Which medications are used in epidural steroid injections (ESIs)?

Updated: Aug 06, 2018
  • Author: Boqing Chen, MD, PhD; Chief Editor: Stephen Kishner, MD, MHA  more...
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The medication composite for an epidural injection consists of a steroid preparation and, in most cases, an anesthetic.

A contrast medium also is generally used, along with fluoroscopic-guided procedures, to verify placement and distribution of the injectate. Newer formulations, labeled as nonionic radiocontrast agents, are commonly used at present for spinal injection procedures. Although these agents do contain iodine atoms, there is minimal free iodine present, allowing for a formulation with a more physiologic osmolality, as well as less free iodine. These media undergo primarily renal excretion with little, if any, metabolism and deiodination.

For patients with a suspected allergy to contrast medium, consideration should be given to pretreatment orally with antihistamines and corticosteroids prior to the procedure. Acute allergic reactions generally occur in the first few minutes after injection. Ideally, therefore, patients should be observed for at least a few minutes after the procedure.

Local anesthetics bind with intracellular sodium channels to prevent sodium influx, which occurs during depolarization of the neural membrane. The nerve impulse fails to propagate if sufficient sodium channels are blocked. When local anesthetics are used to minimize pain during an epidural procedure, the medication is acting on closed sodium channels. In this case, the duration of the local anesthetic is shorter than it is when pain is present and the sodium channels are open.

A local anesthetic's time to onset of action can be decreased by (1) buffering the anesthetic by adding a base (eg, bicarbonate) and (2) increasing its concentration. Typically, 1% lidocaine is used as a skin anesthesia for epidural steroid injections (ESIs).

Anesthetics are classified as amides or esters. Esters, such as procaine, are metabolized by plasma cholinesterase and are then excreted by the kidney. Amides, such as lidocaine and bupivacaine, are metabolized by the liver and then in the kidney. Because amides are metabolized more slowly than esters, they have a longer duration of action.

Different steroid preparations are used for ESIs. Examples include dexamethasone (Decadron), triamcinolone (Kenalog), betamethasone (Celestone), and methylprednisolone (Solu-Medrol).

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