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Mechanism of Action of Aripiprazole Predicts Clinical Efficacy and a Favourable Side-Effect ProfileSecond Institute of New Drug Discovery, Otsuka Pharmaceutical Co., Ltd, Tokushima, Japant_hirose{at}research.otsuka.co.jp
Second Institute of New Drug Discovery, Otsuka Pharmaceutical Co., Ltd, Tokushima, Japan
Aripiprazole Project, Product Planning and Management Group, Otsuka Pharmaceutical Co., Ltd, Tokyo, Japan
Second Institute of New Drug Discovery, Otsuka Pharmaceutical Co., Ltd, Tokushima, Japan
Palatin Technologies, Cranbury, NJ, USA
Psychiatric Genomics, Inc., Gaithersburg, MD, USA
Nagoya University Graduate School of Medicine, Department of Neuropsychopharmacology and Hospital Pharmacy, Japan The antipsychotic efficacy of aripiprazole is not generally associated with extrapyramidal symptoms, cardiovascular effects, sedation or elevations in serum prolactin that characterize typical or atypical antipsychotics. The aim of this study was to clarify the mechanism of action of aripiprazole that underlies its favourable clinical profiles. The preclinical efficacy and side-effect profiles of aripiprazole were evaluated usingseveral pharmaco-behavioural test systems in mice and rats, both in vivo and ex vivo, and compared with those of other conventional and atypical antipsychotics. Each of the antipsychotics induced catalepsy and inhibited apomorphine-induced stereotypy. The catalepsy liability ratios for these drugs were 6.5 for aripiprazole, 4.7 for both olanzapine and risperidone. The ptosis liability ratios for aripiprazole, olanzapine and risperidone were 14, 7.2 and 3.3, respectively. Aripiprazole slightly increased DOPA accumulation in the forebrain of reserpinised mice, reduced 5-HTP accumulation at the highest dose and exhibited a weaker inhibition of 5-methoxy-N,N-dimethyl-tryptamine-induced head twitches. Aripiprazole did not inhibit physostigmine- or norepinephrine-induced lethality in rats. In conclusion, aripiprazole shows a favourable preclinical efficacy and side-effect profile compared to a typical antipsychotics. This profile may result from its high affinity partialagonist activity at D2 and 5-HT1A receptors and its antagonism of 5-HT2A receptors.
Key Words: aripiprazole efficacy olanzapine risperidone side-effects
Journal of Psychopharmacology, Vol. 18, No. 3,
375-383 (2004) This article has been cited by other articles:
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