Chapter 39: Depression & Bipolar Disorder – Pharmacotherapy

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We are diving deep today into, well, one of the most complex areas in clinical practice.

Pharmacotherapy for mood disorders.

Yeah, the big one.

We're tackling major depressive disorder or MDD and bipolar disorders.

These are conditions defined by these really profound changes in mood,

behavior, and even physical function.

Affects millions globally.

And for those of you listening who are training in advanced practice, our goal today isn't just listing drugs, it's more about building a foundational map, you know, a strategy.

We're really trying to distill the key points on selecting, dosing, and maybe most importantly monitoring these complex agents.

You really have to understand the science behind it.

Because it's often a trade -off, right?

Absolutely.

A constant trade -off between getting the best effect and keeping the patient safe, especially with MDD.

And that tension, efficacy versus safety, that's exactly why MDD is so tricky to manage.

There's no single cause.

It's this complicated mix of things.

Physiological, social, genetic,

biochemical factors too.

And this complexity, it leads directly to that high recurrence rate.

The sources mention that over 80 % of patients who have a second episode, they'll likely have a third.

It's a chronic condition for many.

And to treat it effectively, we need to start with the basics, the neurochemistry.

We still talk about the classic catecholamine hypothesis.

That's the one about deficiencies in serotonin, nor pnephrine, or dopamine.

Right, a functional or maybe absolute deficiency.

But the theory that often guides our initial drug choices more practically is the permissive hypothesis.

Okay.

How does that one work?

It basically suggests that reduced serotonin activity kind of opens the door.

It permits a mood disorder to happen.

And then whether it becomes depression or mania, that might depend on what norepinephrine levels are doing.

Interesting.

So it sets the stage.

Exactly.

And you can see how this immediately points towards our first line treatment strategy.

Okay.

Let's connect those dots.

If serotonin is like the gatekeeper, is that why we usually start with drugs that primarily boost serotonin?

That's precisely it.

You target that permissive mechanism first.

But before we jump into specific drugs, we need to be clear on the goal.

Diagnosis first, obviously.

DSM -5 criteria need at least five symptoms in two weeks, including that depressed mood or anhedonia.

Right, the loss of interest or pleasure.

But once you have the diagnosis, the treatment goal itself has actually changed quite dramatically over the years.

Yes.

And this is such a critical point for AP students.

Historically, the aim was just response, maybe a 50 % symptom reduction, a lower score on the HAM -A scale.

Yeah, just getting them better.

But the modern standard, the real clinical goal now is full remission, complete symptom resolution back to their prior level of functioning, and a HAM -D score of seven or less.

And why push for that higher standard?

Because the data is clear.

Anything less than a full remission means a much higher risk of relapse down the road.

And it impacts their life long term, functionally, economically.

Absolutely.

Achieving remission is really key.

And getting to remission isn't instant.

Non -pharmacologic approaches are still vital.

Things like CBT, cognitive behavioral therapy, and IPT, interpersonal therapy.

Often used alone for milder cases or combined with meds for moderate depression, they're foundational.

But for those really severe treatment -resistant cases,

sometimes you need more intensive options.

And that's where you might consider electroconvulsive therapy, ECT.

It's controversial, sure, mainly because of potential memory loss and confusion.

But for refractory, SED, or severe uncomplicated cases, it's highly effective.

We're talking significant improvement in up to 80 % of patients.

It's a powerful tool in the right context.

So once we do commit to medication, pursuing that full remission means we have to think about treatment in distinct phases.

Yes.

Three mandatory phases.

The first is the acute phase, that's the initial treatment period.

Full effect usually takes four to six weeks, but often you see some improvement within the first two weeks.

And that early improvement is important.

Very important.

It's actually a strong predictor of whether the patient will ultimately reach full remission.

So you watch closely early on.

Phase one, acute.

What's next?

Phase two is the continuation phase.

This lasts for about four to six months after the symptoms have gone away.

The whole point here is preventing relapse.

So keep treating even when they feel better.

Crucial.

And then finally, for higher risk patients, there's the maintenance phase.

This could be long -term, even indefinite therapy.

High risk meaning.

Think patients with three or more prior episodes or maybe two episodes within the last five years.

You want to prevent future occurrences.

Got it.

Okay, let's get into the drugs themselves.

The main idea is boosting neurotransmitters in the synapse, mostly by blocking their reuptake.

Right.

And this brings us straight back to that safety issue we mentioned.

The SSRIs, the selective serotonin reuptake inhibitors, they really change the game.

How so?

Well, they're just as effective as the older drugs like the TCAs.

But the huge clinical advantage is their better tolerability profile and, critically,

much lower lethality and overdose.

That's huge when you're dealing with someone potentially at risk of suicide.

Exactly.

Having that wider safety margin with an SSRI is a major factor in why they became first line.

But they're not without issues.

Side effects are a big reason people stop taking them, right?

Definitely.

The biggest one, adverse drug reaction, or ADR, is sexual dysfunction.

The incidence is really high, potentially up to 73%, and peroxetine is often cited as the worst offender.

That's a tough one for adherence.

It really is.

You also see things like temporary GI upset, maybe some anxiety or insomnia initially.

That's often why we suggest taking them in the morning.

Good tip.

And what about major warnings?

The absolute must -know contraindication is with MAO inhibitors.

Combining them risks serotonin syndrome.

Which is serious.

Life -threatening.

You can see symptoms like extreme high fever, muscle rigidity, almost like heat stroke, potentially leading to vascular collapse.

It's from flooding the system with too much serotonin.

Cannot combine those two classes.

Okay.

Duly noted.

So after SSRIs, we have the SNRIs, the serotonin -norepinephrine reuptake inhibitors.

Right.

These block the reuptake of both serotonin and norepinephrine pretty potently.

Does that offer an advantage?

Some evidence suggests maybe a slight edge in achieving remission, perhaps in more severe or treatment -resistant depression.

That dual action might be beneficial.

But there is a trade -off again, I assume.

Always.

With that extra norepinephrine activity, you tend to see more norachinergic side effects compared to SSRIs.

More dry mouth, more constipation, sometimes more insomnia.

And anything specific to watch out for.

Well, with Ventola vaccine specifically, you need to be aware of dose -related side effects.

Nausea is common, but the big one is treatment -emergent hypertension.

Raising blood pressure.

Yeah.

On average, maybe around a 10 -millimilla -Hg increase.

So you absolutely have to monitor blood pressure, especially at higher doses or in patients with pre -existing hypertension.

That's a significant clinical point, and we should probably mention stopping these drugs too.

Oh, definitely.

Abrupt discontinuation of any antidepressant isn't recommended, but it can be particularly unpleasant with SSRIs, and especially SNRIs like Ventola vaccine, you get this discontinuation syndrome.

Flu -like symptoms?

Dizziness?

Agitation?

Yeah.

It can be quite distressing.

You always need to taper them off slowly.

Okay.

So SSRIs and SNRIs are generally first line due to safety.

What about the older drugs, the tricyclics, the TCAs?

You mentioned they're just as effective.

Why aren't they used as much?

It comes down entirely to that risk profile.

Their efficacy is solid, no doubt.

They inhibit norepinephrine and serotonin reuptake, but the problem is they're not very selective.

Meaning they hit other receptors too.

Exactly.

They also block acetylcholine and histamine receptors pretty strongly, and that leads to that really challenging side effect burden.

Right.

Significant anticholinergic effects, dry mouth, constipation, blurred vision, urinary retention, also heavy sedation from the antihistamine action, which is why they're often dosed at bedtime,

and orthostatic hypotension dizziness when standing up.

That sounds like a lot to manage.

It is, but the most serious concern, the life -threatening one, is cardiac toxicity.

TCAs can cause dangerous cardiac conduction abnormalities like QT prolongation.

And an overdose.

Extremely lethal.

They're pro -rhythmic.

A single prescription, if taken all at once in a suicide attempt, can easily be fatal.

That lack of safety margin is why they're second or third line now.

Right.

A stark contrast to the SSRIs.

And if TCAs are risky, where do the MAOIs fit in?

The monoamine oxidase inhibitors.

They're really the last resort, used only when other options have failed.

Why such caution?

Their mechanism involves non -specifically and irreversibly inhibiting both MAOA and MAOB enzymes.

This increases levels of all the monoamines, norepinephrine, serotonin, and dopamine.

Okay.

And the danger there is?

It's not directly from the drug itself, usually.

It's the mandatory, extremely strict dietary restriction.

Patients absolutely must avoid foods high in tiramine.

Like aged cheeses, cured meats.

Tap beer, certain wines, fava beans.

The list is long.

If they ingest tiramine while on an MAOI, it can trigger a potentially fatal hypertensive crisis.

Blood pressure skyrockets.

Wow.

So adherence is paramount.

Immense.

Which is why MAOIs should really only be prescribed by practitioners with significant experience managing them.

The risks are just too high otherwise.

Makes sense.

Okay.

So we have our main lines.

What about when those don't work well enough or the side effects are intolerable?

That's where the atypicals come in.

Exactly.

They offer different mechanisms or side effect profiles useful as alternatives or for augmentation.

Any key ones to highlight?

Well, a really important one clinically is bupropion, brand name Welbutrin.

It's unique.

It's a relatively weak inhibitor of norepinephrine and dopamine reuptake.

And crucially, it doesn't significantly affect the serotonergic system.

Ah, okay.

So why is that important?

It means it generally doesn't cause the sexual dysfunction that's so common with SSRIs and SNRIs.

So if that's a major issue for a patient or if you want to avoid weight gain, bupropion is often a preferred choice.

That's a great clinical pearl.

Any major warnings with bupropion?

Yes.

The big one is that it lowers the seizure threshold.

This risk increases significantly at doses above 450 mg per day, or if the patient drinks alcohol concurrently.

So definitely contraindicated in patients with seizure disorders or eating disorders like bulimia.

Got it.

What other atypicals are commonly used?

Trazodone is another one.

It's actually a pretty weak antidepressant on its own, but it's highly sedating because of its strong antihistamine properties.

So used for sleep?

Primarily, yeah.

Yeah.

It's often used at lower doses as an add -on therapy specifically for insomnia associated with depression rather than as the main antidepressant.

Okay.

And mirtazapine?

Remeron.

Mirtazapine works differently too.

It's an alpha -2 antagonist.

It also has significant antihistamine H1 blocking activity.

Meaning?

Meaning it causes quite a bit of sedation and notably often stimulates appetite and can lead to weight gain.

Which could be good or bad.

Exactly.

Could be a problem for some patients, but actually quite useful for, say, an underweight elderly patient who isn't eating well and also needs help sleeping.

It targets multiple symptoms.

Interesting profiles.

Are there newer agents coming onto the scene?

Yes.

A couple of novel agents worth mentioning.

Viladadone, brand name Vybrid, is one.

It combines SSRI activity with being a partial agonist at the 5 -HT1A serotonin receptor.

And the thinking behind that combo.

The idea is that this dual mechanism might lead to an earlier onset of antidepressant effect compared to standard SSRIs.

Plus, it seems to have a lower risk of causing sexual dysfunction,

generally considered weight neutral too.

So potential advantages in speed and side effects.

What about for very resistant cases?

That's where esketamine comes in, brand name Spravato.

It's delivered as a nasal spray.

Different mechanism and type.

Completely different.

It's an NMDA receptor antagonist.

It's specifically indicated for treatment -resistant depression, always used in addition to an oral antidepressant.

And what's unique about its effects?

Unlike traditional antidepressants that take weeks to work, esketamine reaches its maximum concentration really quickly, like in 20 to 40 minutes.

The effect can be much more rapid.

Wow.

But there must be safety considerations.

Oh, absolutely.

Because of risks like sedation, dissociation, feeling disconnected, and potential for abuse, it requires a strict REMIS program.

Risk evaluation and mitigation strategy.

Meaning, it can only be administered in a certified health care setting, and the patient must be monitored by a health care provider for at least two hours after each dose.

They can't drive or operate heavy machinery for the rest of the day.

That's a significant commitment for both patient and clinic.

It really is.

It reflects the unique nature and risks of the drug.

Okay, so we have this huge array of options, SSRIs, SNRIs, TCAs, MAOIs, Atypicals, novel agents.

How on earth do we actually choose which one to start with?

That's the core question, isn't it?

Since we've established that, generally speaking, efficacy is pretty similar across the main classes for typical MDD.

It's not about which one works best overall.

Not usually for the initial choice, no.

The selection is almost entirely driven by other factors.

Four main things.

Side effect profile, patient history, what worked or didn't work for them before.

Target symptoms are they anxious, fatigue, having trouble sleeping,

and potential drug interactions with other medications they're taking.

Can you give an example?

Sure.

Like we said, if sexual dysfunction is a major concern, you'd likely avoid SSRIs like paroxetine and lean towards Bpropium.

If weight gain is an issue, you'd probably steer clear of mirtazapine or paroxetine.

If the patient takes other drugs metabolized by, say, the CYP3A4 enzyme, you might avoid paroxetine because it inhibits that enzyme.

It's very individualized.

Matching the drug profile to the patient profile.

Precisely.

And those profiles become even more critical when we consider specific populations.

Right, like older adults.

The iatric patients, yeah.

They're generally much more sensitive to side effects, especially anticholinergic effects, confusion, constipation, and orthostatic hypotension, which increases fall risk.

So what's the rule?

The classic rule is start low, go slow.

You typically initiate dosing at about one -third to one -half the usual adult starting dose and increase it more gradually.

Okay.

What about younger patients?

Children and adolescents?

This is a really sensitive area.

There's the FDA black box warning about an increased risk of suicidal thoughts and behaviors in patients under 25 when starting antidepressants.

That requires very careful monitoring.

Extremely careful.

And it's important to know that only two SSRIs are actually FDA approved for depression in this age group.

Phloxetine for age 8 and up and Cytopram for age 12 and up.

You also have to watch closely for agitation or signs of switching into mania, which can sometimes happen.

And women,

particularly during pregnancy.

That's another complex area.

It's always a risk -benefit discussion.

You have to weigh the potential risks of the medication to the fetus against the very real risks of untreated maternal depression to both the mother and the pregnancy outcome.

Postpartum depression is also incredibly common and needs proactive screening and treatment.

Lots of factors to consider.

Before we switch gears, any key monitoring or education points?

Absolutely, Frischl.

You must educate patients that these drugs don't work overnight.

It typically takes four to six weeks for the full effect, though hopefully they'll feel some improvement sooner.

Manage expectations.

Yes.

And emphasize that they need to keep taking the medication even after they feel better.

That continuation phase is vital.

Also, make sure they know what alarm symptoms to watch for, especially increased suicidal thinking early in treatment, and who to contact immediately if that happens.

Excellent points.

Okay, let's transition now to bipolar disorder, BD.

This is different from MDD, right?

Very different.

BD is characterized by these extreme mood swings, from the lows of major depression to the highs of mania or hypomania.

And there are different types.

Correct.

We mainly categorize it as bipolar 1, which requires at least one full manic episode,

and bipolar 2, which involves at least one major depressive episode, and at least one hypomanic episode, which is less severe than mania.

There's also cyclothymic disorder with chronic milder mood fluctuations.

So how does treatment differ from MDD?

Can we just use antidepressants?

That's the critical difference.

Using antidepressant monotherapy, just an antidepressant by itself, like we do in MDD, is generally not recommended in bipolar disorder.

Why not?

Because it carries a significant risk of actually triggering a manic or hypomanic episode, or causing the illness to cycle more rapidly between highs and lows.

Okay, so if antidepressants alone are risky, what's the cornerstone of BD treatment?

It almost always involves combination therapy, using agents from different classes.

The mainstays are mood stabilizers, traditional anticonvulsants that have mood stabilizing properties, and atypical antipsychotics, AAPs.

Can you give examples of each?

The classic mood stabilizer is lithium.

For anticonvulsants, we commonly use valproate, or valproic acid, or valprox, and lamotrigin.

And for AAPs, drugs like olanzapine, quetapine, risperidone, arepiprazole are frequently used.

Which ones do you typically start with?

Well, lithium has very strong evidence supporting its use, especially for long -term maintenance treatment to prevent both manic and depressive episodes.

It's considered a gold standard by many.

But lithium has challenges, right?

Definitely.

The big thing for students to remember is its narrow therapeutic index.

The difference between a therapeutic dose and a toxic dose is small.

So monitoring is key.

Absolutely essential.

You need to regularly monitor lithium blood levels, usually every few months once stable, to avoid toxicity, which can affect the kidneys, thyroid, and central nervous system.

Okay.

What about the anticonvulsants like valproate?

Valproate is also very effective, particularly for mania and maintenance.

But again, monitoring is crucial.

You need to watch liver function tests, LFTs, because of potential liver toxicity, and also check platelet counts due to risk of thrombocytopenia.

It also carries significant risks in pregnancy.

And lamatrigine?

Lamatrigine is often favored for preventing depressive relapses in bipolar II disorder.

The main safety concern you have to educate patients about and monitor for is the risk, though rare, of a serious rash, including Stevens -Johnson syndrome.

Slow -dose titration is key to minimizing this risk.

Right, that slow start is critical.

And the atypical antipsychotics?

AAPs are very effective for treating acute mania, and some are also approved for bipolar depression and maintenance.

Olanzapine and quetchapine are common examples.

But they have their own side -effect concerns.

Yes, particularly metabolic side -effects.

Significant weight gain, increased risk of diabetes,

elevated cholesterol and triglycerides.

These are major long -term health concerns that have to be monitored closely and weighed against the benefits for mood stabilization.

So it sounds like managing BD often involves complex combinations, like maybe an AAP plus a mood stabilizer or anticonvulsant?

Very often, yes.

Finding the right combination and managing the side -effects and monitoring requirements for multiple agents requires really sophisticated clinical skills.

It's much more complex than treating MDD typically is.

That really paints a picture of the landscape, from basic neurotransmitter theories all the way to these intricate treatment regimens for BD, REMNS programs, intense monitoring.

That's a lot to cover.

Definitely.

So just to quickly synthesize some key clinical pearls for our listeners, remember that safety and overdose is a major reason SSRIs and SNRIs are first line for MDD.

Always keep Bupropion in mind for its unique profile, especially regarding sexual side -effects.

And never ever let patients stop these medications abruptly.

Tapering is essential.

Absolutely.

And for Bipolar Discordor, remember, combination therapy is usually necessary, and monotherapy with antidepressants is generally avoided.

Right.

And meticulous monitoring is part of the package, with agents like Lithium, Valprote, Lamotrigine, and the AAPs.

Okay, so here's a final thought to leave our listeners with, based on our discussion.

We talked about that strong evidence showing improvement by week two of antidepressant therapy is a really good predictor of eventual remission.

Yes, that early signal is quite reliable.

So the question for you to consider is, what implications does this early assessment window have for how you manage patient expectations and, importantly, encourage adherence during that really challenging initial acute phase of treatment when they might not be feeling much better yet?

Something to think about in practice.

A great point to ponder.

A brief recap of key therapeutic takeaways and a warm thank you from the last -minute lecture team.