Epidural

The brain and spinal cord are covered by three membranes called meninges. The dura mater is the outermost of these protective membranes. The spinal cord is protected from injury as it goes down the back by passing through the central cavities of the vertebrae in the vertebral column. The epidural space is the space in the central cavities between the dura mater (covering the spinal cord) and the vertebral column.

Epidural administration is an effective means of controlling and relieving chronic pain. It is commonly used in the labor and delivery settings, and in postoperative settings. Drugs that are often used for epidural route are called local anesthetics such as bupivacaine, chloroprocaine, or lidocaine. They are often given concomitantly with other pain medications, especially narcotics, to decrease the dose of opioids and provide multi-nodal pain relief. The advantage of this route of administration is that drug dosages are generally much lower than when given by other routes and typically produce fewer side effects. Studies have shown that epidural administration produces longer lasting pain relief, increased patient alertness, and earlier ambulation.

When epidural administration will be temporary or short-term, a catheter is inserted in the epidural space but is generally not sutured into place. The catheter exits from the insertion site on the back. If the administration will be permanent or long-term, the catheter is "tunneled" and exits on the side of the body or on the abdomen. A variation of the technique is to subcutaneously implant a Port-a-cath® and connect that device to the indwelling catheter.

It is obvious why sterile compounded formulations must be used via this route of administration. Preservatives are strictly contraindicated in epidural formulations to prevent nerve damage.