Psychoactive Drugs

Psychoactive Drugs

1. Routes of administration

Ingestion: absorbed in stomach and large intestine
Inhalation: from lungs into bloodstream; lung damage
Mucous membrane: absorbed via membrane to blood, e.g., nose damage
Injection: muscle, skin, or vein; infections and scars

2. Drug mechanisms

Agonists: mimic or facilitates transmitter action
Antagonists: prevents normal activity of transmitter (binds to receptor site)

3. Terms

Tolerance: Less effect after continued exposure
Withdrawal: Sudden elimination of drug after continued exposure results in "opposite" effect (opponent process and homeostasis).
Physical dependence: withdrawal symptoms
Psychological dependence: addiction in the absence of physical dependence
Addiction: maladaptive use and often difficulty to stop

4. Common drugs

Nicotine:
- Second to caffeine as most used drug in the world. Results in 400,000 deaths/year in US
- Inhaled with quick effect and 2 hr half-life.
- Agonist at specific acetylcholine receptor causing CNS Stim
- Highly addictive with 70% of experimentors becoming addicted
- Effects: alertness, appetite, irritability, cardiovascular, lung cancer and heart disease.
Caffeine:
- Most used drug in world. 80% of adults consume at least 3 cups/day.
- Absorbed in gut in 20 mins, reaches peak in 2 hrs and a 3-5 hr half-life.
- Antagonist of adenosine (sedation) receptor causing CNS Stimulation.
- Addictive with tolerance and withdrawal.
- Effects: alertness and lessens fatigue, nervousness, hypertension, insomnia, anxiety.
Amphetamine:
- Synthetic CNS stimulant.
- Often oral administration with 18-24 hr half-life.
- Influences dopamine and norepinephrine re-uptake as CNS Stim
- Addictive with tolerance and withdrawal
- Effects: euphoria, alertness, decreases appetite, increases activity, arousal, blood pressure, cardiovascular, paranoia.
Cocaine:
- From plant in south america
- Rapid acting and 15-30 min. half-life.
- Influences dopamine and norepinephrine re-uptake as CNS Stim.
- Addictive with rapid tolerance and withdrawal
- Effects: intense euphoria with similar effects of amphetamines.
Alcohol:
- One of the worlds most popular mood-altering drugs. 2/3 of adults in US consume regularly with 10% maladaptive.
  - Ethanol ingested and absorbed in small intestine with peak 30-60 mins and few hours half-life.
  - Absorbed by cns membranes and lessens efficiency and affects GABA and glutamate subtype thus CNS Depressant.
  - Addictive with chronic use for 10% of pop with tolerance and withdrawal.
  - Effects: dose dependent, euphoria, relaxation, less inhibitions, slow reaction time and motor control, unconsciousness and death. Cirrhosis of liver, FAS, Korsakoff’s syndrome.
Marijuana:
- One of the worlds most popular mood-altering drugs. Most used illegal drug in US.
- Usually inhaled with rapid effect. Peak effects 2-3 hrs. Blood level of THC drops quickly as it is absorbed by fat cell which then eliminates slowly. 30 hr half-life.
- Agonist for transmitter with receptors in frontal cortex, basal ganglia/cerebellum.
- Both CNS Depressant and minor Hallucinogen.
- Low addictive potential, some tolerance and withdrawal with chronic use.
- Effects: dose dependent with low dose related to relaxation, increased appetite, euphoria, with higher doses related to perceptual distortions, apathy, anxiety. Some medical uses. Best demonstrated negative effect is lung damage.
Benzodiazapines:
- Most popular minor tranquilizers such as valium and xanax.
- Orally administered with absorption.
- GABA agonist (GABA inhibits transmission) as CNS Depressant.
- Addictive with tolerance and withdrawal. Also synergistic with alcohol.
- Effects: anti-anxiety, lethargy, depression, sleep.
Hallucinogens:
- Mescaline (from peyote), psilocybin, LSD/MDMA/PCP (synthetics)
- Oral with peak in 1 hr and 3 hr half life.
- Seratonin agonist affecting raphe nucleus (lsd and psi)
- Low addictive potential with some tolerance.
- Effects: Perceptual/cognitive distortions and hallucinations (often euphoric). Neuron death with mescaline and especially MDMA. Psychotic breaks with LSD. PCP (not a true hallucinogen) can have tolerance and in high doses violent/psychotic behavior.
Opiates:
- Extracts from the opium poppy (morphine and codeine) with heroin a synthetic derivative.
- Oral or IV varies in onset and half-life.
- Binds to opiate receptors scattered throughout the brain.
- Addictive with tolerance and withdrawal.
- Effects: Medical for pain & coughs. Euphoria with side effects include nausea, vomiting, overdose.