What are the advantages of using intrathecal drug delivery compared to systemic drug administration?
There are several advantages of intrathecal drug delivery over systemic medication administration. Delivery of analgesic drugs (e.g., opioids) to the intrathecal space eliminates first pass metabolism that occurs with oral administration and the larger volume of distribution that occurs with systemic administration, resulting in a much higher effective drug concentration at the site of action. This leads to greater potency and improved side-effect profile compared to systemic administration. In addition, clonidine, bupivacaine, and ziconotide are potent analgesic medications commonly administered by intrathecal administration, but either are ineffective or produce intolerable side effects without significant analgesia when given by systemic administration. Lastly, intrathecal drug delivery is achieved by continuous delivery of concentrated drug stored in an implanted pump; therefore patients with severe, chronic pain treated with intrathecal drug delivery do not necessarily need to rely on self-administration of medications on a frequent, repetitive basis.