A randomized, double-blind study to compare low-dose with standard-dose chymopapain in the treatment of herniated lumbar intervertebral discs.

Postoperative low-back pain and spasm are the main drawbacks of chymopapain chemonucleolysis. To investigate if low-dose chymopapain could reduce this adverse reaction, without modifying the efficacy, 118 patients with persistent low-back and radicular pain due to a lumbar disc herniation underwent chemonucleolysis. 60 patients were randomly selected to receive 2 mL of standard-dose chymopapain (4,000 units) and 58 to receive 2 mL of low dose (2,000 units). The clinical outcome was assessed on study days 1, 30, and 60, and after 1 year by physicians who were unaware of the treatment, and on the basis of the patients' self evaluation. At day 60, Chemonucleolysis was rated as successful in 81% of the cases by the investigator and in 80% by the patient's self assessment. The percentage of good results was remarkably similar in the two treatment groups and this finding was confirmed after 1 year. There was some evidence that the low-dose treatment resulted in less frequent postoperative back pain but the difference was not statistically significant. Moreover, a comparable incidence of acute low-back pain and spasm was observed in the two treatment groups. Low-dose chemonucleolysis appears to be as effective as the standard dose, but the use of 2,000 units does not significantly lower the postoperative back pain.