Modafinil also affects histamine, it releases more to do the opposite of an anti-histamine-wake one up.
It operates on the H3 receptor as does Betahistine-a drug to alleviate tinnitus in Meniere's disease.
At this time I am not sure if modafinil constricts the vessels in the ear or dilates them. If Betahistine dilates the vessels to reduce the pressure, and the tinnitus then I would say modafinil does the opposite. As stated in the conversation above, taking the modafinil made it (the tinnitus) worse.
I hope that is helpful, I am a not a tinnitus sufferer, but I developed ringing in my ears when I took Modafinil.
Regards A
Just to add to the above, the ringing in the ears I experienced was alleviated by a drug called Pregabalin. This mode of action is centred around the GABA neurotransmitter (Gamma Amino Butyric Acid). GABA is responsible for keeping the brain "calm". Modafinil prevents GABA from doing it's job and Glutamate takes priority, activating the brain and making one feel more "disinhibited".
Modafinil also increases noradrenaline and can increase heart rate and blood pressure, leading to (in my case) a pounding pulse that affected my ears (I was aware of my pulse physically and aurally), a clanging in the right ear.
So take it easy with the modafinil.
Regards A