may modestly reduce the rate and possibly the extent of levodopa
absorption. One case describes levodopa toxicity
, which occurred after the withdrawal of an antimuscarinic.
Concurrent use is of established benefit. The presence of a dopa-decarboxylase inhibitor would be expected to minimise the effects of any interaction. There is certainly no need to avoid concurrent use, but it would be prudent to be alert for any evidence of a reduced levodopa
response if antimuscarinics
are added, or for levodopa toxicity
if they are withdrawn.