RT Journal Article SR Electronic T1 Physicochemical stability of binary admixtures of paracetamol and dexketoprofen-trometamol for patient-controlled analgesia use JF European Journal of Hospital Pharmacy JO Eur J Hosp Pharm FD British Medical Journal Publishing Group SP 308 OP 313 DO 10.1136/ejhpharm-2018-001535 VO 26 IS 6 A1 Alfonso Ángel López Navarro A1 María Amparo Martínez Gómez A1 Elena Gras Colomer A1 Pilar Campillos A1 Mónica Climente Martí YR 2019 UL http://ejhp.bmj.com/content/26/6/308.abstract AB Background Intravenous admixtures of dexketoprofen-trometamol and paracetamol are frequently used in clinical practice due to synergism obtained administering both drugs concomitantly. Physicochemical stability of binary admixture containing both drugs is currently unknown.Objective To determine physicochemical stability of binary admixture containing dexketoprofen-trometamol 50 mg and paracetamol 1000 mg in a low-density polyethylene bottle at different storage conditions of light and temperature for advanced preparation.Methods Eight mixtures containing dexketoprofen-trometamol (Enantyum ampule 2 mL) 50 mg and paracetamol (Paracetamol B. Braun bottle 100 mL) 1000 mg were prepared and stored at: room temperature and exposed to light; room temperature and protected from light; refrigerated and exposed to light; and refrigerated and protected from light. From each mixture, aliquots were extracted at different times for 15 days. For physical compatibility, pH measure, gravimetric analysis and visual inspection were carried out. For chemical stability, concentrations of dexketoprofen-trometamol and paracetamol were simultaneously measured by high performance liquid chromatography.Results Only refrigerated mixtures showed incompatibility since white precipitation appeared at day 6, possibly due to paracetamol instability. Remaining drugs concentrations were in all cases≥90% after 15 days.Conclusion Binary mixture containing paracetamol (100 mL) 1000 mg and dexketoprofen-trometamol (2 mL) 50 mg in a low-density polyethylene bottle is physicochemically stable for 5 days under refrigeration and 15 days at room temperature. By considering also microbial contamination, this mixture can be prepared in advance, 5 days stored refrigerated and 2 days stored at room temperature, being unnecessary protection from light.