Drug Therapy Flashcards
history of drug therapy in schizophrenia
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before antipsychotic drugs were introduced in the 1950s, there was no effective treatment for schizophrenia
the standard treatment for schizophrenia consisted of long stays in psychiatric hospitals
following the discovery of dopamine in 1952, drugs were developed that had a direct effect on the action of this neurotransmitter
some drugs such as amphetamines were found to create schizophrenic symptoms in healthy people
other drugs reduced these symptoms in people with schizophrenia — these drugs became known as antipsychotics and were used in drug therapy
what is drug therapy?
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involves treatment of mental disorders such as schizophrenia using antipsychotics to reduce the symptoms of the disorder
what are antipsychotics?
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antipsychotics = drugs that are effective in treating the most disturbing forms of psychotic illness, such as schizophrenia and manic depression
antipsychotics help the person with the disorder function as well as possible in their life, while at the same time increasing their feelings of subjective well-being
usually recommended as the initial treatment for the symptoms of schizophrenia and after this initial treatment, clinicians tend to use a combination of medication and psychological therapy to manage the disorder
they work by reducing dopaminergic transmission which reduces the action of the neurotransmitter dopamine in areas of the brain associated with the symptoms of schizophrenia
types of antipsychotics
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2 types of antipsychotic; typical antipsychotics + atypical antipsychotics
TYPICAL ANTIPSYCHOTICS are used primarily to combat the positive symptoms of schizophrenia, such as hallucinations and thought disturbances (products of an overactive dopamine system)
example = chlorpromazine
ATYPICAL ANTIPSYCHOTICS also combat the positive symptoms of schizophrenia, but there are also claims that they have some beneficial effects on negative symptoms as well
example = clozapine
key definitions…
• drug therapy
• typical antipsychotics
• atypical antipsychotics
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drug therapy = involves treatment of mental disorders such as schizophrenia using antipsychotics to reduce the symptoms of the disorder
typical antipsychotics = are dopamine antagonists in that they bind to but do not stimulate dopamine receptors, thus reducing the symptoms of schizophrenia
atypical antipsychotics = carry a lower risk of extrapyramidal side-effects, have a beneficial effect on negative symptoms and cognitive impairment and are suitable for treatment resistant patients
how do typical antipsychotics work?
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typical antipsychotics were developed in the 1950s
they reduce the effects of dopamine and so reduce the symptoms of schizophrenia
they are dopamine antagonists in that they bind to but do not stimulate dopamine receptors (particularly the D2 receptors in the mesolimbic dopamine pathway), thus blocking their action
by reducing stimulation of the dopamine system in the mesolimbic pathway, antipsychotic drugs such as chlorpromazine eliminate the hallucinations and delusions experienced by people with schizophrenia
Kapur et al (2000) estimate that between 60% and 75% of D2 receptors in the mesolimbic dopamine pathway must be blocked for these drugs to be effective
how effective are typical antipsychotics?
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hallucinations and delusions usually diminish within a few days of beginning medication
although other symptoms may take several weeks before a significant improvement is noted
the effectiveness of typical antipsychotics in reducing symptoms of schizophrenia led to the development of the dopamine hypothesis of schizophrenia
problems with typical antipsychotics
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Kapur et al (2000) estimate that between 60% and 75% of D2 receptors in the mesolimbic dopamine pathway must be blocked for these drugs to be effective
unfortunately, in order to do this, a similar number of D2 receptors in other areas of the brain must also be blocked
this can lead to undesirable side effects, which illustrates the high cost of using typical antipsychotics to treat schizophrenia
there are several dopamine pathways in the brain and it appears that blocking dopamine receptors in only one of them is useful, but blocking dopamine receptors in the remaining pathways may be harmful
this problem has been addressed by the development of atypical antipsychotics
how do atypical antipsychotics work?
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as with typical antipsychotics, atypical antipsychotics also act on the dopamine system by blocking D2 receptors
however, they only temporarily occupy the D2 receptors and then rapidly dissociate to allow normal dopamine transmission
this rapid dissociation is thought to be responsible for the lower levels of extrapyramidal side effects found with these drugs compared to typical antipsychotics
main differences between atypical and typical antipsychotics
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there are three main differences between atypical antipsychotics and typical antipsychotics, atypical antipsychotics….
1) carry a lower risk of extrapyramidal side effects
2) have a beneficial effect on negative symptoms and cognitive impairment
3) are suitable for treatment resistant patients
because atypical antipsychotics have very little effect on the dopamine systems that control movement, they tend not to cause the movement problems found with typical antipsychotics
rapid dissociation is one feature of atypical antipsychotics that distinguish them from typical antipsychotics, but there are others
typical antipsychotics only block D2 receptors, whereas atypical antipsychotics have a stronger affinity for serotonin receptors (particularly the 5-HT2A receptors) and a lower affinity for D2 receptors
it is this characteristic that explains the different effects of atypical compared to typical antipsychotics
overview of the effects of antipsychotics
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typical antipsychotics have a proven effect on positive symptoms of schizophrenia
but they do not have any effect on negative symptoms or cognitive impairment
atypical antipsychotics also have a proven effect on positive symptoms
as well as a claimed effect on negative symptoms and cognitive impairment — but these claims are less well established
x4 evaluation points for drug therapy
support for the effectiveness of antipsychotics
extrapyramidal side effects
strengths of atypical antipsychotics
drug therapy causes motivational deficits
EVALUATION
support for the effectiveness of antipsychotics
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support for the effectiveness of antipsychotics comes from studies that have compared relapse rates for antipsychotics and placebos
Leucht et al (2012) carried out a meta analysis of 65 studies published between 1959 and 2011, which involved nearly 6000 patients
all patients had been stabilised on either typical or atypical antipsychotics
some of these patients were taken off their antipsychotic medication and given a placebo instead while the remaining patients remained on their regular antipsychotics
within 12 months, 64% of patients who had been given the placebo had relapsed compared to 27% of those who stayed on the antipsychotic drug
this suggests that antipsychotics are effective in treating schizophrenia
EVALUATION
extrapyramidal side effects
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typical antipsychotic drugs can sometimes produce movement problems for the patient
these are called extrapyramidal effects because antipsychotic drugs appear to impact on the extrapyramidal area of the brain, which helps control motor activity
the most common side effects are parkinsonian symptoms that resemble the features of the neurological disorder Parkinson’s disease
more than half of the patients taking typical antipsychotics experience these symptoms
furthermore, when people take antipsychotic drugs for an extended period, a second type of extrapyramidal effect can occur
this is known as tardive dyskinesia, which involves involuntary movements of the tongue, face and jaw
these side-effects can be so distressing for the patient that other drugs have to be given to control them or the patient may stop taking the anti-psychotic medication completely
these problems raise significant ethical issues regarding the use of antipsychotics
critics argue that if side effects, death and psychosocial consequences were taken into account, a cost benefit analysis of the advantages of such medication would most probably be negative
recently, in the US, a large out of court settlement was awarded to a tardive dyskinesia sufferer on the basis of Article 3 of the Human Rights Act 1998 which states that “no one shall be subjected to inhuman or degrading treatment or punishment”
EVALUATION
strengths of atypical antipsychotics
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however, atypical antipsychotics are claimed to have a number of advantages when compared to typical antipsychotics
the key advantage being that they result in fewer side effects
atypical antipsychotics, particularly the more recently developed antipsychotics such as olanzapine are less likely to produce the extrapyramidal effects typically found with typical antipsychotics
therefore, patients are more likely to continue with their medication which in turn means they are more likely to see a reduction in their symptoms
Crossley et al (2010) carried out a meta analysis of 15 studies to examine the effectiveness and side-effects of atypical versus typical antipsychotics in the early phase treatment of schizophrenia
they found no significant differences between atypical and typical drugs in terms of their effect on symptoms, but did note clear differences in the type of side-effects experienced
patients on atypical antipsychotics gained more weight than those on typicals, whereas those on typicals experienced more extrapyramidal side-effects
