In the new drug comment Cariprazine hydrochloride for schizophrenia there is a possible error.1 The comment ‘when deciding which drug to prescribe for controlling acute schizophrenia, it may be a consideration that cariprazine takes five days to reach 90% of its steady-state concentration’ could be misleading. The product information states ‘Cariprazine has two pharmacologically active metabolites with similar activities as cariprazine, desmethyl cariprazine (DCAR) and didesmethyl cariprazine (DDCAR). Total cariprazine (sum of cariprazine + DCAR and DDCAR) exposure approaches 50% of steady state exposure in ~ 1 week of daily dosing while 90% of steady state is achieved in 3 weeks’. While the steady-state concentration of the parent compound may be reached in a week, that of the pharmacologically active metabolites (similar potency to parent compound) will take significantly longer.
Carole Ramsay
Pharmacist, Central Adelaide Local Health Network, SA Pharmacy, Woodville South, SA
