Baclofen (Lioresal) in the treatment ofneuroleptic-induced tardive dyskinesia

GABAB Receptor Chemistry and Pharmacology: Agonists, Antagonists, and Allosteric Modulators

The GABA_B receptors are metabotropic G protein-coupled receptors (GPCRs) that mediate the actions of the primary inhibitory neurotransmitter, γ-aminobutyric acid (GABA). In the CNS, GABA plays an important role in behavior, learning and memory, cognition, and stress. GABA is also located throughout the gastrointestinal (GI) tract and is involved in the autonomic control of the intestine and esophageal reflex. Consequently, dysregulated GABA_B receptor signaling is associated with neurological, mental health, and gastrointestinal disorders; hence, these receptors have been identified as key therapeutic targets and are the focus of multiple drug discovery efforts for indications such as muscle spasticity disorders, schizophrenia, pain, addiction, and gastroesophageal reflex disease (GERD). Numerous agonists, antagonists, and allosteric modulators of the GABA_B receptor have been described; however, Lioresal^® (Baclofen; β-(4-chlorophenyl)-γ-aminobutyric acid) is the only FDA-approved drug that selectively targets GABA_B receptors in clinical use; undesirable side effects, such as sedation, muscle weakness, fatigue, cognitive deficits, seizures, tolerance and potential for abuse, limit their therapeutic use. Here, we review GABA_B receptor chemistry and pharmacology, presenting orthosteric agonists, antagonists, and positive and negative allosteric modulators, and highlight the therapeutic potential of targeting GABA_B receptor modulation for the treatment of various CNS and peripheral disorders.

Management of Tardive Syndrome: Medications and Surgical Treatments

Tardive syndrome (TS) is an iatrogenic, often persistent movement disorder caused by drugs that block dopamine receptors. It has a broad phenotype including movement (orobuccolingual stereotypy, dystonia, tics, and others) and nonmotor features (akathisia and pain). TS has garnered increased attention of late because of the Food and Drug Administration approval of the first therapeutic agents developed specifically for this purpose. This paper will begin with a discussion on pathogenesis, clinical features, and epidemiology. However, the main focus will be treatment options currently available for TS including a suggested algorithm based on current evidence. Recently, there have been significant advances in TS therapy, particularly with the development of 2 new vesicular monoamine transporter type 2 inhibitors for TS and with new data on the efficacy of deep brain stimulation. The discussion will start with switching antipsychotics and the use of clozapine monotherapy which, despite the lack of higher-level evidence, should be considered for the treatment of psychosis and TS. Anti-dyskinetic drugs are separated into 3 tiers: 1) vesicular monoamine transporter type 2 inhibitors, which have level A evidence, are approved for use in TS and are recommended first-choice agents; 2) drugs with lower level of evidence for efficacy including clonazepam, Ginkgo biloba, and amantadine; and 3) drugs that have the potential to be beneficial, but currently have insufficient evidence including levetiracetam, piracetam, vitamin B6, melatonin, baclofen, propranolol, zolpidem, and zonisamide. Finally, the roles of botulinum toxin and surgical therapy will be examined. Current therapies, though improved, are symptomatic. Next steps should focus on the prevention and reversal of the pathogenic process.

Gamma-aminobutyric acid agonists for antipsychotic-induced tardive dyskinesia

BACKGROUND

Chronic antipsychotic drug treatment may cause tardive dyskinesia (TD), a long-term movement disorder. Gamma-aminobutyric acid (GABA) agonist drugs, which have intense sedative properties and may exacerbate psychotic symptoms, have been used to treat TD.

OBJECTIVES

1. Primary objectiveThe primary objective was to determine whether using non-benzodiazepine GABA agonist drugs for at least six weeks was clinically effective for the treatment of antipsychotic-induced TD in people with schizophrenia, schizoaffective disorder or other chronic mental illnesses.2. Secondary objectivesThe secondary objectives were as follows.To examine whether any improvement occurred with short periods of intervention (less than six weeks) and, if this did occur, whether this effect was maintained at longer periods of follow-up.To examine whether there was a differential effect between the various compounds.To test the hypothesis that GABA agonist drugs are most effective for a younger age group (less than 40 years old).

SEARCH METHODS

We searched the Cochrane Schizophrenia Group Trials Register (last searched April 2017), inspected references of all identified studies for further trials, and, when necessary, contacted authors of trials for additional information.

SELECTION CRITERIA

We included randomised controlled trials of non-benzodiazepine GABA agonist drugs in people with antipsychotic-induced TD and schizophrenia or other chronic mental illness.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected and critically appraised studies, extracted and analysed data on an intention-to-treat basis. Where possible and appropriate we calculated risk ratios (RRs) and their 95% confidence intervals (CIs). For continuous data we calculated mean differences (MD). We assumed that people who left early had no improvement. We contacted investigators to obtain missing information. We assessed risk of bias for included studies and created a 'Summary of findings' table using GRADE.

MAIN RESULTS

We included 11 studies that randomised 343 people. Overall, the risk of bias in the included studies was unclear, mainly due to poor reporting; allocation concealment was not described, generation of the sequence was not explicit, participants and outcome assessors were not clearly blinded. For some studies we were unsure if data were complete, and data were often poorly or selectively reported.Data from six trials showed that there may be a clinically important improvement in TD symptoms after GABA agonist treatment compared with placebo at six to eight weeks follow-up (6 RCTs, n = 258, RR 0.83, CI 0.74 to 0.92; low-quality evidence). Data from five studies showed no difference between GABA agonist treatment and placebo for deterioration of TD symptoms (5 RCTs, n = 136, RR 1.90, CI 0.70 to 5.16; very low-quality evidence). Studies reporting adverse events found a significant effect favouring placebo compared with baclofen, sodium valproate or progabide for dizziness/confusion (3 RCTs, n = 62 RR 4.54, CI 1.14 to 18.11; very low-quality evidence) and sedation/drowsiness (4 RCTS, n = 144, RR 2.29, CI 1.08 to 4.86; very low-quality evidence). Studies reporting on akathisia (RR 1.05, CI 0.32 to 3.49, 2 RCTs, 80 participants), ataxia (RR 3.25, CI 0.36 to 29.73, 2 RCTs, 95 participants), nausea/vomiting (RR 2.61, CI 0.79 to 8.67, 2 RCTs, 64 participants), loss of muscle tone (RR 3.00, CI 0.15 to 59.89, 1 RCT, 10 participants), seizures (RR 3.00, CI 0.24 to 37.67, 1 RCT, 2 participants), hypotension (RR 3.04, CI 0.33 to 28.31, 2 RCTs, 119 participants) found no significant difference between GABA drug and placebo (very low-quality evidence). Evidence on mental state also showed no effect between treatment groups (6 RCTS, n = 121, RR 2.65, CI 0.71 to 9.86; very low-quality evidence) as did data for leaving the study early (around 10% in both groups, 6 RCTS, n = 218, RR 1.47, CI 0.69 to 3.15; very low-quality evidence). No study reported on social confidence, social inclusion, social networks, or personalised quality of life, a group of outcomes selected as being of particular importance to patients.

AUTHORS' CONCLUSIONS

We are uncertain about the evidence of the effects of baclofen, progabide, sodium valproate or tetrahydroisoxazolopyridinol (THIP) for people with antipsychotic-induced TD. Evidence is inconclusive and unconvincing. The quality of data available for main outcomes ranges from very low to low. Any possible benefits are likely to be outweighed by the adverse effects associated with their use.

Gamma-aminobutyric acid agonists for neuroleptic-induced tardive dyskinesia

BACKGROUND

Chronic antipsychotic drug treatment may cause tardive dyskinesia (TD), a long-term movement disorder. Gamma-aminobutyric acid (GABA) agonist drugs, which have intense sedative properties and may exacerbate psychotic symptoms, have been used to treat TD.

OBJECTIVES

To determine the clinical effects of GABA agonist drugs (baclofen, gamma-vinyl-GABA, gamma-acetylenic-GABA, progabide, muscimol, sodium valproate and tetrahydroisoxazolopyridine (THIP) for people with schizophrenia or other chronic mental illnesses who also developed neuroleptic-induced tardive dyskinesia.

SEARCH STRATEGY

We updated the previous Cochrane review by searching the Cochrane Schizophrenia Group Register (June 2010).

SELECTION CRITERIA

We included reports if they were controlled trials dealing with people with neuroleptic-induced TD and schizophrenia or other chronic mental illness who had been randomly allocated to either non-benzodiazepine GABA agonist drugs with placebo or no intervention.

DATA COLLECTION AND ANALYSIS

Working independently, we selected and critically appraised studies, extracted data and analysed on an intention-to-treat basis. Where possible and appropriate we calculated risk ratios (RR) and their 95% confidence intervals (CI) with the number needed to treat (NNT). For continuous data we calculated mean differences (MD).

MAIN RESULTS

We identified eight small poorly reported studies for inclusion. For the outcome of 'no clinically important improvement in tardive dyskinesia' GABA agonist drugs were not clearly better than placebo (n = 108, 3 RCTs, RR 0.83 CI 0.6 to 1.1). Deterioration in mental state was more likely to occur in people receiving GABA medication (n = 95, 4 RCTs, RR 2.47 CI 1.1 to 5.4), but this effect was influenced by the decision to assign a negative outcome to those who left early before the end of the study. A greater proportion of people allocated GABA medication may fail to complete the trial compared with those allocated placebo (20% versus 9%), but this difference was not statistically significant (n = 136, 5 RCTs, RR 1.99 CI 0.8 to 4.7). There is a suggestion of an increase in ataxia (loss of power of muscular coordination) for both baclofen and sodium valproate (n = 95, 2 RCTs, RR 3.26 CI 0.4 to 30.2), and in sedation (n = 113, 3 RCTs, RR 2.12 CI 0.8 to 5.4) compared with placebo, but this was not significant. Withdrawal of tetrahydroisoxazolopyridine (THIP) may cause seizures.

AUTHORS' CONCLUSIONS

Evidence of the effects of baclofen, progabide, sodium valproate, or THIP for people with antipsychotic-induced TD is inconclusive and unconvincing. Any possible benefits are likely to be outweighed by the adverse effects associated with their use.

Gamma-aminobutyric acid agonists for neuroleptic-induced tardive dyskinesia

BACKGROUND

Chronic antipsychotic drug treatment may cause tardive dyskinesia (TD), a long-term movement disorder. Gamma-aminobutyric acid (GABA) agonist drugs, which have intense sedative properties and may exacerbate psychotic symptoms, have been used to treat TD.

OBJECTIVES

To determine the effects of GABA agonist drugs (baclofen, gamma-vinyl-GABA, gamma-acetylenic-GABA, progabide, muscimol, sodium valproate and tetrahydroisoxazolopyridine (THIP)) for people with antipsychotic-induced tardive dyskinesia (TD) and schizophrenia or other chronic mental illnesses.

SEARCH STRATEGY

We updated the previous Cochrane review by searching the Cochrane Schizophrenia Group Register (September 2003). We searched references for further trial citations and, where possible, contacted authors.

SELECTION CRITERIA

Randomised controlled trials comparing use of non-benzodiazepine GABA agonist drugs with placebo or no intervention, involving people with schizophrenia or other chronic mental illnesses with signs of antipsychotic-induced TD.

DATA COLLECTION AND ANALYSIS

Working independently, we selected and critically appraised studies, extracted data and analysed on an intention-to-treat basis. Where possible and appropriate we calculated risk ratios (RR) and their 95% confidence intervals (CI) with the number needed to treat (NNT). For continuous data Weighted Mean Differences (WMD) were calculated.

MAIN RESULTS

We identified eight small poorly reported studies for inclusion. For the outcome of 'no clinically important improvement in tardive dyskinesia' GABA agonist drugs were not clearly better than placebo (n = 108, RR 0.83 CI 0.6 to 1.1). Deterioration in mental state was more likely to occur in people receiving GABA medication (n = 95, RR 2.47 CI 1.1 to 5.4), but this effect was influenced by the decision to assign a negative outcome to those who dropped out before the end of the study. A greater proportion of people allocated GABA medication may fail to complete the trial compared with those allocated placebo (20% versus 9%), but this difference was not statistically significant (n = 136, RR 1.99 CI 0.8 to 4.7). There is a suggestion of an increase in ataxia (loss of power of muscular coordination) for both baclofen and sodium valproate (n = 95, RR 3.26 CI 0.4 to 30.2), and in sedation (n = 113, RR 2.12 CI 0.8 to 5.4) compared with placebo, but this was not significant. Withdrawal of tetrahydroisoxazolopyridine (THIP) may cause seizures.

REVIEWERS' CONCLUSIONS

Evidence of the effects of baclofen, progabide, sodium valproate, or THIP for people with antipsychotic-induced TD is inconclusive and unconvincing. Any possible benefits are likely to be outweighed by the adverse effects associated with their use.

Gamma-aminobutyric acid agonists for neuroleptic-induced tardive dyskinesia

BACKGROUND

Chronic antipsychotic drug treatment may cause tardive dyskinesia (TD), a long-term movement disorder. The gamma-aminobutyric acid (GABA) agonist drugs have been trialed as a treatment for TD, but these drugs have intense sedative properties and can possibly exacerbate psychotic symptoms.

OBJECTIVES

To determine the effects of GABA agonist drugs (baclofen, gamma-vinyl-GABA, gamma-acetylenic-GABA, progabide, muscimol, sodium valproate and tetrahydroisoxazolopyridine (THIP)) in people with neuroleptic-induced tardive dyskinesia (TD) and schizophrenia or other chronic mental illnesses.

SEARCH STRATEGY

Electronic searches of Biological Abstracts (1982-1998), The Cochrane Library CENTRAL (1998), Cochrane Schizophrenia Group's Register of Trials (1998), EMBASE (1980-1998), LILACS (1982-1996), MEDLINE (1966-1998), PsycLIT (1974-1998), and SCISEARCH were undertaken. References of all identified studies were searched for further trial citations. First authors of each included trial were contacted.

SELECTION CRITERIA

The inclusion criteria for all relevant randomised studies were that they should focus on people with schizophrenia or other chronic mental illnesses, with neuroleptic-induced TD and compare the use of GABA agonist drugs to placebo or no intervention.

DATA COLLECTION AND ANALYSIS

The reviewers extracted the data independently and the odds ratio (OR) and its 95% confidence interval (CI) or the weighted mean difference with 95% CI were estimated. The reviewers assumed that people who dropped out had no improvement.

MAIN RESULTS

Eight studies were able to be included. Results were equivocal, showing only a tendency for clinical improvement for those using GABA agonist drugs but, when analysis of any improvement (rather than clinical improvement) was performed, a significant reduction was noted in the GABA group (OR 0.36 CI 0.15-0.85). This suggests that for every 10 people treated with GABA drugs one person would benefit with a reduction in TD symptoms. People using the interventions had more confusion (OR 7.4 CI 1.3-40.9) and sedation (OR 3.0 CI 1.2-7.6). The numbers of people needed to treat to cause one extra person to experience these side effects were three and six, respectively. Tendency for more deterioration of the TD symptoms (OR 1.72 CI 0. 54-5.5), deterioration of the mental state (OR 3.07 CI 0.78-12.05), and to drop out before the end of the trial (OR 2.05 CI 0.8-5.21) were also observed in those using GABA agonists.

REVIEWER'S CONCLUSIONS

No clear statement about the efficacy of GABA agonist drugs could be provided. From the combined data, GABA agonist drugs tend to be associated with some degree of improvement in TD symptoms, but also with side effects such as confusion and sedation and a deterioration of the person's mental state.

Baclofen-induced dyskinesia

Baclofen (Lioresal) is a derivative of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). It is used to treat spasticity particularly for the relief of flexor spasms, pain, clonus, and muscular rigidity. There have been many rare neurologic side effects reported with its use. These side effects, in particular, hallucinations and seizures, have been observed predominantly following precipitous withdrawal of the drug. We present a case demonstrating a muscular dyskinetic side effect when baclofen treatment was first initiated. The mechanism by which baclofen affects spasticity and how the resulting side effect of dyskinesia developed in our patient is not known. They are, however, most probably related to dopamine receptor hypersensitivity and the resulting imbalance of the dopaminergic/cholinergic systems. Clinicians should be aware of this additional adverse effect of muscular dyskinesia, with the use of baclofen, and its reversibility when baclofen is discontinued.

Recognition and differential diagnosis of tardive dyskinesia

Tardive dyskinesia (TD) is a consequence of chronic neuroleptic therapy. It is an irregular stereotyped movement disorder that is usually choreic in appearance, and is subject to temporary volitional control. Dystonia, akathisia, and tics are uncommon variants of the classic tardive syndrome. Characteristic clinical features including amelioration by action, augementation by distraction, partial volitional suppressibility, and lack of subjective distress help differentiate TD from other movement disorders such as resting tremor, Huntington's disease, spontaneous dyskinesias, and abnormal movements accompanying psychiatric illnesses.

Alterations in cerebral glutamic acid decarboxylase and 3H-flunitrazepam binding during continuous treatment of rats for up to 1 year with haloperidol, sulpiride or clozapine

Rats were treated continuously for 12 months with therapeutically equivalent doses of haloperidol (1.4-1.6 mg/kg/day), sulpiride (102-109 mg/kg/day) or clozapine (24-27 mg/kg/day) and examined for alterations in brain glutamic acid decarboxylase (GAD) and 3H-flunitrazepam binding. Administration of haloperidol, but not sulpiride or clozapine, for 6 or 12 months increased striatal GAD activity. None of the drug treatments altered nigral GAD activity when examined after 1, 3, 6, 9 or 12 months administration. The number of specific 3H-flunitrazepam binding sites (Bmax) in striatal membrane preparations were not altered by 12 months administration of haloperidol, sulpiride or clozapine. Surprisingly, Bmax for 3H-flunitrazepam binding to cerebellar membrane preparations was decreased by 12 months administration of all drug treatments. The dissociation constant (Kd) for 3H-flunitrazepam binding in striatal and cerebellar preparations was not altered. The ability of GABA (0.25-100 microM) alone, and in conjunction with sodium chloride (200 mM), to stimulate specific 3H-flunitrazepam binding in striatal and cerebellar preparations was unaltered by haloperidol, sulpiride or clozapine administration for 12 months. The selective effect of haloperidol, but not sulpiride or clozapine, treatment on striatal GAD activity parallels the ability of haloperidol, but not sulpiride or clozapine, to induce striatal dopamine receptor supersensitivity in the same animals. The actions of haloperidol may reflect its greater ability to induce tardive dyskinesia compared to sulpiride or clozapine.

Clinical and biochemical effects of calcium-hopantenate on neuroleptics-induced tardive dyskinesia

Calcium-hopantenate (HOPA), a derivative of GABA, was administered to 9 psychiatric patients with neuroleptics-induced tardive dyskinesia. In a clinical study, involuntary movements have improved significantly after a 4-8-week medication. Although there was no correlation between the cerebrospinal fluid (CSF) levels of HOPA, GABA, HVA or clinical response, the CSF HOPA levels significantly correlated with changes in the CSF GABA levels. These results suggest that HOPA alleviates the symptoms of tardive dyskinesia being mediated by the central GABAergic mechanisms.

Tardive dyskinesia: nondopaminergic treatment approaches

The continuing concern about tardive dyskinesia (TD) has stimulated a broad search for therapies for this disorder. Since neuroleptic drugs are thought to be the etiological agents, acting presumably through dopamine receptor blockade, nondopaminergic drugs have been the focus of recent study. However, no uniformly safe and effective drug treatment has been identified. Augmentation of cholinergic function is theoretically attractive, but further research is needed to develop practical and effective compounds. GABA drugs do not consistently suppress TD. The effect of benzodiazepines in TD is unclear, but these agents may be of some temporary benefit in patients with distressing symptoms. Lithium, serotonergic compounds, and numerous neuropeptides all fail to have any consistent effect in TD. Early reports of benefit with alpha- and beta-noradrenergic agents are interesting but require further study. Many other drug types have been tried without benefit. For the majority of patients, it may be best to give no drug treatment. Any drug that is capable of suppressing TD may aggravate the disorder in the long term. The potential for a spontaneous gradual remission of TD is an argument in favor of a patient, nonaggressive, and cautiously optimistic approach to this disorder.

A possible neurochemical basis for the neuropsychiatric aspects of baclofen therapy

Baclofen, commonly used to reduce severe muscle spasms in patients with spinal cord injuries, is also active in the brain. A patient with pre-existing bipolar affective disorder developed increased depression while on baclofen, which progressed to a delusional depression when baclofen and haloperidol were rapidly decreased. When the dose of haloperidol was increased to a previously well tolerated dose to deal with the depressive delusion, a pseudoparkinson's state developed. This case demonstrates the interactive effects of baclofen and haloperidol on central noradrenergic and dopaminergic systems and suggests a possible neurochemical basis for the difference between delusional and nondelusional depression that is consistent with the different therapeutic response to psychotropic drugs of patients with these illnesses. The paradoxical appearance of the pseudoparkinson state in this patient when much higher doses of haloperidol had been free of such side effects, may reflect baclofen-induced alterations in receptor sensitivity. It appears that baclofen should be used with caution in patients with neuropsychiatric problems and that, when used, the withdrawal of baclofen should be continued over several weeks to allow receptor sensitivity to return to normal levels.

Sustained improvement in tardive dyskinesia with diazepam: indirect evidence for corticolimbic involvement

A rater-bind, ABA's design study of 21 cases indicates that diazepam significantly improves tardive dyskinesia and that some of the improvement persists for an extended period after diazepam is withdrawn. Since benzodiazepine receptors and sites of action seem to be mainly in the neocortex (especially frontal), limbic cortex, and deep limbs nuclei, and these structures provide most of the input into the nigrostriatopallidal system that probably regulates its role in voluntary movement, it may be suggested that impaired corticolimbic control of basal ganglia may be a factor in the pathogenesis of tardive dyskinesia.

Diazepam in tardive dyskinesia

Tardive dyskinesia, a syndrome of involuntary motor movements, can be a permanent consequence of the long-term use of antipsychotic drugs. While there is no well-established drug treatment, case reports and the results of a few clinical studies suggest that drugs that facilitate the GABA-ergic system may decrease the abnormal movements. One such class of drugs is the benzodiazepines. We administered diazepam to 13 subjects in a 24-week, crossover design study. Tardive dyskinesia and psychopathology were assessed by blind raters using the Abnormal Involuntary Movement Scale and the Brief Psychiatric Rating Scale (BPRS). The means of all movement measurements improved from the baseline, with orofacial, subtotal, symptom severity, and total reaching significance. However, we were unable to demonstrate a drug effect; the patients improved to a similar degree whether or not they received diazepam. Their psychiatric disorders did not worsen with diazepam administration and, in fact, improved slightly; the activation factor of the BPRS was significantly improved over baseline. Our results suggest that diazepam is not effective in managing the movements of tardive dyskinesia and that behavior modification strategies be investigated to help patients control symptoms.

Adverse psychiatric reactions to modern medication

From this survey it will be apparent that many psychiatric reactions to drugs are largely caused by their direct toxic actions or from combinations of drugs. As such, they are often dose related, although age and slow speed of detoxification will increase the risk of patients developing delirium, hallucinations, sleep disturbances, anxiety etc. Similar toxic reactions can also occur when drugs to which a patient has developed some measure of tolerance are abruptly withdrawn. In this context the effects of drugs upon patterns of sleep may be important determinants of adverse withdrawal symptoms. In contrast are the reactions which resemble one or other of the functional psychoses. In these patients it appears that a past history of an affective or schizophrenic psychosis is the best predictor of a similar illness being precipitated by a particular drug. Nonetheless, with substances like reserpine and cycloserine there is good reason for thinking that, given a sufficient quantity, practically any patient can develop an adverse psychiatric reaction.

Dyskinesia: animal experimental correlates

The results of behavioral studies in animals, which demonstrate increased effects of DA agonists after stopping chronic administration of neuroleptics, are consistent with an increased sensitivity of postsynaptic receptor and effector mechanisms in response to chronic disruption of DA transmission (disuse supersensitivity of DA receptors, see review by Moore & Thornburg (1975)). Although this mechanism may be responsible for the reversible withdrawal dyskinesias, it is probably not involved in persistent tardive dyskinesia. The persistence of the latter dyskinesias suggests an irreversible structural or chemical change, but with the exception of a report by Christensen et al. (1970) there is little evidence of neuroleptic-induced degenerative changes in the brains of man or animals. Although the etiology of tardive dyskinesias remains a mystery, pharmacological evidence suggests a functional overactivity of extrapyramidal mechanisms mediated by DA. To date, however, experiments with animal models have not provided a logical explanation for this overactivity.

Depression as a major symptom of multiple sclerosis

Thirty patients suffering from multiple sclerosis have been compared with 30 patients suffering from other chronic neurological diseases. The degree of disability was similar in these two groups. The patients with multiple sclerosis had experienced more episodes of severe depression both before and after the onset of neurological symptoms. The possible reasons for these episodes are discussed and it is concluded that in some patients serious affective disorder may be a presenting or complicating feature of multiple sclerosis.

Pharmacotherapeutic trials in tardive dyskinesia

Some of the clinical factors contributing to the currently unsatisfactory state of therapy for tardive dyskinesia are reviewed. Problems such as lack of clear syndrome delineation and phenomenological description, the lack of standardization in rating scales and the lack of attention to trial design have all probably contributed to a rather confusing picture. Controlled trials suggest that several pharmacological agents may be of therapeutic value but that clinical prediction of an individual's response is impossible. The strategy of acute drug challenge has emerged as perhaps the most promising approach to the definition of pharmacological subtypes and therefore the choice of optimal treatment.

The role of monoamines for the central effects of Baclofen on behavior of rats

Male albino rats given a bilateral injection of Baclofen (Lioresal) (12 micrograms/rat) in the cerebral ventricles showed a behavioral syndrome of activation + ataxia, paddling, tail-pinch hyperresponse and anesthesia. The phase of activation + ataxia was reduced by pretreatment of rats with H 44/68, FLA 63, reserpine, pimozide, phenoxybenzamine, oxypertine or chlorpromazine. The phase of paddling was reduced by pretreatment with FLA 63, reserpine, phenoxybenzamine, oxypertine, chlorpromazine, pimozide + phenoxybenzamine or apomorphine, while administration of clonidine instead of Baclofen caused paddling in non-pretreated rats. The phase of tail-pinch hyperresponse was reduced by reserpine, oxypertine, chlorpromazine or pimozide + phenoxybenzamine, while none of the pretreatments affected Baclofen-induced anesthesia. Drugs which affect mainly tryptaminergic or GABA-ergic functions failed to affect Baclofen-induced behaviors consistently. The findings suggest that dopaminergic and noradrenergic functions play a role in the central effects of Baclofen on behavior of rats.

Baclofen and muscimol: behavioural and neurochemical sequelae of unilateral intranigral administration and effects on 3H-GABA receptor binding

Log dose-response curves for induction of contralateral rotational behaviour in the rat by unilateral intranigral injections of the GABA agonist muscimol and the GABA analogue baclofen have been compared. Baclofen, 5--1000 ng, produced a maximal rotational response that was only 40% of that produced by 0.25--100 ng muscimol, and log dose-response curves failed to show parallelism. The behavioural effects of both drugs were only weakly antagonised by haloperidol and were not antagonised by 6-hydroxydopamine lesions of ipsilateral dopamine (DA) neurons, indicating that these responses were independent of DAergic mechanisms. The effects of baclofen were weakly antagonised by picrotoxin. Intranigral muscimol and baclofen substantially elevated striatal DA concentrations. While muscimol also substantially elevated striatal dihydroxyphenylacetic acid (DOPAC) but not homovanillic acid (HVA), bactofen did not significantly effect either DOPAC or HVA. Baclofein, GABA and muscimol displaced specific 3H-GABA binding in vitro with IC50's of 40 micron, 400 nM and 40 nM respectively. These results indicate that muscimol and baclofen do not act via a unitary GABAergic mechanism, but suggest that baclofen may be a partial GABA agonist, at least at nigral GABA receptors.

Adverse effects in maintenance treatment: practical and theoretical considerations

1. Subsequent to the introduction of therapeutically effective psychotropic drugs, there has been a decrease in the resident population in mental hospitals. 2. Since maintenance therapy with neuroleptics and lithium may alleviate and/or prevent relapse in a considerable percentage of schizophrenic and manic depressive patients, there is a gradual increase of these patients in the community. 3. In this paper some of the adverse effects of long-term pharmacotherapy with psychotropic drugs will be presented, and possible negative effects of the increase in fertile marriages among community-based patients will be discussed.

Baclofen in Parkinson's disease

In a controlled trial, baclofen (mean dose 45 mg daily) signficantly increased disability from Parkinsonism in 12 patients with the long-term levodopa syndrome. Peak dose choreoathetosis was not improved but benefit was observed in all four patients with "off period dystonia." Adverse side effects were common and severe, and included visual hallucinations, vomiting, and dizziness.

Effect of baclofen on tardive dyskinesia

Eighteen chronic psychiatric patients with neuroleptic-induced tardive dyskinesia of 1/2-9 years duration participated in a double-blind crossover study on the effect and side effects of baclofen and placebo in the treatment of tardive dyskinesia. Each treatment phase lasted 3 weeks. Evaluation of the results included an assessment of video-tape recording. Baclofen (20-120 mg daily) reduced the hyperkinesias (median score from 5 to 3, P less than 0.05) and increased the parkinsonism (median score from 5 to 7, P less than 0.01). The effect on the oral movement pattern of tardive dyskinesia was characterized by a reduced frequency, an unchanged or slightly reduced amplitude, and an increased duration of each separate mouth opening and tongue protrusion, a response pattern very similar to the response pattern of alpha-methyl-p-tyrosine, an inhibitor of the catecholamine synthesis. Sediation, muscular weakness, and confusion were observed in 50% of the patients. These side effects, appearing mainly in elderly patients, sometimes set in before the anti-hyperkinetic effect, thus limiting the practical usefulness of baclofen in the treatment of tardive dyskinesia.

Induction of rotational behaviour by intranigral baclofen suggests possible GABA-agonist activity

In rats, unilateral injections of the GABA-derivative baclofen into the zona reticulata of the substantia nigra produced a contralateral rotation that was translated to ipsilateral rotation under the influence of amphetamine. These results mimic those following unilateral elevation of GABA levels in the substantia nigra and suggest that baclofen may have some GABA agonist activity following intracerebral injection.

A double-blind trial of baclofen against placebo in the treatment of schizophrenia

Twenty male chronic schizophrenic patients participated in a double-blond between-patient study of the GABA-like drug baclofen to evaluate the antipsychotic effect of baclofen. No difference was found between the 10 patients who received baclofen and 10 who received placebo with regard to the number of days before a worsening of their psychiatric condition necessitated treatment with chlorpromazine, the total score for psychotic symptoms before and after treatment for 10 weeks, or the total consumption of chlorpromazine. Discontinuation of baclofen did not exacerbate the psychotic symptoms. Baclofen was superior to placebo in the treatment of anxiety, which is of particular interest in view of the recent theories on the mechanism of action of benzodiazepines. The relationship between the gabergic system and the dopaminergic system with regard to the substantia nigra and the corpus striatum is discussed as well as the suggestion based on animal experiments that baclofen has an antipsychotic effect.