To learn about drug elimination, consider Sideshow Bob

Caffeine as a gateway drug, part eight

If you’re new to Lessons on Drugs, welcome! This is post number eight in the Caffeine as a Gateway Drug series, where we explore how drugs work by looking at the world’s favourite drug, caffeine. In this post we’re focusing on how drugs make their way out of the body.

The challenge I’ve set myself is to try and explain how drugs work in enough detail to provide a proper explanation, without requiring people to have a heap of pre-existing knowledge about how the body works, ‘dumbing things down’ and being condescending.

If you want to go back to where it all began, start here: 

What coffee can teach you about how drugs work

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The situation we’re up to is that the caffeine has gotten into the body. It’s now travelling around the body in the bloodstream. This means the drug molecules can go anywhere the blood vessels take them.  

When caffeine molecules make their way to interact with a cell’s receptors, it results in a pharmacological effect. This shows up in the body as things like increased alertness, higher heart rate and more urine being produced. 

But we don’t want the caffeine (or any other drug) to stay in the body forever. The body needs to get rid of it, which we call elimination - our focus for this post.

Before we get stuck into the details, let’s start with a story. 

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Last week I introduced you to my love of early 90s sitcoms. So we’re going to double down on that theme and take a brief look at The Simpsons. 

While The Simpsons may have started on the telly in the late 1980s, my Mum didn’t let us watch it at first. I couldn’t understand why at the time, but now that I’m a parent I’m thinking trying to prevent her own three smart ass kids telling her “don’t have a cow man” and the like might’ve had something to do with it. 

Lucky for me though, the reruns played almost constantly so I soon caught up with what I’d missed once the ban had lifted. Which I don’t think took more than a season or two. 

I’m not trying to portray myself as a Simpsons die hard fan or anything like that. I haven’t watched all 35 seasons. But I sure did watch a lot of it through til the mid 2000s. 

It’s no great surprise that the characters and episodes I enjoyed as a nine year old were a bit different to when I was nineteen and into DeNiro and Kubrick movies. It was around this age the episodes featuring Sideshow Bob became my favourites. 

For the uninitiated, Sideshow Bob is, well…a bit of a psychopath really. He’s ended up in jail more than once due to the actions of Bart Simpson. This gives rise to a recurring vengeance plotline where Bob schemes to murder Bart, which requires him to get out of prison.

There are two main ways Bob escapes prison.  

The first is using the classic power of disguise. Changing his physical appearance. This is the method employed during the Dr Strangelove inspired episode Sideshow Bobs Last Gleaming where he pretends to be a prison guard while on excursion. 

The second method is to use the system to let him out as himself through parole or early release. This is how he gets out in Cape Feare where he pulls off the DeNiro hanging on underside of the moving car trick. 

Well wouldn’t you know it, Caffeine faces the same options when it comes to making it’s way out of the body. There are two main modes of elimination - be physically transformed through the process of metabolism, or exit the body unchanged via the urine. 

In part five, we talked about metabolism which occurs mainly in the liver. Various enzymes change the molecular structure of a drug into different chemical compounds called metabolites.

Caffeine is metabolised by several pathways which results in a variety of metabolites which can themselves be further altered. Some of these metabolites are active, and have drug like actions themselves. Others are merely inactive waste products.

When it comes to caffeine, almost all of it is metabolised before it exits the body. This process of waste products and unchanged drugs leaving the body is called excretion.

The organ with the primary responsibility for excretion is the kidney. Only a small amount of caffeine (less than 5%) makes its way out of the body unchanged. We call this amount the fraction excreted unchanged, and it differs for each drug.

As explained in bodily logistics, the kidneys act as the wastewater management system of the body. They contain tiny units called nephrons that filter the blood to remove waste products.

Other organs also play a supporting role in excretion, depending on the drug. This is why a breathalyser is used to test your alcohol levels - because we get rid of some of the alcohol through the breath. Some drugs and waste products are excreted through other bodily products like sweat, tears, saliva, breastmilk, poo…you get the idea.

The chemical compounds present in the urine and other secretions can change the way they look and smell. Some drugs change the colour - but be aware that pink or red can be a sign of bleeding, so make sure you get that checked out.

The smell of secretions can also become more….distinctive, depending on the chemicals it contains. Coffee is one such substance that can make your pee smell funny, although I don’t think that’s to do with the caffeine as it’s odourless. Caffeine does however, have a bitter taste, so make of that what you will.

Just like if your liver isn’t working well it won’t be able to metabolise drugs as efficiently, the same goes for your kidneys. If they can’t filter the blood efficiently it can result in a build up of waste products in your system. In some cases, this might mean the dose of a particular medicine needs to be reduced, or some drugs might need to be avoided altogether.

The best thing you can do if you’ve got reduced kidney function is to check with your pharmacist to make sure whatever you’re taking is safe for you - and I mean whatever you’re taking. Herbal products, supplements and over the counter medicines can cause just as many problems as prescribed medicines.

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So there you’ve have it - we’ve made it through the entire journey of the coffee through the body, from sip to pee pee! There is one more thing that I want to talk about next week, which might bring the caffeine series to a close - although, I think it’d be nicer to finish on a round number like ten. I’m open to going down some caffeine related rabbit holes if anyone’s got any requests?

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Thanks so much for reading Lessons on Drugs! I hope you found it worth your time.

If you’ve got any general questions, topics you’d like me to cover, thoughts, whatever (well, no abuse please) let me know in the comments. I’m responsive to feedback and it’s nice to know what people find useful or interesting. Giving this post a like is also gratefully received.

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Thanks again, and hope to see you back here next week for more - we’re going to look at drug concentrations in the bloodstream. I know, this sounds intensely dull, but it’s actually super relevant to many people. We’ll talk about things like slow release vs immediate release products, occasional vs regular dosing, missed doses and stuff like that. Making this topic engaging and resisting the math nerd urge to pull out graphs using logarithmic scales is going to be a challenge…but I’m up for it. (Look at me, talking as if I still remember functions and logarithms).