In a alcoholic individual, tolerance to alcohol that disappears as rapidly as it develops is known as

Ans. b (Pharmacokinetic tolerance) (Ref. Harrison 18th/ p 2562)ALCOHOL - BEHAVIORAL EFFECTS, TOLERANCE, AND DEPENDENCE# Even though "legal intoxication" requires a blood alcohol concentration of at least 80 to 100 mg/dL, behavioral, psychomotor, and cognitive changes are seen at levels as low as 20 to 30 mg/dL.# Deep but disturbed sleep can be seen at twice the legal intoxication level, and death can occur with levels between 300 and 400 mg/dL.# Alcohol enhances GABA-A receptors and inhibits NMDA receptors.# Types of compensatory changes after repeated exposure producing tolerance of higher alcohol levels-Metabolic or pharmacokinetic tolerance# First, after 1-2 weeks of daily drinking, metabolic or pharmacokinetic tolerance can develop, with a 30% increase in the rate of hepatic alcohol metabolism.# This alteration disappears almost as rapidly as it develops.Cellular or pharmacodynamics tolerance# Second, cellular or pharmacodynamic tolerance develops through neurochemical changes that may also contribute to physical dependence.# The cellular changes caused by chronic alcohol exposure may not resolve for several weeks or longer following cessation of drinking.Behavioural tolerance# Third, individuals can develop behavioural tolerance, i.e., can learn to adapt their behaviour so that they can function better than expected under drug influence.Functional Tolerance# Humans and animals develop tolerance when their brain functions adapt to compensate for the disruption caused by alcohol in both their behavior and their bodily functions. This adaptation is called functional tolerance.Environment-dependent tolerance# The development of tolerance to alcohol's effects over several drinking sessions is accelerated if alcohol is always administered in the same environment or is accompanied by the same cues. This effect has been called environment- dependent tolerance.Learned tolerance# The development of tolerance also can be accelerated by practicing a task while under the influence of alcohol. This phenomenon is called behaviorally augmented (i.e., learned) tolerance.Educational points:EFFECTS OF BLOOD ALCOHOL LEVELS IN THE ABSENCE OF TOLERANCEBlood Level, mg/dLUsual Effect20Decreased inhibitions, a slight feeling of intoxication80Decrease in complex cognitive functions and motor performance200Obvious slurred speech, motor incoordination, irritability, and poor judgment300Light coma and depressed vital signs400Death