Faculty Bibliography

The pharmacokinetics of levodopa differs when it is combined with benserazide or carbidopa. Peak dopa levels are higher, occur sooner, but decline more rapidly with benserazide. Although many patients respond better to one drug than the other, we sought to exploit the differences in pharmacokinetics by giving both drugs to the same patient. Benserazide was combined with carbidopa in 38 patients who were experiencing a diminished response to carbidopa, including 22 patients with diurnal oscillations in performance, 'wearing off' or on-off phenomena. Previous attempts to change the dose, sequence, or ratio of levodopa to carbidopa in these patients had been unrewarding. Ten of the patients improved on the combination of benserazide and carbidopa, with a 30% decline in disability. The mean dose of levodopa:carbidopa before benserazide was 910:100 (9 to 1 ratio); the mean dose of levodopa:benserazide was 355:90 (4 to 1 ratio). The mean dose of levodopa:carbidopa + benserazide was 925:155 (6 to 1 ratio). The combination of carbidopa with benserazide is useful in some parkinsonian patients

Experience with bromocriptine in 106 patients treated over nine years was reviewed. Most of the patients were already being treated with levodopa (combined with a peripheral decarboxylase inhibitor). These patients, after having initially achieved a good response to levodopa, were no longer responding satisfactorily. Most of the patients were also experiencing diurnal oscillations in performance: 'wearing off' and 'on-off' phenomena. In these patients previous attempts at changing the dose (increasing or decreasing) or changing the scheduling of levodopa had been unsuccessful. Bromocriptine was added to levodopa beginning at a dose of 5 mg/day, and each week was increased by another 5 mg/day. At a dose of bromocriptine of at least 25 mg/day, there was a decrease in disability in the majority of patients with a decrease in the severity of the diurnal oscillations in performance (especially 'wearing off' phenomena). In most patients, the addition of bromocriptine resulted in an approximately 10% reduction in the dose of levodopa. The majority of patients sustained their improvement at least one year. In some patients improvement was sustained for up to five years. The therapeutic efficacy of bromocriptine was limited in many patients by the occurrence of adverse effects including mental changes, dyskinesias, orthostatic hypotension, and nausea. These adverse effects could often be minimized by reducing the dose of bromocriptine or levodopa. All adverse effects were reversible upon stopping the drug. We have found bromocriptine to be a valuable adjunct in the treatment of these patients

In a retrospective study, treatment with lisuride was compared to pergolide in 25 patients with advanced PD in whom the response to levodopa had diminished. Sixteen patients had wearing off and/or ON-OFF phenomena. Lisuride or pergolide, when added to levodopa, resulted in comparable and significant decreases in disability in both ON and OFF periods; pergolide resulted in a greater increase in the number of hours in which patients were ON. Adverse reactions were comparable on both drugs. However, patients who developed an adverse reaction on one drug did not necessarily develop the same reaction on the other drug. Both lisuride and pergolide are effective anti-Parkinson drugs

Cerebrospinal fluid levels of homovanillic acid (HVA) in unmedicated patients with Parkinson's disease were 45% of levels in control subjects. Levels of 3-methoxy-4-hydroxyphenylglycol (MHPG) and platelet monoamine oxidase activity (MAO) did not differ. Within the Parkinson's disease group platelet MAO B activity correlated with HVA (an MAO B substrate) but not MHPG (an MAO A substrate). A mild global dementia was found that did not correlate with the more severe motor deficit. There was a negative correlation between the motor deficit and HVA levels but not with MHPG. Cognitive functioning correlated positively with platelet MAO, and the ratio of HVA to MHPG levels and negatively with MHPG alone. It is postulated that dopaminergic and noradrenergic activity or the functional balance between these systems may contribute to the observed cognitive dysfunction

Lisuride was compared with bromocriptine in 25 parkinsonian patients in whom the response to levodopa had diminished; 19 had 'wearing off,' 'on-off' phenomena, or both. At the time bromocriptine was added to levodopa, the mean age of the patients was 62.7 years and mean disease duration was 8.9 years. Disability decreased by 34% in the on period and by 20% in the off period, and the number of hours the patients were on increased from 9.6 to 12.8. All these changes were significant (p less than or equal to 0.01 to 0.05). Bromocriptine, however, had to be discontinued in 11 patients because of adverse effects. In the remaining 14 patients, bromocriptine was eventually discontinued because of decreased efficacy. Mean dose of bromocriptine was 55 mg (range, 20 to 100 mg). At the time lisuride was added to levodopa the patients were older (65.4 years), had had the disease longer (11.4 years), and were more disabled. Nonetheless, disability decreased in the on period by 33% and in the off period by 17%, and the number of hours the patients were on increased from 3.9 to 8.9. All these changes were significant (p less than or equal to 0.01 to 0.05). The mean dose of lisuride was 2.8 mg (range, 0.6 to 5.0 mg). Lisuride was discontinued in 8 patients because of adverse effects. Both bromocriptine and lisuride are useful in managing patients with advanced Parkinson disease whose response to levodopa has diminished. While it is presently not possible to state which of the drugs is more effective, ultimately their usage will probably be determined by their relative cost

Lisuride was administered to 63 patients with advanced Parkinson's disease (PD) who were no longer satisfactorily responding to levodopa. The group included 40 patients with 'on-off' phenomena. Lisuride alone (13 patients) or combined with levodopa (50 patients) resulted in a 34% decrease in PD disability as assessed in the 'on' period, a 16% decrease in disability as assessed in the 'off' period, and a 96% increase in the numbers of hours in which patients were 'on' (from 5.5 to 10.8 h). All of these changes were significant (p less than or equal to 0.001). 37 of the 63 patients (59%) improved at least one-stage on lisuride. The major adverse effect limiting the use of lisuride was the occurrence of an organic confusional syndrome. This was related, in part, to the presence of an underlying dementia and to the concurrent use of anticholinergic drugs

Treatment with pergolide was compared with bromocriptine in 25 patients, all of whom were also receiving levodopa and in all of whom the response to levodopa had diminished. All 25 patients had 'on-off' phenomena. At the time bromocriptine was added to levodopa, the mean age of the patients was 61.8 years, mean duration of disease was 9.0 years, and mean duration of levodopa treatment was 6.1 years. For the group as a whole, disability as determined in the 'on' period decreased by 36%, from 28.7 to 18.5; and 11 patients improved at least one stage. Disability as determined in the 'off' period decreased by 25%, from 59.5 to 44.4. The number of hours in which patients were 'on' increased by 62%, from 7.1 to 11.5. All of these changes were significant (p less than or equal to 0.05). Bromocriptine had to be discontinued in nine patients (eight because of mental changes). In the remaining 16 patients, bromocriptine was eventually discontinued because of diminishing efficacy. Mean dose of bromocriptine was 50 mg (range, 10-100 mg), and mean duration of treatment was 23 months (range, 2-65 months). At the time of their treatment with pergolide, the patients were older, 65.5 years, had the disease longer, 12.7 years, and were more disabled. Nonetheless, for the group as a whole, disability score as determined in the 'on' period decreased significantly by 40%, from 43.5 to 26.3, and 14 patients improved at least one stage. Disability as determined in the 'off' period decreased significantly by 21%, from 69.0 to 54.8. The number of hours in which patients were 'on' increased significantly by 224%, from 3.4 to 11.0 hr. The mean dose of pergolide was 2.1 mg (range, 0.1-10.0 mg), and the mean duration of treatment was 6.2 months (range, 0.5-20 months). Pergolide was discontinued in eight patients: three because of asymptomatic tachyarrhythmias of unknown clinical significance (detected only by Holter monitoring); two because of orthostatic hypotension; and two because of mental changes. Although pergolide appears to be more potent than bromocriptine because of its greater effect in a larger number of patients at a more advanced stage of their disease, both drugs are useful, and both enhance our ability to manage patients with PD