PSYCHOPHARMACOLOGY

Definition

1. Psychopharmacology

- Is the study of the regulation and stabilization of emotions, behavior, and cognition through the interactions of endogenous signaling substances or chemicals in the brain.

2. Pharmacodynamics

- The study of the biochemical and physiologic effects of drugs and the mechanisms by which the effects are produced.

3. Potency

- Refers to the relative dosage of a drug that is required to achieve a desired effect.

4. Clinical efficacy

- Refers to the maximum clinical response achievable by the administration of a specific drug.

5. Tolerance

- Refers to the need for markedly increased amounts of a specific drug overtime to achieve the same desired effect.

6. Pharmacokinetics

- Is the study of movement of drugs absorption, distribution, metabolism and excretion.

7. Peak Plasma Concentration 

- Defined as the greatest accumulation of the drug in the plasma. It varies depending upon the route of administration and rate of absorption of the drug.

8. Half-life

- Refers to the amount of time it takes for metabolism and excretion to reduce the plasma concentration of a specific drug by half.

Factors affecting Pharmacodynamics and Pharmacokinetics

1. Environment - e.g Diet

2. Culture - e.g Values and beliefs

3. Genetic - e.g African American respond better to TCA, Phenothiazines and Anxiolytics than European Americans, European Americans have higher rates of receptor binding for antidepressants, but respond more slowly - require higher doses.

Lastly, Asian respond to lower antidepressant levels.

Principles that guide Pharmacologic treatment

1. A medication is selected based on its effect on the client's target symptoms.

2. Many psychotropic drugs must be given in adequate dosages for a period of time before their full effect is realized.

3. The dosage of medication is often adjusted to the lowest dosage effective for the client

4. As a rule, elderly persons require lower doses of medication to produce the therapeutic effects

5. Psychotropic medications are often decreased gradually rather than abruptly discontinued.

6. Follow-up care is essential to ensure compliance with the medication regimen.

Classes of Neurotransmitters

1. Amino Acids

• Glutamate 

• Aspartate

• Glycine

• GABA

2. A. Catecholamines

• Dopamine

• Epinephrine

• Norepinephrine

B. Indolamines

• Serotonin

3. Soluble Gases

• Nitrite oxide

• Carbon monoxide

4. Acetylcholine

• Acetylcholine

5. Neuropeptide

• Endorphins

• See appendix VI

Neurotransmitters found in the nervous system

Selected neurotransmitters  that can be altered by psychotropic drugs:

• A. DOPAMINE- primarily affected by antipsychotics

• B. SEROTONIN- primarily affected by antidepressants and antipsychotics.

• C. NOREPINEPHRINE- affected by mood-stabilizing agents.

• D. GABA- primarily affected by antianxiety agents

• E. ACETYLCHOLINE- affected by anticholinesterase agents, antipsychotics and antidepressants.

ANTI PSYCHOTROPIC DRUGS

• Also known as Neuroleptics

• Major tranquilizers

• Used primarily to treat symptoms of psychosis such as hallucinations and delusions, used to treat schizophrenia, bipolar, and other psychoses.

• Discovered accidentally around 1950.

• Chlorpromazine considered the first antipsychotic drug. (Keltner 5th ed)

Mechanism of action

- The major action in the N.S is to block the receptors for the neurotransmitter

Dopamine. (Videbeck2001)

2 Types of Antipsychotic drugs

a. Typical Antipsychotic drugs

b. Atypical Antipsychotic drugs

COMMON

Side-Effects:

1. Extrapyramidal Syndrome/Symptoms

Blockade of D2 receptors in the midbrain region is responsible for the development of EPS.

a. Acute dystonia

- Includes acute muscular rigidity and cramping, a stiff or thick tongue with difficulty of swallowing

- Use to occur in the first week of treatment

- Torticollis, opisthotonus, oculogyric crisis 

Treatment:

Anticholinergic drugs: IM Cogentin or IV Benadryl

b. Pseudoparkinsonism

- Symptoms resemble those of Parkinson's disease and include a stiff, stooped posture, mask like face, decreased arm swing, shuffling and festinating gait, cogwheel rigidity, drooling, tremor, bradycardia and pill-rolling movements of thumb

Treatment:

- Changing antipsychotic drug or adding anticholinergic drug such as Amantadine
c. Akathisia

- Reported by the client as an intense need to move

about

- Client appears restless or anxious and agitated, often with rigid posture or gait and a lack of spontaneous gestures 

Treatment:

- Changing the antipsychotic drug or the addition of an oral agent such as beta-blocker, anticholinergic or benzodiazepine

2. Neuroleptic Malignant Syndrome

- Is a potentially fatal, idiosyncratic reaction to an antipsychotic drug

- Major symptoms: rigidity, high fever, autonomic instability, such as unstable BP, diaphoresis and pallor, delirium and elevated levels of enzymes, particularly СРK

- Dehydration, poor nutrition and concurrent medical illness all increase the risk for NMS.

Treatment:

- Immediate discontinuation of antipsychotic drug, supportive medical treatment until stable.

3. Tardive Dyskinesia

- Syndrome of permanent, involuntary movements, is most commonly caused by long-term use of typical antipsychotic drugs.

Symptoms: involuntary movements of the tongue, facial and neck muscles, upper and lower extremities and truncal musculature. Tongue thrusting and protrusion, lip-smacking, blinking, grimacing and other excessive, unnecessary facial movements.

Treatment:

- Irreversible but the progression can be arrested by discontinuing the drug.

4. Anticholinergic side-effects

- Orthostatic hypotension, dry mouth, constipation, urinary hesitance or retention, blurred near vision, dry eyes, photophobia, nasal congestion and decreased memory

- Usually decrease within 3-4 weeks but do not entirely remit.

• Haldol

- Major tranquilizer

Typical antipsychotic drug

- Decreases the positive symptoms of schizophrenia

Nursing Considerations:

- Decreases delusions, hallucinations, looseness of associations

- Best taken after meals; avoid exposure to sunlight

- Causes hypotension

- Haloperidol (Decanoate) long acting type and is given once a month

• Clozaril

Atypical antipsychotic drug

- Decreases the positive and negative symptoms of schizophrenia

Nursing Considerations:

- Decrease apathy, avolition

- Best taken after meals

- Inform client about the weekly blood check for WBC

- Report signs of infection

- Smoking may decrease drug effectiveness

- Rise slowly to avoid dizziness

- Ice chips or sugarless gum may help relieve dry

mouth

- If WBC count drops below 3,500mm, monitor for signs of infection

- If WBC count drops below 2,000mm, place him in isolation precaution

- May cause respiratory arrest

Antidepressant Drugs

• Used primarily in the treatment of major depressive illness, panic disorder and other anxiety disorders, bipolar depression and psychotic depression.

• Interact with the two neurotransmitters:

Norepinephrine and Serotonin that regulate mood, arousal, attention, sensory processing and appetite.

Divided into 4 groups:

• Tricyclic Antidepressants

• Selective Serotonin Reuptake Inhibitors

• Monoamine Oxidase Inhibitor

• Atypical Antidepressants

1. TCA

- The first choice of drug to treat depression.

- Became available in 1950s

- Potentially lethal when taken overdose

- Cause varying degrees of sedation, orthostatic hypotension and anticholinergic side effects

• Cyclic compounds:

1. Imipramine (Tofranil)

2. Amitriptyline (Elavil)

3. Desipramine(Norpramin)

4. Nortriptyline(Pamelor)

5. Doxepin(Sinequan)

6. Trimipramine (Surmontil)

7. Protriptyline (Vivactil)

8. Maprotiline (Ludiomil)

9. Amoxapine (Asendin)

10. Clomipramine (Anafranil)

• Nursing Implications:

- Do not produce euphoria and are not

addicting

- Overdose however is an issue

- The difference between therapeutic dose and lethal dose is small - OP who are at risk for suicide are often restricted to a 7-day supply.

For Overdose:

• Monitor BP, HR and RR

• Maintain patent airway

• ECG is recommended

• Use cathartics or gastric lavage

• Antidote: Physostigmine (Antilirium)

Client Education

• Take drugs exactly as prescribed.

• Be aware that therapeutic effects may not occur for 2-3 weeks after initial therapy

• Avoid taking OTC cold remedies

• Inform other professionals who may be treating you such as dentist or surgeon of the drug therapy

• Report any adverse effects, such as fever, malaise, sore throat, mouth sores, urinary retention, fainting, irregular heartbeat, restlessness, mental confusion, or seizures

2. MAOIs

- Inhibit the enzyme monoamine oxidase, which is responsible for breaking down excess serotonin and norepinephrine at the synapse; when this enzyme is inhibited, the neurotransmitters remain active at the
Synapse.

-Therapeutic effectiveness is reached in 2 to 4 weeks

Contraindications include:

• Cardiovascular disease or history of stroke

• Hyperthyroidism

• Pheochromocytoma

• Elective surgery (MAOls should be discontinued at least 2 weeks before surgery because MAOIs increase the risk of severe hypotension when anesthesia is given).

Common side effects include:

• Anticholinergic effects

• Cardiovascular effects

• CNS stimulation, resulting in anxiety,
  agitation, restlessness and insomnia( clients
  must report this effect because drugs may need to be discontinued).

Serious side effects include:

• Agranulocytosis

• Hepatic toxicity

• Hypertensive crisis, which is associated with tyramine-containing substances.

• Symptoms include severe occipital headache, nausea, vomiting, elevated blood pressure, photophobia, dilated pupils, and arrhythmia.

• Treatment is directed at measures to decrease blood pressure, such as oral administration of nifedipine (procardia) or I.V. phentolamine (Regitine).

SUBSTANCES THAT INTERACT WITH MAOIS 

3. SELECTIVE SEROTONIN REUPTAKE

INHIBITORS (SSRIs)

• SSRIs specifically affect the neurotransmitter serotonin by preventing its reuptake at the synapse.

• Because other neurotransmitters are not affected, these drugs do not have the same side effects as other antipsychotic

Pharmacokinetics

• The serum half-life is 20 to 168 hours; therefore, SSRIs can be given once daily.

• Tolerance does not develop, and these drugs have a low potential for overdose.

• Therapeutic effectiveness occurs in 2 to 4 weeks.

Contraindications

• Hypersensitivity reactions

• Severe Hepatic or Renal Disease

• Seizures

• Diabetes Mellitus9

Interactions

• Additive CNS depressive effects may occur when combining SRIs with alcohol, antihistamines, and opioids.

• Additive serotonergic effects are possible SSRIs are combined with other antidepressants (TCAs, MAOls); allow a 5-week " washout" period when period when switching from an SSRI to a MAOl.

• • SSRIs may increase the risk of toxicity from other drugs (digitoxin, phenytoin, lithium, warfarin).

COMMON SIDE EFFECTS OF SSRI

4. ATYPICAL ANTIDEPRESSANTS

• These drugs do not have a well explained mechanism of action, although they are thought to act similarly to TCAs.

• Their main advantage over TCAs is fewer side effects, particularly fewer
  anticholinergic and cardiovascular effects.

Contraindications and interactions

• Digoxin preparations (use with trazodone increases the risk of digitalis
  toxicity)

• Zyban, a smoking-cessation medication that contains bupropion (combined use can cause seizures)

Common side effects

• a. Seizures, which are associated with bupropion

• Priapism (prolonged painful penile erection), which is associated with trazodone.

Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs)

• A new generation of antidepressants, SNRIs selectively inhibit the reuptake of both serotonin and norepinephrine.

• SNRIs have the same general uses and characteristics as other antidepressants.

Common side effects

• Gl upset,

• dose-related hypertension,

• insomnia,

• restlessness,

• headache, and

• irritability.

• Caution should be used with nefazone (nefazodone) because serious liver failure has been reported; it has been withdrawn from use in Europe.

MOOD STABILIZERS

• Anti manics

          - lithium carbonate

• Anticonvulsants

• carbamazepine

• valproic acid

• gabapentin

• lamotrigine

• oxcarbazepine

• topiramate

Specific uses

• Treatment of the manic cycle of bipolar disorders

• Prevention of recurrent episodes of mania and depression characteristic in bipolar disorder

• Treatment of schizoaffective disorder and episodes of acute hyperactivity associated with other mental 

• Lithium - normalizes reuptake of serotonin, norepinephrine, acetylcholine and dopamine.

• Valproic acid and carbamazepine - stabilizes mood through kindling effect (snow ball like effect that raises the level of threshold to minor manic episodes thus preventing full blown mania)

Toxic Effects

• Severe diarrhea

• Drowsiness

• Muscle weakness

• Lack of coordination

• Coma and death

Management

• Monitor blood levels periodically. Time of last dose must be accurate so that sample for testing is taken 12 hours after last dose

• Take medications with meals to decrease nausea

• Advise patient not to drive until dizziness and drowsiness subsides

• Increase intake of sodium and fluids.

ANTI ANXIETY DRUGS 

Difference between benzodiazepines and nonbenzodiazepines

• Used to treat anxiety and anxiety disorder, insomnia, OCD, depression, PTSD and alcohol withdrawal.

• Mediates the action of GABA ( major inhibitory neurotransmitter)

• Can cause physical dependence, drowsiness, sedation, poor coordination.

Nursing Management

• Advise clients not to drink alcohol because benzodiazepines potentiate its effects.

• Advise clients to be aware of decreased response time, slower reflexes and possible sedative effects.

• Advise not to discontinue the drug abruptly and without medical advice.

STANDARDS OF PSYCHIATRIC MENTAL HEALTH CLINICAL NURSING PRACTICE:

Standard I. Assessment

• The psychiatric-mental health nurse collects health data. 

Standard II. Nursing diagnosis

• The psychiatric-mental health nurse analyzes the data in determining diagnosis.

Standard III. Outcome identification

• The psychiatric-mental health nurse identifies expected outcomes individualized to the client.

Standard IV. Planning

• The psychiatric-mental health nurse develops a plan of care that prescribes interventions to attain expected outcomes.

Standard V. Implementation

• The psychiatric-mental health nurse implements the interventions identified in the plan of care.

(Re- implementation)

Standard VI. Counseling

• The psychiatric-mental health nurse uses counseling interventions to assist clients in improving or regaining their previous coping abilities, fostering mental health, and preventing mental illness and disability.

Standard VII. Milieu Therapy

• The psychiatric-mental health nurse provides structures, and maintains a therapeutic environment in collaboration with the client and other health care practitioners. 

Standar VIII. Self-care Activities

• The psychiatric-mental health nurse structures interventions around the client’s activities of daily living to foster self-care and mental and physical well-being.

Standard IX. Psychobiologic Interventions

• The psychiatric-mental health nurse uses knowledge of psychobiological interventions and applies clinical skills to restore the client’s health and prevent further disability.

Standard X. Health Teaching

• The psychiatric-mental health nurse, through health teaching, assists clients in achieving, satisfying, productive, and healthy patterns of living.

Standard XI. Case Management

• The psychiatric-mental health nurse provides case management to coordinate comprehensive health services and ensure continuity of care.

Standard XII. Health Promotion and Maintenance

• The psychiatric-mental health nurse employs strategies and interventions to promote and maintain mental health and prevent illness.