Bromocriptine in Parkinson's disease: a double-blind study comparing "low-slow" and "high-fast" introductory dosage regimens in de novo patients. UK Bromocriptine Research Group.

One hundred and thirty four patients with previously untreated Parkinson's disease were recruited to a multicentre double blind study comparing two introductory dosage regimens of bromocriptine: a low/slow regimen increasing to a maximum of 25 mg/day and a high/fast regimen increasing to a maximum of 100 mg/day over a 26 week period. It was hoped to determine the minimum dose of bromocriptine required with either regimen. A patient's ability to achieve a 33% improvement in clinical rating scores was recorded using a combined score of functional disability (Webster) and self rated daily living activities (ADL). Sixty five out of 129 patients (50%) had reached the improvement criteria in 26 weeks, 37 (49%) from the "slow" and 28 (53%) from the "fast" group (N.S.). However, if only those patients still in the trial at the end of 26 weeks are considered the relevant percentages are 73% and 88% (p less than 0.05). Statistical analysis allowing for censored observations was used to examine group differences in dosage and time at improvement. This excluded the patients who had dropped out due to side effects from the calculations. The results indicated a marked difference between groups in both dose (slow 22.0 mg, fast 55.4 mg (p less than 0.01) and time (slow 22.8 weeks and fast 14.4 weeks (p less than 0.05). Severe side effects necessitated withdrawal from the trial in 34 patients, a larger proportion 19 (36%) being in the fast group compared with 15 (20%) from the slow group (p less than 0.05). The number of dropouts due to non effect was 2 (4%) in the fast and 10 (13%) in the slow. The only predisposing factor relating to dropping out due to side effects was a high initial ADL (p < 0.01). It is concluded that bromocriptine is an effective de novo treatment for Parkinson's disease. The "fast" introductory regimen is less well tolerated than the "slow", but the later has the disadvantage of a long delay before patients reach an effective dose. It is recommended that it would be wise to adopt an intermediate dosing strategy.