ABSTRACT Objective: To reduce the cost of the IV additive program at the institution of one of the authors, the Pharmacy Department began to dispense IV medications in syringes. To facilitate this program it was of interest to determine the stability of a dolasetron myselate solution that was half the concentration (10 mg/mL) of the commercially available product (Anzemet, Hoechst Marion Roussel, Montreal, Quebec); the more dilute solution was to be repackaged and stored in 3-mL polypropylene syringes. Methods: On study day zero, dolasetron mesylate for injection 20 mg/mL was diluted with an equal volume of either 0.9% sodium chloride (normal saline; NS) or 5% dextrose in water (D5W). Aliquots were drawn into 3-mL polypropylene syringes, which were stored in a refrigerator (at 4°C) or at room temperature (23°C). On study days 0, 2, 3, 6, 8, 10, 14, 16, 21, 23, 29, and 31, the concentration of dolasetron was determined (by means of a validated reverse-phase stability-indicating liquid chromatographic method with ultraviolet detection at 230 nm), a physical inspection was completed, and the pH was measured. Results: During the study period, all samples retained at least 96.1% of the initial dolasetron concentration. There was no significant effect of time, temperature, or solvent on dolasetron stability. No degradation products were revealed by inspection of chromatograms obtained during the stability study. All solutions were initially clear and colourless and remained so for the duration of the study. There was no significant change in pH over the study period. Conclusions: Solutions of dolasetron mesylate 10 mg/mL prepared in NS or D5W and stored in polypropylene syringes at 4°C or 23°C retained more than 96% of their initial concentration during 31 days of storage. RESUME Objectif : Afin de reduire le cout du programme d’additifs aux solutes de l’etablissement auquel un des auteurs est rattache, le departement de pharmacie a commence a distribuer des medicaments intraveineux dans des seringues. Pour faciliter ce programme, on a juge pertinent de determiner la stabilite des solutions de mesylate de dolasetron preparees a une concentration deux fois moindre (10 mg/mL) que celle du produit disponible dans le commerce (Anzemet, Hoechst Marion Roussel Canada Inc., Montreal (Quebec)); les solutions ainsi diluees etaient reconditionnees dans des seringues de 3 mL en polypropylene. Methodes: Au jour 0 de l’etude, le dolasetron pour injection a 20 mg/mL a ete dilue dans un volume egal de chlorure de sodium a 0,9 % (NS) ou de solution aqueuse de dextrose a 5 % (D5W) ; les aliquots ont ete aspires dans les seringues de 3 mL en polypropylene, qui ont ete conservees dans un refrigerateur (a 4 °C) ou entreposees a la temperature ambiante (23 °C). Aux jours 0, 2, 3, 6, 8, 10, 14, 16, 21, 23, 29 et 31, on a determine la concentration de dolasetron (au moyen d’une epreuve de stabilite par chromatographie liquide en phase inverse avec detection UV a 230 nm), effectue une inspection visuelle et mesure le pH des solutions. Resultats : Au cours de l’etude, tous les echantillons ont conserve au moins 96,1 % de leur concentration initiale de dolasetron. Aucun effet significatif sur la stabilite du dolasetron lie au temps, a la temperature ou au diluant n’a ete observe. L’inspection des chromatogrammes n’ont revele la presence d’aucun produit de degradation. Toutes les solutions etaient au depart limpides et incolores et le sont demeurees pendant toute la duree de l’etude. Aucun changement significatif du pH n’a ete observe au cours de l’etude. Conclusions : Les solutions de mesylate de dolasetron a des concentrations de 10 mg/mL de NS ou de D5W, entreposees dans des seringues de polypropylene a 4 °C ou a 23 °C ont conserve plus de 96 % de leur concentration initiale de dolasetron pendant 31 jours.