Prochlorperazine tablets repackaged into dose administration aids: can the patient be assured of quality?

Patients are increasingly requiring their medications to be repackaged into dose administration aids because of the positive outcomes associated with reduction in medication related hospitalization and adverse effects due to improved medicines management. Since the stability of these repackaged medications is not the responsibility of manufacturer, it is important that drug substances with potential stability issues be identified. Thus the objective of this study was to evaluate the stability of prochlorperazine, a light sensitive drug repackaged into dose administration aids (DAAs), in order to provide guidelines to the pharmacist and advice to the patient on appropriate storage.

Prochlorperazine tablets were stored repackaged in DAAs and in their original packaging for 8 weeks at ambient (25 +/- 1 degrees C; 60 +/- 1.5% RH), accelerated (40 +/- 1 degrees C; 75 +/- 1.5% RH) and in-use conditions encountered in situ both in a pharmacy and the patients' home. They were assessed for both chemical (using a validated HPLC method) and physical stability according to British Pharmacopoeial (BP) standards. In addition, photostability testing was undertaken under ICH conditions.

Chemical and physical stability was confirmed to be within BP Limits. There were, however, noticeable organoleptic changes in the tablets stored under in-use conditions with a progressive grey discolouration over the 8 weeks, starting in week 2.

Despite the confirmation of physical and chemical stability within BP limits, the discoloration and the potential for photodegradants to cause adverse effects in patients must lead us to draw the conclusion that the quality of this medication has been compromised. Pharmacists thus need to take this into account in repackaging and storage of prochlorperazine in DAAs and advise patients to store their DAA protected from light, heat and humidity.