Influence of levodopa on orthostatic hypotension in Parkinson's Disease

Orthostatic hypotension presents in all phases of Parkinson's Disease (PD) and occurs in about 80% of patients. There is some debate in the literature as to the relationship of orthostasis to the standard drug treatments. A distinct tendency towards hypotension has been found, especially for treatment with levodopa (LD). We therefore wanted to investigate the influence of LD on blood pressure response in PD patients.

We examined prospectively PD patients using lying-to-standing orthostatic tests (the modified Schellong test). The patients underwent measurements on two consecutive days, starting in the morning after a 12-hour period of restriction of food and medication. The second measurement ensued under the same condition of food restriction but consecutive to their usual LD dosage. Measurements were performed every minute for 10 minutes after rising. Measurements compared the maximum drop in blood pressure to the average resting blood pressure (after a 10-minute period of lying recumbent).

We examined 99 PD patients (72 male, 27 female) with a mean age of 74 years (SD = 7.8; range 52-88). The duration of the disease (i.e. time from first diagnosis to date of examination) was on average seven years (SD = 4.4, range 0-19 years). The drop in blood pressure after orthostasis without levodopa medication reached on average 45.46 mmHg (SD = 23.76; SEM = 2.39), and the average drop after levodopa medication was 43.75 (SD = 17.88; SEM = 1.8). There was no significant statistical difference (t[98] = 0.91; p = 0.37). Subdivision into patient groups with (n = 32) or without (n = 67) antihypertensives revealed a similar result for these subgroups, i.e. no statistically significant difference in blood pressure drop in conditions with or without levodopa administration. There was no significant correlation of Hoehn & Yahr stage with drop in blood pressure.

Orthostatic hypotension frequently occurs in patients with PD, occasionally with serious consequences. LD has often been viewed as essentially causing this state. Our study did not confirm this supposition, but rather revealed merely a minor association in individual cases.