Chemical stability of tramadol hydrochloride injection admixed with selected pain drugs.
BACKGROUND
Tramadol hydrochloride (HCl) and ketorolac tromethamine are analgesic drugs, which are commonly used in combination in postoperative pain management. According to some studies, metoclopramide and magnesium sulfate (MgSO(4)) as adjuvant agents can improve analgesia and decrease the need for other pain drugs.


METHODS
The chemical stability of tramadol HCl combined with ketorolac tromethamine and metoclopramide HCl has been studied using a stability-indicating high-performance liquid chromatographic assay method. Calibration curves were produced using linear regression of the peak area against concentration of each drug, with an r(2) value ≥ 0.96. Our aim was to investigate the stability of admixture solution of tramadol HCl combined with ketorolac tromethamine and metoclopramide HCl for 48 h (25°C) and 5 days (5°C), with MgSO(4), which has never been assessed.


RESULTS
Data obtained for admixtures prepared and stored at temperatures of 25°C and 5°C, show that all drugs have reached at least 98% of the initial concentration.


CONCLUSIONS
For the purpose of pre-preparing drug admixtures to use with confidence, tramadol HCl infusions may be prepared in advance and then thawed before use in clinical units. On the basis of our results, the intravenous mixture of tramadol (7.69 mg/mL), metoclopramide (0.19 mg/mL), ketorolac (1.15 mg/mL), and magnesium sulfate (77 mg/mL) may be considered for a possible commercial formulation.
Department of Chemistry and Pharmaceutical Technology, Faculty of Pharmacy, University of Palermo, Via Archirafi 32, 90123 Palermo, Italy.
V
V
Di Stefano
R
R
Pitonzo
S
S
Bavetta
P
P
Polidori
Mg
M
Sidoti