Acute toxicity pilot evaluation of proliferol in rats and swine

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 (1×), medium (5×), or high (10×) 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.

Early inflammatory response of knee ligaments to prolotherapy in a rat model

Prolotherapy is an alternative injection-based therapy for chronic musculoskeletal pain. Three different proliferants, D-glucose (dextrose), phenol-glucose-glycerine (P2G), and sodium morrhuate, used in prolotherapy are hypothesized to strengthen and reorganize chronically injured soft tissue and decrease pain through modulation of the inflammatory process. Our hypothesis is that commonly used prolotherapy solutions will induce inflammation (leukocyte and macrophage infiltration) in medial collateral ligaments (MCLs) compared to needlestick, saline injection, and no-injection controls. MCLs of 84 Sprague- Dawley rats were injected one time at both the tibial and femoral insertions. Immunohistochemistry (IHC) was used to determine the inflammatory response at three locations (tibial and femoral insertions and midsubstance) 6, 24, and 72 h after dextrose injection compared to saline- and no-injection controls and collagenase (positive control) (n = 4). qPCR was used to analyze gene expression 24 h postinjection (n = 4). Sodium morrhuate, P2G, and needlestick control were also investigated after 24 h (n = 4). In general, inflammation (CD43+, ED1+, and ED2+ cells) increased after prolotherapy injection compared to no-injection control but did not increase consistently compared to saline and needlestick control injections. This response varied by both location and proliferant. Inflammation was observed at 6 and 24 h postinjection but was resolved by 72 h compared to no-injection controls (p < 0.05). CD43+ leukocytes and ED2+ macrophages increased compared to needlestick and saline-injection control, respectively, 24 h postinjection (p < 0.05). Prolotherapy injections created an inflammatory response, but this response was variable and overall, not uniformly different from that caused by saline injections or needlestick procedures.

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.

Evidence-informed management of chronic low back pain with prolotherapy

The management of chronic low back pain (CLBP) has proven to be very challenging in North America, as evidenced by its mounting socioeconomic burden. Choosing among available nonsurgical therapies can be overwhelming for many stakeholders, including patients, health providers, policy makers, and third-party payers. Although all parties share a common goal and wish to use limited health-care resources to support interventions most likely to result in clinically meaningful improvements, there is often uncertainty about the most appropriate intervention for a particular patient. To help understand and evaluate the various commonly used nonsurgical approaches to CLBP, the North American Spine Society has sponsored this special focus issue of The Spine Journal, titled Evidence-Informed Management of Chronic Low Back Pain Without Surgery. Articles in this special focus issue were contributed by leading spine practitioners and researchers, who were invited to summarize the best available evidence for a particular intervention and encouraged to make this information accessible to nonexperts. Each of the articles contains five sections (description, theory, evidence of efficacy, harms, and summary) with common subheadings to facilitate comparison across the 24 different interventions profiled in this special focus issue, blending narrative and systematic review methodology as deemed appropriate by the authors. It is hoped that articles in this special focus issue will be informative and aid in decision making for the many stakeholders evaluating nonsurgical interventions for CLBP.