Hi, thanks for asking in Healthcare Magic.
, a Tricyclic anti depressant
is also used in severe fibromyalgia
pain (your chronic chest pain
). The giddiness is due to the drug. Amitriptyline results in postural hypotension
ie., sudden fall in BP and this causes giddiness. Tolerance (adaptation) occurs for this side effect and so you will be able to overcome this side effect after some time as it will go away.
The optimal effect of this drug is seen only at a particular (narrow range) plasma concentration ie between 50 to 100 ng/ml. Concentration higher or lower than this will not be very effective. Also wide difference in plasma concentration is achieved in different persons.
Though the analgesic (pain relieving) dose varies between 25 to 150 mg/day the optimal dose is 75 mg/day. With this dose, the analgesic action starts within a period of 1 to 7 days. You are taking a sub clinical dose, your dose needs to be increased on a weekly basis. The anti depressant effect starts in 2 weeks time.
Analgesic mechanism is not known. But it is thought to modulate pain signalling in the spinal cord.
I hope this is useful to you.