Acute toxicity evaluation of proliferol: a dose-escalating, placebo-controlled study in swine.

Prolotherapy is one of the many treatments available for chronic musculoskeletal disorders. A commonly used drug contains dextrose 12.5%, glycerin 12.5%, phenol 1.0%, and lidocaine hydrochloride 0.25% in aqueous solution (recently termed Proliferol). For chronic low back pain, this is injected into lumbosacral ligaments to stimulate connective tissue repair. Despite generally positive clinical results, the toxicity of this drug is not well characterized and was assessed in 48 (24 male, 24 female) Yucatan miniature swine randomly assigned to low (1x), medium (5x), or high (10x) dose or saline placebo. Outcomes included clinical observations, clinical chemistry, hematology, coagulation, urinalysis, toxicokinetics, and full gross and microscopic histopathology after 24 hours or 14 days. Findings attributable to Proliferol after 24 hours included dose-response elevations in alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, and creatine kinase, which returned to normal after 14 days. There were no remarkable findings in hematology, coagulation, or urinalysis. Urine concentrations of lidocaine and phenol both peaked after 8 hours. Histopathology findings after 24 hours included hemorrhage, inflammation, necrosis, and vascular changes in the ligaments and adjacent soft tissues at the sites of injection. After 14 days, there was evidence of repair under way, with fibrosis and skeletal muscle regeneration at the injection sites.

Acute toxicity evaluation of proliferol: a dose-escalating, placebo-controlled study in rats.

Proliferol is an investigational new drug containing lidocaine hydrochloride 0.25%, dextrose 12.5%, glycerin 12.5%, and phenol 1.0% in aqueous solution. Despite extensive human experience with similar drugs administered by intraligamentous injection for chronic musculoskeletal disorders, little is known concerning preclinical toxicity. The purpose of this study was to assess the acute toxicity of intramuscular Proliferol in 96 (48 male, 48 female) Charles River strain rats, which were randomly assigned to low- (1x), medium- (5x), or high- (10x) dose Proliferol (derived from a human dose of 20 ml on a volume per bodyweight basis), or high-dose saline placebo. Observations included clinical observations, biochemistry, hematology, urinalysis, and full histopathology after 24 h or 14 days. There were no signs of ill health or reaction to treatment, and gait and body temperature were within normal limits. Biochemistry findings at 24 h included elevated aspartate aminotransferase, alanine aminotransferase, and haptoglobin; at 14 days all values were within normal ranges. Urinalysis findings at 24 h included increased urobilinogen and blood in all dose groups compared with placebo. Urine concentrations of phenol and lidocaine were greatest at 2 h and absent at 24 h. Histopathology findings included localized acute inflammatory soft tissue changes at the injection sites at 24 h and skeletal muscle regeneration at 14 days, which were consistent with the anticipated mechanism of action of Proliferol. There was no evidence of systemic toxicity from intramuscular injection of Proliferol in rats at up to 10x the human dose.