Week 10 - Chapter 31 Antipsychotic Drugs and Their Use in Schizophrenia Flashcards
Akathisia
Akathisia is characterized by pacing and squirming brought on by an uncontrollable need to be in motion. This profound sense of restlessness can be very disturbing. The syndrome usually develops within the first 2 months of treatment. Like other early EPS, akathisia occurs most frequently with high-potency FGAs.
- -Three types of drugs have been used to suppress symptoms: beta blockers, benzodiazepines, and anticholinergic drugs. Although these drugs can help, reducing antipsychotic dosage or switching to a low-potency FGA may be more effective.
- -It is important to differentiate between akathisia and exacerbation of psychosis. If akathisia were to be confused with anxiety or psychotic agitation, it is likely that antipsychotic dosage would be increased, thereby making akathisia more intense.
Atypical Antipsychotics
a.k.a Second-Generation (Atypical) Antipsychotics (SGA)
The SGAs produce moderate blockade of receptors for dopamine and much stronger blockade of receptors for serotonin. Because dopamine receptor blockade is only moderate, the risk of EPS is lower than with the FGAs. However, although the SGAs carry a reduced risk of EPS, they carry a significant risk of metabolic effects—weight gain, diabetes, and dyslipidemia—that can cause cardiovascular events and early death.
–Furthermore, like the FGAs, the SGAs can cause sedation and orthostatic hypotension, and can increase the risk of death when used to treat dementia-related psychosis in older adults. Finally, even though SGAs have no clear clinical advantage over FGAs, the SGAs cost 10 to 20 times as much.
Butyrophenones
Butyrophenones are 1 of 4 major categories of FGAs. They are the family to which haloperidol belongs. Haloperidol is the prototype of the high-potency FGAs
Cognitive Symptoms
Cognitive symptoms include disordered thinking, reduced ability to focus attention, and prominent learning and memory difficulties. Subtle changes may appear years before symptoms become florid, when thinking and speech may be completely incomprehensible to others. Cognitive symptoms may respond equally to FGAs and SGAs.
Conventional Antipsychotics
a.k.a First-generation antipsychotics (FGAs)
First-generation antipsychotics can be classified as low potency, medium potency, or high potency (Table 31–2). The low-potency drugs, represented by chlorpromazine, and the high-potency drugs, represented by haloperidol, are of particular interest.
- -It is important to note that, although the FGAs differ from one another in potency, they all have the same ability to relieve symptoms of psychosis. Recall that the term potency refers only to the size of the dose needed to elicit a given 320response; potency implies nothing about the maximal effect a drug can produce.
- -Although these agents produce identical antipsychotic effects, they differ significantly in side effects. Hence, by knowing the potency category to which a particular neuroleptic belongs, we can better predict its undesired responses.
Depot Preparation of Drug
Depot antipsychotics are long-acting, injectable formulations used for long-term maintenance therapy of schizophrenia. The objective is to prevent relapse and maintain the highest possible level of functioning. As a rule, the rate of relapse is lower with depot therapy than with oral therapy. Depot preparations are valuable for all patients who need long-term treatment—not just for patients who have difficulty with adherence.
–Following the injection, active drug is slowly absorbed into the blood. Because of this slow, steady absorption, plasma levels remain relatively constant between doses. The dosing interval is 2 to 4 weeks.
Dopamine System Stabilizers (DDS)
A unique class of antipsychotic drugs with the ability to modulate the activity of dopamine receptors—rather than simply cause receptor activation or blockade. At synapses where transmitter concentrations are high, DDSs will compete with the transmitter for receptor binding, and hence will reduce receptor activation. Approved indications are schizophrenia, acute bipolar mania, major depressive disorder, agitation associated with schizophrenia or bipolar mania, and irritability associated with autism spectrum disorder. -Aripiprazole is the most common type of DDS that has a more favorable safety profile than any other SGA, but may be less effective than some.
Dystonia (Acute)
Typically, the patient develops severe spasm of the muscles of the tongue, face, neck, or back. Oculogyric crisis (involuntary upward deviation of the eyes) and opisthotonus (tetanic spasm of the back muscles causing the trunk to arch forward, while the head and lower limbs are thrust backward) may also occur. Severe cramping can cause joint dislocation. Laryngeal dystonia can impair respiration.
Extrapyramidal Symptoms
Three of these reactions—acute dystonia, parkinsonism, and akathisia—occur early in therapy and can be managed with a variety of drugs. The fourth reaction—tardive dyskinesia—occurs late in therapy and has no satisfactory treatment.
–SAFTEY ALERT: For many patients, EPS are uncomfortable, disturbing, and sometimes, dangerous. Some manifestations of EPS, such as tardive dyskinesia, are irreversible. It is crucial for the RN to monitor patients treated with antipsychotic medications for evidence of EPS, and to report this immediately if present.
High-Potency Agents
Compared with the low-potency FGAs, the high-potency FGAs cause more early EPS, but cause less sedation, orthostatic hypotension, and anticholinergic effects. Because they cause fewer side effects, high-potency agents are generally preferred for initial therapy.
Haloperidol is an example of this type of agent.
Low-Potency Agents
The risk of early extrapyramidal reactions (dystonia, akathisia, parkinsonism) is relatively low. However, the risk of TD is the same as with all other FGAs. Chlorpromazine lowers seizure threshold.
Negative Symptoms
- Social withdrawal
- Emotional withdrawal
- Lack of motivation
- Poverty of speech
- Blunted affect
- Poor insight
- Poor judgment
- Poor self-care
Neuroleptic Malignant Syndrome
Neuroleptic malignant syndrome (NMS) is a rare but serious reaction that carries a 4% risk of mortality—down from 30% in the past, thanks to early diagnosis and intervention. Primary symptoms are “lead pipe” rigidity, sudden high fever (temperature may exceed 41°C), sweating, and autonomic instability, manifested as dysrhythmias and fluctuations in blood pressure. Level of consciousness may rise and fall, the patient may appear confused or mute, and seizures or coma may develop. Death can result from respiratory failure, cardiovascular collapse, dysrhythmias, and other causes. NMS is more likely with high-potency FGAs than with low-potency FGAs.
SAFETY ALERT: Neuroleptic malignant syndrome can be fatal if not treated promptly. The RN must recognize the signs and symptoms of NMS and report them immediately. Treatment with dantrolene and bromocriptine may be ordered by the provider.
Parkinsonism
ntipsychotic-induced parkinsonism is characterized by bradykinesia, mask-like facies, drooling, tremor, rigidity, shuffling gait, cogwheeling, and stooped posture. Symptoms develop within the first month of therapy and are indistinguishable from those of idiopathic PD.
Neuroleptics cause parkinsonism by blocking dopamine receptors in the striatum.
–Neuroleptic-induced parkinsonism is treated with some of the drugs used for idiopathic PD. Specifically, centrally acting anticholinergic drugs (eg, benztropine, diphenhydramine) and amantadine [Symmetrel] may be employed. Levodopa and direct dopamine agonists (eg, bromocriptine) should be avoided because these drugs activate dopamine receptors, and might thereby counteract the beneficial effects of antipsychotic treatment.
–Use of antiparkinsonism drugs should not continue indefinitely. Antipsychotic-induced parkinsonism tends to resolve spontaneously, usually within months of its onset.
Phenothiazines
Phenothiazines were the first modern antipsychotic agents. Chlorpromazine, our prototype of the low-potency neuroleptics, belongs to this family.
