A qualitative and quantitative evaluation of amantadine in the treatment of Parkinson's disease

Abstract

A double-blind crossover trial of amantadine vs. placebo was carried out involving 42 patients with Parkinson's disease: 64 per cent of the patients on amantadine experienced subjective improvement compared to 21 per cent on placebo. A comprehensive battery of qualitative and quantitative tests was carried out on each patient on entry to the study, after previous standard treatment was discontinued or reduced to a minimal tolerable dose, while on placebo, and while on amantadine, at 3 week intervals. Almost all relevant symptoms and physical signs improved, and the neurologists judged amantadine superior to placebo in 74 per cent of the patients. Quantitative measurement revealed significant improvement in 10 of 19 tests of simulated activities of daily living, in several tests of strength and station, and in all tests of coordination and gait. When the amantadine scores were compared to the placebo scores, an average improvement of 29 per cent occurred in the simulated activities of daily living, 14 per cent in tests of coordination, 11 per cent for gait and 3 per cent for strength. Sensation and neuropsychologic performance were unaffected and side effects were minimal. Comparison of amantadine scores with entry scores obtained when the patients were on standard anti-Parkinsonian medications suggested that amantadine may also be superior to classical medications. The response to amantadine was not related to age, sex, or severity of disease, but those who responded were found to have a significantly longer duration of illness. Amantadine is a nontoxic, easily administered drug useful in the treatment of Parkinson's disease.It should be emphasized that the quantitative tests used in this study yielded interval data. This resulted in more valid comparisons with normal, particularly when expressed in terms of the percent of the age-matched normal function.Finally, this is the first report which describes a battery of quantitative tests designed to measure in part the effect of a drug on activities of daily living. It could be that these results were the most indicative of a significant effect in this experiment, since it is an improvement in the accomplishment of activities of daily living, not neurological tests, by which a patient with Parkinsonism bases his judgement of the effectiveness of a non-toxic treatment.