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Pharmacology (MPAS) > Lecture 12: Anxiolytics and hypnotics > Flashcards

Lecture 12: Anxiolytics and hypnotics Flashcards

1
Q

What does anxiolytic mean?

A

Calming effects

Relief of anxiety

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2
Q

What does hypnotic mean?

A

Promotes drowsiness

Promotes onset and maintenance of sleep

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3
Q

What is the basic foundation of benzodiazepines?

A

Benzene ring

Diazepine ring

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4
Q

Structure of barbiturates

A

Related to structure of barbituric acid

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5
Q

What is the action size for BZD? Structure?

A

GABA-A receptor (chloride channel)

hetero-oligomeric glycoprotein with 2 alpha subunits, 2 beta subunits and 1 gamma subunit

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6
Q

What is GABA?

A

GABA is primary inhibitory neurotransmitter in brain

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7
Q

Isoforms of alpha subunit of GABA-A receptor

A

alpha 1: hypnotic

alpha 2-5: sedation, psychomotor effect

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8
Q

What happens when GABA-A receptor is activated?

A

Chloride influx

Hyperpolarization of neurons and decrease in neuronal activity

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9
Q

What happens when BZDs bind to GABA-A receptor?

A

Enhance GABA actions (not direct activation of receptor)

Increases frequency of channel opening events

Reduces excitability of neurons (CNS depressant)

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10
Q

Affinity of BZD for GABA-B receptors

A

Low affinity

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11
Q

What happens when barbiturates bind to GABA receptor?

A

Increase duration of channel-opening events

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12
Q

Effect of barbiturates at high concentration

A

GABA-mimetic effect

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13
Q

Other effect of barbiturates

A

Inhibit glutamate AMPA receptor

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14
Q

General concept of PK

A

Absorption

Distribution

Metabolism

Elimination

See figure

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15
Q

What are factors that affect onset of CNS drugs?

A

Onset: time for drugs to be effective after administration

Lipophilicity affects this (due to BBB)

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16
Q

What are factors that affect duration of CNS drugs?

A

Duration: the amount of time that a measurable drug effect persists

Biotransformation affects this

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17
Q

Biotransformation reactions that have effect on duration of CNS drugs

A

Microsomal oxidation (Cytochrome P450 isozymes: phase I reactions)

Conjugation (phase II reactions)

Metabolic conversion to more water-soluble metabolites is required for clearance of CNS drugs from the body

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18
Q

What are factors that affect onset of BZDs?

A

Lipophilicity

Triazolam > diazepam > lorazepam, oxazepam

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19
Q

BZDs with long half-lives

A

Chlordiazepoxide

Diazepam

Prazepam

Clorazepate

Flurazepam

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20
Q

BZDs with short half-lives

A

Lorazepam and oxazepam (Without active metabolites)

Alprazolam and triazolam (With active metabolites but short half-lives)

21
Q

Therapeutic uses of BZDs related to half life

A

Short acting: preferable for hypnotic

Longer acting: preferable for anxiolytic

22
Q

Consideration with BZDs with long half-lives

A

Cause cumulative effects with multiple doses

23
Q

Where are BZDs excreted?

A

Kidney

24
Q

Clinical considerations regarding BZD PK

A

Can cross placental barrier: pregnant patients

Can be detectable in breast milk: Infants

Older patients, patients with liver diseases

Redistributed to adipose tissue: obese
patients

25
Q

Lipophilicity of barbiturates

A

Lipophilic: absorbed and distributed rapidly.

26
Q

Where does metabolism of barbiturates occur?

A

Liver

but slowly (with the exception
of thiopental)
27
Q

What do barbiturates induce?

A

Cyt-P450

28
Q

Duration of action of barbiturates

A

Ultra-short-acting (30 min) — thiopental for induction of anesthesia

Short-acting (18-48 hours) — secobarbital, pentobarbital for hypnotic and sedative

Long-acting (4-5 days) — phenobarbital for seizures

29
Q

Therapeutic uses of BZDs

A

1) For relief of anxiety (sedative)
2) For treatment of insomnia (hypnotic)
3) For sedation and amnesia before and during surgical procedures
4) For treatment of epilepsy and seizure states
5) For muscle relaxation in specific neuromuscular disorders
6) For control of ethanol withdrawal symptoms or other sedative-hypnotic withdrawal states

30
Q

Examples of anxiety disorders

A

Generalized anxiety disorder (GAD)

Panic disorder

Social phobia

Post-traumatic stress disorder (PTSD)

Obsessive-compulsive disorder (OCD)

31
Q

Symptoms of anxiety disorders

A

vary depending on the type of anxiety
disorder, but general symptoms include:

Feelings of panic, fear and uneasiness

Uncontrollable, obsessive thoughts

Nightmares

Problems sleeping

Cold or sweaty hands and/or feet

Shortness of breath

Palpitations

Dry mouth

Numbness or tingling in the hands or feet

Nausea

Muscle tension

Dizziness

32
Q

Management of acute anxiety vs long term

A

Acute: Use BZDs for rapid control

Long term: SSRIs

33
Q

Symptoms of insomnia

A

trouble falling or staying asleep, which leads to sleep deprivation.

Lying awake for a long time before falling asleep

Sleeping for only short periods

Being awake for much of the night

Waking up too early

34
Q

Physiology of sleep

A

NREM (stage 1-4) and REM

Stage 1: light sleep during which the muscles begin to relax

Stage 2: brain activity slows down and eye movement stops.

Stages 3/4: deep sleep during which all eye and muscle movement ceases.

REM (rapid eye movement): paradoxical sleep, rapid eye movement where most muscles are paralyzed

See figure

35
Q

BZDs as hypnotics

A

decrease the latency to sleep onset and increase Stage II of NREM

decrease both REM and slow wave sleep.

36
Q

How to select drugs for difficulty falling asleep? Frequent awakenings?

A

Difficulty falling asleep: Fast-acting, shorter duration drug (triazolam)

Frequent awakenings: drug of medium duration (lorazepam)

37
Q

Drugs used for sedation and amnesia before and during surgery

A

Cause anterograde amnesia

Midazolam and lorazepam

38
Q

CNS depression: barbiturates vs BZDs

A

Barbiturates cause higher CNS depression than BZDs

Sedation -> hypnosis -> anasthesia -> coma

39
Q

Therapeutic uses of Barbiturates

A

Rarely used as sedatives and hypnotics (replaced bu BZDs for anxiety and insomnia)

Used as anticonvulsant in epilepsy and seizure (phenobarbital)

Component of balanced anesthesia (thiopental)

40
Q

Adverse effects of BZDs

A

CNS depression: Drowsiness, confusion, anterograde amnesia, dizziness, lethargy, ataxia

May persist and cause “hangover”

Safe, except when used in combination with other CNS depressants

41
Q

BZDs and tolerance

A

Pharmacodynamic tolerance

down-regulation of brain BZD receptors

42
Q

What is tolerance?

A

decreased responsiveness to a drug following repeated treatment.

43
Q

What is dependence?

A

an altered physiologic state that requires continuous drug administration to prevent withdrawal symptoms.

44
Q

What are the withdrawal symptoms of BZD?

A

relapse or rebound anxiety, insomnia, restlessness, etc.

45
Q

Which type of BZDs produce worse withdrawal symptoms?

A

Withdrawal symptoms are more common and more severe in patients on BZDs with short half-lives

46
Q

What does chronic use of BZDs produce?

A

Tolerance and dependence

Patients on long term BZD must be tapered

47
Q

Considerations with BZDs

A

Prescriptions should be written for short periods.

Depressant effects on psychomotor and cognitive functions.

Used in combination with alcohol or other CNS
depressants (e.g. alcohol).

Older patients, patients with liver diseases

Obese patients

Unauthorized dosage increases

48
Q

Contraindications with BDZs

A

Myasthenia gravis

Narrow-angle glaucoma

Alcoholism

Severe sleep apnea

Pregnant or nursing mothers

Pharmacology (MPAS) (19 decks)

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