inhalation, FiH₂ makes this particularly clear.

With hydrogen water, rapid increases and decreases in exhaled H₂ demonstrate the same principle.

With bathing, pharmacokinetic mapping is only beginning to develop.

What does it mean to say that “H₂ stays in the body”?

This wording is common, but potentially misleading.

Molecular hydrogen does not behave as a storage compound.

After exposure ends, concentrations decline.

After hydrogen water is consumed, exhaled H₂ returned close to baseline within approximately an hour in a small human study.

After inhalation stops, arterial H₂ concentrations fall even faster.

Experimental studies also indicate that H₂ may leave some tissues more slowly than it leaves arterial blood, meaning that a blood concentration measured in one location does not necessarily reveal what is happening in all tissues at the same moment.

A more accurate description is therefore:

H₂ has a dynamic tissue distribution and is progressively eliminated after exposure ends.

Not:

“Hydrogen stays in the body for X hours.”

Where does H₂ eventually go?

The lungs are one of the main routes of elimination.

This becomes particularly clear after hydrogen-rich water is consumed, when H₂ appears in exhaled breath shortly after drinking.

In one small mass-balance study, the authors estimated that approximately 59% of ingested H₂ was subsequently exhaled, while only around 0.1% was released through the skin.

They described the remainder as hydrogen “consumed” within the body.

That final category, however, requires considerable caution.

It does not mean that we know precisely:

• what every H₂ molecule reacted with,
• in which tissue,
• through which mechanism,
• or that the entire unaccounted fraction represents one specific biological reaction.

More recent work continues to highlight uncertainty about the exact metabolic fate of molecular hydrogen.

Brief molecular presence does not necessarily mean a brief biological consequence

This raises an important question.

If H₂ is eliminated relatively quickly, how can some experimental studies observe biological changes later?

The answer is not yet fully resolved.

A biological signal does not have to last exactly as long as the physical presence of the molecule that initiated it.

This is common in physiology:

a brief stimulus can initiate a longer-lasting cellular response.

With H₂, researchers are investigating possible relationships with:

• redox signalling,
• mitochondrial processes,
• gene regulation,
• inflammatory pathways,
• oxidised lipid mediators.

The precise primary mechanism, however, remains under investigation, and this article deliberately does not confuse pharmacokinetics with mechanism.

Recent reviews from 2025–2026 continue to emphasise that important questions remain open regarding both the mechanism and metabolic behaviour of H₂.

Pharmacokinetics is not efficacy

This distinction is essential.

Demonstrating that H₂:

• entered the blood,
• reached a tissue,
• or remained measurable for a particular period

does not automatically demonstrate a clinical effect.

Pharmacokinetics asks:

What happens to the molecule in the body?

Efficacy asks a different question:

Does that exposure produce a meaningful biological or clinical outcome?

These questions must be investigated separately.

Confusing them is one of the most common problems in molecular hydrogen marketing.

Technical number → exposure → biological response

At least three levels exist between a specification on a device and a biological result.

LEVEL 1 — TECHNOLOGY

What does the device create?

For example:

• ppm H₂ in water,
• ml/min of gas,
• H₂ concentration in bath water.

LEVEL 2 — EXPOSURE

What actually reaches the person?

For example:

• H₂ concentration in the water at the moment it is consumed,
• FiH₂ at the airway,
• H₂ concentration at the water–skin interface during bathing.

LEVEL 3 — BIOLOGICAL RESPONSE

What subsequently occurs in:

• blood,
• tissues,
• cells,
• signalling pathways.

These levels cannot be treated as interchangeable.

Therefore:

a higher technical specification does not automatically mean a greater biological response.

The TANVEA Hydrogen Systems™ framework

For molecular hydrogen, it is therefore more useful to use the following framework:

SOURCE → EXPOSURE → DISTRIBUTION → RESPONSE

SOURCE

What does the technology produce?

EXPOSURE

What actually comes into contact with the body?

DISTRIBUTION

Where does H₂ go, by what route and over what time?

RESPONSE

What does the body subsequently do?

This framework separates:

technology from physiology

and

physiology from biological outcome.

That distinction is essential if we want to understand molecular hydrogen properly.

What we know with the greatest confidence today

We know:

H₂ is rapidly absorbed after hydrogen-rich water is consumed and appears in exhaled breath.

We know that experimental oral administration can create pronounced H₂ exposure in portal circulation.

We know that inhaled H₂ crosses the lungs into blood and can be measured directly in human arterial and venous blood.

We know that during inhalation, the actual inspired fraction — FiH₂ — is more physiologically meaningful than the generator’s ml/min output alone.

We know that, experimentally, H₂ distributes into different organs at different rates.

We also know that H₂ can pass transdermally from hydrogen-rich bath water into the circulation in a minipig model.

What we still do not know well enough

We cannot yet define one universal:

• optimal concentration,
• optimal exposure duration,
• optimal frequency

for every route and every individual.

We do not have enough high-quality human pharmacokinetic data for hydrogen bathing.

We do not have enough direct head-to-head pharmacokinetic studies comparing:

water vs inhalation vs bathing

under equivalent conditions.

And we still do not fully understand which molecular mechanisms explain biological responses observed after measurable H₂ concentrations have already fallen substantially.

The latest scientific work therefore continues to call for better standardisation of delivery, improved exposure measurement and stronger pharmacokinetic and clinical studies.

The central idea

Hydrogen water, inhalation and hydrogen bathing are not three versions of the same delivery method.

They are three different gateways into the body.

Hydrogen water:

intestine → portal circulation → liver → further distribution

Inhalation:

alveoli → blood → arterial circulation → tissues

Hydrogen bath:

water → skin → local tissues → circulation

The molecule is the same.

But:

the timing, site of first contact, concentration gradient and route of distribution are not.

That is why the quality of molecular hydrogen exposure cannot be reduced to one number.

Not ppm.

Not ml/min.

Not bath-water concentration.

Biological reality depends on the entire chain:

SOURCE → EXPOSURE → DISTRIBUTION → RESPONSE

That is the difference between being able to produce H₂ and understanding how the body actually encounters it.

WHAT IS IMPORTANT TO UNDERSTAND

This article describes the pharmacokinetics and physiology of molecular hydrogen, not treatment protocols.

Demonstrating H₂ absorption or distribution does not by itself demonstrate clinical efficacy.

Results from animal studies cannot automatically be transferred to humans, and findings from one exposure route cannot automatically be extrapolated to another.

TANVEA Hydrogen Systems™ therefore distinguish between:

device performance, actual exposure, pharmacokinetics and biological response.

Only by understanding these together can molecular hydrogen be evaluated scientifically.

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How does molecular hydrogen from hydrogen water enter the body?

After consumption, H₂ is dissolved in the fluid within the gastrointestinal tract and can diffuse across the mucosa into the blood.

Experimental pharmacokinetic studies show a marked rise in H₂ in veins draining the small intestine and subsequently in portal circulation toward the liver. Human studies also show a rapid increase in exhaled H₂ after drinking hydrogen-rich water.

How does H₂ enter the blood during inhalation?

H₂ enters the alveolar space of the lungs.

The difference in partial pressure between the alveoli and blood enables H₂ to dissolve in plasma and subsequently distribute through the arterial circulation.

During controlled inhalation, H₂ concentration can be measured directly in human arterial and venous blood.

 

Why is ml/min alone not enough when evaluating a hydrogen inhalation system?

Because ml/min describes the output of the device.

It does not automatically describe the fraction of H₂ in the gas the person actually inhales.

That fraction is also influenced by ventilation, inspiratory flow, the delivery interface and dilution with ambient air.

For this reason, the parameter FiH₂ — fraction of inspired hydrogen has been proposed.

 

Does H₂ from a hydrogen bath pass through the skin?

Direct experimental evidence from a hairless minipig model shows that H₂ in hydrogen-rich bath water can cross the skin and increase blood H₂ concentrations, while levels remained below detection during control bathing without H₂.

The precise pharmacokinetics of this route in humans, however, remain insufficiently characterised.

Does molecular hydrogen remain in the body for a long time?

Not as a storage molecule.

After exposure ends, H₂ concentrations decline rapidly, and a substantial proportion of molecular hydrogen is eliminated through exhalation. After drinking hydrogen-rich water, exhaled H₂ returned close to baseline within approximately 60 minutes in a small human study. After inhalation ends, arterial concentrations decline even faster.

The rapid disappearance of the molecule itself, however, does not mean that any biological response initiated by the exposure must stop at the same moment. Experimental research indicates that H₂ may influence mitochondrial, redox and other cellular regulatory mechanisms whose downstream effects may continue after measurable H₂ concentrations have fallen.

The duration, significance and precise mechanisms of such downstream responses in humans have not yet been sufficiently characterised. It is therefore more accurate to speak of a possible longer-lasting biological response following a brief H₂ exposure, rather than saying that hydrogen itself “remains in the body”.

Is inhalation automatically more effective because H₂ enters the bloodstream directly?

No.

Faster or more direct systemic pharmacokinetics does not by itself prove greater biological or clinical efficacy.

Such a claim would require high-quality direct comparative studies between routes of administration.

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SCIENTIFIC FOUNDATION & SELECTED LITERATURE

LeBaron T.W., Ohno K., Salomez-Ihl C. et al.
Respiratory-physiology modeling of therapeutic hydrogen inhalation: defining the fraction of inspired hydrogen (FiH₂) and flow-rate requirements.
Respiratory Research. 2026;27:259.
DOI: 10.1186/s12931-026-03664-9.
Key current paper on FiH₂, partial pressure, Henry’s law and physiological interpretation of inhaled H₂.

Nguyen Puente B., Habet V., Wheeler C.R., Kheir J.N.
Emerging Clinical Applications for Molecular Hydrogen.
Respiratory Care. 2026;71(3):328–338.
DOI: 10.1177/19433654251398759.
Current clinical review of inhaled H₂ and remaining standardisation challenges.

Johnsen H.M., Hiorth M., Klaveness J.
Molecular Hydrogen Therapy—A Review on Clinical Studies and Outcomes.
Molecules. 2023;28(23):7785.
DOI: 10.3390/molecules28237785.

Shimouchi A. et al.
Breath hydrogen produced by ingestion of commercial hydrogen water and milk.
Biomarker Insights. 2009;4:27–32.
DOI: 10.4137/BMI.S2209.

Shimouchi A., Nose K., Shirai M., Kondo T.
Estimation of Molecular Hydrogen Consumption in the Human Whole Body After the Ingestion of Hydrogen-Rich Water.
Advances in Experimental Medicine and Biology. 2012;737:245–250.
DOI: 10.1007/978-1-4614-1566-4_36.

Ichihara G. et al.
Pharmacokinetics of hydrogen after ingesting a hydrogen-rich solution: A study in pigs.
Heliyon. 2021;7:e08359.
DOI: 10.1016/j.heliyon.2021.e08359.

Sano M. et al.
Pharmacokinetics of a single inhalation of hydrogen gas in pigs.
PLOS ONE. 2020;15:e0234626.
DOI: 10.1371/journal.pone.0234626.

Ono H. et al.
A basic study on molecular hydrogen (H₂) inhalation in acute cerebral ischemia patients for safety check with physiological parameters and measurement of blood H₂ level.
Medical Gas Research. 2012.

Yamamoto R. et al.
Hydrogen gas distribution in organs after inhalation: Real-time monitoring of tissue hydrogen concentration in rat.
Scientific Reports. 2019.

Liu C. et al.
Estimation of the hydrogen concentration in rat tissue using an airtight tube following the administration of hydrogen via various routes.
Scientific Reports. 2014;4:5485.
DOI: 10.1038/srep05485.

Iwai S. et al.
Direct evidence of hydrogen absorption from the skin – a pig study.
Archives of Medical Science – Civilization Diseases. 2023;8:9–17.
DOI: 10.5114/amscd.2023.129194.

Li J. et al.
Advances in hydrogen delivery strategies for therapeutic applications.
Advanced Drug Delivery Reviews. 2026;228:115734.
DOI: 10.1016/j.addr.2025.115734.

Status quo, challenges and future directions of hydrogen medicine.
Fundamental Research. 2026;6(2):1242–1246.

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FINAL NOTE

TANVEA Library content is educational in nature. It does not replace medical diagnosis, treatment or individual advice from a qualified healthcare professional. Pharmacokinetic findings from animal studies cannot automatically be transferred to humans, nor can findings from one device, concentration or route of exposure automatically be applied to another.