Answer and explanation:
If a drug that interfered with the functioning of microtubules found in axons were to be developed, I would expect that axonal transport would be inhibited or at least severely impaired.
Microtubules are proteins made of tubulin that are of key importance in the transport of different proteins, organelles, and synaptic vesicles (among others) to and from the neuron's soma through its axon. Microtubules are part of the cytoskeleton, they rearrange themselves in order to run along the length of the axon so motor proteins like kinesin and dynein can carry diverse structures all through the neuron.
If microtubules were to cease functioning, axonal transport would stop and many processes of great importance for the nervous system, such as neurotransmission, would be hugely affected. This would most likely produce neurological disease.