24. Drug Abuse And Dependence: General Principles, Opioids, Anti-Anxiety And Hypnotic Drugs, Inhalants, Ethanol

Front 1

What characterises drug dependence?

Back 1

Drug dependence or addiction refers to the state when drug-taking becomes compulsive and starts to take precedence over other needs. There is an excessive craving for the drug.

Front 2

What characterises physical dependence?

Back 2

If withdrawal from the drug causes physical symptoms (an abstinence syndrome), the drug causes physical dependence.

Front 3

What characterises psychological dependence?

Back 3

If withdrawal from the drug causes drug-seeking behaviour from the affected person, the drug causes psychological dependence.

Front 4

What is positive reinforcement?

Back 4

Positive reinforcement refers to how a stimulus makes you more likely to seek out the stimulus again later.

Euphoria causes significant positive reinforcement, as the addict wants to experience the euphoria again later.

Front 5

What characterises drug abuse?

Back 5

Drug abuse or substance abuse refer to the use of drugs unfairly or immorally.

Front 6

What characterises tolerance?

Back 6

Tolerance is defined as when a drug causes decreased pharmacological effects after repeated administration.

It often accompanies dependence.

Front 7

What two types of (acquired) tolerance exist?

Back 7

Pharmacokinetic tolerance

Pharmacodynamic tolerance

Front 8

What characterises pharmacokinetic tolerance?

Back 8

Pharmacokinetic tolerance occurs when enzymes that metabolize the drug are induced, increasing the metabolism of the drug.

Front 9

What characterises pharmacodynamic tolerance?

Back 9

Pharmacodynamic tolerance is adaptive changes that alter the pharmacodynamics of the drug, such as decreased receptor density or changes in the signal transduction pathway of the receptors

Front 10

Which opioids are commonly abused?

Back 10

Morphine, heroin, fentanyl, methadone

Front 11

What are the effects of opioids?

Back 11

Opioids give a strong sense of euphoria, similar to that of an orgasm. This euphoria is followed by a calm, even-tempered mind (called a high), which is again followed by sedation and a deep sleep (called a nod).

They also cause respiratory depression, myosis and convulsions.

Front 12

How does pharmacodynamic tolerance develop to opioids?

Back 12

Expression of adenylyl cyclase is increased

Front 13

What will occur if a person addicted to opioids doesn't use opioids for a few days, and then start again?

Back 13

Tolerance to the respiratory depression caused by morphine only lasts for a few days. If an addict has a short abstinence period of a few days, they will lose the tolerance to respiratory depression. If this addict then takes an equally large dose of opioids like he used to, he will develop respiratory arrest and death.

Front 14

What are the symptoms of opioid intoxication?

Back 14

- Myosis

- Shallow breathing

- Loss of consciousness

Front 15

What is the treatment for opioid intoxication?

Back 15

Naloxone, a µ receptor antagonist.

Front 16

What are the symptoms of opioid withdrawal?

Back 16

- Anxiety

- Hyperventilation

- Mydriasis

- Muscle pain

- Vomiting

Front 17

What drugs can be used to treat opioid abuse?

Back 17

Methadone, buprenorphine, naltrexone

Front 18

How can using methadone or buprenorphine treat opioid abuse?

Back 18

Methadone and buprenorphine are long-acting opioids that don't cause euphoria. By substituting addictive opioids with methadone or buprenorphine, we can prevent withdrawal symptoms from appearing without causing euphoria.

Front 19

How can naltrexone be used to treat opioid abuse?

Back 19

Naltrexone is a µ receptor antagonist. If a person who takes naltrexone uses opioids, they won't experience euphoria and so there will be no positive reinforcement

Front 20

Describe the tolerance that occurs during alcohol abuse.

Back 20

Alcohol causes both pharmacodynamic and pharmacokinetic tolerance.

The former develops as the density of CNS receptors like GABA-A and NMDA receptors change.

The latter develops as alcohol induces the expression of CYP2E1

Front 21

Describe the phases of alcohol withdrawal.

Back 21

The first phase is characterised by sympathetic activation, insomnia and anxiety.

The second phase is characterised by generalized tonic-clonic seizures.

The third phase is called delirium tremens. It's characterised by confusion, hallucinations, dehydration, agitation and arrhythmias. Delirium tremens can be fatal

Front 22

What is the treatment for alcohol withdrawal and delirium tremens?

Back 22

Benzodiazepines and antipsychotics.

Thiamine should be given, and electrolytes and fluid should be monitored.

Front 23

Which drugs can be useful in treating alcohol abuse?

Back 23

Disulfiram, naltrexone and acamprosate

Front 24

What is the mechanism of action of disulfiram, and how can it help treating alcohol abuse?

Back 24

Disulfiram is an aldehyde dehydrogenase inhibitor.

If a person who takes disulfiram relapses and drinks alcohol, acetaldehyde will accumulate and they will experience acetaldehyde syndrome.

Front 25

What is the mechanism of action of naltrexone, and how can it help treating alcohol abuse?

Back 25

Naltrexone is a µ receptor antagonist. If a person who takes naltrexone relapses and drinks alcohol they will not experience any euphoria.

Front 26

What is the mechanism of action of acamprosate, and how can it help treating alcohol abuse?

Back 26

Acamprosate is an NMDA glutamate receptor antagonist. It reduces the craving for alcohol.

Front 27

What are the symptoms of benzodiazepine overdose? What can make the overdose more dangerous?

Back 27

Benzodiazepine overdose is rarely fatal, it will only induce a deep sleep.

It can be fatal if combined with other CNS depressants, like alcohol.

Front 28

What are the symptoms of barbiturate overdose?

Back 28

Barbiturate overdose causes significant respiratory and cardiovascular depression.

Front 29

How does tolerance develop for benzodiazepines?

Back 29

Pharmacodynamic tolerance develops as the GABA-A receptor is downregulated.

Front 30

Does tolerance develop to respiratory depression in barbiturate abuse?

Back 30

No, so if a person increases their dose to maintain the sedation effect they may experience respiratory depression.

Front 31

What are the symptoms of benzo and barbiturate withdrawal?

Back 31

Seizures.

Front 32

What is the treatment for benzo or barbiturate abuse?

Back 32

Treatment of benzo or barbiturate abuse involves giving the affected person long-acting drugs and slowly decreasing their dose until the person is drug-free. Complete detoxification can usually be achieved in some months.