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Routes of drug entry

Created by Carole Yue.

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  • hopper cool style avatar for user ☣Ƹ̵̡Ӝ̵̨̄Ʒ☢ Ŧeaçheя  Simρsoɳ ☢Ƹ̵̡Ӝ̵̨̄Ʒ☣
    With those transdermal delivery systems, can't a lot of different things affect the absorption of the medication? like body temperature, environmental temperature, metabolism, heart rate, even skin conductivity, couldn't they all have radical impacts on the absorption rates of a dermal delivered medication? Thanks! T.S.
    (11 votes)
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    • male robot hal style avatar for user Okilus
      You're right. Some factors are constant enough that do not need to be considered. One of them is the body temperature. Metabolism isn't that different from person to person, and what it mostly affects is how quickly the drug is used, rather than absorbed. But what affects drug delivery through the trans-dermal route the most is skin conductivity. Drugs have different properties. Some are fat soluble, and some are not. Nicotine is water soluble, and that's why when administered in high doses, it can seep through your skin and into the blood stream. Fat soluble drugs do not do as well. That's a huge setback, because trans-dermal delivery is the proffered way of drug delivery in medicine as well. All the doctors will have to do is to give you a stamp, and you'll be set for several doses, as these patches last for a much longer time than a pill does. One solution for this set back is making tiny spikes on the drug patch that scratch their way through the dead layer of your skin, where the drug can be absorbed more easily. If the spikes are just the right size you won't even feel them.
      (5 votes)
  • male robot hal style avatar for user Wudaifu
    How can the intravenous route of drug administration be faster than the inhalation technique, since intravenously injected drugs must return to the right atrium, enter the right ventricle, be pumped to the lungs, and then return to the left atrium and left ventricle before being pumped out through the aorta to the rest of the body, whereas inhaled drugs go directly to the pulmonary system before returning to the left atrium & ventricle to be distributed to the systemic circulation? Inhaled drugs completely bypass the right atrium & right ventricle. I think that inhaled drugs get to your brain quicker than IV drugs.
    (6 votes)
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    • mr pink red style avatar for user doctor_luvtub
      There is some truth to what Tina says, that diffusion slows the effect of the inhalation technique, but far more significant in the arena of drug abuse is the effect of dosage. For most drugs of abuse, it is a lot easier to get a big dose on board by injection, rather than inhalation. Moreover, with injection, all of a given drug dosage gets into the bloodstream, while the lungs are about 1/3 deadspace and a fair proportion of drug that makes it to the alveoli never makes that final diffusive journey into the pulmonary capillaries.
      (6 votes)
  • cacteye purple style avatar for user Esther
    Can someone please explain what an Epi-Pen is? I've seen it a lot but don't really understand it.
    (3 votes)
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    • orange juice squid orange style avatar for user briancsherman
      An Epi-Pen is an injector for the drug epinephrine. Epinephrine is usually injected into a person's muscle. The Epi-Pen contains a set amount of the drug and a spring loaded needle, making it much easier for a person to take the medication than if it was in a traditional needle and syringe.

      Epinephrine is a hormone, also known as adrenaline. It acts as a vasoconstrictor (makes blood vessels smaller), increases blood glucose, and increases blood flow to muscles. It is most commonly used for allergic reactions.
      (6 votes)
  • old spice man blue style avatar for user Clarke
    should a depressed person take drugs ?
    (2 votes)
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  • male robot hal style avatar for user Wudaifu
    How can the intravenous route of drug administration be faster than the inhalation technique, since intravenously injected drugs must return to the right atrium, enter the right ventricle, be pumped to the lungs, and then return to the left atrium and left ventricle before being pumped out through the aorta to the rest of the body, whereas inhaled drugs go directly to the pulmonary system before returning to the left atrium & ventricle to be distributed to the systemic circulation? Inhaled drugs completely bypass the right atrium & right ventricle. I think that inhaled drugs get to your brain quicker than IV drugs.
    (4 votes)
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    • male robot johnny style avatar for user Gyroscope99
      You have to consider the rate of gas exchange occurring in the lungs on the alveolar sacs as well. But I believe that either of these react within seconds as shown in the video so it's very close. It may depend on the chemical structure of the drug, it's solubility, and other factors that affect blood transport.
      (2 votes)
  • duskpin ultimate style avatar for user Adelissa
    Is sublingual application quicker than ingesting?
    (3 votes)
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  • leafers seed style avatar for user allykettering1
    Does intramuscular count as injection as well?
    (2 votes)
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  • primosaur ultimate style avatar for user Rexlito
    Are there patches for other drugs besides nicotine?
    (1 vote)
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    • leafers seedling style avatar for user rgracestewart
      Opiate patches are also available such as Pethidine, however this is a highly addictive drug and is best avoided prescribing to people in the first place. It depends on the properties of the drug whether it can be administered as a patch, such as the molecule size etc
      (4 votes)
  • blobby green style avatar for user Dylan Valenzuela
    For somebody who smokes Marijuana everyday after about a month and a half of being sober from it..would the effect of it be stronger or lighter if the person were to smoke again? I used to smoke and stopped but then smoked again after a month or so and it had no effect..why is that?
    (2 votes)
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  • leafers ultimate style avatar for user Jonas Chromik
    Why are faster routes of administration associated with higher addiction potential? Is it because there is a more obvious connection between substance and effect?
    (1 vote)
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    • duskpin ultimate style avatar for user Betty :)
      I think it's because some routes of administration lead to higher bioavailability. This means that a higher percentage of the drugs eventually end up in your systemic circulation. For example, if you take a tablet orally, and only 50% of it ends up being circulated (the other 50% was broken down by your liver, or on the way there), then it only has a 50% bioavailability compared to if it was injected intravenously, where it would have a 100% bioavailability. Thus, if something has a higher concentration in your system, there's more potential for an addiction to form.
      (1 vote)

Video transcript

Although there are surprisingly high number of ways of getting drugs into your body, called routes of entry, we're just going to talk about some of the most common. So one that might come to mind pretty easily when you think about, maybe hard-core drugs is injection, so we'll talk about that. The other main routes are oral entry and inhalation. Oral entry means that you swallow something, so that could be a pill or some alcohol. Either way you're eating or drinking it. You're ingesting it in some way, and this is one of the slowest routes of entry because it has to go through your gastrointestinal tract in order to get absorbed by your bloodstream, which can take about half an hour, give or take a few minutes. Inhalation, on the other hand, which is when you snort or smoke or breathe in the drugs is actually much faster because once you inhale it, it pretty much goes straight to your brain. It can be there within 10 seconds, and then you start feeling the effects. So this would be, a lot of times, tobacco or cocaine is often snorted. And finally the most direct route is injection. With injection, we're usually talking about intravenous injection, which means it goes right into a blood vein. This begins to take effect within seconds. Intravenous injection can be very dangerous because you're much more likely to inject bacteria or other unexpected toxins along with the drugs, especially if you're using unsterilized paraphernalia. So if someone else has used the needle before you, then this increases the likelihood you'll be exposed to something harmful, such as HIV. OK, so those are the three most common routes of entry and I'm just going to mention two more that are moderately common, transdermal and intramuscular. Transdermal entry means that the drug is absorbed through the skin. This is how patches like the nicotine patch, for example, works. The drug in the patch has to be pretty potent and it can be released into the bloodstream over several hours. Intramuscular entry means that a needle is stuck directly into the muscle, so before we talked about intravenous injection, this is intramuscular. Depending on the chemical properties of the drug, this method can deliver the drugs to your system very quickly or more gradually. One example of a really quick entry for intramuscular injection is when an EpiPen is administered to someone experiencing a severe allergic reaction. So when people have such a reaction, their airway start to close up, so they need to get a dose of epinephrine into their body to open their airways as quickly as possible. If you've ever seen or done this, the needle usually goes into a large muscle in your thigh because studies have shown that to have the most access points to blood vessels, you need to stick it in that particular muscle, so the epinephrine can take effect really quickly. Many vaccines are also administered intramuscularly which is why your arm gets sore after some shots, like the flu shot or something. Now I've been talking about how fast these different drugs take effect based on the route of entry which might be clearly relevant in the case of the EpiPen when you're trying to save someone's life. But another important element connected to the rate of absorption is the potential to produce dependence. People are more likely to become dependent on drugs that take effect more quickly. For example, injected drugs have higher addictive potential than pills.