Repeated use of a drug usually enables the body to develope
tolerance to it's effects. Tolerance occurs with all drugs, but
it can occur slowly or rapidly, and last for a longer or shorter
time, depending on the type of drug. Tolerance to opiates can
take weeks or months to envole and then equally long to resolve,
while tolerance to hallucinogens occurs within a day but is
resolved within a week. Tolerance to a drug takes place in
several ways such as the following: The body speeds up the
metabolism of the drug in order to eliminate it. This is usually
accomplished by an increase in the production of enzymes in the
liver that break down the drug. One way of testing the burden of
drugs in the body is by measuring these enzymes-if they are
high, the body is suffering from the drug effects. With repeated
use, the brain's neurons become less sensitive to the effects of
the drug and may even produce an antidote or antagonist to the
drug. Most neurons react to the overwhelming presence of a
neurotransmitter like dr