Drug dependence is a syndrome comprised of physical dependence and psychological dependence
Its usage has replaced the older, ambiguous term "drug addiction"
Physical Dependence
A complex process whereby chronic administration of a drug results in resetting of the body's homeostatic mechanisms and a new equilibrium point is reached
It is characterised by tolerance and withdrawal
syndrome on cessation of administration of the drug, which disturbs the new equilibrium point
Tolerance and withdrawal are physiological reactions and do not imply psychological dependence
Psychological Dependence
The state where drug taking becomes a need which surpasses all other aspects of life
Tolerance
The phenomenon whereby increased amounts of drug are needed to be taken to achieve the same drug effect
Withdrawal Syndrome
A constellation of signs and symptoms that occurs after the abrupt cessation of a chronically administered drug
Addiction
A chronic state of physical or psychic dependence on the effects of a drug beyond that required to achieve a recognised therapeutic outcome
This term has been replaced by the term "drug dependence"
Opioids & Dependence
Opioid Tolerance
Tolerance begins 12-24 hrs after administration and peaks in 2 days
May be due to
down regulation of receptors
uncoupling from secondary messengers
↓
affinity for opioid receptors
Opioid Withdrawal Syndrome
Withdrawal occurs 15-20 hrs after cessation and lasts 5-7 days