• A Paavola, P Tarkkila, M Xu, T Wahlström, J Yliruusi, and P Rosenberg.
• Department of Pharmacy, University of Helsinki, Finland.
• Pharm. Res. 1998 Mar 1;15(3):482-7.

PurposeReduction of the frequency of injections and localization of the absorption of drug molecules to the injection site would be of great advantage in epidural pain treatment. The epidural use of a controlled release gel of lidocaine and ibuprofen was studied.MethodsThe effect of a poloxamer gel (25%) containing 2% lidocaine.HCl and 2% ibuprofen.Na on the duration of analgesia after epidural administration to pigs was compared with drug in solution. Analgesia was assessed by observing the motor function and the nociceptive reflex-withdrawal response to painful pressure stimulation on the feet. Pharmacokinetic and histological examinations were performed.ResultsAnalgesia lasted significantly longer after epidural lidocaine gel injection in comparison with the solution. The gel prolonged the systemic absorption, thereby increasing the epidural availability of lidocaine for spinal analgesia. Although the absorption of ibuprofen was prolonged after epidural gel injection, the duration of analgesia as compared with the solution was not prolonged. After epidural injection, only slight inflammatory changes were observed in the tissue structures of the epidural space, but none in the spinal cord.ConclusionsThese results demonstrate poloxamer gel to be a promising controlled-release, injectable epidural formulation for the management of pain.

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