How fast do inhaled drugs reach the brain?

The title says it all really. I have discovered that the time for blood to complete the entire vascular circuit is about a minute. The time for an injection into an arm vein to reach the brain is about 30 seconds. If memory serves, for an injection into a vein to reach the brain, it has to travel to the heart, pass through the lungs, back to the heart, and out the aorta before it can reach the brain, quite a round trip for 30 seconds! So, how long does it take blood to just travel from the lungs to the brain?

(I’m curious to know what’s the minimum time it should have taken for Anya Amasova’s knockout cigarette to have dropped James Bond in The Spy who loved Me.)

I think what you’re looking for isn’t the time it takes blood to reach the brain from the lungs, but the time in which an effective dose of the drug reaches the brain from the lungs. The transport of the drug in the blood to the brain, won’t be the limiting factor, but instead the method delivering the drug to the lungs and its absorption rate across the membranes of the alveoli. IIRC inhalational induction of anaesthesia is much slower than IV induction.

If you take a drag off a cigarette, you can feel the effects in about 5 seconds.

I figured as much, I’ve done my research on chloroform! On the other hand, IV induction using very potent agents such as etomidate or sodium pentothal is more or less governed by the transport rate. So assuming a hideously potent inhaled drug, what is the transport rate from the lungs to the brain?

Which effects? Many (most?) of the physiologic effects of nicotine don’t originate in the brain, but in the end organ. Meaning you’ll feel your heart rate increase when the nicotine gets to the heart not when it gets to the brain.

I thought the brain had to tell the heart to speed up?

To the OP, I’d have to say it depends on the drug. Some kick in before you can breath out, and some take a few minutes to take effect.

ETA: Although that is probably highly dependent on the efficacy of the drug, as stated earlier.

The effects in your head. Have you ever been a smoker? If not, ask a smoker how long it takes from when you take a drag to when you feel it in your head.

Well, that’s an answer! Assuming we’re talking about a drug that affects the brain, the transport time of something that kicks in before you can breath out is a couple of heartbeats or less… or else it works by a different mechanism.

Everything I’ve read about drug addiction and the like has said that inhalation is the fastest way to get something to the brain, because it immediately goes to the heart and up to the brain. But injection is the fastest way to get a large amount of something to the brain, even though it takes a few seconds longer to get there. Which is why lots of addicts prefer the injected route, for the huge “rush” you get when a high dosage of whatever it is hits your brain. You may get the effects faster via inhalation, but they’re smaller effects, since there’s a limited amount of stuff you can absorb through your alveoli at once.

I’ve no experience with inhaling drugs, never having been asthmatic or a smoker, but any time I’ve had IV injected morphine or Demerol in the hospital, it has taken effect within 15-20 seconds.

Ofcourse, absorbtion doesn’t begin at the alveoli. A drug can be absorbed through the mucus membranes too.

I’ve been looking for some info on PET scans that use an inhaled radiolabelled tracer, and how long it takes for the tracer to show up in the brain, but so far I’ve not found anything relevant (other than that this is one of the tests used to determine the pharmacodynamics of a new inhaled drug). Maybe someone with better google-fu will find something.

No, the Autonomic Nervous System acts independently of higher brain functioning most of the time.

You’re going to have to be more specific by what you mean by ‘effects in your head’; this is General Questions. I am NOT a smoker, but I am a physician, so I’m familiar with the anatomy and physiology of the pulmonary, cardiovascular and nervous systems.

Alternatively, if the drug is inhaled through the nose, it may be transported via the olfactory nerve to the olfactory bulb and thence to the brain. IIRC, oxytocin can be administered this way to post-natal women to aid in bonding with their infants and breastfeeding more easily. If administered in this manner, the result would be almost instantaneous.

Good point. But the vast majority of the drug would be absorbed through the alveoli, wouldn’t it?

Waaaaaait a minute. Olfactory nerves respond to chemical stimuli that are then translated into electrical signals that go to the brain. How can the effects of a chemical that works in the brain be transmitted by electrical signals? If oxytocin is administered nasally, I believe it still is being transmitted via the circulatory system. Where’s Doc Quagdop?

It’s hard to be more specific except to say it’s often a mildly euphoric feeling. Or, if you are having a nic-fit, i.e. a craving for a cigarette, the craving starts to fade about 5 seconds after you take a drag.

If you do a google search on “nicotine” “drag” “inhale” “seconds” and “brain,” you can find plenty of articles.

gurgle
gurgle
gurgle
gurgle
pause
pause
cough :o
1 mississippi
2 mississippi
3 mississippi
4 mississippi
5 mississippi
exhale
9 mississippi
10 mississippi
whoa :stuck_out_tongue: :cool:

um…about fifteen seconds. :cool:

I would place money on at least part of that being down to the placebo effect. I know that nicotine is active in incredibly small amounts, but I just don’t see how it can be absorbed, transported and then bound to the receptors in 5 seconds. And I’m a smoker. Smoking has a pschological component, and first puff “euphoria” that you describe may be down to that.

Well, I suppose you could test it with a blind study and nicotine-free cigarettes.

Here’s an article that says Nicotine "provides its user with an almost immediate “kick” of euphoria that is the result rapidly changing brain chemistry beginning within 7 seconds of the first puff on a cigarette. "

I think someone here needs to huff some 1-1-1 tricholroethane*. About two seconds, I reckon, from my ill-spent youth.
*Not genuine advice.

When the IV and inhalation route are just not enough, some addicts have tried injecting directly into the carotid artery, to get the stuff to the brain faster. (ETA: The carotid feeds the brain)

Complications of this route, like stroke and/or death, are rather common.

Also, some have tried direct infusion into the CNS, via catheters placed into the lumbar spinal canal, or even the ventricles of the brain. This too has a certain degree of morbidity about it, if not done by medical professionals. And even then, too.

Too many addicts in such a hurry…