Dystonia, neuroleptic dose, and anticholinergic drugs

The Dystonias

Dystonia is a difficult problem for both the clinician and the scientist. It is sufficiently common to be seen by almost all physicians, yet uncommon enough to prevent any physician from gaining broad experience in its diagnosis and treatment. Each case represents a difficult challenge even to the specialist. The basic scientist is faced with investigating a disorder that is without relevant animal models and which is so rare that obtaining suitable tissue for study is a major obstacle. Dystonia may be idiopathic, or associated with lesions from many sources, including a variety of rare diseases. If idiopathic, it may be genetically transmitted or sporadic. If genetically transmitted, it may be generalized or focal, with symptoms varying in different members of the same family. It may be refractory to treatment, or it may respond to any one of a number of individual drugs that have very different mechanisms of action. For idiopathic dystonias, no clear method of genetic transmission has been established and no consistent pathology identified.

Drugs with anticholinergic properties and cognitive performance in the elderly: results from the PAQUID Study

OBJECTIVES

To measure the association between the use of drugs with anticholinergic properties and cognitive performance in an elderly population, the PAQUID cohort.

METHODS

The sample studied was composed of 1780 subjects aged 70 and older, living at home in South western France. Data on socio-demographic characteristics, medical history and drug use were collected using a standardized questionnaire. Cognitive performance was assessed using the following neuropsychological tests: the Mini-Mental State Examination (MMSE) which evaluates global cognitive functioning, the Benton Visual Retention Test (BVRT) which assesses immediate visual memory, and the Isaacs' Set Test (IST) which assesses verbal fluency. For each test, scores were dichotomized between low performance and normal to high performance using the score at the 10th percentile of the study sample as the cut-off point, according to age, gender and educational level. The association between the use of drugs with anticholinergic properties and cognitive performance was examined using logistic regression models, adjusting for several potential confounding factors.

RESULTS

About 13.7% of the subjects used at least one drug with anticholinergic properties. In multivariate analyses, the use of these drugs was significantly associated with low performance in the BVRT [odds ratio (OR) = 1.6; 95% confidence interval (CI) 1.1, 2.3] and in the IST (OR = 1.9; 95% CI 1.3, 2.8). The association found with low performance in the MMSE (OR = 1.4; 95% CI 1.0, 2.1) was barely statistically significant.

CONCLUSION

These findings suggest that the use of drugs with anticholinergic properties is associated with low cognitive performance among community-dwelling elderly people.

Comparison of central and peripheral pharmacologic effects of biperiden and trihexyphenidyl in human volunteers

In this double-blind, randomized study, indices of central (memory, sedation) and peripheral (salivation, ratio of R-R interval on electrocardiogram) muscarinic function were evaluated in 14 healthy volunteers who received trihexyphenidyl, biperiden, and placebo. Additionally, serum drug levels were obtained 2 hours after oral administration. All subjects participated in three study sessions. During each session, subjects received two doses of biperiden (4 mg), trihexyphenidyl (5 mg), or placebo, and four series of tests were administered. The tests included the determination of cardiac response to standing (R-R ratio), mouth salivation, finger-tapping speed, digit span (forward and backward), a selective reminding task, and visual analog scales (VAS). On the VAS, subjects rated biperiden as significantly more sedating than either trihexyphenidyl or placebo, and both biperiden and trihexyphenidyl were associated with more dizziness than was placebo. Saliva production was significantly reduced by both trihexyphenidyl and biperiden compared with placebo. Digit span performance was significantly decreased in only the backward direction. The selective reminding task revealed highly significant decrements in the number of words recalled and consistent long-term retrieval after both biperiden and trihexyphenidyl. Delayed recall was significantly decreased by both active drugs. Both trihexyphenidyl and biperiden caused a significant increase in the R-R ratio comparison with placebo. With the exception of the VAS measurement of sedation, the effects caused by biperiden and trihexyphenidyl did not differ. The results of this study do not support the hypothesis that the side effect profile of biperiden is significantly different from that of trihexyphenidyl.

Development and application of a specific and sensitive radioimmunoassay for trihexyphenidyl to a pharmacokinetic study in humans

A radioimmunoassay (RIA) for trihexyphenidyl was developed through the use of a bovine thyroglobulin conjugate of trihexyphenidyl hemisuccinate. Immunization of New Zealand white rabbits with this drug-protein conjugate yielded antisera, for which the antibody titer and specificity were evaluated. An antiserum that had the highest titer and minimal cross-reactivities to major metabolites of trihexyphenidyl, such as trihexyphenidyl N-oxide (2%), hydroxytrihexyphenidyl (1%), and the antipsychotic drugs fluphenazine (< 1%), flupenthixol (< 1%), chlorpromazine (< 1%), and haloperidol (< 1%), was selected for development of a RIA. The described RIA enables the quantitation of 7.8 pg of trihexyphenidyl in 200 microL of human plasma with a mean coefficient of variation of < 6% across the range of the standard curve. Assay specificity was further demonstrated by comparison of results obtained directly and after selective extraction of trihexyphenidyl from replicate samples. This RIA procedure was applied to the analysis of steady state plasma samples obtained from patients undergoing treatment with trihexyphenidyl (2-8 mg) and plasma samples obtained from eight healthy male volunteers after administration of a single 4 mg oral dose of the drug. The results of the latter single dose studies demonstrated that the mean +/- SD for the peak concentration (Cmax), the time to Cmax (Tmax), the rate of absorption (Ka), and the area under the curve from 0 to 72 h (AUC0-72) were found to be 7.15 +/- 2.58 ng/mL, 1.32 +/- 0.58 h, 2.07 +/- 0.93 1/h, and 201 +/- 71 ng h/mL, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Amitriptyline, clovoxamine and cognitive function: a placebo-controlled comparison in depressed outpatients

No longer prescribed only for vegetative signs of depression, tricyclic antidepressants also lessen depressive cognitive distortions. Less clear is whether they ameliorate depressed patients' other cognitive deficits in memory, information processing speed, and psychomotor performance. We tested the alternative hypothesis that amitriptyline, because of its anticholinergic and sedative properties, would exacerbate depressed patients' cognitive disturbances. Depressed outpatients received double-blind placebo (n = 15), amitriptyline (n = 10), or clovoxamine fumarate (n = 10), a serotonin reuptake inhibitor relatively lacking in anticholinergic properties. Depression, memory, and psychomotor performance were assessed at baseline and after 7 and 28 days of drug treatment. Depression was alleviated after all treatments, including placebo. Only amitriptyline impaired performance on tests of memory, producing a significant decrement, relative to placebo, after 4 weeks of treatment. None of the treatments adversely affected performance on psychomotor tasks. These findings add to the evidence that antidepressant drugs with high anticholinergic activity can impair memory, despite alleviation of depression.

Prophylactic antiparkinson drug use: II. Withdrawal after long-term maintenance therapy

Although the efficacy of long-term neuroleptic treatment of schizophrenic patients is generally accepted, the use of concurrent antiparkinson drugs is less well defined. The value of prolonged antiparkinson drug use in preventing extrapyramidal side effects is controversial. More than 30 studies of antiparkinson drug withdrawal have attempted to answer this question. The authors reviewed all double-blind, placebo-controlled studies, and found most to contain serious methodologic or statistical flaws. There is evidence to support the long-term use of these agents in preventing extrapyramidal side effects. The authors offer an analysis of the benefits and risks that are involved with prophylactic antiparkinson drug use, and conclude that most patients would benefit from maintenance therapy.

Effects of treatment with trihexyphenidyl on cognitive function in early Parkinson's disease

13 patients with PD of recent onset underwent a series of neuropsychological tests for frontal lobe associated functions (Sternberg paradigm, WCST, CVLT) before and during treatment with Artane. Test results at baseline were not significantly different from those of an age-matched control group (n = 13). Retesting after a mean of 2 weeks' treatment with trihexyphenidyl revealed only slight impairment in CVLT while performance on the other tests remained unchanged.

Risk management for extrapyramidal symptoms

Extrapyramidal symptoms (EPS), the side effects of antipsychotic medications, have become the focus of much attention from clinical researchers, the courts, consumer groups, and even the U.S. Congress. The major clinical manifestations of EPS, the etiology, symptoms, and treatments are reviewed. The literature identified risk factors for EPS--those specific to the patient, to the particular antipsychotic agent used, and to the nature of the ongoing treatment for EPS. By quantifying these factors, weighting them according to the known risks, a risk management tool is developed for use in predicting which patients are at higher risks for EPS, in evaluating treatment, and in assessing the responses of patients to changes in their condition and to the subsequent adjustments in treatment. The risk management tool provides guidelines for the continual evaluation of these changes, with the goal of minimizing the risks for EPS.

Anticholinergic serum levels and cognitive performance

Integrity of central cholinergic neurotransmission is essential for adequate cognitive functioning. Many psychotherapeutic medications have anticholinergic side-effects. In order to determine the impact of circulating anticholinergic activity on cognitive performance, 28 geropsychiatric inpatients underwent cognitive testing at different levels of anticholinergic serum activity. In 10 subjects with a diagnosis of probable Alzheimer's disease, significant deterioration of selected cognitive functions was observed at anticholinergic serum levels that caused no dysfunction in the 18 non-demented subjects. The data suggest that non-demented elderly patients with psychiatric problems tolerate psychotropic pharmacotherapy without significant negative impact on their cognitive competency. By contrast, patients with Alzheimer's disease are at risk of additional impairment. The introduction of anticholinergic serum activity as a monitoring technique for safe psychopharmacotherapy in geriatric patients is discussed.