To the Editor:—

There have been several cases of epidural hematoma after administrations of low-molecular-weight heparin, enoxaparin. We describe a case of epidural hematoma in a patient taking pentosan polysulfate sodium.

A 63-yr-old woman was referred to the pain clinic after reporting chronic lower back pain. The magnetic resonance films showed severe degenerative disc disease, spinal stenosis from T11 to L4, and bilateral facet hypertrophy at multiple levels. Her medical history was significant for interstitial cystitis, and she was taking pentosan polysulfate sodium (Elmiron; Baker Norton Pharmaceuticals, Inc., Miami, FL). She was also taking 300 mg gabapentin (Neurontin; Parke-Davis, Morris Plains, NJ) three times a day and 25 mg amitriptyline (Elavil; Zeneca Pharmaceuticals, Wilmington, DE) orally at night. Lumbar epidural steroid injection, without stopping her current medications, was planned and was performed under fluoroscopic guidance uneventfully. Two weeks later, because there was no improvement in the pain, a second epidural steroid injection was performed, along with bilateral L3–L4, L4–L5, and L5–S1 facet steroid injections under fluoroscopic guidance. Approximately 8 h after the procedure, the patient reported severe lower back pain, and physical examination revealed lower back tenderness with decreased range of motion at the lumbosacral spine, with no sensory or motor deficit. The magnetic resonance scans revealed an epidural collection of blood from T11 to L3. It was initially elected to observe her, but 12 h later, numbness developed in her right foot, and she underwent immediate laminectomy from T11 to L2, with uneventful evacuation of the epidural blood clot. No other abnormalities were detected. Postoperatively, there was no neurologic deficit, and the patient left for home 3 days later.

In this patient, there was no history of bleeding disorder, and she was not taking any conventional anticoagulant medication. She was taking pentosan polysulfate for treatment of interstitial cystitis. Pentosan polysulfate is a semi-synthetic compound similar to low-molecular-weight heparin with a weak anticoagulant property. The oral bioavailability of the drug is minimal. 1Pentosan is shown to be efficacious in the treatment of pain, the urgency, and the frequency associated with interstitial cystitis. 2Although the exact mechanism of action for pentosan in interstitial cystitis is not known, it is thought to act as a buffer to control cell permeability, preventing irritating solutions in the urine from reaching cells. The elimination half-life of the drug is approximately 4–6 h, and the liver and spleen are the primary sites for metabolism. Pentosan can decrease factor V concentration, but serious bleeding complications associated with its use are rare. 3 

We cannot be certain that this patient’s epidural hematoma was related to pentosan; it might have been a direct consequence of multiple needle punctures. However, an extensive epidural hematoma that leads to neurologic symptoms, as seen in this patient, is unlikely to arise from needle trauma alone. To the best of our knowledge, there are no cases of epidural hematoma in association with pentosan reported in the medical literature, and this is probably the first case that suggests an association with pentosan use.

Faaij RA, Srivastava N, van Griensven JM, Schoemaker RC, Kluft C, Burggraaf J, Cohen AF: The oral bioavailability of pentosan polysulphate sodium in healthy volunteers. Eur J Clin Pharmacol 1999; 54: 929–35
Hwang P, Auclair B, Beechinor D, Diment M, Einarson TR: Efficacy of pentosan polysulfate in the treatment of interstitial cystitis: A meta-analysis. Urology 1997; 50: 39–43
De Prost D, Guerot C, Karsenty F: Pentosane polysulfate: The effect on hemostasis of a continuous 3-day infusion. Clin Pharmacol Ther 1985; 38: 171–5