PH2113 - Abuse of drugs in theory & practice Flashcards
What is Drug Abuse?
Administration of any pharmacological substance in a way which deviates from approved medical/social paterns
How can self-administration lead to drug abuse?
Excessive self medication
Abuse of drugs in sport
Patient non-compliance
How can administration by others lead to drug abuse?
Over, or mis-prescribing
- pharmacist responsible
Unnecessary counter prescribing
- pharmacist responsible
Excessive antibiotic addition to animal foodstuffs in factory farming
Give examples of legal drugs that can be abused
Caffeine
Alcohol
Tobacco
Give examples of OTC drugs that can be abused
Codeine based medicines
Dextromethorphan based medicines
Sedative antihistamines
Decongestants
- pseudoephedrine
- ephedrine
Laxatives
Give examples of prescribed medicines that can be abused
Opioid analgesia
Benzodiazepines
What are the three classes of illegal drugs?
Class A, B and C
Give examples of Class A drugs
Heroin
Cocaine
Ecstasy
LSD
Morphine
Give examples of Class B drugs
Amphetamines
Ketamine
Cannabis
Barbiturates
Give examples of Class C drugs
Benzodiazepines
Anabolic steroids
Amphetamine-related drugs
Human Chorionic Gonadotrophin (HCG)
What is addiction?
Complex process involving the interaction of biological, psychological and social factors
What are the biological factors that contribute to addiction?
Genetic predisposition
Neuroplasticity
- dopamine mediated pathways in the prefrontal cortex and amygdala
Tolerance
- desensitisation
- tachyphylaxis
Withdrawal
What are the psychological factors that contribute to addiction?
Impulsivity
Anxiety/other distress
Reward sensitivity
What are the social factors that contribute to addiction?
Drug use by friends or family
Childhood neglect and trauma
Poverty
- homelessness
- unemployment
- poor education
What is tolerance?
The need to employ increasing doses of drug in order to produce the same effect as on first exposure
What are the three types of tolerance?
Metabolic/dispositional tolerance
- metabolic/PK
Physiological/functional tolerance
- PD/non-associative
Behavioural/conditioned tolerance
- behavioural/learned/context-specific
What is dependence?
A state/condition where there is compulsion to take a drug continually in order to experience its effects and sometimes to avoid the physical discomfort of its absence
Tolerance may/may not be presence
What are the two types of drug dependence?
Psychological
Physical
What are the four key characteristics of tolerance?
Reversible
- once exposure to the drug is discontinued
Dependent on the dose and frequency of drug exposure
Variable time course and extent of tolerance development between different drugs
Not all drug effects develop the same amount of tolerance
How does metabolic/dispositional tolerance take place?
Adaptations in drug ADME
- less drug at action site
- need to take more
Barbiturates/alcohol
- induce hepatic microsomal enzymes
- enhance metabolism so metabolised faster
How does physiological/functional tolerance take place?
Changes in properties and function of target tissue
- less sensitive to the substance
Give examples of how physiological/functional tolerance takes place
Changes in receptor number/density
Receptor uncoupling
Exhaustion of mediators
Tolerance at reuptake transporter
What are the two mechanisms of functional tolerance?
Changes in receptor number/density
- compensatory changes
- hours/days
Receptor down-regulation
- usually with agonists on prolonged exposure
Receptor up-regulation
- usually with antagonists or low levels of endogenous agonist/transmitter
- denervation
