Antispasticity drugs: mechanisms of action

New developments for the pharmacological treatment of alcohol withdrawal syndrome. A focus on non-benzodiazepine GABAergic medications

Alcohol withdrawal syndrome (AWS) can be a life-threatening condition affecting some alcohol-dependent patients who abruptly discontinue or decrease their alcohol consumption. The main objectives of the clinical management of AWS include: to decrease the severity of symptoms, prevent more severe withdrawal clinical manifestations and facilitate entry of the patient into a treatment program in order to attempt to achieve and maintain long-term abstinence from alcohol. At present, benzodiazepines represent the drugs of choice in the treatment of AWS. However, in line with the possible side effects and addictive properties related to benzodiazepine use, there is growing evidence to suggest that non-benzodiazepine GABAergic compounds represent promising medications in the treatment of alcohol-dependent patients. This review focuses on research into non-benzodiazepine GABAergic medications for the treatment of AWS. Among them, carbamazepine, gabapentin and valproic acid are the most studied. The studies on carbamazepine seem to be the most compelling. Preliminary data have also suggested the possible utility of baclofen and topiramate, although further evidence is needed. The promising results in terms of both safety and efficacy are reported. However, we also note the need of more methodologically controlled studies on a greater number of patients, involving more complicated forms of AWS.

Gabapentin for decerebrate rigidity: a case report

A 48-year-old woman suddenly lost consciousness as a result of a right rostral pontine tegmentum haemorrhage. The patient presented with decerebrate rigidity (DR) and regained full consciousness 5 days after the initial onset. The patient was given gabapentin 1200 mg/day nasogastrically and her DR significantly improved, although other antiepileptic drugs such as phenytoin and carbamazepine were given in larger dosages to decrease muscle hypertonicity. The patients' preserved consciousness and motor-evoked potentials to transcranial magnetic stimulation indicated a derangement of the extrapyramidal tracts with preservation of the pyramidal tracts. This case report discusses the possible mechanisms of action of gabapentin in DR.

Effectiveness and safety of baclofen for maintenance of alcohol abstinence in alcohol-dependent patients with liver cirrhosis: randomised, double-blind controlled study

BACKGROUND

Intervention to achieve alcohol abstinence represents the most effective treatment for alcohol-dependent patients with liver cirrhosis; however, anticraving drugs might worsen liver disease. We aimed to investigate the effectiveness and safety of baclofen in achieving and maintaining alcohol abstinence in patients with liver cirrhosis.

METHODS

Between October, 2003, and November, 2006, 148 alcohol-dependent patients with liver cirrhosis were referred to the Institute of Internal Medicine, Rome, Italy. 84 were randomly allocated either oral baclofen or placebo for 12 weeks. Primary outcome was proportion of patients achieving and maintaining alcohol abstinence. Measures of this outcome were total alcohol abstinence and cumulative abstinence duration, which were assessed at outpatient visits. Relapse was defined as alcohol intake of more than four drinks per day or overall consumption of 14 or more drinks per week over a period of at least 4 weeks. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00525252.

FINDINGS

Of 42 patients allocated baclofen, 30 (71%) achieved and maintained abstinence compared with 12 (29%) of 42 assigned placebo (odds ratio 6.3 [95% CI 2.4-16.1]; p=0.0001). The number of dropouts (termination of treatment) did not differ between the baclofen (6/42 [14%]) and placebo (13/42 [31%]) groups (p=0.12). Cumulative abstinence duration was about twofold higher in patients allocated baclofen than in those assigned placebo (mean 62.8 [SE 5.4] vs 30.8 [5.5] days; p=0.001). No hepatic side-effects were recorded.

INTERPRETATION

Baclofen is effective at promoting alcohol abstinence in alcohol-dependent patients with liver cirrhosis. The drug is well tolerated and could have an important role in treatment of these individuals.

The GABAB receptor agonist baclofen prevents heroin-induced reinstatement of heroin-seeking behavior in rats

Opiate addiction is a chronic relapsing disorder characterized by high rates of relapse. The gamma-aminobutyric acid GABA(B) receptor agonist baclofen is known to affect the reinforcing effects of several drugs of abuse, including heroin, as well as to decrease cue-maintained responding for heroin, cocaine and nicotine and suppress alcohol deprivation effect in rats. Here we studied the effect of baclofen on the reinstatement of extinguished heroin-seeking behavior triggered by a priming injection of heroin in abstinent rats trained to stably self-administer heroin (30 microg/kg per infusion) under a continuous reinforcement schedule. Following extinction, the effect of non-contingent non-reinforced primings with heroin, baclofen or heroin/baclofen combination on the resumption of responding was evaluated. Results indicate that heroin priming (0.25mg/kg) promptly reinitiated heroin-seeking behavior, an effect dose-dependently reduced by baclofen at doses (0.625 and 1.25mg/kg) not affecting responding per sè. Importantly, baclofen did not affect locomotion either alone or in combination with heroin, dispelling any doubt as to the eliciting of possible non-specific (motor) effects. The present results show that GABA(B) receptor activation may reduce the propensity to resume drug-induced heroin-seeking behavior thus offering a possible approach in maintaining opiate abstinence.

The effects of transcutaneous electrical nerve stimulation (TENS) on spasticity in multiple sclerosis

Spasticity is a common and often disabling symptom associated with multiple sclerosis (MS). Transcutaneous electrical nerve stimulation (TENS) has been found effective in reducing spasticity in conditions such as stroke, but there is little evidence to support its use in MS. The aim of this study was to evaluate the effectiveness of TENS on spasticity in MS and, furthermore, to compare two different application times. Thirty-two subjects were randomized into two groups, and a single, blind, crossover design was used to compare two weeks of 60 minutes and 8 hours daily of TENS applications (100 Hz and 0.125 ms pulse width). Outcomes were examined using the Global Spasticity Score (GSS), the Penn Spasm Score (PSS), and a visual analogue scale (VAS) for pain. The results of the study demonstrated that there were no statistically significant differences in the GSS following either 60 minutes or 8 hours daily of TENS (P=0.433 and 0.217, respectively). The 8-hour application time led to a significant reduction in muscle spasm (P=0.038) and pain (P = 0.008). Thus, this study suggests that, whilst TENS does not appear to be effective in reducing spasticity, longer applications may be useful in treating MS patients with pain and muscle spasm. Multiple Sclerosis 2007; 13: 527-533. http://msj.sagepub.com

Intrathecal antispastic drug application with implantable pumps: results of a 10 year follow-up study

Since 1986, more than 300 patients received an intrathecal baclofen (ITB) pump for the treatment of severe spasticity. Chronic ITB administration is a safe and effective method, which significantly decreases pathologically exaggerated muscle tone and improves the quality of life in most patients. This therapy is indicated in severe spasticity of cerebral or spinal origin that is unresponsive to oral antispastic medications. It is also useful in patients who may experience intolerable side effects when they receive orally effective baclofen doses. The therapeutic dose required to treat spasticity of cerebral origin is about three times higher than in spasticity of spinal origin. In carefully selected patients who suffer from spasticity, pump implantation is a cost-effective treatment which improves their quality of life. In our series with a follow-up period of 10 years, the ITB dose remained constant and no development of tolerance was observed in most patients. Destructive procedures such as myelotomy are no longer performed in our department in order to treat spasticity.

Cervical Catheter Tip Placement for Intrathecal Baclofen Administration

OBJECTIVE:

Intrathecal baclofen can reduce congenital and posttraumatic spasticity. Traditionally, the catheter tip for baclofen delivery is placed in a low thoracic position, which can result in a lumbar-to-cisternal cerebrospinal fluid baclofen concentration gradient. We investigated whether more rostral catheter placement was technically feasible, safe, and able to control upper extremity spasticity.

METHODS:

The records of 48 patients with a baclofen pump were reviewed retrospectively to evaluate the safety and efficacy of cervically placed intrathecal catheters for baclofen administration. Twenty-three patients had a catheter located in a cervical position and 25 had a catheter in a thoracic position (control group). Complications, including baclofen overdose, mechanical failures, and infections, were noted. Pre- and postoperative Ashworth scores were determined by a physical therapist using a standardized protocol.

RESULTS:

The mean duration of the follow-up period was 10 months. The groups were not significantly different in patient age, baclofen dose, or duration of follow-up, but differed somewhat in the causes of spasticity. For patients with a cervical catheter tip position, upper extremity Ashworth scores decreased significantly from 4.0 ± 0.8 (standard deviation) preoperatively to 3.0 ± 0.9 postoperatively (P = 0.003). In both groups, lower extremity spasticity was significantly reduced. Postoperatively, one patient with a cervical catheter developed aspiration pneumonia, possibly because of sedation. Other complications included hardware infections, mechanical malfunctions, and pseudomeningoceles.

CONCLUSION:

In this series, placement of intrathecal baclofen catheters in the cervical region resulted in equal control of spasticity in the upper and lower extremities and did not increase complications related to the catheter position.

Baclofen: a new drug for the treatment of alcohol dependence

Recent preclinical and clinical studies have suggested that baclofen, the prototypic gamma-aminobutyric acid B (GABA(B)) receptor agonist, is a promising pharmacological compound for use in the treatment of alcohol dependence. In particular, baclofen has been found to suppress symptoms of alcohol withdrawal syndrome with an efficacy comparable with that of the 'gold standard' diazepam. Moreover, baclofen has proven effective in the prevention of relapse due to its ability to reduce alcohol intake and craving in alcoholic patients. Baclofen proved to be manageable, producing no significant side effects and displaying no addictive properties. The efficacy of the drug in the management of both alcohol withdrawal syndrome and relapse prevention should entail a vastly simplified pharmacotherapy of alcohol dependence.

Treatment of dystonia

Dystonia may be a sign or symptom, that is comprised of complex abnormal and dynamic movements of different etiologies. A specific cause is identified in approximately 28% of patients, which only occasionally results in specific treatment. In most cases, treatment is symptomatic and designed to relieve involuntary movements, improve posture and function and reduce associated pain. Therapeutic options are dictated by clinical assessment of the topography of dystonia, severity of abnormal movements, functional impairment and progression of disease and consists of pharmacological, surgical and supportive approaches. Several advances have been made in treatment with newer medications, availability of different forms of botulinum toxin and globus pallidus deep brain stimulation (DBS). For patients with childhood-onset dystonia, the majority of whom later develop generalized dystonia, oral medication is the mainstay of therapy. Recently, DBS has emerged as an effective alternative therapy. Botulinum toxin is usually the treatment of choice for those with adult-onset primary dystonia in which dystonia usually remains focal. In patients with secondary dystonia, treatment is challenging and efficacy is typically incomplete and partially limited by side effects. Despite these treatment options, many patients with dystonia experience only partial benefit and continue to suffer significant disability. Therefore, more research is needed to better understand the underlying cause and pathophysiology of dystonia and to explore newer medications and surgical techniques for its treatment.

Development of GABA-sensitive spasticity and rigidity in rats after transient spinal cord ischemia: a qualitative and quantitative electrophysiological and histopathological study

Transient spinal cord ischemia may lead to a progressive degeneration of spinal interneurons and subsequently to increased hind limb motor tone. In the present work we sought to characterize the rigidity and spasticity components of this altered motor function by: i) tonic electromyographic activity measured in gastrocnemius muscle before and after ischemia, ii) measurement of muscle resistance during the period of ankle flexion and corresponding changes in electromyographic activity, iii) changes in Hoffmann reflex, and, iv) motor evoked potentials. In addition the effect of intrathecal treatment with baclofen (GABAB receptor agonist; 1 microg), nipecotic acid (GABA uptake inhibitor; 300 microg) and dorsal L2-L5 rhizotomy on spasticity and rigidity was studied. Finally, the changes in spinal choline acetyltransferase (ChAT) and vesicular glutamate transporter 2 and 1 (VGLUT2 and VGLUT1) expression were characterized using immunofluorescence and confocal microscopy. At 3-7 days after ischemia an increase in tonic electromyographic activity with a variable degree of rigidity was seen. In animals with modest rigidity a velocity-dependent increase in muscle resistance and corresponding appearance in electromyographic activity (consistent with the presence of spasticity) was measured during ankle rotation (4-612 degrees /s rotation). Measurement of the H-reflex revealed a significant increase in Hmax/Mmax ratio and a significant loss of rate-dependent inhibition. In the same animals a potent increase in motor evoked potential amplitudes was measured and this change correlated positively with the increased H-reflex responses. Spasticity and rigidity were consistently present for a minimum of 3 months after ischemia. Intrathecal treatment with baclofen (GABA B receptor agonist) and nipecotic acid (GABA uptake inhibitor) provided a significant suppression of spasticity, rigidity, H-reflex or motor evoked potentials. Dorsal L2-L5 rhizotomy significantly decreased muscle resistance but had no effect on increased amplitudes of motor evoked potentials. Confocal analysis of spinal cord sections at 8 weeks-12 months after ischemia revealed a continuing presence of ChAT positive alpha-motoneurons, Ia afferents and VGLUT2 and VGLUT1-positive terminals but a selective loss of small presumably inhibitory interneurons between laminae V-VII. These data demonstrate that brief transient spinal cord ischemia in rat leads to a consistent development of spasticity and rigidity. The lack of significant suppressive effect of dorsal L2-L5 rhizotomy on motor evoked potentials response indicates that descending motor input into alpha-motoneurons is independent on Ia afferent couplings and can independently contribute to increased alpha-motoneuronal excitability. The pharmacology of this effect emphasizes the potent role of GABAergic type B receptors in regulating both the spasticity and rigidity.

The GABAB receptor allosteric modulator CGP7930, like baclofen, reduces operant self-administration of ethanol in alcohol-preferring rats

GABA systems have been implicated as targets for ethanol at the cellular, molecular and behavioural level. The present study was designed to further examine the potential of the GABA(B) receptor as a target for regulating operant alcohol responding. Given that the prototypic agonist, baclofen, reduces the self-administration of alcohol, we hypothesized that the GABA(B) receptor allosteric modulator, CGP7930, might have similar actions but a reduced side-effect profile. In this context, inbred alcohol-preferring (iP) rats were trained to respond for 10% v/v ethanol in a fixed ratio paradigm; all drug testing was performed under an FR3 schedule. Both baclofen and CGP7930 independently reduced voluntary responding for 10% ethanol in a dose-related manner. Neither drug impacted upon responding for water. A combination of subthreshold doses of baclofen and CGP7930 was also able to reduce operant responding for ethanol, suggesting that CGP7930 is indeed acting to facilitate GABA(B) receptor-mediated signalling in this paradigm. These data demonstrate the potential of positive allosteric modulators of metabotropic GABA(B) receptors to regulate alcohol responding.

Cerebral palsy: comprehensive review and update

Cerebral palsy (CP) is a common pediatric disorder occurring in about 2 to 2.5 per 1000 live births. It is a chronic motor disorder resulting from a non-progressive (static) insult to the developing brain. CP is the clinical presentation of a wide variety of cerebral cortical or sub-cortical insults occurring during the first year of life. The commonest cause of CP remains unknown in 50% of the cases; prematurity remains the commonest risk factor. Children with CP suffer from multiple problems and potential disabilities such as mental retardation, epilepsy, feeding difficulties, and ophthalmologic and hearing impairments. Screening for these conditions should be part of the initial assessment. The child with CP is best cared for with an individualized treatment plan that provides a combination of interventions. This requires the provision of a number of family-centered services that make a difference in the lives of these children and their families. Management of spasticity can be challenging with a wide variety of possible therapeutic interventions. The treatment must be goal oriented, such as to assist with mobility, reduce or prevent contractures, improve positioning and hygiene, and provide comfort. Each member of the child's multidisciplinary team, including the child and both parents, should participate in the serial evaluations and treatment planning.

Baclofen in the treatment of alcohol withdrawal syndrome: a comparative study vs diazepam

PURPOSE

Benzodiazepines are the drugs of choice in the treatment of alcohol withdrawal syndrome (AWS). Recent data have shown that baclofen may reduce AWS symptoms. At present, no comparative studies between baclofen and any benzodiazepine used in AWS treatment are available. Accordingly, the present study was designed to compare efficacy, tolerability and safety of baclofen versus diazepam in the treatment of AWS.

SUBJECTS AND METHODS

Thirty-seven patients with AWS were enrolled in the study and randomly divided into 2 groups. Baclofen (30 mg/day for 10 consecutive days) was orally administered to 18 patients (15 males, 3 females; median age: 46.5 years). Diazepam (0.5-0.75 mg/kg/day for 6 consecutive days, tapering the dose by 25% daily from day 7 to day 10) was orally administered to 19 patients (17 men, 2 women; median age: 42.0 years). The Clinical Institute Withdrawal Assessment (CIWA-Ar) was used to evaluate physical symptoms of AWS.

RESULTS

Both baclofen and diazepam significantly decreased CIWA-Ar score, without significant differences between the 2 treatments. When CIWA-Ar subscales for sweating, tremors, anxiety and agitation were evaluated singly, treatment with baclofen and diazepam resulted in a significant decrease in sweating, tremors and anxiety score, without significant differences between the 2 drug treatments. Both treatments decreased the agitation score, although diazepam was slightly more rapid than baclofen.

CONCLUSION

The efficacy of baclofen in treatment of uncomplicated AWS is comparable to that of the "gold standard" diazepam. These results suggest that baclofen may be considered as a new drug for treatment of uncomplicated AWS.

Prolonged intrathecal baclofen withdrawal syndrome. Case report and discussion of current therapeutic management

The authors describe a patient who experienced a prolonged course of intrathecal baclofen withdrawal syndrome after removal of an implantable baclofen pump for treatment of pump infection and meningitis. The current literature outlines management options for the acute management of this syndrome. In this report the authors discuss the long-term presentation of this syndrome and suggest a treatment strategy for management of the syndrome. A 37-year-old man who presented with a baclofen pump infection and meningitis experienced acute onset of intrathecal baclofen withdrawal syndrome 12 hours after the pump had been surgically removed. The patient's symptoms evolved into a severe, treatment-refractory withdrawal syndrome lasting longer than 1 month. Oral baclofen replacement with adjunctive administration of parenteral gamma-aminobutyric acid agonists only served to stabilize the patient's critical condition throughout his hospital course. Replacement of the baclofen pump and restoration of intrathecal delivery of the medication was necessary to trigger the patient's dramatic recovery and complete reversal of the withdrawal syndrome within approximately 48 hours. These findings indicate that a more direct method of treating infected baclofen pumps than immediate surgical removal is necessary to prevent the onset of intrathecal baclofen withdrawal syndrome. Various options for preventing the onset of the syndrome while simultaneously treating the infection are discussed.

How many cravings? Pharmacological aspects of craving treatment in alcohol addiction: a review

In the last decade, craving has increasingly been considered an important target for the treatment of patients with alcohol problems, and several drugs able to interfere with the neurotransmitters involved in craving mechanisms have been experimented. However, different subtypes of patients could have different mechanisms at the basis of alcohol craving. In this review, the main drugs currently used in the treatment of patients with alcohol problems are described. A hypothesis of pharmacological treatment of the different types of craving is also discussed.

Safety and Efficacy of GABAergic Medications for Treating Alcoholism

This article highlights the proceedings of a symposium presented at the 27th Annual Scientific Meeting of the Research Society on Alcoholism in Vancouver, British Columbia, Canada, June 29, 2004. The organizers and co-chairs were Bankole A. Johnson, MD, PhD, and Robert M. Swift, MD, PhD. The presentations included (1) Introduction, by Bankole A. Johnson; (2) Safety, Tolerability, and Efficacy of gamma-Hydroxybutyric Acid and Baclofen in the Treatment of Alcohol Addiction, by Giovanni Addolorato; (3) Safety of Gabapentin in Treating Alcoholism, by Hugh Myrick; (4) New Data on the Safety and Effectiveness of Topiramate in the Treatment of Alcohol Dependence, by Bankole A. Johnson; (5) Evaluating the Risk of Benzodiazepine Prescription to Alcohol-Dependent Individuals, by Domenic A. Ciraulo; and (6) Safety and Efficacy of GABAergic Agents in Treating Alcoholics: Discussion, by Robert M. Swift.

Carbamazepine toxicity following Oxybutynin and Dantrolene administration: a case report

OBJECTIVE

To report a case of Carbamazepine toxicity following the administration of Oxybutynin and Dantrolene.

STUDY DESIGN

A case report.

SETTING

The Spinal Rehabilitation Department, Loewenstein Hospital, Raanana, Israel.

METHODS

A patient with C6D tetraplegia who sustained intoxication because of drug interaction is presented. She had been treated by Carbamazepine 1000 mg/day for neuropathic pain for 2 years without clinical or laboratory signs of toxicity. After administration of Oxybutynin concomitantly with an increase in the dose of Dantrolene, she presented the clinical symptoms and laboratory finding of Carbamazepine intoxication. Trying to adjust the treatment to the patient's requirements, Carbamazepine together with Oxybutynin and Dantrolene was readministrated in lower doses.

RESULTS

The combination of these drugs, even small doses, caused toxicity. Adding Dantrolene and Oxybutynin elevated the blood level of Carbamazepine, possibly by inhibition of cytochrome P450.

CONCLUSION

A possible pharmacokinetic interaction between Dantrolene and Oxybutynin should be borne in mind when considering Carbamazepine medication for a patient with a spinal cord lesion.

Effects of baclofen on spinal reflexes and persistent inward currents in motoneurons of chronic spinal rats with spasticity

In the months after spinal cord injury, motoneurons develop large voltage-dependent persistent inward currents (PICs) that cause sustained reflexes and associated muscle spasms. These muscle spasms are triggered by any excitatory postsynaptic potential (EPSP) that is long enough to activate the PICs, which take > 100 ms to activate. The PICs are composed of a persistent sodium current (Na PIC) and a persistent calcium current (Ca PIC). Considering that Ca PICs have been shown in other neurons to be inhibited by baclofen, we tested whether part of the antispastic action of baclofen was to reduce the motoneuron PICs as opposed to EPSPs. The whole sacrocaudal spinal cord from acute spinal rats and spastic chronic spinal rats (with sacral spinal transection 2 mo previously) was studied in vitro. Ventral root reflexes were recorded in response to dorsal root stimulation. Intracellular recordings were made from motoneurons, and slow voltage ramps were used to measure PICs. Chronic spinal rats exhibited large monosynaptic and long-lasting polysynaptic ventral root reflexes, and motoneurons had associated large EPSPs and PICs. Baclofen inhibited these reflexes at very low doses with a 50% inhibition (EC50) of the mono- and polysynaptic reflexes at 0.26 +/- 0.07 and 0.25 +/- 0.09 (SD) microM, respectively. Baclofen inhibited the monosynaptic reflex in acute spinal rats at even lower doses (EC50 = 0.18 +/- 0.02 microM). In chronic (and acute) spinal rats, all reflexes and EPSPs were eliminated with 1 microM baclofen with little change in motoneuron properties (PICs, input resistance, etc), suggesting that baclofen's antispastic action is presynaptic to the motoneuron. Unexpectedly, in chronic spinal rats higher doses of baclofen (20-30 microM) significantly increased the total motoneuron PIC by 31.6 +/- 12.4%. However, the Ca PIC component (measured in TTX to block the Na PIC) was significantly reduced by baclofen. Thus baclofen increased the Na PIC and decreased the Ca PIC with a net increase in total PIC. By contrast, when a PIC was induced by 5-HT (10-30 microM) in motoneurons of acute spinal rats, baclofen (20-30 microM) significantly decreased the PIC by 38.8 +/- 25.8%, primarily due to a reduction in the Ca PIC (measured in TTX), which dominated the total PIC in these acute spinal neurons. In summary, baclofen does not exert its antispastic action postsynaptically at clinically achievable doses (< 1 microM), and at higher doses (10-30 microM), baclofen unexpectedly increases motoneuron excitability (Na PIC) in chronic spinal rats.

Efectividad de la gabapentina en el tratamiento de la espasticidad: estudio aleatorizado, a doble ciego y controlado con placebo

BACKGROUND AND OBJECTIVE

We aimed to demonstrate the efficacy and safety of gabapentin for the treatment of spasticity in patients with upper motor neuron syndrome.

PATIENTS AND METHOD

Thirty patients with pyramidal-tract lesions were randomized to up to 3,600 mg/day of gabapentin (n = 15) or placebo (n = 15) in a double-blind, pilot 10-week trial. The primary efficacy variable was the Ashworth Scale score. Secondary variables included the Spasm Frequency Scale, maximal range of movement, H/M Amplitude Ratio, and the Barthel Index for quality of life. Adverse events were recorded. All data were analyzed on an intent-to-treat basis.

RESULTS

Demographic and baseline characteristics were similar between the 2 treatment groups. The gabapentin group showed significant improvement in Ashworth Scale total scores, and scores for individual affected muscle groups. Fifteen of the randomized patients had spasms; the total Spasm Frequency Scale score was not significantly different between groups. Nevertheless, when affected individual muscle groups were analyzed, a significant effect of gabapentin vs placebo was observed at all visits. Gabapentin did not modify the scores of the range of movement, the H/M Amplitude Ratio, or the Barthel Index tests. No gait or displacement impairment were seen during treatment with gabapentin. Related adverse events occurred less frequently in the gabapentin group, and fewer gabapentin patients withdrew because of adverse events.

CONCLUSIONS

Gabapentin demonstrated efficacy and safety at doses between 2,700 and 3,600 mg/day as a therapy for the spasticity associated with the upper motor neuron syndrome.

COMPLETE AND PROLONGED SUPPRESSION OF SYMPTOMS AND CONSEQUENCES OF ALCOHOL-DEPENDENCE USING HIGH-DOSE BACLOFEN: A SELF-CASE REPORT OF A PHYSICIAN

AIMS

To test whether the dose-dependent motivation-suppressing effect of baclofen in animals could be transposed to humans, and suppress craving and sustain abstinence.

METHODS

Neurologists safely use up to 300 mg/day (10 times the dosage currently used for alcohol dependence) of high-dose oral baclofen, to control spasticity, in order to avoid invasive therapy. I am a physician with alcohol dependence and comorbid anxiety. I self-prescribed high-dose baclofen, starting at 30 mg/day, with 20 mg increments every third day and an (optional) additional 20-40 mg/day for cravings.

RESULTS

Cravings became easier to combat. After reaching the craving-suppression dose of 270 mg/day (3.6 mg/kg) after 5 weeks, I became and have remained free of alcohol dependence symptoms effortlessly for the ninth consecutive month. Anxiety is well controlled. Somnolence disappeared with a dosage reduction to 120 mg/day, now used for the eighth consecutive month.

CONCLUSIONS

High-dose baclofen induced complete and prolonged suppression of symptoms and consequences of alcohol dependence, and relieved anxiety. This model, integrating cure and well-being, should be tested in randomized trials, under medical surveillance. It offers a new concept: medication-induced, dose-dependent, complete and prolonged suppression of substance-dependence symptoms with alleviation of comorbid anxiety.

Neurophysiologic evaluation of spastic hypertonia: implications for management of the patient with the intrathecal baclofen pump

A number of techniques attempt to objectively quantify various clinical characteristics associated with spastic hypertonia and related motor disorders. These range in cost, complexity, physiologic basis of measured response, and invasiveness. With a greater range of treatment options for spasticity and an increase in the number of centers participating in studies of interventions for spasticity, published reports reflect increasing use of objective quantification techniques. We review studies that highlight the potential utility of neurophysiologic techniques, including the H-reflex, F-wave, and flexion withdrawal reflex, in the objective evaluation of response to intrathecal baclofen administration. The accumulated knowledge suggests that neurophysiologic evaluation is useful for assessing spinal cord responsiveness, and we recommend it as an adjunct to clinical evaluation when judging the overall effectiveness of intrathecal baclofen administration.

A benefit-risk assessment of baclofen in severe spinal spasticity

Baclofen is used for treatment of the spasticity of spinal origin that is a common sequela of spinal cord injury and multiple sclerosis; spasticity occurs in about 50% of patients affected by these disorders. In open-label studies of oral baclofen, the drug improved spasticity in 70-87% of patients; additionally, improvement in spasms was reported in 75-96% of patients. In double-blind, crossover, placebo-controlled trials, baclofen was reported to be effective, producing statistically significant improvements in spasticity. Tizanidine is the antispasticity drug that has been most widely compared with oral baclofen; studies have generally found the two drugs to have equivalent efficacy. However, tizanidine has better tolerability, in particular weakness was reported to be occur less frequently with tizanidine than with baclofen. The main adverse effects of oral baclofen include: sedation or somnolence, excessive weakness, vertigo and psychological disturbances. The incidence of adverse effects is reported to range from 10% to 75%. The majority of adverse effects are not severe; most are dose related, transient and/or reversible. The main risks of oral baclofen administration are related to withdrawal: seizures, psychic symptoms and hyperthermia can occur. These symptoms improve after the reintroduction of baclofen, usually without sequelae. When not related to withdrawal; these symptoms mainly present in patients with brain damage and in the elderly. The limited data on baclofen toxicity in patients with renal disease suggest that administration of the drug in these persons may carry an unnecessarily high risk. Intrathecal baclofen is indicated for use in patients with spasticity of spinal origin unresponsive to treatment with maximum doses of oral baclofen, tizanidine and/or dantrolene. The benefits of continuous intrathecal baclofen infusion have been demonstrated: >80% and >65% of patients have improvement in tone and spasms, respectively. The main risks of intrathecal baclofen infusion are symptoms related to overdose or withdrawal; the latter is more important because of the associated severe effects on clinical status and the possibility of death, but it is responsive to rapid treatment. Overdose primarily arises from drug test doses or human error during refill and programming of the pump, and withdrawal most commonly occurs as a result of a problem with the delivery system. Since the adverse consequences do not exceed the benefits of oral and intrathecal baclofen for patients with spinal spasticity, the benefit/risk assessment is favourable.

Comparative efficacy and safety of skeletal muscle relaxants for spasticity and musculoskeletal conditions: a systematic review

Skeletal muscle relaxants are a heterogeneous group of medications used to treat two different types of underlying conditions: spasticity from upper motor neuron syndromes and muscular pain or spasms from peripheral musculoskeletal conditions. Although widely used for these indications, there appear to be gaps in our understanding of the comparative efficacy and safety of different skeletal muscle relaxants. This systematic review summarizes and assesses the evidence for the comparative efficacy and safety of skeletal muscle relaxants for spasticity and musculoskeletal conditions. Randomized trials (for comparative efficacy and adverse events) and observational studies (for adverse events only) that included oral medications classified as skeletal muscle relaxants by the FDA were sought using electronic databases, reference lists, and pharmaceutical company submissions. Searches were performed through January 2003. The validity of each included study was assessed using a data abstraction form and predefined criteria. An overall grade was allocated for the body of evidence for each key question. A total of 101 randomized trials were included in this review. No randomized trial was rated good quality, and there was little evidence of rigorous adverse event assessment in included trials or observational studies. There is fair evidence that baclofen, tizanidine, and dantrolene are effective compared to placebo in patients with spasticity (primarily multiple sclerosis). There is fair evidence that baclofen and tizanidine are roughly equivalent for efficacy in patients with spasticity, but insufficient evidence to determine the efficacy of dantrolene compared to baclofen or tizanidine. There is fair evidence that although the overall rate of adverse effects between tizanidine and baclofen is similar, tizanidine is associated with more dry mouth and baclofen with more weakness. There is fair evidence that cyclobenzaprine, carisoprodol, orphenadrine, and tizanidine are effective compared to placebo in patients with musculoskeletal conditions (primarily acute back or neck pain). Cyclobenzaprine has been evaluated in the most clinical trials and has consistently been found to be effective. There is very limited or inconsistent data regarding the effectiveness of metaxalone, methocarbamol, chlorzoxazone, baclofen, or dantrolene compared to placebo in patients with musculoskeletal conditions. There is insufficient evidence to determine the relative efficacy or safety of cyclobenzaprine, carisoprodol, orphenadrine, tizanidine, metaxalone, methocarbamol, and chlorzoxazone. Dantrolene, and to a lesser degree chlorzoxazone, have been associated with rare serious hepatotoxicity.

Spinal cord injury and use of botulinum toxin in reducing spasticity

Spasticity is commonly seen after spinal cord injury, and a large percentage of patients with spinal cord injury will need treatment to control it. Although oral medications do a fair job of controlling spasticity in most patients, some patients will need additional forms of treatment. In many cases, oral medications alone do not adequately control spasticity or the patient cannot tolerate the side effects. In these instances, botulinum toxin may help control the spasticity for approximately 3 months after injection. The amount of botulinum toxin and the injection sites can be tailored to meet individual patient needs. Botulinum toxins can reduce spasticity, improve function, and reduce the amount of needed assistance.

Baclofen antagonizes nicotine-, cocaine-, and morphine-induced dopamine release in the nucleus accumbens of rat

Evidence recently provided has suggested a specific involvement of the GABAergic system in modulating positive reinforcing properties of several drugs of abuse through an action on mesolimbic dopaminergic neurons. The GABA(B) receptor agonist baclofen has been proposed as a potential therapeutic agent for the clinical treatment of several forms of drug addiction. In the present study, using the in vivo microdialysis technique, we investigated the effect of baclofen on nicotine, cocaine, and morphine-induced increase in extracellular dopamine (DA) levels in the shell of the nucleus accumbens, a brain area supposedly involved in the modulation of the central effects of several drugs of abuse, of freely moving rats. As expected, nicotine (0.6 mg/kg s.c.), morphine (5 mg/kg s.c.), and cocaine (7.5 mg/kg i.p.) administration in rats induced a marked increase in extracellular DA concentrations in the nucleus accumbens, reaching a maximum value of +205 +/- 8.4%, +300 +/- 22.2%, and +370 +/- 30.7%, respectively. Pretreatment with baclofen (1.25 and 2.5 mg/kg i.p.) dose-dependently reduced the nicotine-, morphine-, and cocaine-evoked DA release in the shell of the nucleus accumbens. Furthermore, baclofen alone did not elicit changes in basal DA extracellular levels up to 180 min. Taken together, our data are in line with previous reports demonstrating the ability of baclofen to modulate the mesolimbic DAergic transmission and indicate baclofen as a putative candidate in the pharmacotherapy of polydrug abuse.

Suppression of Alcohol Delirium Tremens by Baclofen Administration: A Case Report

Delirium tremens (DT) is a clinical condition that appears in some patients affected by severe alcohol withdrawal syndrome (AWS). DT represents a serious complication, being characterized by elevated morbidity and mortality. Benzodiazepines are presently the drug of choice; however their use is related to several side effects. Baclofen is a stereoselective gamma-aminobutyric acid (GABAB) receptor agonist. Recent studies show that baclofen is able to suppress alcohol withdrawal symptoms. At present there are no data on the effects of baclofen administration in AWS complicated by DT. Here, we report a case of DT successfully treated with baclofen. This result indicates that the efficacy of baclofen in the treatment of DT should be examined in future clinical trials.

Pharmacokinetics of a single oral dose of baclofen in pediatric patients with gastroesophageal reflux disease

Transient relaxation of the lower esophageal sphincter (TLESR) is the predominant mechanism of gastroesophageal reflux (GER) in adults and children. Baclofen [4-amino-3-(p-chlorophenyl)-butanoic acid], a gamma-aminobutyric acid (GABA)-B receptor agonist used for the management of spasticity, has been recently shown to significantly inhibit GER in healthy adults without any relevant side effects. The objective of this study was to evaluate the pharmacokinetics of baclofen in a pediatric population with GER disease. In an open-label single-dose pharmacokinetic study, eight children with the diagnosis of GER made on clinical grounds received an oral dose of baclofen, 2.5 mg. Blood samples were drawn from an indwelling venous catheter, and urine was collected during a postdose period of 8 hours. The concentration of baclofen in these body fluids was determined using a validated high-performance liquid chromatography (HPLC) method with electrochemical detection after OPA-sulfite derivatization. Pharmacokinetic data were analyzed using the nonlinear regression program Scientist. Serum concentration-time curves could be best described using a two-compartment open model with a lag time. Mean plasma clearance (Cl) was 315.9 mL/h/kg; volume of distribution (Vd) was 2.58 L/kg; and half-life (T(1/2)beta) was 5.10 hours. No side effects were noted. As half-lives were comparable with those found in adult studies, the risk for accumulation seems not greater in children than in adults. Body composition can have a strong influence on the Vd of baclofen and, therefore, on the dose needed to obtain therapeutic plasma levels. Dosing according to clearly defined age groups with the help of therapeutic drug monitoring seems preferable. In view of the negative correlation between body weight and Vd, dosing according to body weight using adult pharmacokinetic data does not seem an effective way for using baclofen in children.

Reversible coma in children after improper baclofen pump insertion

We report the occurrence of delayed postoperative coma in five of nine consecutive children following surgery for insertion of baclofen infusion pumps. We suspect that improper technique resulted in an inadvertent administration of an intrathecal baclofen bolus. We suggest ways to minimize this risk.

Open-label dose-titration safety and efficacy study of tizanidine hydrochloride in the treatment of spasticity associated with chronic stroke

BACKGROUND AND PURPOSE

Spasticity is a frequently observed motor impairment that develops after stroke; it can cause pain and disability in those affected. The objective of the present study was to evaluate the safety and efficacy of tizanidine, a centrally acting alpha(2)-adrenergic agonist, in the treatment of stroke-related spasticity.

METHODS

Forty-seven patients, who were a minimum of 6 months poststroke and had significant spasticity, were studied at 4 centers. Tizanidine was administered in an open-label manner for 16 weeks, beginning at 2 mg/d and slowly titrated to a maximum of 36 mg/d. The Modified Ashworth Scale, muscle strength testing, functional assessments, and Pain and Functional Spasticity Questionnaires were administered at baseline and at 4, 8, 16, and 18 weeks (after 1 week off tizanidine).

RESULTS

Spasticity was significantly improved between baseline and week 16, with a decrease in total upper extremity Modified Ashworth Scale score of 2.80+/-0.47 (P<0.0001). No decline in strength was noted. Treatment with tizanidine resulted in a significant improvement in pain intensity (P=0.0375), quality of life (P=0.0001), and physician assessment of disability (P=0.0001). The most frequent side effects were somnolence (62%) and dizziness (32%). No serious adverse events were considered to be drug related. Ten of 47 patients (21%) were able to reach the maximum daily dosage of 36 mg.

CONCLUSIONS

Overall, the data suggest that tizanidine is safe and efficacious in the treatment of stroke-related spasticity, preserving muscle strength while reducing muscle tone and painful spasms in affected patients.

The use of baclofen in cluster headache

Cluster headache is a rare, clinically well-characterized disabling disorder that occurs in both episodic and chronic forms. The very painful short-lived unilateral headache attacks are associated with autonomic dysfunction. A large number of drugs such as ergotamines, steroids, methysergide, lithium carbonate, verapamil, valproate, capsaicin, leuprolide, clonidine, methylergovine maleate, methylphenidate, and melatonin are considered beneficial for prophylaxis. Nevertheless, this extremely painful condition is occasionally refractory to conventional treatment. The antispastic agent baclofen has been shown to possess an antinociceptive activity. Its efficacy in neuralgias, central pain following spinal lesions, painful strokes, migraine, and medication misuse chronic daily headache suggests that it may be useful for prevention of cluster headache attacks. Therefore, we treated 16 symptomatic patients with cluster headache with daily baclofen, 15 to 30 mg, in three divided doses for the cluster period and 2 weeks after. Within a week, 12 patients reported the cessation of attacks. One was substantially better and became attack free by the end of the following week. In the remaining three patients, the attacks worsened and corticosteroids were prescribed. One of these was also given verapamil. Three of the 16 patients had an additional cluster period, which cleared with a second course of baclofen. In this pilot study, baclofen seemed to be effective, safe, and well tolerated for cluster headache, and seemed to retain its efficacy on repeated clusters.

Pharmacotherapy of spasticity: oral medications and intrathecal baclofen

Spasticity is a common problem in children with neurologic impairment, particularly in those with cerebral palsy. Clinicians commonly make use of oral medications to attempt to reduce spasticity and increase function. Little has been published in the literature concerning the use of these medications in children and their effects on both muscle tone and function. This article is a review of the sites of action, side effects, and efficacy of benzodiazepines, baclofen, dantrolene sodium, alpha2-adrenergic agonists, and gabapentin. A brief review of intrathecal baclofen is included as well.

Hip Spasticity and Strength in Children with Spastic Diplegia Cerebral Palsy

Hip spasticity and strength from 44 children with cerebral palsy (CP) and 44 children with able bodies (AB) were compared. For spasticity, a KinCom dynamometer abducted the passive hip at 4 different speeds and recorded the resistive adductor torques. Work values for the torque-angle data were calculated at each speed. Linear regression derived the slope for the line of best fit for the work-velocity data to determine the spasticity measure. For strength, the KinCom rotated the hip from maximum adduction to maximum abduction at a speed of 10°/s while the child performed a maximum abduction concentric contraction. Tests were reversed to record maximum adduction. Maximum torques and work by the abductors and adductors were calculated. Spasticity in the adductors for the CP group was significantly greater than values recorded for the AB group. All strength measures were significantly less than the AB group. Results provide objective information, quantifying hip spasticity and strength in children with CP.

Drugs used to treat spasticity

Spasticity is a common and disabling symptom for many patients with upper motor neuron dysfunction. It results from interruption of inhibitory descending spinal motor pathways, and although the pathophysiology of spasticity is poorly understood, the final common pathway is overactivity of the alpha motor neuron. Therapy for spasticity is symptomatic with the aim of increasing functional capacity and relieving discomfort. Any approach to treatment should be multidisciplinary, including physical therapy, and possibly surgery, as well as pharmacotherapy. It is important that treatment be tailored to the individual patient, and that both patient and care giver have realistic expectations. Pharmacotherapy is generally initiated at low dosages and then gradually increased in an attempt to avoid adverse effects. Optimal therapy is the lowest effective dosage. Baclofen, diazepam, tizanidine and dantrolene are currently approved for use in patients with spasticity. In addition, clonidine (usually as combination therapy), gabapentin and botulinum toxin have shown efficacy, however, more studies are required to confirm their place in therapy. Intrathecal baclofen, via a surgically implanted pump and reservoir, may provide relief in patients with refractory severe spasticity.

Tizanidine in the management of spasticity and musculoskeletal complaints in the palliative care population

Spasticity and other muscle symptoms in the palliative care patient can contribute to suffering, significantly detracting from overall quality of life. Current therapy primarily includes use of centrally acting muscle relaxants, which are beneficial in treating some symptoms, but frequently have extensive side effects, such as sedation and muscle weakness. Tizanidine, a central alpha 2 adrenergic agonist, has been shown in clinical studies to be as effective as other commonly used antispastic agents, but without debilitating muscle weakness. Tizanidine can cause sedation, which is minimized by dose titration. When taken at night, patients report improvement in getting to sleep and little drowsiness or "hangover sensation" upon waking. Tizanidine is potentially helpful to many palliative care patients with chronic muscle pain and sleep disturbances.