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

AMAN~ADINE hydrochloride (adamantanamine, Symmetrel) has been used for several years as an antiviral agent effective in prophylaxis against Asian influenza (A,) [ 1,2]. Schwab et al [3] first used amantadine in Parkinson’s disease after one patient reported remission of her symptoms while taking the drug to prevent influenza. Schwab and his associates treated 163 Parkinsonian patients with 100-308 mg of amantadine daily. Sixty-six per cent of the group exhibited subjective or objective improvement of akinesia, rigidity, and/or tremor, and sustained benefit was noted in over half of the patients for a period of 3-8 months. Weeth et al [4] treated 39 patients in a similar open trial and found mild to moderate improvement in 23 patients (59 per cent). Parkes et al [5] conducted a double-blind crossover trial of amantadine (200 mg/day) vs. placebo, each given for a fortnight, involving 37 patients. Thirty-five patients completed the trial, and 26 of them expressed a preference for amantadine, five preferred placebo and four had no preference. The symptoms improved in order of greatest frequency were mobility, tremor, facial expression, speech, general well-being and balance. They also evaluated general history, functional disability, walking history, appearance, tremor, rigidity, limb dexterity, mood, time to walk 25 yd, and time to write a set phrase. All scores except walking history and rigidity improved significantly (p < 0.05) when amantadine was compared to placebo. The mean time required to walk 25 yd was reduced from 29 to 25 set, and the time to write a set phrase decreased from 40 to 37 sec. The only significant difference found between the group giving a clear preference for amantadine and the group that did not was age,