chapter 19. mental disorders

8/13/2019 Chapter 19. mental disorders

1/30

Psychiatric-Mental Health Nurses Association

of the Philippines, Inc. (PMHNAP)

Chapter 19

Antidepressant Drugs


2/30

Keltners Psychiatric Nursing Philippine edition

Used in the treatment of depression and other

disorders.

Goals of antidepressant medications are as follows:oAlleviate depressive symptoms

o Restore normal mood

o Prevent recurrence of depression

o Prevent a swing into mania for bipolar patients

Antidepressant Drugs


3/30


Biochemical Theory of Depression

Linking of neurotransmitter depletion to depression.

Synthesizing of agents that would increase the

intrasynaptic availability of certain neurotransmitters,

such as norepinephrine, serotonin, and dopamine. Elevations in these neurotransmitter levels occur

within hours of treatment initiation.

Receptor changes take approximately 2 to 4 weeks

and genetic changes even longer.


4/30


Psychopharmacologic treatment

1. Selective serotonin reuptake inhibitors (SSRIs)

2. Norepinephrine and dopamine reuptake inhibitors

(NDRIs)

3. Selective serotonin-norepinephrine reuptakeinhibitors (SNRIs)

4. Alpha-2 antagonism with 5-HT2and 5-HT3

antagonism

5. Nonselective inhibition of norepinephrine and

serotonin

6. Inhibition of enzymes


5/30


Selective Serotonin Reuptake Inhibitors

Have fewer side effects than TCAs and are far less

dangerous than MAOIs.

The first-line drugs for treatment of depression.

Have fewer anticholinergic, cardiovascular, andsedating side effects.

Risk of suicidal thinking & behavior when prescribed

to children, adolescents, and young adults.

Antidepressant apathy syndrome (AAS)

o lack of motivation, indifference, disinhibition, and poor

attention


6/30


Pharmacologic Effect

The antidepressant effect of SSRIs is thought to be

linked to their inhibition of serotonin reuptake into

neurons.

These drugs do not bind significantly to histaminic,cholinergic, dopaminergic, or adrenergic receptors,

thus reducing many of the side effects that plague

people who are taking TCAs.


7/30


Pharmacokinetics

SSRIs are absorbed in the GI tract. Peak plasma

levels are achieved for most of these drugs between

4 and 6 hours. SSRIs are metabolized in the liver

and have relatively long serum half-lives. The longhalf-lives allow once-daily dosing schedules. Both

fluoxetine and sertraline have active metabolites

that significantly extend their half-lives. Abrupt

cessation is associated with the development of

specific signs and symptoms.


8/30


Side Effects

Have relatively few anticholinergic, antihistaminic, or

antiadrenergic effects; thus, they do not cause the

same intensity of side effects associated with TCAs.

Dry mouth, blurred vision, sedation, andcardiovascular symptoms are not common.

GI symptoms: nausea, diarrhea, loose stools, and

weight loss or gain are relatively common.

Hyponatremia has occurred with these drugs, mostlyin older patients.


9/30


Central nervous system (CNS) effects include

headache, dizziness, tremors, anxiety, insomnia,

decreased libido, impotence, ejaculatory delay, and

decreased orgasm. Anxiety, insomnia, and sexual dysfunction.

o Sexual dysfunction is a major factor in decisions

about compliance. With the increasing incidence of

premature ejaculation, and some SSRIs are used todelay orgasm in these men.

Side Effects


10/30


Interactions

SSRIs interact with several drugs and some of these

interactions are related to SSRI inhibition of the

cytochrome P-450 enzyme system.

Combining SSRIs and MAOIs has proven to befatal. This phenomenon is called serotonin

syndromeor serotonin toxicity.


11/30


Nursing Implications

Therapeutic Versus Toxic Drug Levels

o SSRIs have a low potential for overdose. Toxic

symptoms include nausea, vomiting, tremor,

myoclonus, and irritability.

Use During Pregnancy

o SSRIs are pregnancy category B drugs (meaning that

risks to the fetus have not been established).

Use in Older Adultso SSRIs are safe for use in older adults because of the

good side-effect profile of these drugs.


12/30


Five Important Issues

Related to Antidepressant Use

1. Serotonin syndrome: hyperthermia, rigidity,

cognitive impairments, and autonomic symptoms.

2. Antidepressant apathy syndrome: lost of interest inlife and the events around them.

3. Antidepressant withdrawal syndrome: Abrupt

discontinuation produces withdrawal symptoms.


13/30


4. Antidepressant loss of effectiveness: Sometimes

these drugs just quit working (also known as drug

poop out).

5. Antidepressant-induced suicide: These drugs carry

a black box warning about suicide; particularly in

18- to 24-year-olds early in treatment.

Five Important Issues

Related to Antidepressant Use


14/30


Citalopram

Escitalopram

Fluoxetine

Fluoxetine/Olanzapine

Fluvoxamine

Paroxetine

Sertraline

Selective Serotonin Reuptake Inhibitors


15/30


Novel Antidepressants

Bupropion

Venlafaxine, Desvenlafaxine, Duloxetine

Trazodone

Mirtrazine

Scopolamine


16/30


Pharmacologic Effects

TCAs block the reuptake of norepinephrine and

serotonin, thereby increasing the intrasynaptic levels

and alleviating the symptoms of depression.

TCAs are significantly more effective for severedepression than were SSRIs.

Blocking neurotransmitter reuptake causes greater

neurotransmitter availability and thus prolongs the

stimulating action. A lag period of 2 to 4 weeks before an

antidepressant effect is observed.


17/30


Other Therapeutic Effects

Sedation

Lethargy

Improved appetite

Anxiety reduction Urinary hesitancy


18/30


Pharmacokinetics and Dosing

TCAs are absorbed well from the GI tract and are

usually given orally (PO).

TCAs are metabolized in the liver, and some

metabolites have antidepressant effects. Peak plasma concentrations are reached in 2 to 4

hours; only about 30% to 70% of an oral dose

reaches the bloodstream.


19/30


20/30


Side Effects

Undesirable side effects of both the peripheral

nervous system (PNS) and the CNS.

Tertiary amines have more frequent and more

severe side effects than secondary amines. PNS side effects

oAnticholinergic, cardiac, and antiadrenergic effects.

CNS side effects

o Sedation and cognitive or psychiatric effects

Suicide


21/30


Suicide

A clear association exists between suicide and

depression.

Most individuals who commit suicide are found to

have demonstrated characteristics of depression. However, antidepressants can energize patients

who have been too depressed to act on their

suicidal thoughts.

TCAs are generally highly toxic, which means thatthe actual drug a patient is taking to treat depression

could be used to overdose and die.


22/30


Suicide

TCAs account for slightly less than 10% of all deaths

from intentional drug overdose.

21% of all suicide completers took TCAs, whereas

44% tested positive for novel antidepressants and35% for SSRIs.

Novel antidepressants have a lower potential for

lethal overdose and might be better suited for

actively suicidal patients.


23/30


Interactions

Central Nervous System Depression

o Increased CNS depression might occur when TCAs

are taken with CNS depressants (e.g., alcohol,

benzodiazepines).

Cardiovascular and Hypertensive Effects

o Cardiovascular arrhythmias or hypertension can

occur when sympathomimetic drugs are given with

TCAs.

o Interactants to avoid include norepinephrine,

dopamine, ephedrine, and phenylpropanolamine.


24/30


Interactions

Cardiovascular (continuation)

o Severe MAOI/TCA reactions, includes high fever,

seizures, and a fatal hypertensive crisis, can occur if

combined. MAOIs are not usually prescribed unless

TCAs have failed.

Additive Anticholinergic Effects

oAdditive anticholinergic effects can occur when TCAs

are given with other anticholinergic drugs, including

antipsychotics, antiparkinsonian drugs, and

antihistamines. Older adult patients are especially

susceptible.


25/30


Nursing Implication

Therapeutic versus toxic blood levels

Use during pregnancy

Use in older adults

Side effects Interactions

Teaching patients


26/30


Tricyclic Antidepressants

Amitriptyline

Amoxapine (Asendin)

Desipramine

Imipramine Nortriptyline


27/30


Monoamine Oxidase Inhibitors

Pharmacologic Effects

o Blocks monoamine oxidase, a major enzyme involved

in the metabolic decomposition and inactivation of

norepinephrine, serotonin, and dopamine.

Absorption, Distribution, and Administration

o Well absorbed from the GI tract and are given PO.

o Metabolized in the liver.

o MAOIs do not present the same age-related risksassociated with other drugs.


28/30


Side Effects

Causes CNS, cardiovascular, and anticholinergic

side effects.

Serious life-threatening reactions can occur whenirreversible MAOIs interact with certain drugs or

foods.

Increases the availability of biogenic amines in the

brain; CNS hyperstimulation might occur.



29/30


Drug-Drug Interaction

o Those that cause hypertension

o Those that cause severe anticholinergic responses

o Those that cause profound CNS depression

Food-Drug Interaction

o Tyramine-rich foods



30/30


Nursing Implication

Therapeutic versus toxic drug levels

o Cheeking and hoarding

Use in pregnancy

Use in older adults Side effects

Indications and contraindications

Teaching patients

chapter 19. mental disorders

Documents