On the site of action of diazepam in spasticity in man

GABA-stimulated adipose-derived stem cells suppress subcutaneous adipose inflammation in obesity

Accumulating evidence suggests that subcutaneous and visceral adipose tissues are differentially associated with metabolic disorders. In obesity, subcutaneous adipose tissue is beneficial for metabolic homeostasis because of repressed inflammation. However, the underlying mechanism remains unclear. Here, we demonstrate that γ-aminobutyric acid (GABA) sensitivity is crucial in determining fat depot-selective adipose tissue macrophage (ATM) infiltration in obesity. In diet-induced obesity, GABA reduced monocyte migration in subcutaneous inguinal adipose tissue (IAT), but not in visceral epididymal adipose tissue (EAT). Pharmacological modulation of the GABA_B receptor affected the levels of ATM infiltration and adipose tissue inflammation in IAT, but not in EAT, and GABA administration ameliorated systemic insulin resistance and enhanced insulin-dependent glucose uptake in IAT, accompanied by lower inflammatory responses. Intriguingly, compared with adipose-derived stem cells (ADSCs) from EAT, IAT-ADSCs played key roles in mediating GABA responses that repressed ATM infiltration in high-fat diet-fed mice. These data suggest that selective GABA responses in IAT contribute to fat depot-selective suppression of inflammatory responses and protection from insulin resistance in obesity.

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.

Oral pharmacotherapy for the movement disorders of cerebral palsy

Movement disorders are a well-recognized feature of some patients with cerebral palsy and often require treatment. However, treatments have been symptomatic and empiric, and there have been few pharmacologic studies. The major movement disorders in cerebral palsy are dystonia and the hyperkinesias choreoathetosis and myoclonus. They may occur in combination, often accompanied by spasticity and sometimes by epilepsy. Some drugs are useful treatments for all of these problems, but others may improve one while worsening another. Pitfalls in management include not diagnosing metabolic/degenerative disorders, which may mimic cerebral palsy, or not recognizing reversible complications of cerebral palsy, which may exacerbate symptoms. This review attempts to summarize empiric drug use and recommendations for therapy, drug studies in extrapyramidal cerebral palsy, and prospects for new drugs or models for the problem. Many new pharmacologic agents are available for study in cerebral palsy. Better methods of detecting basal ganglia injury after perinatal injury in asymptomatic infants may allow early intervention in the biologic process of recovery and adaptation.

Pharmacotherapy of spasticity: some theoretical and practical considerations

The availability of new antispasticity agents has greatly extended the therapeutic arm of the neurologist and has obviated the need for destructive neurosurgical procedures in many instances. Baclofen remains the single most useful agent, but in certain circumstances, benzodiazepines and dantrolene sodium are useful alternative or adjunctive treatments. Tizanidine has been recently introduced, and early experience with this agent appears to be favourable. A variety of new drugs are awaiting further evaluation. The effective use of these agents demands an understanding of their principal mechanisms of action, knowledge of their predictable side effects, and a familiarity with the underlying neurological disorders. The monitoring of clinical efficacy is difficult and is often dependent upon subjective evaluation. The application of electrophysiological studies might facilitate the monitoring of treatment and the prediction of optimum treatment strategies for individual patients. The use of these pharmacological agents, from the perspective of a clinician, will be discussed.

Antispasticity drugs: mechanisms of action

Several different drugs are now used, or are potentially useful, to treat patients with spasticity. Although these compounds vary in their actions on spinal neurons and reflex arcs, it is possible to formulate reasonable hypotheses regarding their modes of action. The benzodiazepines bind to specific benzodiazepine receptors linked to classic gamma-aminobutyric acid (GABA) receptors located on the terminals of primary afferent fibers. This binding results in an increased affinity of the GABA receptor for the amino acid, an augmented flux of chloride ions across the terminal membrane, and an increase in the amount of presynaptic inhibition. Baclofen activates GABAB receptors putatively located on the same terminals. Activation of these receptors retards the influx of calcium ions into the terminals, thereby reducing the evoked release of excitatory amino acids and possibly other transmitters. Progabide and its metabolites act on both classic and GABAB receptors. Glycine works on specific inhibitory receptors located on spinal interneurons and motoneurons. The phenothiazines act on the brainstem to alter the function of fusimotor fibers. Phenytoin and carbamazepine reduce the afferent output of muscle spindles. Dantrolene diminishes the activation of the contractile process in muscle fibers by reducing the release of calcium ions from the sarcoplasmic reticulum. This review summarizes the data supporting these concepts.

The effect of diazepam on presynaptic inhibition in patients with complete and incomplete spinal cord lesions

The effect of diazepam on presynaptic inhibition in man has been examined in 5 patients with complete spinal transections and 7 patients with incomplete lesions. The inhibition of the H reflex by vibration applied to the tendo Achilles was used to assess presynaptic inhibition of the Ia monosynaptic pathway. Diazepam increased this inhibition in the patients with incomplete lesions, but had no significant effect on the inhibition in the patients with complete spinal transections. Evidently diazepam can enhance presynaptic inhibition in man. The effect, however, cannot be demonstrated in patients with longstanding complete spinal lesions possibly because of some alteration in the segmental presynaptic inhibitory mechanism in this group.

Pharmacology of M & B 18,706, a drug which selectively reduces decerebrate rigidity

1 (+/-)-10-(3-Dimethylamino-2-methylpropyl)-2-valeroylphenothiazine hydrochloride (M & B 18,706) has been compared with dimethothiazine, chloropromazine, diazepam and baclofen for potency in reducing decerebrate rigidity in the cat and rat and for activity in causing ataxia or sedation.2 When given intravenously M & B 18,706 had seven times the potency of dimethothiazine and one-half the potency of chlorpromazine in reducing the rigidity of the intercollicular decerebrate cat. When administered orally M & B 18,706 and chlorpromazine were equi-potent in reducing rigidity but M & B 18,706 was less effective than chlorpromazine in producing ataxia in this species.3 In the rat, M & B 18,706 had one-quarter the potency of chlorpromazine for reducing decerebrate rigidity but had from 1/20th to 1/200th its potency in tests for sedative or tranquillizing activity.4 M & B 18,706, like dimethothiazine and chlorpromazine, had little effect on the rigidity of ischaemic decerebrate cats and failed to inhibit polysynaptic spinal reflexes.5 M & B 18,706 had intravenous potency comparable to chlorpromazine in reducing the pressor action of noradrenaline in the spinal cat.

A clinical and statistical study of the phases of electroplexy

In a previous paper (Tresise and Stenhouse, 1968a), the authors quantitated the normal time response patterns in the phases of electroplexy, where the four anaesthetics, methohexitone sodium, thiopentone, amylobarbitone sodium and diazepam were used in sub-anaesthetic doses. Patients treated without anaesthesia were included in the study. The dependence of the times of subsequent events on the time of clonus onset in the orbicularis oculi muscles were also established. The statistical technique employed in that study was simple linear regression. The interrelationships between the various factors indicated the desirability of extending the study by the use of multiple regression techniques. This paper presents the results of the extended study.

Baclofen in the treatment of spasticity

Baclofendagger (Lioresal), a derivative of gamma-aminobutyric acid, was introduced in 1966 as a possible treatment for spasticity due to corticospinal tract lesions. Preliminary studies suggested that it may be more effective than other spasmolytic agents currently available, and a double-blind controlled trial in a group of 23 patients against placebo has shown it to be significantly more effective.

A new agent for the control of spasticity

In a preliminary controlled trial, CIBA 34,647-Ba, a gamma aminobutyric acid derivative, was found to be more effective than placebo in reducing spasticity due to spinal injuries. In an uncontrolled trial, 34,647-Ba also appeared more effective than diazepam. The intensity of spasticity was measured electromyographically by the amplitude of the stretch reflex at various velocities, and the results were correlated with those obtained by clinical assessment. 34,647-Ba was effective in both complete and incomplete spinal cord lesions and it is suggested that it has an action at the spinal level. No significant side-effects were encountered.