SEVERE TOXIC REACTION TO COMBINED AMITRIPTYLINE AND THIORIDAZINE

The Link Between Amitriptyline and Movement Disorders: Clinical Profile and Outcome

INTRODUCTION

Amitriptyline (AMT) is a tricyclic antidepressant. In this review, we evaluate the clinical and epidemiological profile, pathological mechanisms and management of AMT-associated movement disorders.

MATERIALS AND METHODS

A search for relevant reports in 6 databases was performed. Studies that reported patients developed only ataxia or tremor after AMT use were excluded.

RESULTS

A total of 48 reports on 200 cases were found. AMT-associated movement disorders included myoclonus (n = 26), dyskinesia (n = 11), dystonia (n = 8), stutter (n = 5), akathisia (n = 3) and restless legs syndrome (n = 1). For less well-defined cases, 99 patients had dyskinesia, 19 had psychomotor disturbances, 3 had myoclonus, 11 had dystonia, 12 had Parkinsonism and 1 each had akathisia and extrapyramidal symptoms. Mean and standard deviation (SD) and median ages were 45.40 years (SD 16.78) and 40 years (range 3.7-82 years), respectively. Over half were women (58.13%) and the most common indication was depression. Mean and median AMT doses were 126 mg (SD 128.76) and 75 mg (range 15-800 mg), respectively. In 68% of patients, onset of movement disorders was <1 month; time from AMT withdrawal to complete recovery was <1 month in 70% of cases. A weak negative linear correlation (r = -0.0904) was found between onset of movement disorders and AMT dose. AMT withdrawal was the most common treatment.

CONCLUSION

Amitriptyline is associated with various movement disorders, particularly myoclonus, dystonia and dyskinesias. Stutters and restless legs syndrome are some of the less common associations.

Interactions of CNS Drugs: Psychotherapeutic Agents—The Antipsychotic Drugs

Aspects of the pharmacology of the phenothiazine antipsychotic agents pertinent to possible interactions are reviewed. Pharmacokinetic interactions of possible clinical importance are the interference with the absorption of the phenothiazines by antacids, reversal of the hypotensive effect of guanethidine by psychotropic drugs, blockade of the effects of levodopa in Parkinson's disease, and stimulation of phenothiazine-metabolizing enzymes by phenobarbital. Pharmacologically, phenothiazines may potentiate certain depressant effects of other CNS depressants or add to the anticholinergic side effects of a number of other drugs. The phenothiazines appear to antagonize both the CNS stimulant and the anorexic effects of amphetamines and related substances. Other reactions of possible concern are the phenothiazine-induced hypoglycemia, the relationship of lithium toxicity to sodium intake, and the number of false positive pregnancy tests in patients on phenothiazine therapy.

Toxic psychosis due to antiparkinsonian drugs

Nine cases of transient toxic-delirious reactions during combined antipsychotic-antiparkinsonism treatment have been described. A few days prior to the onset of the reaction, all patients had been placed on an antiparkinsonian drug.

Three clinical phases were observed: an autonomic stage (sympathicotonic signs: mydriasis, dry mouth, anorexia, excitement, disorientation, insomnia, severe constipation); a strio-thalamic phase (dyskinesias, visual and tactile hallucinations) and a post-delirious state (increased sleep and integration).

The pathogenic factors which play a role in this atropine-like toxic condition, such as age, individual susceptibility, drug response per se and the influence of rapid dose changes were briefly discussed.