drugs and our society how drugs work in the body and the mind

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.