Drugs and Our Society

How Drugs Work in the Body and the Mind

Pharmacology of Drugs1. Pharmacology relates to the way drugs

are:- administered to the body- how they are absorbed- how distributed through the body- how metabolized by the body- and how excreted from the body

2. There are 4 primary routes through which drugs are administered- oral / inhalation / injection / absorption

Administration of Drugs3. Ingesting drugs (oral) produces different

effects from inhaling- smoking marijuana has a different effect from ingesting it- chewed tobacco is absorbed differently from smoked tobacco- the effects of injected narcotics are more intense than other forms

4. Not all drugs can be injected, such as marijuana- resin and water don’t mix

Admin of Drugs, cont- it is less likely to be abused than

narcotics and opiates- which can be injected

5. Cocaine is more likely to be abused than caffeine- the effects of cocaine are much

more powerful- it takes effect more quickly. Depending on administration- injected more powerful than snorting

Admin of Drugs, cont6. Alcohol is metabolized in the liver

- primary absorption site is the small intestine- removed through exhaling / sweat / urination- rate of 3/4th ounce per hour

7. Snort cocaine- mucous membranes in nose absorb drug quickly- effects are felt within minutes

Admin of Drugs, cont8. Amphetamines taken orally

- produce peak effects in 2 to 3 hours- eliminated in 2 to 3 days- effect of injected amphetamines is 5 minutes

9. Caffeine effects is between 15 to 45 minutes- metabolized in the liver- removed by the kidneys

Admin of Drugs, cont10.Marijuana smoked allows half of the THC

to be absorbed through lungs- before entering the bloodstream- the liver initially detoxifies the THC- it is removed primarily through feces

Oral Administration1. Ingesting by mouth is the oldest and easiest

way- digesting / then absorbing into the bloodstream

2. Absorption time is longer after ingestion- between 5 and 30 minutes- not complete until after 6 to 8 hours

3. Gastrointestinal system consists of the esophagus, stomach / intestines- enables body to absorb nutrients- and remove waste

Oral Administration, cont4. Interior of stomach is highly acidic

- drugs can be impacted by acidity- this can weaken effect of morphine

/ heroin / cocaine- which are highly alkaline drugs

5. From small intestine to bloodstream- drugs then processed by the liver- liver “metabolizes” the drug- enzymes break the drug down

Oral Administration, cont6. A larger dosage is needed when taken

orally7. 200 drugs show increase in enzyme

activity- Phenobarbital has effect and duration decreased- valium and marijuana the active metabolites produce similar effects to the parent drug and prolongs the effect considerably

Oral Administration, cont8. Ingesting drugs on a full

stomach or an empty stomach - does make a difference in the effect drugs will have on the

body

Injection1. Parenteral drug use refers to the

injection of drugs- injected drugs reach the brain quickly- the fastest means of injection is intravenous (IV): within a vein- it is called “mainlining”- with prolonged use, the vein wall loses strength and elasticity- and the vein can collapse

Injection2. Heroin injected into the forearm

- 10 to 15 seconds to the heart / lung / and brain- blood vessel walls are relatively insensitivity- irritating material can also be injected- it is possible to deliver high concentrations of a drug

3. Another method is intramuscular- which is injection into a muscle

4. Muscle tissue serves as a filter, so the absorption time is slower

Injection, cont5. Example:

- onset of euphoria after injecting heroin intravenously is 7 to 8 seconds- intramuscular the euphoric onset is

5 to 8 minutes- the more blood vessels the muscle has, the faster the absorption- deltoid muscle injections are faster than the buttocks

Injection, cont6. Subcutaneous injection

- injecting just below the layers of the skin- the drug is absorbed less evenly and slowly- it is also referred to as a “skin pop”

or “skin popping”

Inhalation1. This is where drugs are absorbed into

the bloodstream via the lungs2. Speed and efficiency are quite high

- due to the accessibility of capillary walls- from the lungs, drugs go directly to

the brain in 5 to 8 seconds- effects usually are brief

3. Smoking tobacco / marijuana / crack- ‘huffing’ glue, paint, other inhalants

Absorption Through Skin or Membranes

1. Quick absorption - 15 to 20 seconds2. Mucous membranes

- found in the nose / mouth / rectal / and vaginal areas- drug adheres to membrane- dissolves into bloodstream

3. Intranasal- sniff / snort a drug such as cocaine- in dust or powder form

Absorption Through Skin or Membranes4. Transdermal application

- ointment applied to skin- patch placed directly on the

skin

How Drugs Exit the Body1. The body has a fairly efficient system to

rid itself of unwanted substances- gases and solvent vapors can be eliminated in exhaled breath- small amounts can be eliminated through sweat / saliva / or feces- but primarily through urine

2. The major job of elimination is the liver and kidneys- the “dynamic duo” of excretion

Kidneys1. Two organs about the size of a fist

- located on either side of the spine2. Primary functions:

- maintain balance between water and salt in body fluids- and the excretion of excess water in the form of urine

3. It functions as a complex filtering system- the kidneys physically remove certain substances from the blood

Kidneys, cont4. - it filters everything out

- then selectively reabsorbs what is required

5. The kidney can make urine acidic or basic- the pH value can be manipulated- pH value refers to the acidity of a solution

Liver1. A large organ located high in the

stomach under the diaphragm2. Function

- compare it to a chemical factory- molecules are modified to form new

useful substances- toxic molecules are changed into less harmful substances

3. Changes made by molecules are called ENZYMES- depending on the drug / liver can create additional enzymes

Liver, cont- metabolizes (breaks down) the

molecules- the product of metabolism is metabolites, which are more useful and less toxic- they breakdown drugs into less active forms, called detoxification

4. Metabolites of certain drugs can be more active than the original (active metabolites) - good examples are THC and psilocybin

Rate of Excretion1. Kidneys operate most efficiently with

high concentrations of the drug in the blood

2. Concentration falls- kidneys cannot filter out the drug at

the same rate3. Rate of excretion can be described in

terms of ‘half-life’- time for the body to eliminate half- of a given blood level of drug

Rate of Excretion, cont4. Half the original blood level is eliminated

in 30 minutes- 30 minutes later, level is 25%- 30 minutes later, level is 12.5%

5. Every 30 minutes the body gets rid of half the drug circulating in the blood- so the half-life of the drug is 30 minutes

6. Half-life equals 1 hour- 50% / 25% / 12.5% / 6.25% / etc.