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Anesthesia & Analgesia:
doi: 10.1097/00000539-200003000-00055
PEDIATRIC ANESTHESIA: Letters to the Editor

A Simple Technique to Reduce Preservative/Excipient Related Neurotoxicity of Intrathecal (Spinal) Drugs

Munir, Muhammad A. MD; Krishnan, Sunder MD; Ahmad, Mahmood MD

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Department of Anesthesiology University of Arkansas for Medical Sciences Little Rock, AR 72205-7199

A recent report by Hodgson et al. (1) assessed the neurotoxicity of drugs given intrathecally. We agree with the principle of adopting a high degree of suspicion toward the possibility of neurotoxicity of intrathecally given drugs and developing a systemic approach to determine potential neurotoxicity.

Neurotoxicity associated with benzyl alcohol (BA) and polyethylene glycol (PEG), including sterile meningitis, arachnoiditis, and pachymeningitis has been reported (2,3). Dilution (1:10) of corticosteroid suspension with normal saline or local anesthetic to decrease preservative/excipient concentration is a common practice. However, the resulting lower concentration of steroid requires an increased volume of injectate.

We have reported a simple technique to decrease the absolute amount of preservative and excipient in the steroid preparation (4). The vial of the depot steroid is left undisturbed for 24 h. The supernatant (BA/PEG) is aspirated and replaced with an equal volume of 0.9% saline just before injecting. Gas chromatography has revealed a 43% smaller concentration of preservative/excipient, whereas quantitative spectrophotometric analysis has shown equivalent concentrations of steroids in treated, as well as untreated, samples.

Until the neurotoxicity of preservative/excipient is disproved, we suggest that this simple technique be followed to avoid the neurotoxicity related to BA and PEG.

Muhammad A. Munir MD

Sunder Krishnan MD

Mahmood Ahmad MD

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1. Hodgson PS, Neal JM, Pollock JE, Liu SS. The neurotoxicity of drugs given intrathecally (spinal). Anesth Analg 1999; 88:797–809.

2. Benzon HT. Epidural steroid injections for low back pain and lumbosacral radiculopathy. Pain 1986; 24:277–95.

3. Deland FH. Intrathecal toxicity studies with benzyl alcohol. Toxicol Appl Pharmacol 1973; 25:153–6.

4. Ahmad M, Munir MA, Ackerman WE, et al. A simple technique to reduce preservative related neurotoxicity in epidural corticosteroid injections [abstract]. Anesth Analg 1999; 88:S269.

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