Mastering Autonomic Drugs

Simon Carver

Hey everyone, welcome back to "Got to be a Nurse, Baby!" I’m Simon Carver, and as usual, I’m here with Lachlan Reed. Today, we’re diving headfirst into drugs that mess with one of our favorite body systems—the autonomic nervous system, or ANS. Buckle up, because this one’s got a few twists and turns.

Lachlan Reed

G’day crew. Now, if you've listened to our neuropharm episode or the last time we talked about nervous system drugs, you'll remember the ANS is this wild web, running the bits of you that pretty much keep themselves ticking—heart rate, digestion, you name it. Most folks don’t even notice it...until things go haywire.

Simon Carver

That’s right. I always think of the ANS like a city’s power grid. You’ve got parasympathetic lines—the “rest and digest” sort—keeping your homes cozy, your streetlights glowing. Then there’s the sympathetic lines, “fight or flight,” that crank up the juice if there’s trouble—like a blackout or a kangaroo stampede. And the drugs we’re talking about today? Well, they’re like reaching straight into the breaker box. Sometimes you’re gently flipping a light switch, sometimes you’re yanking the whole main lever.

Lachlan Reed

I love that, mate. Because the minute you mess with the main switches, you get big changes—sometimes good, sometimes not-so-flash. So the main classes we’re checking out today: cholinergic drugs—which ramp up parasympathetic activity; cholinergic blocking drugs—shut down those same lines; then adrenergic drugs—get your sympathetic system all pumped up; and, of course, adrenergic blockers, which, well, hit the brakes on that system.

Simon Carver

Exactly—so if you’re following along with past episodes, this is a bit of a deeper dive into what we started when we covered autonomic drugs in the “Mastering Nervous System Drugs” episode. But today, we’re not just talking what they do, but the big “how” and “why nurses gotta know this” angles, too.

Lachlan Reed

Yeah, and let’s be real—understanding these drugs means you can spot when things are going sideways before it gets ugly. Like, you don’t need to know every receptor in your sleep, but knowing which direction you’re flipping the switch? Absolutely, that saves lives. Right, let’s kick on and get into how these meds actually work.

Lachlan Reed

Alrighty, let’s start with the cholinergics—the parasympathomimetics, if you wanna get fancy. There are two main kinds: outright agonists like acetylcholine or bethanechol, and then anticholinesterases, which block the enzyme that breaks down acetylcholine—so stuff like neostigmine or donepezil. They basically boost that “rest and digest” vibe everywhere—think slower heart, more saliva, kicking up the gut. Good for stuff like atonic bladder, some GI problems, glaucoma, and yeah, even Alzheimer’s.

Simon Carver

Exactly, and the most common trip-ups with these? The “side effect bundle.” You’ll see folks with nausea, maybe some diarrhea, blurred vision, sometimes bradycardia. As a nurse, man, you gotta watch for those. If you see someone looking green, breathing shallow, heart rate dropping—think about those cholinergics. The anticholinesterases, like donepezil, especially for dementia, can also cause arrhythmias, headaches, even seizures or breathing trouble in higher doses—so don’t just hand them over and walk away.

Lachlan Reed

Yeah, not the sort of med to give and then go for a cuppa! Oh, this takes me back to clinicals—my first time trying to give an albuterol neb, I’ll be straight, I panicked. The patient’s heart rate shot up and I thought, did I break them? But of course—adrenergics! Albuterol mimics the sympathetic drive, so you get a fast heart, shaky hands, sometimes a bit of anxiety. That’s the magic of adrenergics in action.

Simon Carver

That’s the stuff! So, adrenergic drugs split into catecholamines—like epinephrine, dopamine, norepinephrine, dobutamine—and noncatecholamines like phenylephrine or albuterol. Catecholamines are the real “fight-or-flight” superstars: they’ll push up your heart rate, clamp down your blood vessels, open up your lungs. You’ll use them for shock, cardiac arrest, crazy stuff. Noncatecholamines, they do kind of similar things but can be more targeted—phenylephrine for that gnarly nasal congestion, albuterol for asthma. Side effects? Headache, anxiety, arrhythmias, even tissue necrosis if you mess up the IV line with some of these. That’ll stick in your brain.

Lachlan Reed

That’s the one, mate. So always be watching for those side effects. Especially with adrenergics, you want your patient wide awake and not quietly cooking up a cardiac arrhythmia. And, ah, check the compatibilities, by the way—mixing some of these with MAOIs, antidepressants, or even other sympathomimetics can get pretty wild.

Simon Carver

And if you’re thinking, “well that sounds a bit much to keep straight,” you’re not alone. I still scribble reminder notes on my pockets sometimes: “Albuterol = shaky, check pulse!” and “Bethanechol = bathroom trips and blurriness.” But let’s move on to what happens if you throw a wrench in the system—y’know, the blockers. They’re just as important for nurses to master.

Simon Carver

Alright, time to talk about “cutting the wires.” Anticholinergic agents, like atropine and scopolamine, do the opposite of cholinergic drugs. So instead of boosting that rest-and-digest, you’re flipping it down. These are used a lot pre-op to dry up secretions, for certain GI issues, and to fix scary slow hearts—bradycardia. But you’ll see dry mouth, blurred vision, a big jump in heart rate—classic anticholinergic effects, and you know, sometimes patients get so dry they complain their tongue is sticking to their teeth.

Lachlan Reed

Yeah, and those side effects are no joke—tachycardia, decreased sweating, overheating even, so always keep your eyes peeled, especially with older folks or anyone with glaucoma. Oh, and always check for drug interactions—these can go off if given with tricyclic antidepressants, antipsychotics, or even with other anticholinergics. Mixing and matching’s a recipe for disaster, so keep things simple and check the chart.

Simon Carver

Now, adrenergic blockers? Things get interesting. Alpha blockers—like prazosin or phentolamine—are all about relaxing blood vessels, so blood pressure drops. Good for hypertension, peripheral vascular problems, even that rare tumor, pheochromocytoma. Watch for orthostatic hypotension, edema, cardiac arrhythmias... You know, if you stand up and the room starts spinning, think alpha blockers or a dose too high.

Lachlan Reed

And then you’ve got the beta blockers—metoprolol, carvedilol, all that lot. Huge in practice for hypertension, migraines, arrhythmias, angina. They put the brakes on the sympathetic system, but, mate, if you overdo it? You get bradycardia, low blood pressure, sometimes even bronchospasm—so not for your asthmatics. I always tell patients, “Don’t get up too quick, you might feel like you stood up in a wind tunnel or like you’ve had a tussle with a kangaroo and lost.”

Simon Carver

Best analogy yet! Seriously, knowing those reactions, and teaching your patients to track their own symptoms, might be the most important thing you do in a shift. So just picture this: let’s say you’re running from a kangaroo—then suddenly your beta blocker’s doing its thing and you’re so dizzy you can barely move. If you as the nurse haven’t taught that patient, you’re gonna have a rough day. It all comes back to good assessment, patient education, evaluating understanding, and checking for the classic side effects. That’s the real nursing process in all these cases.

Lachlan Reed

Spot on, mate. And before we wrap—remember, your best tool’s always assessment. You look for the good changes and the bad, talk with the patient, explain honestly, and never skip the side effect chat. If you’re not sure, ask someone. Every med can turn a simple fix into a tricky emergency if you’re not paying attention.

Simon Carver

Couldn’t say it better. We’ve covered a lot of ground with the ANS drugs today—agonists, antagonists, blocking and boosting. I hope you feel a little more confident next time you grab the MAR. We’ll be back with another episode soon, so stay curious out there and keep asking those “why” questions—it honestly makes you a better nurse.

Lachlan Reed

Thanks for tuning in, everyone. Simon, always top chatting with you—and you lot listening, don’t forget, teamwork makes the dream work. Keep learning, and we’ll see you next time! See ya, mate.

Simon Carver

Take care, everyone. Good luck on the floor, and we’ll catch you on the next one. Bye now!