Module 3 - Psychopharmacology and Biologic Treatments

Neurotransmitters

Chemical messengers that enable neurons to communicate with each other and other target cells, like muscle and gland cells.

Key neurotransmitters:

• Serotonin - mood, sleep, appetite

• Dopamine - reward, movement, pleasure

• Norepinephrine - alertness, "fight-or-flight“

• Gamma-aminobutyric acid (GABA) - calming the nervous system

Neurotransmitter Inbalances

Imbalances in neurotransmitter levels are associated with various mental health conditions, such as depression, anxiety, schizophrenia, and addiction.

Psychiatric Medications Target

The target for psychiatric medications is predominantly the CNS at the cellular and synaptic levels.

Pharmacodynamics

What a drug does to the body; involves receptor binding, post-receptor effects, and chemical interactions.

Receptors

Proteins that are embedded within the cell membrane and have binding sites for naturally occurring chemicals and drugs.

Agonists

Drugs that act at the receptor sites. When bound to receptors, these chemicals produce the same biological effect as the neurotransmitter itself.

Antagonists

Chemicals blocking the biologic effect at a given receptor.

Inverse Agonist

Chemicals that produce an opposite response to what an endogenous neurotransmitter produces.

Selectivity

The drug’s ability to affect one receptor type over others. The more selective a drug is, the more likely it is to affect only the receptors it is meant to affect.

Specificity

The drug’s ability to affect one receptor subtype over another. For example, a drug may be selective for adrenergic receptors but more specifically affect the beta-1 receptor over other subtypes.

Affinity

The degree of attraction, or strength of the bond, between a drug and its receptor.

Intrinsic Activity

The ability of the drug to produce a biologic response once it binds to a receptor.

Ion Channels

Some drugs act directly on ion channels embedded in the nerve cell membrane.

Medications targeting ion channels are used to treat numerous diseases by either blocking or activating specific channels to modulate cellular function.

Enzymes

Complex proteins that catalyze specific biochemical reactions within cells and are the targets for some drugs used to treat mental disorders.

Carrier Proteins

Neurotransmitters interact with receptors and are then transported back into the neuronal cell by carrier proteins.

A primary action of most antidepressants is to increase the number of neurotransmitters in the synapse by blocking their reuptake.

Efficacy

The ability of a drug to produce a desired response.

Potency

Considers the amount of drug required to produce the desired biological response.

Drug Toxicity

The point at which concentrations of the drug in the body have gone beyond the safe range and may become harmful or poisonous.

Therapeutic Index

A ratio between the median toxic dose and the median effective dose.

A high TI means that there is a large range between the dose at which the drug begins to take effect and the dose that would be toxic to the body.

Pharmacokinetics

How the body affects a substance after administration.

Describes the four stages of absorption, distribution, metabolism, and excretion of drugs.

Absorption

The movement of the drug from the site of administration into the plasma.

Distribution

Reflects how easy it is for a drug to pass out of the systemic circulation and move into other types of tissues, such as the brain, organs, skin, or bone, where target receptors are found.

Metabolism

The process by which the drug is altered, usually by adding to the drug molecule or breaking the drug molecule into smaller pieces.

Most metabolism is carried out in the liver.

Excretion

Elimination of drugs from the body, either unchanged or as metabolites.

Clearance refers to the total volume of blood, serum, or plasma from which a drug is completely removed from the bloodstream per unit of time.

Variations in Drug Effects

Many factors affect drug absorption, distribution, metabolism, and excretion. These factors include age, genetics, and ethnicity.

Initiation Phase

Before beginning to take medications, patients must undergo several assessments:

1. Psychiatric evaluation, including health history and previous medication treatment response.

2. Attitudes toward drug treatments and patient-specific goals.

3. CBC, liver and kidney function tests, electrolyte levels, and ECG.

4. Tools to measure depression and anxiety

5. Current medications

6. Illicit drug use, alcohol, and tobacco use.

Stabilization Phase

The medication dosage is often adjusted to achieve the maximum amount of improvement with a minimum number of side effects.

Nurses must closely monitor temp, BP, pulse, mental status, common side effects, and unusual adverse reactions.

Maintenance Phase

Medications may be continued to prevent relapse or reoccurrence once the individual’s target symptoms have improved.

Reoccurrence refers to an entirely new episode that occurs over time after a full remission was achieved.

Discontinuation Phase

Many psychotropic drugs require a tapered discontinuation.

Tapering involves slowly reducing dosage while monitoring closely for withdrawal symptoms and for the reemergence of key symptoms.

Psychosis

Positive Symptoms

• Excessive distortion of normal function

• Hallucinations (mostly auditory)

• Delusions

• Paranoia

Negative Symptoms

• Decrease or loss of emotional response

• Lack of spontaneous speech

• Flat emotional levels

• Inappropriate social responses

Antipsychotic Medications

Types

• Typical (1st generation): used to treat psychosis

  • Phenothiazines: Chlorpromazine (CPZ), Largactil, and Fluphenazine

  • Non-Phenothiazines: Haldol, Flupentixol, Loxapine

• Atypical (2nd generation): fewer side effects and movement disorders

  • Clozapine (Clozaril), Olanzapine (Zyprexa), Quetiapine (Seroquel), Risperidone (Risperdal)

Medication-Related Movement Disorders

Dystonia: involuntary muscle spasms, abnormal postures

Parkinsonism: rigidity, akinesia (slow movement), tremor, loss of spontaneous movements

Akathisia: inability to sit still, restlessness

Treatment: medications

Tardive Dyskinesia

Irregular, repetitive involuntary movements of the mouth, face and tongue, including chewing, tongue protrusion, lip smacking, puckering of the lips, and rapid eye blinking.

Treatment: irreversible

Neuroleptic Malignant Syndrome (NMS)

A life-threatening reaction to antipsychotic drugs characterized by fever, altered mental status, muscle rigidity, and autonomic dysfunction

Mood Stabilizers

For treating Bipolar I and 2 disorders.

Lithium carbonate: the gold standard for acute mania and maintenance of bipolar disorders.

• Monitor salt intake and dehydration: ↑ sodium intake ↓ level of sodium

Anticonvulsants used when patients have not responded to lithium.

Antidepressants

Selective Serotonin Reuptake Inhibitors (SSRIs)

• Fluoxetine (Prozac)

• Citalopram (Celexa)

• Escitalopram (Lexapro)

• Side Effects: serotonin syndrome

Selective Serotonin-norepinephrine Reuptake Inhibitors (SSNRIs)

• Venlafaxine (Effexor) - also treats panic and social anxiety disorders

• Desvenlafaxine (Pristiq) - also treats panic and social anxiety disorders

• Duloxetine (Cymbalta) - also treats anxiety and certain types of chronic pain

• Side Effects: serotonin syndrome

Tricyclic (TCAs)

• Amitriptyline (Elavil)

• Clomipramine (Anafranil)

• Side Effects: sedation, ortho hypotension, anticholinergic

Monoamine Oxidase Inhibitors (MAOIs)

• Inhibit the enzyme responsible for metabolism of serotonin, dopamine, norepinephrine, and tyramine

• Side Effects: dry mouth, nausea, constipation

Antianxiety and Sedative-Hypnotic Medications

Used for anxiety, not long-term

Benzodiazepines

• Diazepam (Valium)

• Lorazepam (Ativan)

• Alprazolam (Xanax)

Non-Benzodiazepines

• Buspirone (BuSpar)

• Zopiclone (Imovane)

Stimulants

Amphetamines

• Dextroamphetamine (Dexedrine)

• Methylphenidate (Ritalin)

• Pemoline (Cylert)

• Used in treating narcolepsy, ADHD, and obesity

Electroconvulsive Therapy (ECT)

Initiate generalized seizures by an electrical current.

Repeats 2-3x per week

Side Effects: memory loss, hypo- or hypertension, brady- or tachycardia.