Chapter 43: Substance Use Disorders IV: Major Drugs of Abuse Other Than Alcohol and Nicotine

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You know, when you think about the human body, it's essentially this massive, highly secured building.

Yeah, that's a good way to look at it.

Right.

There are billions of these intricate locks, which are our receptors, and normally your body only prints the exact physiological keys needed to open very specific doors at very specific times.

Exactly.

Keys to manage pain or to sleep or, you know, to feel rewarded.

Yeah, and it's an incredibly tightly regulated ecosystem.

It is.

Baseline homeostasis entirely depends on those keys staying out of the wrong hands, so to speak.

Right.

But then you introduce exogenous chemicals.

Suddenly, someone has just handed out master keys to a group of reckless joyriders.

Doors are kicked wide open, alarm systems get completely disabled, and the building's normal physiology is just hijacked.

It really is a hostile takeover.

It totally is.

Well, welcome to this deep dive.

If you are a nursing student prepping for exams or clinicals, you are absolutely in the right place.

You really are.

Today, okay, let's unpack this.

We are focusing on Chapter 43 from Lane's Pharmacology for Nursing Care.

We're looking at the major drugs of abuse.

Yeah, excluding alcohol and nicotine, since those usually get their own dedicated chapters.

So we are unpacking how these compounds manipulate the body and, more importantly, the clinical reasoning you need to anticipate the fallout.

Because if you understand the mechanism, you don't just memorize a list of symptoms.

You can actually predict them.

Exactly.

So to really understand that hijacking process, you have to look at how different drug classes target specific vulnerabilities.

Yeah, and Table 43 .1 in the text actually sets this up perfectly.

It categorizes abused drugs into seven main classes.

Right, so that's opioids, psychostimulants, depressants, psychedelics, dissociative drugs, anabolic steroids, and miscellaneous agents.

Exactly.

And we're going to follow the chapter's exact chronological order today.

Let's look at opioids first.

Let's do it.

There's this common stereotype that opioid abuse primarily stems from, like prescriptions gone wrong.

But the data shows most illicit abuse actually begins recreationally.

Oh, really?

Yeah.

That being said, there is a very specific documented vulnerability for health care providers.

Oh, right.

Of course.

Physicians, nurses, pharmacists, they abuse opioids at a noticeably higher rate than other groups with similar education levels.

Which, I mean, that just comes down to proximity, right?

Access creates an occupational hazard.

It really does.

Yeah.

But to understand why opioids are so universally gripping, we have to look at the pharmacokinetics, particularly with heroin.

Right, because heroin is like the perfect example of pharmacokinetics driving addiction.

Exactly.

When it's injected intravenously, its incredibly high lipid solubility allows it to cross the blood -brain barrier almost instantly.

So fast.

Yeah.

The user experiences this intense rush or kick in just like seven to eight seconds.

That is an astonishingly fast onset.

It is.

But the clinical pearl here is that the initial intense rush only lasts about 45 seconds.

Wait, really?

Only 45 seconds?

Yeah, less than a minute.

What users are actually chasing, the primary driver of the abuse, is the prolonged sense of euphoria that settles in afterward.

Ah, okay.

And constantly chasing that euphoria inevitably brings us to tolerance.

Right.

The body adapts to the constant receptor stimulation.

It's kind of like building a callus on your hands from lifting heavy weights.

Eventually, you need a lot more friction to feel anything.

That's a great analogy.

But here is the critical safety question for nursing practice.

If a user's brain builds a massive tolerance to that euphoric high,

are their respiratory centers building that same tolerance?

The pharmacological answer to that is incredibly specific, and it's honestly what makes opioids so dangerous.

Okay, break it down for us.

So, tolerance develops to the euphoria, the nausea, and thankfully to the respiratory depression.

Okay, so they move in tandem.

Right.

As a dependent user takes higher and higher doses to get high,

their baseline for respiratory depression shifts with it.

However, they never develop tolerance to constipation or meiosis.

Wait, never?

Never.

So let me get this straight.

You could have a chronic user taking massive, seemingly lethal doses of an opioid.

Their breathing might remain stable because of that parallel tolerance, but their pupils will still be pinpoint, and their GI tract will be completely paralyzed.

That is the exact clinical picture you'll see.

Wow.

And when that tolerance is breached, or say, an opioid -naive person takes a massive dose, by crushing a controlled release med like OxyContin, the system fails.

You see the classic overdose triad.

That's respiratory depression, coma, and meiosis.

And seeing that triad means you're instantly reaching for naloxone, Narcan.

Absolutely.

It's a pure opioid antagonist.

It rapidly displaces the opioid from the receptors, and it reverses the poisoning.

But the half -life creates a massive nursing implication here.

It really does.

The half -life of naloxone is significantly shorter than the half -life of the opioids it reverses.

Right.

So you give a dose, the patient wakes up, their respiratory drive normalizes, and it looks like a totally successful intervention.

Yeah, but then an hour later, that naloxone metabolizes and clears.

And the offending opioid is still heavily saturated in their system.

Exactly.

So they will slip right back into a fatal overdose.

Nursing management requires anticipating repeated administration of naloxone until the opioid concentrations have naturally dropped.

Which, I mean, that can sometimes take days.

Yeah, it requires intense continuous monitoring.

Okay, so getting a patient through an acute overdose is one hurdle.

But long -term management is an entirely different strategy, right?

Yeah, completely different.

And the text lays this out in Table 43 .2.

We see three main pharmacological approaches for maintenance and suppressive therapy.

Okay, let's go through them.

First is methadone, which is a full opioid agonist.

Right.

Methadone substitutes for the abused opioid to prevent withdrawal and illicit drug seeking.

So it's a controlled replacement.

Exactly.

For suppressive therapy, providers give the patient progressively larger doses until they reach a very high baseline, like around 120 milligrams a day.

Now that's high.

It is.

This builds such a high degree of cross -tolerance that if the patient tries to shoot up street heroin, they won't feel any euphoria at all.

But because methadone is a Schedule II full agonist, administration is strictly limited to approved certified treatment programs.

Got it.

Now, the alternative to that is buprenorphine, which is an agonist antagonist.

Right.

It's a partial agonist at mu receptors and an antagonist at kappa receptors.

So it has a built -in sealing effect for respiratory depression.

Exactly.

It's significantly safer than methadone, which is why trained providers can actually prescribe it in a standard primary care office.

And we frequently see it prescribed as suboxone, right, which is buprenorphine combined with naloxone.

Yes, very common.

Now, wait a minute.

Let me think about the mechanism here.

If you are trying to manage opioid use, putting an antagonist into the very pill you are prescribing seems, I don't know, kind of counterintuitive.

It does sound weird at first.

Unless it's a built -in deterrent.

You hit the nail on the head.

Suboxone is administered sublingually.

If taken correctly, under the tongue, the naloxone basically isn't absorbed well through the oral mucosa.

Okay.

But if a user tries to, say, melt the tablet and inject it intravenously for a rush… Then the naloxone hits the bloodstream instantly at full bioavailability, and it throws the patient into immediate agonizing withdrawal.

Oh, wow.

That is brilliant pharmacological drug design.

It's a booby trap.

It really is.

It's a pharmacological booby trap designed to prevent IV abuse.

Amazing.

Okay, the final long -term option is naltrexone, a pure antagonist.

Right.

But you cannot give that to someone actively dependent, or you'll trigger that exact same severe withdrawal.

So it's used strictly after detox to block the receptor.

Exactly.

If they relapse, they feel nothing.

Plus, it's available as a monthly intramuscular injection called Vivitrol.

Which solves a lot of compliance issues, I'd imagine.

Absolutely.

Before we move away from opioids, though, we really should touch on Kratom.

Oh, yeah.

Kratom.

It's an unscheduled herbal supplement, right?

Yeah.

But its active compounds hit opioid receptors.

At high doses, it causes opioid -like euphoria.

But at low doses, it acts more like a stimulant.

And the concern for nurses is the rising number of fatalities associated with taking Kratom alongside other substances.

Yeah, it's basically an unregulated wild card in the system right now.

Okay.

So we've been discussing drugs that depress the respiratory drive.

Which naturally brings us to general central nervous system depressants.

Specifically, the contrast between barbiturates and benzodiazepines.

Right.

They both slow things down, but the mechanism of danger with barbiturates is just a completely different beast.

What's fascinating here is how the barbiturate trap is a perfect example of a drug outsmarting the body's compensatory mechanisms.

How so?

Well, with opioids, tolerance to the high and tolerance to respiratory depression develop in parallel, right?

Barbiturates like amobarbital, they do not work that way.

Tolerance develops to the subjective intoxicating effects.

But almost zero tolerance develops to the respiratory depression.

Oh, man.

So as the user continuously increases their dose to chase that initial high, they are literally closing the gap between the effective dose and the lethal dose.

Exactly.

The therapeutic index just narrows until it vanishes completely.

It's a legal trap.

It is.

Furthermore, physical dependence on barbiturates creates a withdrawal syndrome that is severe and potentially fatal.

Which is a stark contrast to opioid withdrawal, right?

Because opioid withdrawal is agonizing, but it's rarely life -threatening on its own.

Management for barbiturate withdrawal requires cross -dependence, usually by substituting a long -acting barbiturate like phenobarbital and slowly tapering it.

And we have to highlight a massive safety alert here for the nursing students listening.

Yes, very important.

With opioids, we have naloxone to save the day.

For a barbiturate overdose, there is absolutely no pharmacological antidote.

And at all.

Management is strictly supportive.

You intubate, you ventilate, and you just wait for the drug to clear.

That is terrifying.

The lack of an antidote and that shrinking therapeutic index are exactly why modern medicine largely shifted to benzodiazepines.

They are profoundly safer.

Oh, much suffer.

An oral overdose of a benzodiazepine alone is rarely lethal, provided it isn't mixed with other CNS depressants like alcohol.

And if a severe overdose does happen, we do have a specific antagonist for benzos, right?

They do.

Flumazenil.

But nurses must remember that withdrawal from benzodiazepines requires a very slow, months -long tapering process to prevent severe abstinence syndrome.

Okay.

Let's flip the switch.

We've seen what happens when the central nervous system is suppressed.

What happens when it's pushed into absolute overdrive?

You mean the psychostimulants?

Yes.

Cocaine, methamphetamine, and synthetic cacanones.

So, cocaine functions primarily by blocking the reuptake of dopamine.

This leaves a massive surplus in the brain's reward circuit, which triggers intense euphoria.

But the clinical presentation varies wildly based on the rod of administration, right?

It does.

Like, crack cocaine is the base form.

It's heat stable, so it's smote.

Absorption through the pulmonary bed is so rapid that the high hits almost instantly, kind of mimicking an IV injection.

Right.

And then you have cocaine hydrochloride, the powder form.

It's heat unstable, so it's snorted.

And we know chronic snorting leads to atrophy of the nasal mucosa and septal necrosis.

Yes.

The necrosis occurs because cocaine is a very potent local vasoconstrictor.

Okay.

Repeated intranasal use clamps down the mucosal blood vessels so aggressively that the tissue is literally starved of oxygen.

It's local ischemia leading to tissue death.

Wow.

And systemic toxicity is basically that local effect just amplified across the entire body.

Exactly.

And overdose is a catastrophic cardiovascular crisis.

You'll see severe hypertension, ventricular arrhythmias, hemorrhagic stroke, hyperpyrexia.

So nursing interventions focus on managing those symptoms.

You give IV diazepam for seizures and anxiety and IV nitroproside for severe hypertension.

But let's look at the arrhythmias and the tachycardia for a second.

If a patient's heart is racing dangerously out of control, a standard clinical reflex might be to push a beta blocker.

Mm -hmm.

But that's contraindicated here, isn't it?

It is severely contraindicated.

Giving a beta blocker during cocaine toxicity can actually be fatal.

Wait, why?

Because cocaine stimulates both alpha and beta -adrenergic receptors.

If you administer a beta blocker, you antagonize the beta -2 receptors, which are responsible for coronary vasodilation.

Oh, I see where this is going.

Yeah.

That leaves the alpha -1 receptors completely unopposed.

You get massive unchecked vasoconstriction in the coronary arteries.

Which effectively chokes off blood flow to the heart and precipitates a massive myocardial infarction.

Exactly.

Unopposed alpha stimulation.

Do not give beta blockers for cocaine toxicity.

Do not give beta blockers.

That is a clinical reasoning pearl that absolutely saves lives.

For sure.

Okay, let's look at methamphetamine.

It shares the stimulant profile, but its mechanism is slightly different, right?

It is.

Methamphetamine primarily forces the active release of norepinephrine and dopamine from the nerve terminals, rather than just blocking their reuptake.

And the adverse effects are just devastating.

Very much so.

It induces a psychosis that is clinically indistinguishable from paranoid schizophrenia.

Wow.

It physically damages dopaminergic nerve terminals, which result in long -term cognitive deficits.

And then there's the notorious meth mouth.

Right.

Rampant tooth decay driven by a combination of drug -induced serostomia or dry mouth, bruxism, and poor hygiene.

Exactly.

And unlike opioid or alcohol use disorder, pharmacological treatments for meth addiction really haven't proven highly effective yet.

So recovery relies heavily on cognitive behavioral therapy, specifically structured programs like the Matrix model.

Yes.

We should also briefly mention synthetic cathinones.

The so -called bath salts.

Right.

They share structural similarities with amphetamines, but induce just horrific adverse effects.

Profound paranoia, severe agitation, hallucinations, and delirium.

Okay.

So stimulants hijack the dopamine and norepinephrine pathways.

But our next agent acts on a completely unique endogenous reward system in the brain.

Right.

Marijuana.

The pharmacology of marijuana is deeply fascinating because the psychoactive component, THC, doesn't just bump into random receptors.

It binds to specific cannabinoid receptors.

Yes.

And the body actually synthesizes its own natural ligand for these exact receptors.

It's called anandamide.

Right.

So THC essentially mimics anandamide, binding to receptors heavily concentrated in brain regions governing pleasure, memory, appetite, and sensory perception.

Exactly.

Here's where it gets really interesting, though.

The pharmacokinetics completely dictate the user experience, especially regarding the route of administration.

I always think of oral marijuana like edibles as a delayed fuse.

That's a perfect way to put it.

Because when marijuana is smoked, the pulmonary absorption is rapid.

It delivers about 60 % of the THC directly into the bloodstream, peaking in 10 to 20 minutes.

Right.

But oral ingestion is a totally different pathway.

Practically all of it is absorbed by the gut, but then it immediately routes straight to the liver.

That extensive hepatic first -pass metabolism is crucial to understand.

It really is.

The liver inactivates the vast majority of the THC before it ever reaches systemic circulation.

Wow.

Consequently, an oral dose must be 3 to 10 times greater than a smoke dose to achieve a comparable effect.

And the onset is severely delayed, right?

Yeah.

Sometimes taking over an hour to manifest, and the effects can last up to 12 hours.

This pharmacokinetic profile perfectly explains why oral users frequently overdose.

They consume it, feel absolutely nothing after 30 minutes, assume the dose was too low, and then consume more.

Exactly.

It's a classic trap.

Marijuana is also pharmacologically unique, because it produces a triad of subjective effects not seen together in other psychoactive drugs.

Euphoria, sedation, and hallucinations.

Right.

But chronic use isn't without clinical consequence.

There's amyotivational syndrome,

characterized by apathy, poor grooming, and dullness.

And then there's a highly paradoxical condition, cannabinoid hyperemesis syndrome, or CHS.

This one is so wild.

We typically utilize cannabinoids as anti -medics, right?

Right.

Yet CHS presents as cyclic, intractable nausea and vomiting in chronic users.

And the diagnostic presentation is incredibly distinct.

These patients will take repeated, scalding hot showers or baths.

Yes, because the extreme heat provides the only temporary relief from the cyclic vomiting.

It's so bizarre.

But outside of recreational use, the clinical applications of purified cannabinoids are well established.

Box 43 .1 and table 43 .3 go into this.

Right.

We have Drawn Avenal, an approved synthetic THC used to suppress emesis in chemotherapy patients and stimulate appetite in AIDS patients.

We also have Epidiolex, which is a CBD -based liquid formulated specifically for severe pediatric seizure disorders like Lennox -Gastaut and Dravet syndromes.

But administering medical marijuana or CBD requires intense vigilance regarding drug interactions.

This is so important.

THC and CBD are potent inhibitors of the CYP450 liver enzymes.

Specifically, the CYP2C9 and CYP3A4 pathways.

This is where the clinical reasoning really comes into play for a nurse.

If a patient is taking warfarin and they begin utilizing marijuana, the cannabinoids inhibit the liver's ability to metabolize that blood thinner.

Exactly.

The warfarin accumulates in the blood, driving up the INR, and drastically increasing the patient's risk of a severe hemorrhagic event.

You have to monitor those enzyme pathways.

Absolutely.

Okay, let's move from cannabis to drugs that fundamentally distort reality.

Psychedelics and dissociative drugs.

Right.

Drugs that mimic dream states while the patient remains fully conscious.

The prototype psychedelic is LSD, which primarily activates serotonin 2 receptors in the brain.

And what sets LSD apart is its physiological footprint.

Yeah.

It induces massive rapid tolerance.

Dosing just three days in a row renders the drug essentially inert.

Wow.

Yet despite this rapid tolerance, it produces zero physical dependence and absolutely no withdrawal syndrome upon cessation.

Okay, so if there is no physical toxicity, the primary danger is entirely psychological.

So a patient arriving in the ER experiencing a bad trip,

severe panic, the terrifying sensation that their identity is just disintegrating, that requires specific management.

How does a nurse handle that?

The frontline intervention is psychological.

You're talking down the patient, providing continuous emotional support in a quiet, low -stimulus environment.

And pharmacologically.

An anxiolytic like the azepam can be administered to calm severe panic.

But you must avoid neuroleptics.

So no antipsychotics.

Exactly.

Administering an antipsychotic like haloperidol can paradoxically intensify the panic and make the hallucinatory experience even worse.

You also have to assess for HPPD, right?

Hallucinogen Persisting Perception Disorder.

Yes.

That's where users experience episodic visual flashbacks long after the drug is metabolized,

pointing to persistent alterations in the visual pathways.

Okay, let's pivot to the dissociative drugs.

Originally developed as surgical anesthetics, we're looking at PCP, ketamine, and dextromethorphan.

Yeah, that last one always catches people off guard.

Dextromethorphan is the standard ingredient in over -the -counter cough syrup.

Wait, cough syrup is in the same category as PCP.

It is.

At therapeutic doses, it functions safely as a cost -suppressant.

However, when ingested at five to ten times the normal dose, it metabolizes into a compound called dextromethorphan.

Dextromethorphan acts by blocking NMDA glutamate receptors in the brain, which is the exact same mechanism of action utilized by PCP and ketamine.

So at massive doses, individuals experience euphoria, disorientation, and hallucinations that closely mirror a PCP trip.

Exactly.

And the toxicity profile of PCP itself is basically a nightmare scenario in the ER.

High doses trigger acute psychosis, severe hypertension, and a muscular rigidity so profound that it induces severe hyperthermia and rhabdomyolysis.

Right.

And the muscle breakdown from that rhabdo can rapidly destroy renal function.

So what's the treatment?

To treat this specific toxicity, alongside supportive care and diazepam procedures, we administer dantrolene.

Ah, dantrolene.

Yes, it's a direct acting muscle relaxant.

By suppressing the severe muscle contractions, dantrolene mitigates the massive heat generation and halts the progression of the rhabdomyolysis.

OK, that dual action brings us to a drug that bridges multiple categories we've talked about.

MDMA or ecstasy?

Right.

It possesses both the stimulant properties of an amphetamine and the psychedelic properties of mescaline.

So if we connect this to the bigger picture, how does that work pharmacologically?

The mechanism of MDMA really explains the profound neurological danger.

It blocks the reuptake of serotonin, but it simultaneously forces the rapid release of massive stores of serotonin, dopamine, and norepinephrine.

Wow.

It just floods the system.

Yeah.

It floods the synaptic cleft to create feelings of profound empathy and sensory enhancement.

But the physiological toll is severe.

Evidence indicates that MDMA can irreversibly destroy serotonergic neurons, doesn't it?

Irreversible neuronal destruction.

Yes.

And given serotonin's critical role in memory consolidation, users frequently suffer from permanent memory impairment long after they stop using.

Exactly.

And because of its amphetamine -like properties,

MDMA toxicity presents with the exact same severe hyperthermia and rhabdomyolysis we just saw with PCP.

Right.

So the specific pharmacological intervention to halt the heat generation and muscle breakdown is, again, dantrolene.

Spot on.

Dantrolene.

Okay.

Let's close out with our final category,

inhalants.

They fall into three distinct classes,

starting with anesthetics like nitrous oxide, which behave pharmacologically much like alcohol.

And the second class?

The second class consists of volatile nitrites, commonly referred to as poppers, like amylnitrite.

Okay.

And what do they do?

Nitrites are unique because they induce massive venodilation,

blood pools in the venous system, causing a profound drop in blood pressure.

Oh, wow.

But their specific toxicity is mythmoglobinemia.

That's a condition where the hemoglobin in the blood loses its ability to release oxygen to the tissues.

That sounds incredibly dangerous.

It is.

If this occurs, the specific pharmacological antidote is methylene blue, administered alongside supplemental oxygen.

Methylene blue.

Got it.

The final class comprises organic solvents, right?

Tullowine, paint thinner, model airplane glue?

Yes.

These are particularly devastating because they are disproportionately abused by young children lacking access to other substances.

That's heartbreaking.

What's the acute danger with solvents?

Sudden death from fatal cardiac arrhythmias.

And there are no antidotes.

None.

None.

Management is entirely supportive, focusing on stabilizing vital signs and respiratory function.

Well, we have covered a massive spectrum of pharmacology today, moving through the precise mechanisms these compounds use to manipulate physiological systems.

It's a lot of information.

But understanding those mechanisms is what allows you to anticipate the crisis before it happens.

Exactly.

But I want to leave you with a provocative thought that builds on everything we've just discussed today.

Okay, let's hear it.

We spent this entire time categorizing these drugs by their traditional mechanisms, right?

How they lock into existing serotonin, dopamine, or opioid pathways.

But what happens when artificial intelligence accelerates the design of entirely novel synthetic molecules?

We could soon see designer drugs that bypass these classic receptor pathways entirely, creating new mechanisms of intoxication that literally defy our current pharmacological categories and render our standard antidotes useless.

Oh, wow.

That is a sobering reality.

Right.

The landscape of toxicology might be on the verge of a massive, unpredictable evolution.

As the chemical landscape shifts,

a solid foundation in core physiological principles will be the only way to recognize and treat those novel toxicities.

Exactly why diving deep into the why is so crucial.

Well, thank you so much for tuning in and studying with us today.

On behalf of the Deep Dive and the Last Minute Lecture team, we wish you the absolute best of luck on your nursing exams and in your clinical practice.

Until next time.