Absorption efficiency and excretion profile of a prolonged‐action form of chlorpromazine

In a rigidly controlled study, equal dosage regimens of chlorpromaZine (CPZ) tablets and sustained release capsules were compared to determine whether one dosage form was more efficient than the other in delivering the drug for absorption. Comparisons were made by determining the levels of CPZ metabolites recovered from the urine of 15 schizophrenic patients taking the two dosage forms in successive courses. Determinations were made at selected intervals during drug administration over an 11 day period and for 2 days after the drug was discontinued. The determinations showed that the two forms are equally efficient, that CPZ is as available for absorption from sustained release capsules as from tablets. They also showed that CPZ from the capsules is absorbed over a longer period than from the tablets. The pattern of urinary recovery from the sustained release capsule paralleled that from the standard tablet regimen. Variation in urinary recovery from subject to subject was no greater with the sustained release capsule than with the standard tablet regimen it is intended to replace.