Botulinum toxin therapy: reduction of injection site pain by pH normalisation

A Retrospective Comparison of Onabotulinum Toxin A and Incobotulinum Toxin A in Terms of Efficacy, Tolerability, Duration of Effect, and Pain on Injection Administration Site for the Treatment of Chronic Migraine

Background Onabotulinum toxin A (OnA) is a well-tolerated and effective treatment for chronic migraine (CM). However, based on research indications that incobotulinum toxin A (InA) would be equally effective, a Veterans Health Administration medical center mandated a two-year trial of InA as a more cost-effective alternative to OnA. Although InA is used for many similar indications as OnA, it is not Food and Drug Administration-approved for treating CM, and complications occurred in several patients with CM following this treatment change. We conducted this retrospective analysis to evaluate differences in the efficacy of OnA and InA and identify the reasons for the adverse effects of InA in some of these patients. Methods We performed a retrospective review of 42 patients who had been effectively treated with OnA and were then switched to InA. The differences between treatment responses to OnA and InA were assessed through the evaluation of pain on injection, number of headache days, and duration of action. Patients received injections at 10- to 13-week intervals. Those who reported severe pain on injection of InA were switched back to OnA. Results Severe burning pain on InA injection was reported by 38% of patients (nine males and seven females, i.e., a total of 16 patients out of 42 patients). One male patient reported the same degree of pain from both InA and OnA injections. A total of 66.7% of women with obesity and 83.3% of men with obesity or diabetes experienced severe pain on injection. Neither migraine suppression nor the duration of effect was significantly different between OnA and InA. Conclusions OnA is better tolerated than InA in the treatment of CM. InA appears to effectively suppress migraines, but some patients complain of a severe localized burning sensation during the injections. Some of these patients, all of whom were previously treated with OnA, requested to switch back to OnA. This suggested that InA is not equivalent to OnA in terms of tolerability and effectiveness. The present study found 2.38% of patients experienced an insufficient duration of effect with InA, and none with OnA. However, these lower rates may, in part, be due to variability in injection intervals in this sample, which could be because of scheduling considerations at the Harry S. Truman Veterans Health Administration Medical Center. In cases where OnA fails because of the development of antibodies, it might be reasonable to switch to InA treatment. Reformulation of InA with a pH-buffered solution may eliminate the difference in pain on injection. InA would then be a good alternative to OnA for treating CM.

Injection Site Pain, Onset and Duration of Action of Botulinum Toxin Reconstituted in Normal Saline With and Without Sodium Bicarbonate: A Prospective, Single Center, Randomized, Double-Blind Interventional Study

Purpose: This study was designed to investigate the effects of botulinum toxin type A injections diluted with the mixture of sodium bicarbonate and normal saline on pain reduction, onset of action, and duration of action. Methods: This is a prospective, randomized, double-blind clinical study, which included 30 female patients (age >25). The patients were randomized to receive botulinum toxin injections diluted with normal saline and sodium bicarbonate on one side of the face and saline control injections on the other side. Pain severity was assessed using visual analogue scale. The onset and duration of action were recorded according to the patients' subjective opinions after 1 week and 3 months, respectively. Results: Lower pain intensity ratings were observed when botulinum toxin was diluted with 0.05 and 0.1 mL of sodium bicarbonate as compared to saline. Regarding the onset of action, the botulinum toxin injections diluted with saline and 0.1-mL sodium bicarbonate side showed faster response in many patients than other dilutions (P < .001). Both the 0.05-mL and 0.1-mL sodium bicarbonate concentrations showed longer duration effects on patients than other concentrations. Conclusion: The use of sodium bicarbonate and saline in a mixture for the dilution of botulinum toxin can decrease patients' discomfort and provide a faster action with longer duration effects.

Onabotulinumtoxin Type A reconstitution with preserved versus preservative-free saline in chronic migraine (B-RECON). A randomised, double-blind trial

INTRODUCTION

Onabotulinumtoxin type A (BoNTA) is manufactured as powder that requires reconstitution with normal saline prior to injection. Previous literature has suggested that preserved saline (PS) exerts a local anaesthetic effect, and reduces the procedure discomfort when used in reconstitution in lieu of preservative-free saline (PFS). However, this was mainly studied in the aesthetics indications of BoNTA, and never in its use for the treatment of chronic migraine. The distinction is important as chronic migraine population suffers high incidence of scalp allodynia which makes it more prone to injection site pain. In addition, the pain of the procedure itself may be related to the spike of migraine frequency in the immediate postprocedural period which can occur in up to 5% of patients receiving the treatment. Our trial aimed to study the difference in procedural pain scale, and postprocedural headache rating with the use of PS vs PFS in constitution of BoNTA when used as a treatment for chronic migraine.

METHODS

68 subjects were consecutively enrolled in an outpatient setting at a large tertiary headache centre over a period of 6 months. Subjects were randomised into PS or PFS group. BoNTA was administered as per standard protocol in both groups. Injection site pain scores and frequency of headache days in the immediate following week were recorded. Wilcoxon rank sum tests were used to compare differences in between groups using SPSS software.

RESULTS

Analysis (SAS V 9.4) revealed that those receiving [PF] had significantly higher procedure pain scores than those receiving [P] (5.3 vs 3.2, respectively). There was no difference in the headache or migraine frequency in the immediate postprocedural period.

CONCLUSION

This study supports the use of PS (bacteriostatic) over PFS for reconstitution of BoNTA in chronic migraine as it reduces the discomfort of the injection sites.

Therapeutically relevant features of botulinum toxin drugs

Botulinum toxin (BT) drugs were introduced in the late 1980s. They are now used worldwide in a large number of indications. This huge market and its future opportunities have attracted a number of companies about to enter the competition with projects to develop new BT drugs. We want to outline features of BT drugs that are relevant for their therapeutic use and - with that - are also relevant to compare and to evaluate new BT drugs and to guide their further development. BT drugs may vary in their content of botulinum neurotoxin, complexing proteins and excipients. Their manufacturing is complex and directly influences core features of the final drug. It includes breeding, purification, botulinum neurotoxin activation, stabilisation, potency control, labelling and testing, specific biological activity and packaging. The manufacturer's support concerning product documentation and support, reliability of drug supply, counterfeit protection and - last but not least - competitive pricing is also important. Further developments include the indication spectrum, the market penetration, the drug's duration of action, liquid preparations, transdermal applications, improving antigenicity and a bio-similarity registration process. Most projects, however, will try to produce Botox® analogs at reduced sale prices.

Botulinum toxin: Pharmacology and injectable administration for the treatment of primary hyperhidrosis

Hyperhidrosis is a dermatological condition defined by excessive sweating beyond thermoregulatory needs with significant effects on patients' quality of life. Hyperhidrosis is categorized as primary or secondary: primary hyperhidrosis is mostly focal and idiopathic, whereas secondary hyperhidrosis is commonly generalized and caused by an underlying medical condition or use of medications. Various surgical and nonsurgical therapies exist for primary hyperhidrosis. Although botulinum toxin is one of the deadliest toxins known, when used in small doses, it is one of the most effective therapies for primary hyperhidrosis. Botulinum toxin injections are widely used as a second-line primary hyperhidrosis treatment option once topical treatment strategies have failed. This article provides an overview of the commercially available botulinum toxin formulations and their applications in the treatment of primary hyperhidrosis.

Clinical Pharmacology of Botulinum Toxin Drugs

Botulinum toxin (BT) has changed from a deadly poison to a novel therapeutic principle for a large number of disorders in many medical areas.BT drugs are special in many ways: they are biologicals, their active ingredient BT is not patentable, their spectrum of clinical applications is extremely broad, their dose range is enormous, their mode of action is local and their life cycles are special.This review covers BT's therapeutic mode of action, time course of action, target tissues, pharmacological profile, adverse effects, interactions, potency labelling and antigenicity as well as BT's therapeutic preparations.

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

OBJECTIVE

To investigate the clinical, cytological, and histopathological adverse effects of intra-articularly injected botulinum toxin A in dogs and to study whether the toxin spreads from the joint after the injection.

METHODS

A longitudinal, placebo-controlled, randomized clinical trial was conducted with six healthy laboratory Beagle dogs. Stifle joints were randomized to receive either 30 IU of onabotulinum toxin A or placebo in a 1:1 ratio. Adverse effects and spread of the toxin were examined by evaluating dynamic and static weight-bearing of the injected limbs, by assessing painless range of motion and pain on palpation of joints, and by performing synovial fluid analysis, neurological examination, and electrophysiological recordings at different examination time-points in a 12-week period after the injections. The dogs were then euthanized and autopsy and histopathological examination of joint structures and adjacent muscles and nerves were performed.

RESULTS

Intra-articular botulinum toxin A did not cause local weakness or injection site pain. Instead, static weight-bearing and painless range of motion of stifle joints decreased in the placebo limbs. No clinically significant abnormalities associated with intra-articular botulinum toxin A were detected in the neurological examinations. Electrophysiological recordings showed low compound muscle action potentials in two dogs in the botulinum toxin A-injected limb. No significant changes were detected in the synovial fluid. Autopsy and histopathological examination of the joint and adjacent muscles and nerves did not reveal histopathological adverse effects of the toxin.

CONCLUSION

Intra-articular botulinum toxin A does not produce significant clinical, cytological, or histopathological adverse effects in healthy dogs. Based on the electrophysiological recordings, the toxin may spread from the joint, but its clinical impact seems to be low.

Strategies to decrease injection site pain in botulinum toxin therapy

Botulinum toxin is now used for numerous indications including dystonias, spasticity, cerebral palsy, hyperhidrosis, cosmetics and chronic migraine. It has to be injected into its target tissues thus causing injection site pain. We wanted to compare the efficacy of various analgesic interventions suggested for reduction of injection site pain. In 13 healthy controls, pain thresholds in the fingertips II and III bilaterally were determined by the Mechanical Pain Threshold Test and the Repetitive Pain Stimulation Test at baseline and under nitrous oxide/oxygen, ice spray, local anaesthetic cream and forearm ischaemia. All interventions studied produce statistically significant and robust elevations of the pain threshold in both tests. Nitrous oxide/oxygen had stronger effects than the other interventions, although this superiority was statistically significant only in the Repetitive Pain Stimulation Test and not against ice spray. Also considering duration, localisation and penetration depth of analgesic effects, hyperhidrosis treatment may benefit from nitrous oxide/oxygen, ice spray and local anaesthetic cream. In palmar hyperhidrosis, forearm ischaemia is possible and also reduces botulinum toxin washout. Cosmetic indications may also benefit from nitrous oxide/oxygen and local anaesthetic cream. For botulinum toxin therapy of spasticity, dystonia and tremor, only nitrous oxide/oxygen may offer intramuscular analgesic effect. Its systemic and prolonged effect is also an advantage in injections in several body parts. Future studies are necessary to test the influence of penetration depth and combinations of analgesic interventions.

Botulinum Neurotoxins: Biology, Pharmacology, and Toxicology

The study of botulinum neurotoxins (BoNT) is rapidly progressing in many aspects. Novel BoNTs are being discovered owing to next generation sequencing, but their biologic and pharmacological properties remain largely unknown. The molecular structure of the large protein complexes that the toxin forms with accessory proteins, which are included in some BoNT type A1 and B1 pharmacological preparations, have been determined. By far the largest effort has been dedicated to the testing and validation of BoNTs as therapeutic agents in an ever increasing number of applications, including pain therapy. BoNT type A1 has been also exploited in a variety of cosmetic treatments, alone or in combination with other agents, and this specific market has reached the size of the one dedicated to the treatment of medical syndromes. The pharmacological properties and mode of action of BoNTs have shed light on general principles of neuronal transport and protein-protein interactions and are stimulating basic science studies. Moreover, the wide array of BoNTs discovered and to be discovered and the production of recombinant BoNTs endowed with specific properties suggest novel uses in therapeutics with increasing disease/symptom specifity. These recent developments are reviewed here to provide an updated picture of the biologic mechanism of action of BoNTs, of their increasing use in pharmacology and in cosmetics, and of their toxicology.

Botulinum toxin drugs: brief history and outlook

The global botulinum toxin (BT) market is currently undergoing rapid changes: this may be the time to review the history and the future of BT drug development. Since the early 1990s Botox(®) and Dysport(®) dominated the international BT market. Later, Myobloc(®)/NeuroBloc(®), a liquid BT type B drug, came out, but failed. Xeomin(®) is the latest major BT drug. It features removal of complexing proteins and improved neurotoxin purity. Several new BT drugs are coming out of Korea, China and Russia. Scientific challenges for BT drug development include modification of BT's duration of action, its transdermal transport and the design of BT hybrid drugs for specific target tissues. The increased competition will change the global BT market fundamentally and a re-organisation according to large indication groups, such as therapeutic and cosmetic applications, might occur.