10 years ago the NIMH’s Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) published its findings. This USA-based, public health-focused clinical trial compared the effectiveness of an older, typical and four newer (available since the 1990s), atypical antipsychotic medications in over 1400 people with schizophrenia. Rather surprisingly, the older, typical agent generally performed as well as the newer atypical medications in terms of the length of time patients took a drug before being switched to another therapy - either due to lack of efficacy or intolerable adverse events. This finding, it is claimed, evoked major criticism of pharmaceutical companies, thereby decelerating further research into antipsychotics. And no major changes in prescribing habits ensued. However, that was 10 years ago. Can we still draw the same conclusions regarding atypical antipsychotics today? Sadly, the author of the CATIE study was unable to attend despite his being scheduled. Even so, data presented at CINP 2016 gave food for thought.
Atypicals are not just D2 receptor blockers
What’s the difference between an atypical and a typical antipsychotic? Quite a lot as Herbert Meltzer, USA, explained. Generally, typical antipsychotics are a single class of drugs – D2 receptor blockers - with secondary actions causing dose-related extrapyramidal symptoms (EPS) e.g. parkinsonism and tardive dyskinesia, at clinically effective doses. They act mainly to improve positive symptoms.
Typical antipsychotics are D2 receptor blockers - with secondary actions causing dose-related extrapyramidal symptoms at clinically effective doses
Atypicals – a class or a mixed bunch?
Atypical antipsychotics, on the other hand, cause minimal EPS, but some are associated with prolactin increases at clinically effective doses and some cause weight gain – a serious drawback. Generally, they are a more disparate ‘class’ than the typical antipsychotics but have in common their potent direct and indirect 5-HT2A partial agonistic effects rather than being solely D2 receptor antagonists.
Indeed, studies show atypicals to be multifaceted in their receptor interactions, not solely with different serotonergic but also with muscarinic, nicotinic and other neuroreceptors. Atypicals also influence neurogenesis and synaptic maturation, formation and dissolution. Overall, they are a heterogeneous bunch. Thus, atypicals show multiple actions, some unique, that add to their efficacy as well as to their side-effect profiles. They generally improve positive symptoms, some improve cognition and some reduce suicide risk.
Atypicals show multiple actions, some unique, that add to their efficacy as well as to their side-effect profiles
As Prof Meltzer stated, atypicals have made an outstanding contribution to enhancing our understanding of schizophrenia through identifying new drug targets. The potential for personalized medicine is just coming on line. With all these receptor targets available, shouldn’t we be matching patients to an individual drug?
NeSSy - a tailored approach
And this seems to be precisely what Gerhard Gründer, Germany, has been doing. He described the multicentre, randomized, double-blind Neuroleptic Strategy Study (NeSSy) clinical trial.
Quality of life was statistically and clinically significantly more improved with atypical antipsychotics only when the antipsychotic was tailored for each patient
In this trial quality of life (QoL) was statistically and clinically significantly more improved with atypical compared to typical antipsychotics but only when selection of the antipsychotic was tailored for each specific patient. However, in terms of psychopathology rated by psychiatrists, no significant differences were noted.
So, like CATIE, no benefit in primary outcome was noted in NeSSy. But, unlike CATIE, benefit was seen when atypical agent was matched to patient. Might it be there is something lacking in psychiatric clinical trials?
What’s lacking?
CATIE, despite conforming to accepted best practice, might have yielded some positive benefits for atypicals, compared to typicals, if the heterogeneity of both the study population and each drug’s mechanism of action had been incorporated into its design.
CATIE might have yielded some positive benefits for atypicals, if heterogeneity of population and mechanism of action had been incorporated into its design
Taking the patient’s perspective into consideration when determining study endpoints might also have been beneficial. Considering QoL, social function and patient well-being are meaningful patient-orientated goals. However, Professor Grunder suggested, from the patient’s perspective, studies to investigate the longer term effects of antipsychotic exposure on brain structure should also be considered. Less exposure to drug may in itself be beneficial.
The main references for CATIE and NeSSy are cited below:
Our correspondent’s highlights from the symposium are meant as a fair representation of the scientific content presented. The views and opinions expressed on this page do not necessarily reflect those of Lundbeck.
