A patient of Alzheimer's disease is on rivastigmine therapy and develops symptoms of depression. Use of which of the following drug would decrease efficacy of rivostigmine -

Ans. is 'a' i.e., TCAs o Cholinergic transmission is diminished in Alzheimer's disease. o All agents that benefit the conduction act to enhance acetyhcholine activity by inhibition of the acetylcholinesterase which metabolises and inactivates acetylcholine. o Consequently acetylcholine remains usable for longer. o Rivastigmine acts in similar way. o Tricyclic antidepressants (TCAs) have anticholinergic propey, therefore they counteract that cholinergic effect of rivastigmine.