An elderly male with history of parkinsonism on treatment with levodopa visited your clinic complaining of tremors for which dopamine agonists ropinirole was added and slowly dose increased in subsequent visits but without much response and tremors persisted. What will be the appropriate next step in treatment?

Centrally acting anticholinergic drugs such as trihexyphenidyl and benztropine were used historically for the treatment of PD, but they lost or with the introduction of dopaminergic agents. Their major clinical effect is on tremor, although it is not ceain that this benefit is superior to what can be obtained with agents such as levodopa and dopamine agonists. Still, they can be helpful in individual patients with severe tremor. Ref harrison 20th edition page 3128