Lecture 26

Biology of Substance Abuse

Drug Administration and Absorption

• Ingestion

• Injection– Subcutaneously (SC)– Intramuscularly (IM)– Intravenously (IV)

• Inhalation

• Absorption through mucous membranes

Drug Tolerance

• Definition

• Metabolic tolerance

• Functional tolerance

• Cross tolerance

• No unitary mechanism

Addicts

• Habitual drug users– Adverse effects on their health, social life– May be linked to psychological

dependence

Tobacco

• Nicotine

• Acts on the nicotinic receptor (a type of acetylcholine receptor)

• Increases blood pressure, heart rate, and release of epinephrine (adrenaline)

• Addiction may have a genetic basis….?

• Many side effects and withdrawal symptoms

Alcohol

• Most used and abused

• Affects general nervous system

• Activates a specific type of GABA and glutamate receptor

• Addiction has a major genetic component

• Long term use can cause irreversible damage to the brain, liver, heart, and stomach

Marijuana

• Active ingredient is THC

• Intensifies sensory experiences, increases appetite

• Lack of energy and ambition

• Many medical uses

• Binds to cannabinoid receptors in the brain, but the exact mechanisms of action are not clear

Cocaine and Amphetamines

• Crack cocaine

• Extremely addictive, mild withdrawals

• Blocks reuptake of NE and DA (catecholamines)

• Effects are brief

Opiates

• Include morphine, heroin, codeine

• Produces a pleasant state and decreases sensitivity to pain

• Bad side effects

• Attaches to endogenous receptors

Biopsychological Theories of drug addiction

• Moral model

• Disease model

• Physical-dependence theory

• Positive-incentive theory

Vulnerability to Drugs

• Biological factors

• Personal characteristics

• Family situation

• Social and community factors

Treatment for Drug Abusers

• Drugs for detoxification

• Agonists of drugs that produce addiction states

• Antagonists to the addictive drug

• Anti-craving medications

• Medication that blocks drug metabolism