Abstract

The administration of drugs via patient controlled intravenous analgesia (PCIA) is routinely practiced for the management of postoperative pain. A combination of lornoxicam and opioid analgesics such as morphine, tramadol, or fentanyl is often administered for the management of severe pain to ensure that a minimal dose of each is used. Unfortunately, no data are available about compatibility and stability of lornoxicam in combination with these opioid analgesics. The aim of this study was to evaluate the compatibility and stability of these mixtures in polypropylene syringes for up to 168 h. Admixtures were assessed for 168 h (7 days) after preparation stored at 25°C and protected from sun light exposure. Samples were withdrawn from each bag immediately after preparation and at predetermined intervals (2, 4, 8, 24, 48, 72, 120, and 168 h after preparation). Admixtures were visually inspected for precipitation, cloudiness, and discoloration at each sampling interval. Drug concentration was determined using high performance liquid chromatographic analysis. At ambient temperature, the drug mixtures lornoxicam/morphine and lornoxicam/tramadol were clear in appearance and no color change or precipitation was observed during the study period. After 168 h of storage, the maximum losses obtained were lower than 10% for three drugs. On the contrary, fentanyl showed an evident decrease of its concentration in its mixture with lornoxicam. After 168 h, fentanyl concentration was less than 10% of the starting concentrations. The results indicate that, at ambient storage conditions, the drug mixtures lornoxicam/morphine and lornoxicam/tramadol in 0.9% sodium chloride injection were physically and chemically stable for at least 168 h when stored in polypropylene syringes. However, the lornoxicam ⁄fentanyl mixture was physically incompatible.

Key words: Lornoxicam, tramadol, morphine, fentanyl, drug interactions, compatibility, patient controlled analgesia.