Assessing adverse effects of intra-articular botulinum toxin A in healthy Beagle dogs: A placebo-controlled, blinded, randomized trial

Therapeutic Applications of Botulinum Neurotoxins in Veterinary Medicine

Botulinum neurotoxins (BoNTs) are emerging as multipurpose therapeutic compounds for the treatment of several different syndromes involving peripheral and central nervous systems, and muscular and musculoskeletal disorders both in human and veterinary medicine. Therefore, the study of BoNTs is rapidly developing and identifying newly produced BoNT variants. Efforts should be made to clarify the biological and pharmacological characteristics of these novel BoNTs as well as the natural ones. The high potential of BoNTs as a therapeutic compound for medical syndromes lies in its ability to reach a specific cell type while bypassing other cells, thus having mild or no side effects. In this paper the recent developments in BoNTs are reviewed with the aim of analyzing the current knowledge on BoNTs' biological mechanisms of action, immunogenicity, formulations, and therapeutic applications in the veterinary field, highlighting advantages and drawbacks and identifying the gaps to be filled in order to address research priorities.

The safety of botulinum neurotoxin type A's intraarticular application in experimental animals

In vivo studies of botulinum neurotoxin type A (BoNT-A) enabled characterization of its activity in the nociceptive sensory system separate from its preferred action in motor and autonomic nerve terminals. However, in the recent rodent studies of arthritic pain which employed high intra-articular (i.a.) doses (expressed as a total number of units (U) per animal or U/kg), possible systemic effects have not been conclusively excluded. Herein we assessed the effect of two pharmaceutical preparations, abobotulinumtoxinA (aboBoNT-A, 10, 20, and 40 U/kg corresponding to 0.05, 0.11, and 0.22 ng/kg neurotoxin) and onabotulinumtoxinA (onaBoNT-A, 10 and 20 U/kg corresponding to 0.09 and 0.18 ng/kg, respectively) injected into the rat knee, on safety-relevant readouts: digit abduction, motor performance and weight gain during 14 days post-treatment. The i. a. toxin produced dose-dependent impairment of the toe spreading reflex and rotarod performance, which was moderate and transient after 10 U/kg onaBoNT-A and ≤20 U/kg aboBoNT-A doses, and severe and long-lasting (examined up to 14 days) after ≥20 U/kg of onaBoNT-A and 40 U/kg aboBoNT-A. In addition, lower toxin doses prevented the normal weight gain compared to controls, while higher doses induced marked weight loss (≥20 U/kg of onaBoNT-A and 40 U/kg aboBoNT-A). Commonly employed BoNT-A formulations, depending on the doses, cause local relaxation of the surrounding muscles and systemic adverse effects in rats. Thus, to evade possible toxin unwanted local or systemic spread, careful dosing and motor testing should be mandatory in preclinical behavioral studies, irrespective of the sites and doses of toxin application.

Safety and synovial inflammatory response after intra-articular injection of botulinum toxin type A in healthy horses

Botulinum toxin type A (BoNT-A) is a promising alternative for patients suffering from chronic joint pain. The aim of this study was to investigate whether a single injection of BoNT-A would produce adverse effects on clinical parameters and synovial parameters as well as lameness. One randomly selected radiocarpal joint was treated with 50 U of BoNT-A in eight horses, and the contralateral joint received saline solution. All horses received injections at day 0 and were re-evaluated twice daily for seven days for heart rate (HR), respiratory rate (RR), rectal temperature (RT), mucous membrane color, capillary refill time, intestinal motility, appetite, water intake, defecation, urination, and attitude. At these same time points, joint pain and circumference were assessed. Objective lameness evaluations were performed once daily for seven days and synovial fluid samples were collected at baseline, post-injection hour (PIH) 24 and PIH 168 and evaluated for synovial fluid parameters. HR and RT remained clinically unaltered, despite oscillations over time (p=0.001). The remaining clinical parameters were unaltered by treatment or time (p>0.05). Joint pain was not elicited by flexion and palpation in both limbs as well as carpal circumference was not altered (p=0.88). Lameness was observed only on saline limbs. Cellular parameters evaluated in synovial fluid samples from both carpi had significantly increased from baseline to PIH 24, decreasing at PIH 168 (p<0.05). It was concluded that the injection of 50 U BoNT-A is suggested to be a safe therapy for intra-articular use in horses and must be verified by further investigation.

The Use of Botulinum Toxin for the Treatment of Chronic Joint Pain: Clinical and Experimental Evidence

Chronic osteoarthritis pain is an increasing worldwide problem. Treatment for osteoarthritis pain is generally inadequate or fraught with potential toxicities. Botulinum toxins (BoNTs) are potent inhibitors of neuropeptide release. Paralytic toxicity is due to inhibition at the neuromuscular junction, and this effect has been utilized for treatments of painful dystonias. Pain relief following BoNT muscle injection has been noted to be more significant than muscle weakness and hypothesized to occur because of the inhibition of peripheral neuropeptide release and reduction of peripheral sensitization. Because of this observation, BoNT has been studied as an intra-articular (IA) analgesic for chronic joint pain. In clinical trials, BoNT appears to be effective for nociceptive joint pain. No toxicity has been reported. In preclinical models of joint pain, BoNT is similarly effective. Examination of the dorsal root ganglion (DRG) and the central nervous system has shown that catalytically active BoNT is retrogradely transported by neurons and then transcytosed to afferent synapses in the brain. This suggests that pain relief may also be due to the central effects of the drug. In summary, BoNT appears to be safe and effective for the treatment of chronic joint pain. The long-term effects of IA BoNT are still being determined.

New analgesic: Focus on botulinum toxin

In 2010, Kissin concluded pessimistically that of the 59 new drugs introduced in the fifty-year period between 1960 and 2009 and still in use, only seven had new molecular targets. Of these, only one, sumatriptan, was effective enough to lead to the introduction of multiple drugs targeting the same target molecules (triptans) (Kissin, 2010). Morphine and acetylsalicylic acid (aspirin), introduced for the treatment of pain more than a century ago, continue to dominate biomedical publications despite their limited effectiveness in many areas (e.g., neuropathic pain) and serious adverse effects. Today, are we really closer to ideal analgesics that would work hard enough, long enough, and did not have unwanted side effects? The purpose of the present article is to analyze where we are now. Several drugs, like long-acting opioids or botulinum toxins open some hope. Advantage of botulinum toxin A is unique duration of action (months). New discoveries showed that after peripheral application botulinum toxin by axonal transport reaches the CNS. Major analgesic mechanism of action seems to be of central origin. Will botulinum toxin in the CNS bring new indications and or/adverse effects? Much more basic and clinical research should be in front of us. Although relatively safe as a drug, botulinum toxin is not without adverse effect. Policy makers, clinicians and all those applying botulinum toxin should be aware of that. Unfortunately the life without the pain is still not possible.

Intra-articular botulinum toxin type A for treatment of knee osteoarthritis: Clinical trial

In recent years, there is a growing interest in new medical applications of botulinum toxin, including pain control, osteoarthritis treatment, and wound healing. While clinical applications of botulinum toxin seem promising, existing evidence regarding the therapeutic effects is still inadequate. The aim was to assess the efficacy of a single injection of abobotulinumtoxin A into the knee joint cavity to reduce pain in elderly people. We carried out a single group clinical trial in a University Hospital. Thirty participants (24 women) more than 50 years of age with knee osteoarthritis were included. Diagnosis of osteoarthritis was based on clinical and radiologic findings. We gave a single injection containing 250 units of Dysport (= 100 units of botulinum neurotoxin type A) diluted with 5 ml of normal saline. The primary outcome measure was knee pain. The secondary outcome was the patients' opinion about their knee and associated problems measured with the Knee injury and Osteoarthritis Outcome Score. The outcomes were measured at the baseline and at 4 weeks after the intervention. Within-group comparisons based on the Knee injury and Osteoarthritis Outcome Scores showed favorable results for joint pain and stiffness, sports, severity of symptoms, quality of life, and daily activities (all p-values < 0.001). Also, pain intensity, joint effusion, knee clicking and locking, and flexion-extension scores showed significant beneficial results (all p-values ≤ 0.005). We concluded that botulinum neurotoxin type A is an effective and safe initial treatment of knee osteoarthritis with clear clinical advantages. Patients' satisfaction, minimum adverse effects in addition to single-dose prescription make the toxin as a choice for the first-line therapy of osteoarthritis at least at the short-term in elderly people. The symptom relief increases the patient's compliance and willing to participate in other therapeutic programs. REGISTRATION: Iranian Registry of Clinical Trials (IRCT) website http://www.irct.ir/, a WHO Primary Register setup, with registration code: Irct ID: IRCT20180416039323N1.

Intra-articular botulinum toxin A (BoNT/A) for pain management in dogs with osteoarthritis secondary to hip dysplasia: A randomized controlled clinical trial

The aim of this study was to evaluate the efficacy and safety of the intra-articular (IA) injection of botulinum toxin type A (BoNT/A) to the management of chronic pain in dogs. In a randomized, controlled, double-blinded study sixteen dogs with osteoarthritis secondary to hip dysplasia were distributed into two groups: 25 IU BoNT/A (BoNT) or saline solution (Control) was administered IA in each affected joint. All dogs received oral supplements (90 days) and carprofen (15 days). The dogs were assessed by a veterinarian on five occasions and the owner completed an assessment form at the same time (baseline to 90 days). The data were analyzed using unpaired-t test, Fisher's exact test, analysis of variance and the Tukey's test (P<0.05). There were no differences between groups in the veterinarian and owner assessments. Lower scores were observed in both groups during 90 days after IA therapy in the owner assessments (P<0.001). Compared with baseline, the Vet score was lower from 15-90 days after IA injection in the BoNT group, and at 15 and 30 days in the Control group (P<0.001). Both treatments were safe and reduced the clinical signs associated with hip osteoarthritis. However, IA BoNT/A (25 IU) did not provide better pain relief than the control treatment.