Introduction
What is a drug?
- A substance that is used "primarily to bring about a change in some existing process or
state”, be it psychological, physiological or biochemical.
- “Chemical entity, or mixture, other than those providing maintenance of normal health (e.g.
food) that alters biological functioning” (WHO)
- Food effects studied by nutritionists.
- Drug effects are studied by pharmacologists
Sources of active compound
- Naturally occurring - e.g. Opium from poppy; Morphine from opium; cocaine from coca
plant; Ephedrin from Ephedra plant (Ma huang)
- Semi-synthetics - e.g. Heroin from morphine; LSD from Ergot fungus)
- Synthetics (“Designer drugs”) - e.g. Methadone; Amphetamine; Fentanyl, MDMA
Drug scheduling in the US
- Schedule 1 – Most potential for abuse and
dependence, no medicinal qualities (heroin, LSD,
marijuana, ecstasy)
- Schedule 2 – High potential for abuse and
dependence, some medicinal qualities (cocaine,
meth, oxycontin, Adderall)
- Schedule 3 – Moderate potential for abuse and
dependence, acceptable medicinal qualities,
doctor’s prescription required (ketamine,
steroids, testosterone, codeine)
- Schedule 4 – Low potential for abuse and
dependence, acceptable medicinal qualities,
prescription required (Valium, Xanax, tramadol)
- Schedule 5 – Lowest potential for abuse and
dependence, acceptable medicinal qualities,
prescription required (Lomotil, Lyrica)
UK has 3 main drug-control instruments
- The Misuse of Drugs Act 1971 (“controlled drugs”) - ”The main purpose of the Act is to
prevent the misuse of controlled drugs and achieves this by imposing a complete ban on the
possession, supply, manufacture, import and export of controlled drugs except as allowed
by regulations or by licence from the Secretary of State.”
- The Human Medicines Regs. 2012 (“medicinal products”)
- The Psychoactive Substance Act 2016 (“psychoactive substances”)
,UK Misuse of Drugs Act 1971 – penalties for possession and dealing
- Class A (ecstasy, LSD, heroin, cocaine, crack, magic mushrooms, amphetamines if prepared
for injection)
- Possession – up to seven years in prison or an unlimited fine for both. Dealing – up to life in
prison or an unlimited fine for both.
- Class B (amphetamines, cannabis, Ritalin)
- Possession – up to five years in prison or an unlimited fine for both. Dealing – up to 14 years
in prison or an unlimited fine for both.
- Class C (tranquilisers, some painkillers, ketamine)
- Possession – up to two years in prison or an unlimited fine for both. Dealing – up to 14 years
in prison or an unlimited fine for both.
Why do people take (some) drugs?
- Experimentation: novelty seeking; exploration
- Pleasure: drugs as desired rewards (liking/desire)
- Medication: to relieve unpleasant states (anxiety, depression, pain)
- Peer pressure: to be cool...
What is not addiction
- Experimental use
- Recreational (casual) use
- Circumstantial use
- Many drink (too much) alcohol regularly but only a minority drink to meet criteria for abuse
and/or dependence
Addiction is...?
- “A syndrome manifested by a behavioral pattern in which the use of a given psychoactive
drug ... is given much higher priority than other behaviors that once had higher value.” “At
the extreme, the dependence syndrome is associated with compulsive drug-using behavior”
(Bull. World Health Org. 1981, 59:229-230)
, - It also, “exhibits the characteristic of a chronic relapsing disorder”. (J.H. Jaffe, in The
Pharmacological Basis of Therapeutics, 1990)
Pharmacokinetics
- Pharmacology - “The branch of medicine that deals with the uses, effects, and modes of
actions of drugs”.
- Pharmacokinetics - movement of drug to (and from) its site of action, Subfield of
pharmacology dealing with: "the absorption, distribution, biotransformation and excretion
of drugs".
- "kinesis" = movement or to move” - (this is a large field of study and we’ll only cover the
basics)
- Bioavailability refers to how
much of the drug will get to
the brain, for how long and
how fast.
- Drug administration,
absorption and distribution - if
a drug is taken orally, it
needs to move from the
gastrointestinal system,
through several membranes
and into the blood supply. It
then needs to cross the
blood-brain barrier in order
to reach the brain.
- Binding - drugs that are highly absorbable are taken up by fats which will slowly leak out
over time.
- The absorption phase is when there is more drug coming in than going out. The elimination
phase is when there is more drug going out than coming in. There is never really a stable
point of equal amounts of drug coming in and going out, unless you are on a drip.
- Tachyphylaxis is when repetitive drug exposure decreases the responsiveness of the drug –
tolerance.
Factors affecting absorption
- Drug solubility – how easy it is to cross cell membranes.
- Ionisation – how charged the drug molecule is. The more charged a drug molecule is, the
less likely it is to be absorbed.
- Blood circulation at the site of administration – if there is more blood circulation at the site
of administration, there are more capillaries to get absorbed by.
- Surface area of the absorbing surface – if the surface area of the capillaries is large, more
likely to get absorbed by capillaries.
- The last 2 factors are determined by: “Route of administration”
, Oral (peroral or PO; absorption through gastrointestinal tract, not mouth)
- The stomach has fatty acids which destroys most of the drug.
- The rate of metabolism is directly related to the amount of drug you take. More drug = more
metabolism. Therefore, it’s a safe way of taking drugs as it’s hard to overdose.
- First pass metabolism most often results in drug degradation.
- The effect of first pass metabolism is that there is slow release of the drug. They use this for
kids so that it lasts a long time and it’s hard for children to accidentally overdose.
Non-invasive routes of administration
- Nasal – through the nose
- Sublingual – under the tongue
- Rectal – through the anus (effective if someone is throwing up or is unconscious)
- Transdermal – through the outer skin (very slow, used for slow release such as the patch to
inhibit smoking craving)
- Pulmonary absorption – inhalation (very effective and fast because the lungs are a huge
surface area with lots of capillaries and goes through the arterial side straight to the brain).
Pulmonary absorption is as fast, if not faster, than intravenous injection.
Transdermal/parenteral
- Transdermal/parenteral are invasive methods where the skin barrier is broken.
- Subcutaneous = under the skin
- Intramuscular = Into the muscle
- Intravenous = Into the vein
- Intra-arterial is used in epileptic patients who can’t use medication. Intra-arterial injection
shuts down one hemisphere so you can ask questions and see where the origin is.
- Intra-peritoneal = into fluid surrounding intestines
- Intracranial = straight into the brain
- Intra-cerebro-ventricular = into ventricles
- The half-life of a drug is the time it takes for the amount of a drug's active substance in your
body to reduce by half. A drug with a long half-life will last longer in the body than a drug
with a shorter half-life.
- Choosing a route: Depends whether the objective is a high peak concentration, or a steady
state (e.g. methadone).
- To achieve a feeling of rush or euphoria, drug users prefer a route that gives highest peak
concentration.
- For the majority of medical applications, wish to treat a condition with the minimum
effective concentration, over an extended period.
- Transdermal fentanyl (Duragesic © patch) is used to provide a prolonged, steady analgesic
effect to relieve serious pain.
- Sublingual fentanyl (Actiq © - raspberry-flavored fentanyl lollipops) - absorbed through
buccal membranes for rapid adjustment of pain levels.
- Fentanyl is one of the most highly abused substances by medical personnel (~75% of these
abusers are anesthesiologists, who have access). For max. subjective effects, can be smoked
or injected IV.
What is a drug?
- A substance that is used "primarily to bring about a change in some existing process or
state”, be it psychological, physiological or biochemical.
- “Chemical entity, or mixture, other than those providing maintenance of normal health (e.g.
food) that alters biological functioning” (WHO)
- Food effects studied by nutritionists.
- Drug effects are studied by pharmacologists
Sources of active compound
- Naturally occurring - e.g. Opium from poppy; Morphine from opium; cocaine from coca
plant; Ephedrin from Ephedra plant (Ma huang)
- Semi-synthetics - e.g. Heroin from morphine; LSD from Ergot fungus)
- Synthetics (“Designer drugs”) - e.g. Methadone; Amphetamine; Fentanyl, MDMA
Drug scheduling in the US
- Schedule 1 – Most potential for abuse and
dependence, no medicinal qualities (heroin, LSD,
marijuana, ecstasy)
- Schedule 2 – High potential for abuse and
dependence, some medicinal qualities (cocaine,
meth, oxycontin, Adderall)
- Schedule 3 – Moderate potential for abuse and
dependence, acceptable medicinal qualities,
doctor’s prescription required (ketamine,
steroids, testosterone, codeine)
- Schedule 4 – Low potential for abuse and
dependence, acceptable medicinal qualities,
prescription required (Valium, Xanax, tramadol)
- Schedule 5 – Lowest potential for abuse and
dependence, acceptable medicinal qualities,
prescription required (Lomotil, Lyrica)
UK has 3 main drug-control instruments
- The Misuse of Drugs Act 1971 (“controlled drugs”) - ”The main purpose of the Act is to
prevent the misuse of controlled drugs and achieves this by imposing a complete ban on the
possession, supply, manufacture, import and export of controlled drugs except as allowed
by regulations or by licence from the Secretary of State.”
- The Human Medicines Regs. 2012 (“medicinal products”)
- The Psychoactive Substance Act 2016 (“psychoactive substances”)
,UK Misuse of Drugs Act 1971 – penalties for possession and dealing
- Class A (ecstasy, LSD, heroin, cocaine, crack, magic mushrooms, amphetamines if prepared
for injection)
- Possession – up to seven years in prison or an unlimited fine for both. Dealing – up to life in
prison or an unlimited fine for both.
- Class B (amphetamines, cannabis, Ritalin)
- Possession – up to five years in prison or an unlimited fine for both. Dealing – up to 14 years
in prison or an unlimited fine for both.
- Class C (tranquilisers, some painkillers, ketamine)
- Possession – up to two years in prison or an unlimited fine for both. Dealing – up to 14 years
in prison or an unlimited fine for both.
Why do people take (some) drugs?
- Experimentation: novelty seeking; exploration
- Pleasure: drugs as desired rewards (liking/desire)
- Medication: to relieve unpleasant states (anxiety, depression, pain)
- Peer pressure: to be cool...
What is not addiction
- Experimental use
- Recreational (casual) use
- Circumstantial use
- Many drink (too much) alcohol regularly but only a minority drink to meet criteria for abuse
and/or dependence
Addiction is...?
- “A syndrome manifested by a behavioral pattern in which the use of a given psychoactive
drug ... is given much higher priority than other behaviors that once had higher value.” “At
the extreme, the dependence syndrome is associated with compulsive drug-using behavior”
(Bull. World Health Org. 1981, 59:229-230)
, - It also, “exhibits the characteristic of a chronic relapsing disorder”. (J.H. Jaffe, in The
Pharmacological Basis of Therapeutics, 1990)
Pharmacokinetics
- Pharmacology - “The branch of medicine that deals with the uses, effects, and modes of
actions of drugs”.
- Pharmacokinetics - movement of drug to (and from) its site of action, Subfield of
pharmacology dealing with: "the absorption, distribution, biotransformation and excretion
of drugs".
- "kinesis" = movement or to move” - (this is a large field of study and we’ll only cover the
basics)
- Bioavailability refers to how
much of the drug will get to
the brain, for how long and
how fast.
- Drug administration,
absorption and distribution - if
a drug is taken orally, it
needs to move from the
gastrointestinal system,
through several membranes
and into the blood supply. It
then needs to cross the
blood-brain barrier in order
to reach the brain.
- Binding - drugs that are highly absorbable are taken up by fats which will slowly leak out
over time.
- The absorption phase is when there is more drug coming in than going out. The elimination
phase is when there is more drug going out than coming in. There is never really a stable
point of equal amounts of drug coming in and going out, unless you are on a drip.
- Tachyphylaxis is when repetitive drug exposure decreases the responsiveness of the drug –
tolerance.
Factors affecting absorption
- Drug solubility – how easy it is to cross cell membranes.
- Ionisation – how charged the drug molecule is. The more charged a drug molecule is, the
less likely it is to be absorbed.
- Blood circulation at the site of administration – if there is more blood circulation at the site
of administration, there are more capillaries to get absorbed by.
- Surface area of the absorbing surface – if the surface area of the capillaries is large, more
likely to get absorbed by capillaries.
- The last 2 factors are determined by: “Route of administration”
, Oral (peroral or PO; absorption through gastrointestinal tract, not mouth)
- The stomach has fatty acids which destroys most of the drug.
- The rate of metabolism is directly related to the amount of drug you take. More drug = more
metabolism. Therefore, it’s a safe way of taking drugs as it’s hard to overdose.
- First pass metabolism most often results in drug degradation.
- The effect of first pass metabolism is that there is slow release of the drug. They use this for
kids so that it lasts a long time and it’s hard for children to accidentally overdose.
Non-invasive routes of administration
- Nasal – through the nose
- Sublingual – under the tongue
- Rectal – through the anus (effective if someone is throwing up or is unconscious)
- Transdermal – through the outer skin (very slow, used for slow release such as the patch to
inhibit smoking craving)
- Pulmonary absorption – inhalation (very effective and fast because the lungs are a huge
surface area with lots of capillaries and goes through the arterial side straight to the brain).
Pulmonary absorption is as fast, if not faster, than intravenous injection.
Transdermal/parenteral
- Transdermal/parenteral are invasive methods where the skin barrier is broken.
- Subcutaneous = under the skin
- Intramuscular = Into the muscle
- Intravenous = Into the vein
- Intra-arterial is used in epileptic patients who can’t use medication. Intra-arterial injection
shuts down one hemisphere so you can ask questions and see where the origin is.
- Intra-peritoneal = into fluid surrounding intestines
- Intracranial = straight into the brain
- Intra-cerebro-ventricular = into ventricles
- The half-life of a drug is the time it takes for the amount of a drug's active substance in your
body to reduce by half. A drug with a long half-life will last longer in the body than a drug
with a shorter half-life.
- Choosing a route: Depends whether the objective is a high peak concentration, or a steady
state (e.g. methadone).
- To achieve a feeling of rush or euphoria, drug users prefer a route that gives highest peak
concentration.
- For the majority of medical applications, wish to treat a condition with the minimum
effective concentration, over an extended period.
- Transdermal fentanyl (Duragesic © patch) is used to provide a prolonged, steady analgesic
effect to relieve serious pain.
- Sublingual fentanyl (Actiq © - raspberry-flavored fentanyl lollipops) - absorbed through
buccal membranes for rapid adjustment of pain levels.
- Fentanyl is one of the most highly abused substances by medical personnel (~75% of these
abusers are anesthesiologists, who have access). For max. subjective effects, can be smoked
or injected IV.
