Discuss the concept of "Insanity" under the provisions of the IPC. Prolonged drinking alcohol condition falls under the category of insanity and not intoxication. Comment.

As far as litigation is concerned, it depends on the evidential value of an expert after examining the person.  Adjudication depends on the expert medical certificate alone.

If the person is having history of prolong  alcohol drinking habits is called addict but not as insane .  And further more, only psychiatric can only judge or conclude about his insanity  after his medical examination. 

As per your query, let me tell you that Section 84 of the Indian Penal Code says that any act done by a person who is of unsound mind at the time of doing act and the person is incapable of knowing the nature of the act and the person does not know that the act which he is doing is wrong or contrary to Law.

English Law considers insanity as a valid defense. The House of Lords constituted the very first committee that was meant to set down rules for plea of insanity.

These rules are as follows:
⭕All are presumed to be sane , until contrary be proved for the satisfaction of the Court,

⭕To claim the defense of the Insanity , one should clearly show that at the time of the act the accused was suffering from the defect or mental illness,

⭕At the time of doing act he did not know the nature of the act,

⭕At the time of doing the act the accused do not know the that what he was doing was wrong

Alcohol abuse can cause signs and symptoms of depression, anxiety, psychosis, and antisocial behavior, both during intoxication and during withdrawal. At times, these symptoms and signs cluster, last for weeks, and mimic frank psychiatric disorders (i.e., are alcohol–induced syndromes).
Thus, it's just to say tha prolonged alcoholism tends to fall under insanity rather than that of intoxication.

Hope It Helps!

Regards
Kevin M. Paul